Placenta - Abnormalities

From Embryology
Embryology - 18 Jan 2018    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)



Placental implantation abnormalities

The placenta is a mateno-fetal organ which begins developing at implantation of the blastocyst and is delivered with the fetus at birth. As the fetus relies on the placenta for not only nutrition, but many other developmentally essential functions, the correct development of the placenta is important to correct embryonic and fetal development.

Abnormalities can range from anatomical associated with degree or site of inplantation, structure (as with twinning), to placental function, placento-maternal effects (pre-eclampsia, fetal erythroblastosis) and finally mechanical abnormalities associated with the placental (umbilical) cord.

Morbidly adherent placenta (MAP) is the general clinical term used to describe the different forms of abnormal placental implantation (Accreta, Increta and Percreta). Clinical ultrasound indicators are the presence of an interruption of the bladder line, absence of a retroplacental clear zone, and the presence of placental lacunae.

A 2009 longitudinal Norwegian study suggests an association between large placenta relative to fetal size "disproportionately large placenta relative to birth weight was associated with increased risk of (adult) cardiovascular disease death."[1] See also the DOHAD hypothesis.

This current page lists some abnormalities associated with the placenta and also provides links to other resources. (See also Week 2 Abnormalities - Hydatidiform mole)

Placenta Links: Introduction | Lecture - Placenta | Lecture Movie | Practical - Placenta | Implantation | Villi Development | Trophoblast | Maternal Decidua | Endocrine | Cord | Membranes | Abnormalities | Stage 13 | Stage 22 | Histology | Vascular Beds | Blood Vessel Development | Stem Cells | 2013 Meeting Presentation | Placenta Terms | Category:Placenta
Historic Embryology - Placenta 
1883 Embryonic Membranes | 1907 Development Atlas | 1909 | 1910 Textbook | 1917 Textbook | 1921 Textbook | 1921 Foetal Membranes |1921 human | 1921 Pig implantation | 1922 Single placental artery | 1923 Placenta Review | 1939 umbilical cord | 1943 human and monkey | 1944 chorionic villus and decidua parietalis | 1946 placenta ageing | 1960 monkey | 1972 Placental circulation | Historic Disclaimer

Some Recent Findings

  • Hypoxic ischemic encephalopathy in newborns linked to placental and umbilical cord abnormalities[2] "Birth asphyxia and hypoxic ischemic encephalopathy (HIE) of the newborn remain serious complications. We present a study investigating if placental or umbilical cord abnormalities in newborns at term are associated with HIE. A prospective cohort study of the placenta and umbilical cord of infants treated with hypothermia (HT) due to hypoxic brain injury and follow-up at 12 months of age has been carried out. ...A velamentous or marginal umbilical cord insertion and histological abruption was associated with the risk of severe HIE. Velamentous or marginal umbilical cord insertion was found in 39% among HIE cases compared to 7% in controls." Neural System - Abnormalities
  • The branching pattern of villous capillaries and structural changes of placental terminal villi in type 1 diabetes mellitus[3] "In this paper, normal placental terminal villi and pathological villi of type 1 diabetic placentas were compared concerning the structure of villous stroma, spatial arrangement of villous capillary bed and quantitative assessment of capillary branching pattern. ...The quantitative assessment of capillary branching has shown that villous capillaries are more branched in diabetic placentas. It is concluded that type 1 maternal diabetes enhances the surface area of the capillary wall by elongation, enlargement of diameter and higher branching of villous capillaries and disrupts the stromal structure of terminal villi." Maternal Diabetes
  • Velamentous cord insertion caused by oblique implantation after in vitro fertilization and embryo transfer[4] "We present a case of a 36-year-old pregnant female after intracytoplasmic sperm injection. Ultrasonographic examination at 8 weeks' gestation revealed umbilical cord insertion with a viable fetus located on the septum membrane of dichorionic twin pregnancy near the anterior wall, while the other fetus was observed to have vanished. Next, this umbilical cord was seen to connect to the anterior wall and the placenta developed on the posterior wall later in the pregnancy. As a result, velamentous cord insertion with long membranous umbilical vessels developed at the time of delivery. The present case indicates that the assessment of the cord insertion site during the early gestation period is very important to predict any abnormality of the cord insertion site at the time of delivery. Furthermore, this case is valuable to understand the pathophysiological development of the placenta and velamentous cord insertion. "
More recent papers  
Mark Hill.jpg
PubMed logo.gif

This table shows an automated computer PubMed search using the listed sub-heading term.

  • Therefore the list of references do not reflect any editorial selection of material based on content or relevance.
  • References appear in this list based upon the date of the actual page viewing.

References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.

Links: References | Discussion Page | Pubmed Most Recent | Journal Searches

Search term: Placenta Abnormalities

N V Nizyaeva, T V Sukhacheva, G V Kulikova, M N Nagovitsyna, N E Kan, O R Baev, S V Pavlovich, R A Serov, A I Shchegolev, R A Poltavtseva Morphological Features of Mesenhymal Stroma Cells of Chorionic Villi. Vestn. Akad. Med. Nauk SSSR: 2018, 72(1);76-83 PubMed 29308857

Mohammad Zare Mehrjardi, Farzaneh Shobeirian The role of the placenta in prenatally acquired Zika virus infection. Virusdisease: 2017, 28(3);247-249 PubMed 29291210

Mohammad Zare Mehrjardi Watch out for congenital Zika syndrome in non-endemic regions. J Perinat Med: 2017; PubMed 29267173

Melonie Heron Deaths: Leading Causes for 2015. Natl Vital Stat Rep: 2017, 66(5);1-76 PubMed 29235984

Search term: Placenta Previa

Xian-Ying Cheng, Li Cheng, Wen-Juan Li, Ling-Hua Qian, Yong-Qin Zhang The effect of surgery on subsequent pregnancy outcomes among patients with cesarean scar diverticulum. Int J Gynaecol Obstet: 2018; PubMed 29341106

Tingting Sha, Xunqiang Yin, Wenwei Cheng, Isaac Yaw Massey Pregnancy-related complications and perinatal outcomes resulting from transfer of cryopreserved versus fresh embryos in vitro fertilization: a meta-analysis. Fertil. Steril.: 2018; PubMed 29331236

Heather J Baldwin, Jillian A Patterson, Tanya A Nippita, Siranda Torvaldsen, Ibinabo Ibiebele, Judy M Simpson, Jane B Ford Antecedents of Abnormally Invasive Placenta in Primiparous Women: Risk Associated With Gynecologic Procedures. Obstet Gynecol: 2018; PubMed 29324602

Fatimat M Akinlusi, Kabiru A Rabiu, Idayat A Durojaiye, Adeniyi A Adewunmi, Tawaqualit A Ottun, Yusuf A Oshodi Caesarean delivery-related blood transfusion: correlates in a tertiary hospital in Southwest Nigeria. BMC Pregnancy Childbirth: 2018, 18(1);24 PubMed 29320992

Placenta Shape

Circumvallate placenta

Placentas are generally round or oval in shape and can also be "irregular" (multilobate, "star") shapes. These irregular shaped placentas have been associated with lower birth weight for placental weight suggesting an altered function. [5]

Embryo Virtual Slides

Human Circumvallate Placenta

Circumvallate placenta 01.jpg

 ‎‎Mobile | Desktop | Original

Placenta Abnormal | Embryo Slides
Circumvallate placenta is an abnormally shaped placenta where the chorionic membranes are not inserted at the edge of the placenta, but are located inward from the margins toward the placental cord. The membranes are described as "doubled back" over the fetal surface of the placenta.

Placenta Weight

A recent Canadian study of 87,600 singleton births[6] has identified a number of risk factors for both high and low placental weight. Some factors are associated either before, after or both accounting for birthweight.

Low placental weight

  • chronic hypertension (before and after accounting for birthweight).
  • pre-eclampsia (before, but not after adjustment for birthweight).

High placental weight

  • anaemia (before and after adjustment for birthweight).
  • gestational diabetes (before and after adjustment for birthweight).
  • smoking (after adjustment for birthweight).
  • Placental and cord determinants include chorioamnionitis, chorangioma/chorangiosis, circumvallate placenta and marginal cord insertion.

Placenta Accreta

MRI Placenta accreta showing uterine bulging into the bladder.[7]

Abnormal adherence, with absence of decidua basalis. The incidence of placenta accreta also significantly increases in women with previous cesarean section compared to those without a prior surgical delivery.[8][9]

Placenta accreta 01.jpg

Ultrasound features:[10]

  1. Deficiency of retroplacental sonolucent zone
  2. Vascular lacunae
  3. Myometrial thinning
  4. Interruption of bladder line

Placenta Increta

Placenta Increta occurs when the placenta attaches deep into the uterine wall and penetrates into the uterine muscle, but does not penetrate the uterine serosa.

Placenta increta accounts for approximately 15-17% of all placenta abnormality cases.

Placenta previa and increta 02.jpg

Placenta Increta and Previa[11]

Placenta Percreta

MRI Surgery
Placenta percreta 04.jpg Placenta percreta 03.jpg
Placenta Percreta MRI[12] Surgical photograph
Showing the placenta extending through uterine wall (+) and covered by
thin serosal layer (arrow), no features of bladder invasion.

Placental villi penetrate myometrium and through to uterine serosa.

See clinical article on the laparoscopic management of placenta percreta. [13]

Placenta percreta 01.jpg

Placenta Percreta Histopathology[14]

Placenta Previa

historic model of Placenta Previa (praevia)

Historically, Paul Portal (1630-1703), a French physician[15], was the first to describe in 1685 a case of placenta previa in his "The Compleat Practice of Men and Women Midwives".

In this placental abnormality, the placenta overlies internal cervical os of uterus, essentially covering the birth canal. This condition occurs in approximately 1 in 200 to 250 pregnancies and risk factors include prior cesarean delivery, pregnancy termination, intrauterine surgery, smoking, multifetal gestation, increasing parity, and maternal age. A retrospective study of from 59,149 women of 724 pregnancies (1.2%) diagnosed with a complete or partial previa, identified no associated with fetal growth restriction.[16]

In the third trimester and at term, abnormal bleeding can require caesarian delivery and can also lead to Abruptio Placenta.

Ultrasound screening programs during 1st and early 2nd trimester pregnancies now include placental localization. Diagnosis can also be made by transvaginal ultrasound.

Placenta previa 01.jpg

Placenta previa MRI[12]

A 2007 Canadian study[17] identified that following first live birth delivery by caesarean section there is a 47% increased risk of placenta praevia and 40% increased risk of placental abruption in the second pregnancy with a singleton.

See also recent advances in the management of placenta previa. [18][9]

Ultrasound Placenta Previa

Placenta previa - anterior.jpg Placenta previa ultrasound 01.jpg
Anterior placenta position (upper arrow) in relation to cervix os (lower arrow). Posterior placenta position (arrow) in relation to cervix os (triangle).
Ultrasound placenta previa 01.jpg
US Placenta Previa GA33week icon.jpg
 ‎‎Placenta Previa
Page | Play

Ultrasound movie showing the fetal (GA 33 week) placenta.

Placental tissue is seen on the anterior and posterior uterine wall and completely covers the cervix.

Links: Ultrasound

Vasa Previa

Vasa previa (vasa praevia) placental abnormality where the fetal vessels lie within the membranes close too or crossing the inner cervical os (opening) and generally diagnosed (98%) by ultrasound. This occurs normally in 1:2500-5000 pregnancies and leads to complications similar too those for placenta previa.[19][9] Approximately 28% of prenatally diagnosis cases result in emergent preterm delivery.[20]

Type II is defined as the condition where the fetal vessels are found crossing over the internal os connecting either a bilobed placenta or a succenturiate lobe with the main placental mass.[21]

There are suggestions that colour doppler ultrasound can be used to visualise the blood vessels in high-risk cases and if required elective caesarean performed at 35–36 weeks in cases diagnosed as vasa praevia.[22]

Two main associations:

  1. velamentous insertions (25–62%)
  2. vessels crossing between lobes in succenturiate or bilobate placentas (33–75%)

Some recent evidence of successful in utero laser ablation of type II vasa previa at 22.5 weeks of gestation.

US Vasa Previa GA32week.jpg
 ‎‎Vasa Previa
Page | Play

Vasa previa ultrasound movie

Management of vasa previa

The following text is from a recent paper identifying the Canadian guidelines for the management of vasa previa.[23]

  1. If the placenta is found to be low lying at the routine second trimester ultrasound examination, further evaluation for placental cord insertion should be performed. (II-2B)
  2. Transvaginal ultrasound may be considered for all women at high risk for vasa previa, including those with low or velamentous insertion of the cord, bilobate or succenturiate placenta, or for those having vaginal bleeding, in order to evaluate the internal cervical os. (II-2B)
  3. If vasa previa is suspected, transvaginal ultrasound colour Doppler may be used to facilitate the diagnosis. Even with the use of transvaginal ultrasound colour Doppler, vasa previa may be missed. (II-2B)
  4. When vasa previa is diagnosed antenatally, an elective Caesarean section should be offered prior to the onset of labour. (II-1A)
  5. In cases of vasa previa, premature delivery is most likely; therefore, consideration should be given to administration of corticosteroids at 28 to 32 weeks to promote fetal lung maturation and to hospitalization at about 30 to 32 weeks. (II-2B)
  6. In a woman with an antenatal diagnosis of vasa previa, when there has been bleeding or premature rupture of membranes, the woman should be offered delivery in a birthing unit with continuous electronic fetal heart rate monitoring and, if time permits, a rapid biochemical test for fetal hemoglobin, to be done as soon as possible; if any of the above tests are abnormal, an urgent Caesarean section should be performed. (III-B
  7. Women admitted with diagnosed vasa previa should ideally be transferred for delivery in a tertiary facility where a pediatrician and blood for neonatal transfusion are immediately available in case aggressive resuscitation of the neonate is necessary. (II-3B)
  8. Women admitted to a tertiary care unit with a diagnosis of vasa previa should have this diagnosis clearly identified on the chart, and all health care providers should be made aware of the potential need for immediate delivery by Caesarean section if vaginal bleeding occurs. (III-B).

Abruptio Placenta

Represents interruption of the placenta by partial or complete separation, retroplacental blood clot formation and abnormal hemorrhage prior to delivery. There is significant perinatal mortality associated with abruptio placenta.[24]

Placenta Variants

Multilobed placenta succenturiata

Bilobed Placenta

Placenta with two equal-sized lobes connected by a thin bridge. No identified risks of this structure.

Bilobed placenta with velamentous cord insertion.jpg

Circumvallate placenta

Chorionic plate smaller than basal plate, edges rolled. Placental abruption and haemorrhage risks.

Placenta Membranacea

A rare placental abnormality where either all (diffuse placenta membranacea) or part (partial placenta membranacea) is covered by chorionic villi (placental cotyledons). Clinically the abnormality presents with vaginal bleeding, in the second or third trimester or during labor, due to an associated placenta previa.[25] Ultrasound has been used to detect this condition.[26]

Succenturiate placenta

Additional lobule separate from the main part of placenta. Risk of vessel rupture and placenta retention.

Links: Ultrasound

Chronic Intervillositis

(massive chronicintervillositis, chronic histiocytic intervillositis) Rare placental abnormality and pathology defined by inflammatory placental lesions, mainly in the intervillous space (IVS), with a maternal infiltrate of mononuclear cells (monocytes, lymphocytes, histiocytes) and intervillous fibrinoid deposition.

Chronic intervillositis of the placenta. Jacques SM, Qureshi F. Arch Pathol Lab Med. 1993 Oct;117(10):1032-5.

Placental Mesenchymal Dysplasia

Due to a similar "grape-like" placental appearance, this rare disorder placental mesenchymal stem villous hyperplasia has been mistaken both clinically and macroscopically for a partial hydatidiform molar pregnancy. The disorder also has a high incidence of both intrauterine growth restriction (IUGR) and fetal death.[27] The placental abnormality may be detected, but difficult to diagnose, by ultrasound.[28]

Current research suggests that placental cells may be originated from a mixed population of androgenetic (paternal-derived genome only) and biparental cells.[29] This means that chorionic villus sampling can provide a differential diagnosis between this and a partial mole.[30]


This condition is also known as gestational proteinuric hypertension and occurs in occurs in approximately 2 to 4% of all pregnancies. The pathogenesis of eclamptic convulsions remains unknown and women with a history of eclampsia are at increased risk of eclampsia (1-2%) and preeclampsia (22-35%) in subsequent pregnancies. "Magnesium sulfate is the drug of choice for reducing the rate of eclampsia developing intrapartum and immediately postpartum."(see Sibai BM. 2005).

Recent research using a large population study in Norway has shown a strong generational association such that daughters of women who had pre-eclampsia during pregnancy had more than twice the risk of pre-eclampsia themselves. The paper concludes "Maternal genes and fetal genes from either the mother or father may trigger pre-eclampsia. The maternal association is stronger than the fetal association. The familial association predicts more severe pre-eclampsia."[31]

Diabetic Placenta

Maternal Type 1 diabetes can alter placental vascular development. Effects may be due to either maternal hyperglycaemia or fatal hyperinsulinaemia with high glucose and insulin shown in other systems to alter vascularity, increasing vascular endothelial growth factor (VEGF), nitric oxide (NO) and protein kinase C (PKC).[32][33]

Features of the placental vessels include:

  • Increased angiogenesis
  • altered junctional maturity and molecular occupancy
  • increased leakiness

The placental terminal villi also show vascularity changes including both hypovascularity and hypervascularity. A recent study of the normal and diabetic placenta,[3] shows the diabetic placenta terminal villi were:

  • hypovascular villi - had a smaller diameter and a wavy course
  • hypervascular villi - had numerous capillaries, reduced stroma and were large in diameter.

Specific changes included:

  • villous stroma - collagen envelope around capillaries looked thinner and the network of collagen fibers seemed less dense.
  • stromal cells - loss of desmin filaments.
  • villous capillaries - were more branched.

Links: Maternal Diabetes

Placental Chorioangioma

Chorioangiomas are the most common tumour of the placenta, occurring in approximately 1 % of all placentas and are generally benign vascular tumours (haemangiomas).

  • Small chorioangiomas are generally not clinically significant and usually found incidentally.
  • Large chorioangiomas have been associated with a range of fetal conditions (fetal anemia, thrombocytopenia, hydrops, hydramnios, intrauterine growth retardation) including prematurity and stillbirth.
Placental Chorioangioma Ultrasound
Placental chorioangioma ultrasound 01.jpg Placental chorioangioma ultrasound 02.jpg
Ultrasound scan placenta and chorioangioma Ultrasound blood flow in chorioangioma
Placental Chorioangioma
Placental chorioangioma 01.jpg Placental chorioangioma 02.jpg Placental chorioangioma 03.jpg

Example of a placental chorioangioma forming a yellowish, well-circumscribed firm mass (5 cm × 5 cm) connected by two vessels to the placenta. Histopathologic examination revealed a placental disc 15 cm × 17 cm × 13 cm, with a three-vessel umbilical cord that was attached peripherally and measured 9 cm × 1.5 cm. The weight of the placenta was 530 g. The tumor was confirmed to be a chorioangioma.[34]

Hydatidiform Mole

Hydatidiform Mole

Another type of abnormality is when only the conceptus trophoblast layers proliferates and not the embryoblast, no embryo develops, this is called a "hydatidiform mole" (HM), which is due to the continuing presence of the trophoblastic layer, this abnormal conceptus can also implant in the uterus. The trophoblast cells will secrete human chorionic gonadotropin (hCG), as in a normal pregnancy, and may appear maternally and by pregnancy test to be "normal". Prenatal diagnosis by ultrasound analysis demonstrates the absence of a embryo.

There are several forms of hydatidiform mole: partial mole, complete mole and persistent gestational trophoblastic tumor. Many of these tumours arise from a haploid sperm fertilizing an egg without a female pronucleus (the alternative form, an embryo without sperm contribution, is called parthenogenesis). The tumour has a "grape-like" placental appearance without enclosed embryo formation. Following a first molar pregnancy, there is approximately a 1% risk of a second molar pregnancy.

  • The incidence of hydatidiform mole varies between ethnic groups, and typically occurs in 1 in every 1500 pregnancies.
  • All hydatidiform mole cases are sporadic, except for extremely rare familial cases.
  • A maternal gene has been identified for recurrent hydatidiform mole (chromosome 19q13.3-13.4 in a 15.2 cM interval flanked by D19S924 and D19S890).[35]

Links: Hydatidiform Mole | Week 2 - Abnormalities

Mole Types

Complete mole - chromosomal genetic material from the ovum (egg) is lost, by an unknown process. Fertilization then occurs with one or two sperm and an androgenic (from the male only) conceptus (fertilized egg) is formed. With this conceptus the embryo (fetus, baby) does not develop at all but the placenta does grow but it is abnormal and forms lots of cysts and has no blood vessels. These cysts look like a cluster of grapes and that is why it is called a hydatidiform mole (grape like). A hydatidiform mole miscarries by about 16 to 18 weeks gestational age. Since the diagnosis can be made by ultrasound before that time, it is better for you to have an evacuation of the uterus (D & C) so that there is no undue bleeding and no infection. Human chorionic gonadotropin (hCG) will assist in making the diagnosis.

Partial mole - three sets of chromosomes instead of the usual two and this is called triploidy. With such a pregnancy the chromosomal (genetic) material from the ovum (egg) is retained and the egg is fertilized by one or two sperm. Since with partial mole there are maternal chromosomes there is a fetus but because of the three sets of chromosomes this fetus is always grossly abnormal and will not survive. (Text modified from: International Society for the Study of Trophoblastic Diseases,see also JRM Gestational Trophoblastic Disease)

Tumour Growth

Like any tumour, unless removed there is a risk of progression:

Stage I: Tumor confined to uterus (non-metastatic)
Stage II: Tumor involving pelvic organs and/or vagina
Stage III: Tumor involving lungs, with or without involving pelvic structures and/or vagina
Stage IV: Tumor involving distant organs

Placental Mesenchymal Dysplasia

Due to a similar "grape-like" placental appearance, this rare disorder has been mistaken both clinically and macroscopically for a partial hydatidiform molar pregnancy. This disorder also has a high incidence of intrauterine growth restriction (IUGR) and fetal death.

Twin Pregnancy Mole

Hydatidiform mole and co-existent healthy fetus is a very rare condition with only 30 cases documented in detail in the literature.[36]

Links: International Society for the Study of Trophoblastic Diseases | Sydney Gynaecological Oncology Group Gestational Trophoblastic Disease | The Journal of Reproductive Medicine Gestational Trophoblastic Disease (1998) | Dana-Farber Cancer Institute Gynecologic Oncology Program

Cord Abnormalities

Velamentous Cord Insertion[37]

Velamentous Cord Insertion

(velamentous insertion) Clinical term for describing a placental abnormality where the placental cord inserts into the chorion laeve (placental membranes) away from the edge of the placenta. The placental vessels can also diverge as they traverse between the amnion and chorion before reaching the placenta.The placental vessels are therefore unprotected by Wharton's jelly where they traverse the membranes before they come together into the umbilical cord. This can cause hemorrhage if the vessels are damaged when the membranes are ruptured prior to birth. The condition is more common in monozygotic twins (15%) and triplets.

Velamentous cord insertion, with a low uterine body implantation site, has also been shown to affect fetal heart rate.[38]

Bilobed placenta with velamentous cord insertion.jpg

A bilobed placenta with velamentous cord insertion.

Cord Vessel Number

Placental cord ultrasound 02.jpg
Cord with one artery and one vein

Persistent Right Umbilical Vein

A fairly rare anomaly, a study of 15,237 obstetric ultrasound examinations performed after 15 weeks' gestation identified only 33 cases of persistent right umbilical vein.[39] Some studies have identified associated fetal anomalies with this condition[40], including cardiac abnormalities.[41]

Cord Knotting

Placental cord true knot
There are few abnormalities associated with umbilical cord development, other that abnormally short or long cords, which in most cases do not cause difficulties.

In some cases though, long cords can wrap around limbs or the fetus neck, which can then restrict blood flow or lead to tissue or nerve damage, and therefore effect develoment.

Cord knotting can also occur (1%) in most cases these knots have no effect, in some cases of severe knotting this can prevents the passage of placental blood.

Umbilical cord torsion

Placenta- umbilical cord torsion.jpg Rare umbilical cord torsion, even without knot formation can also affect placental blood flow, even leading to fetal demise.[42]

Cord Length

Furcate cord

Refers to the separation of placental vessels before their attachment into the placenta.[43]

Fetal Erythroblastosis

This disease is also called Haemolytic Disease of the Newborn, an immune problem from fetus Rh+ /maternal Rh-, leakage from fetus causes anti-Rh antibodies, which is then dangerous for a 2nd child.


Placental Infections

Listeria maternal-fetal barrier

Several infective agents may cross into the placenta from the maternal circulation, as well as enter the embry/fetal circulation. The variety of bacterial infections that can occur during pregnancy is as variable as the potential developmental effects, from virtually insignificant to a major developmental, abortive or fatal in outcome.

Placental Malaria

Malaria (plasmodium falciparum)

Pregnant women have an increased susceptibility to malaria infection. Malarial infection of the placenta by sequestration of the infected red blood cells leading to low birth weight and other effects. There are four types of malaria caused by the protozoan parasite Plasmodium falciparum (main), Plasmodium vivax, Plasmodium ovale, Plasmodium malariae). This condition is common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).

Links: Abnormal Development - Malaria

Placental Herpesvirus

A recent paper has identified using an in vitro model that human herpesvirus 8 (HHV-8) can infect the placenta[44]

Cytomegalovirus Placentitis

Clinical term for the cytomegalovirus infection of the placenta.

A earlier histological study[45] identified fixed connective tissue cells predominantly infected cell type in placental tissue. In addition, endothelial cells, macrophages and in some cases trophoblast infection. While a more recent in vitro study[46] suggests that all villi cell types are likely to be infected.

Links: Cytomegalovirus | Abnormal Development - Viral Infection

Placental Membranes

There are few documented abnormalities associated with feral membranes (chorion, amnion). Ultrasound measurement of abnormal yolk sac size/shape in early embryonic development has been suggested as an indicator of early gestational loss. The most common literature described abnormalities are those associated with abnormal vasularization of the chorion.


ICD Code: O41.1 Infection of amniotic sac and membranes Amnionitis Chorioamnionitis Membranitis Placentitis

The best known environmental effect is infection of chorion and/or amnion referred to as chorioamnionitis.[47]

Chronic chorioamnionitis histology.jpg

Chronic Chorioamnionitis Histology[48]

  • Stage 1 ((a, b) inflammation showing infiltration of lymphocytes limited to the chorionic trophoblast layer (a). CD3 immunostaining demonstrates that the majority of these cells are T cells (b).
  • Stage 2 (c, d) inflammation is characterized by infiltration of lymphocytes into the chorioamniotic connective tissue layer ((Stain - Haematoxylin Eosin), c), which are largely CD3+ T cells (d).

Links: Bacterial Infection | Placental Membranes

Placental Pathology

The following pathology information from[49].

Chronic Villitis

This condition can occur following placental infection leading to maternal inflammation of the villous stroma, often with associated intervillositis. The inflammation can lead to disruption of blood flow and necrotic cell death.

Massive Chronic Intervillositis

(MCI) The maternal blood-filled space is filled with CD68-positive histiocytes and an increase in fibrin, occuring more commonly in the first trimester.

Meconium Myonecrosis

The prolonged meconium exposure leads to toxic death of myocytes of placental vessels (umbilical cord or chorionic plate).


A fetal malignancy that leads to an enlarged placenta, with tumor cells in the fetal circulation and rarely in the chorionic villi.


(protein C or S deficiency, factor V Leiden, sickle cell disease, antiphospholipid antibody) This condition can generate an increased fibrin/fibrinoid deposition in the maternal or intervillous space, this can trap and kill villi.

International Classification of Diseases

XV Pregnancy Childbirth

O12 Gestational oedema and proteinuria without hypertension


  • O12.0 Gestational oedema
  • O12.1 Gestational proteinuria
  • O12.2 Gestational oedema with proteinuria

O13 Gestational hypertension without significant proteinuria


Incl.: Gestational hypertension NOS Mild pre-eclampsia

O14 Gestational hypertension with significant proteinuria

[pregnancy-induced] Excl.: superimposed pre-eclampsia (O11)

  • O14.0 Moderate pre-eclampsia
  • O14.1 Severe pre-eclampsia
  • O14.2 HELLP syndrome Combination of hemolysis, elevated liver enzymes and low platelet count
  • O14.9 Pre-eclampsia, unspecified

O15 Eclampsia

Incl.: convulsions following conditions in O10-O14 and O16 eclampsia with pregnancy-induced or pre-existing hypertension

  • O15.0 Eclampsia in pregnancy
  • O15.1 Eclampsia in labour
  • O15.2 Eclampsia in the puerperium
  • O15.9 Eclampsia, unspecified as to time period Eclampsia NOS

  • Abruptio placentae (641.2)
  • Placenta previa (641.0, 641.1)
  • Postpartum hemorrhage (666.0–666.2)


  1. Kari R Risnes, Pål R Romundstad, Tom I L Nilsen, Anne Eskild, Lars J Vatten Placental weight relative to birth weight and long-term cardiovascular mortality: findings from a cohort of 31,307 men and women. Am. J. Epidemiol.: 2009, 170(5);622-31 PubMed 19638481
  2. Josefine Nasiell, Nikos Papadogiannakis, Erika Löf, Fanny Elofsson, Boubou Hallberg Hypoxic ischemic encephalopathy in newborns linked to placental and umbilical cord abnormalities. J. Matern. Fetal. Neonatal. Med.: 2015;1-6 PubMed 25714479
  3. 3.0 3.1 M Jirkovská, T Kučera, J Kaláb, M Jadrníček, V Niedobová, J Janáček, L Kubínová, M Moravcová, Z Zižka, V Krejčí The branching pattern of villous capillaries and structural changes of placental terminal villi in type 1 diabetes mellitus. Placenta: 2012, 33(5);343-51 PubMed 22317894
  4. Junichi Hasegawa, Shinji Iwasaki, Ryu Matsuoka, Kiyotake Ichizuka, Akihiko Sekizawa, Takashi Okai Velamentous cord insertion caused by oblique implantation after in vitro fertilization and embryo transfer. J. Obstet. Gynaecol. Res.: 2011, 37(11);1698-701 PubMed 21651650
  5. M Yampolsky, C M Salafia, O Shlakhter, D Haas, B Eucker, J Thorp Modeling the variability of shapes of a human placenta. Placenta: 2008, 29(9);790-7 PubMed 18674815
  6. Helen McNamara, Jennifer A Hutcheon, Robert W Platt, Alice Benjamin, Michael S Kramer Risk factors for high and low placental weight. Paediatr Perinat Epidemiol: 2014, 28(2);97-105 PubMed 24354883
  7. Anne-Sophie Riteau, Mikael Tassin, Guillemette Chambon, Claudine Le Vaillant, Jocelyne de Laveaucoupet, Marie-Pierre Quéré, Madeleine Joubert, Sophie Prevot, Henri-Jean Philippe, Alexandra Benachi Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of placenta accreta. PLoS ONE: 2014, 9(4);e94866 PubMed 24733409 | PLoS One.
  8. S M Zaideh, A T Abu-Heija, M F El-Jallad Placenta praevia and accreta: analysis of a two-year experience. Gynecol. Obstet. Invest.: 1998, 46(2);96-8 PubMed 9701688
  9. 9.0 9.1 9.2 Yinka Oyelese, John C Smulian Placenta previa, placenta accreta, and vasa previa. Obstet Gynecol: 2006, 107(4);927-41 PubMed 16582134
  10. Charleen Sze-Yan Cheung, Ben Chong-Pun Chan The sonographic appearance and obstetric management of placenta accreta. Int J Womens Health: 2012, 4;587-94 PubMed 23239929
  11. Kyong Wook Yi, Min-Jeong Oh, Tae-Seok Seo, Kyeong A So, Yu Chin Paek, Hai-Joong Kim Prophylactic hypogastric artery ballooning in a patient with complete placenta previa and increta. J. Korean Med. Sci.: 2010, 25(4);651-5 PubMed 20358016 | PMC2844598 | J Korean Med Sci.
  12. 12.0 12.1 Binoj Varghese, Navdeep Singh, Regi A N George, Sareena Gilvaz Magnetic resonance imaging of placenta accreta. Indian J Radiol Imaging: 2013, 23(4);379-85 PubMed 24604945 | PMC3932583 | Indian J Radiol Imaging.
  13. Melanie Endres Ochalski, Amy Broach, Ted Lee Laparoscopic management of placenta percreta. J Minim Invasive Gynecol: 2009, 17(1);128-30 PubMed 20129349
  14. Minna Tikkanen, Vedran Stefanovic, Jorma Paavonen Placenta previa percreta left in situ - management by delayed hysterectomy: a case report. J Med Case Rep: 2011, 5;418 PubMed 21867547 | PMC3177929 | J Med Case Reports.
  15. P M Dunn Paul Portal (1630-1703), man-midwife of Paris. Arch. Dis. Child. Fetal Neonatal Ed.: 2006, 91(5);F385-7 PubMed 16923941
  16. Lorie M Harper, Anthony O Odibo, George A Macones, James P Crane, Alison G Cahill Effect of placenta previa on fetal growth. Am. J. Obstet. Gynecol.: 2010, 203(4);330.e1-5 PubMed 20599185
  17. Q Yang, S W Wen, L Oppenheimer, X K Chen, D Black, J Gao, M C Walker Association of caesarean delivery for first birth with placenta praevia and placental abruption in second pregnancy. BJOG: 2007, 114(5);609-13 PubMed 17355267
  18. Amar Bhide, Basky Thilaganathan Recent advances in the management of placenta previa. Curr. Opin. Obstet. Gynecol.: 2004, 16(6);447-51 PubMed 15534438
  19. Yinka Oyelese, John C Smulian Placenta previa, placenta accreta, and vasa previa. Obstet Gynecol: 2006, 107(4);927-41 PubMed 16582134
  20. Society for Maternal-Fetal Medicine (SMFM) Publications Committee. Electronic address:, Rachel G Sinkey, Anthony O Odibo, Jodi Dashe Society for Maternal-Fetal Medicine (SMFM) Consult Series #37: Diagnosis and Management of Vasa Previa. Am. J. Obstet. Gynecol.: 2015; PubMed 26292048
  21. Rubén A Quintero, Eftichia V Kontopoulos, Patricia W Bornick, Mary H Allen In utero laser treatment of type II vasa previa. J. Matern. Fetal. Neonatal. Med.: 2007, 20(12);847-51 PubMed 18050017
  22. P Sinha, S Kaushik, N Kuruba, S Beweley Vasa praevia: a missed diagnosis. J Obstet Gynaecol: 2008, 28(6);600-3 PubMed 19003654
  23. Robert Gagnon, Lucie Morin, Stephen Bly, Kimberly Butt, Yvonne M Cargill, Nanette Denis, Marja Anne Hietala-Coyle, Kenneth Ian Lim, Annie Ouellet, Maria-Hélène Raciot, Shia Salem, Diagnostic Imaging Committee, Lynda Hudon, Melanie Basso, Hayley Bos, Marie-France Delisle, Dan Farine, Kirsten Grabowska, Savas Menticoglou, William Mundle, Lynn Murphy-Kaulbeck, Tracy Pressey, Anne Roggensack, Maternal Fetal Medicine Committee Guidelines for the management of vasa previa. J Obstet Gynaecol Can: 2009, 31(8);748-60 PubMed 19772710
  24. Hamisu M Salihu, Brigitte Bekan, Muktar H Aliyu, Dwight J Rouse, Russell S Kirby, Greg R Alexander Perinatal mortality associated with abruptio placenta in singletons and multiples. Am. J. Obstet. Gynecol.: 2005, 193(1);198-203 PubMed 16021079
  25. Atif Ahmed, Enid Gilbert-Barness Placenta membranacea: a developmental anomaly with diverse clinical presentation. Pediatr. Dev. Pathol.: 2003, 6(2);201-2 PubMed 12532260
  26. B S Wilkins, G Batcup, P S Vinall Partial placenta membranacea. Br J Obstet Gynaecol: 1991, 98(7);675-9 PubMed 1883791
  27. Truc Pham, Julie Steele, Carla Stayboldt, Linda Chan, Kurt Benirschke Placental mesenchymal dysplasia is associated with high rates of intrauterine growth restriction and fetal demise: A report of 11 new cases and a review of the literature. Am. J. Clin. Pathol.: 2006, 126(1);67-78 PubMed 16753607
  28. Edi Vaisbuch, Roberto Romero, Juan Pedro Kusanovic, Offer Erez, Shali Mazaki-Tovi, Francesca Gotsch, Chong Jai Kim, Jung-Sun Kim, Lami Yeo, Sonia S Hassan Three-dimensional sonography of placental mesenchymal dysplasia and its differential diagnosis. J Ultrasound Med: 2009, 28(3);359-68 PubMed 19244073
  29. Wendy P Robinson, Julie L Lauzon, A Micheil Innes, Ken Lim, Snezana Arsovska, Deborah E McFadden Origin and outcome of pregnancies affected by androgenetic/biparental chimerism. Hum. Reprod.: 2007, 22(4);1114-22 PubMed 17185351
  30. M Arigita, M Illa, A Nadal, C Badenas, A Soler, N Alsina, A Borrell Chorionic villus sampling in the prenatal diagnosis of placental mesenchymal dysplasia. Ultrasound Obstet Gynecol: 2010, 36(5);644-5 PubMed 20503241
  31. Rolv Skjaerven, Lars J Vatten, Allen J Wilcox, Thorbjørn Rønning, Lorentz M Irgens, Rolv Terje Lie Recurrence of pre-eclampsia across generations: exploring fetal and maternal genetic components in a population based cohort. BMJ: 2005, 331(7521);877 PubMed 16169871
  32. Lopa Leach Placental vascular dysfunction in diabetic pregnancies: intimations of fetal cardiovascular disease? Microcirculation: 2011, 18(4);263-9 PubMed 21418381
  33. Lopa Leach, Alice Taylor, Flavia Sciota Vascular dysfunction in the diabetic placenta: causes and consequences. J. Anat.: 2009, 215(1);69-76 PubMed 19563553
  34. Inas Babic, Maha Tulbah, Wesam Kurdi Antenatal embolization of a large placental chorioangioma: a case report. J Med Case Rep: 2012, 6;183 PubMed 22759589 | PMC3419096 | J Med Case Rep
  35. Y B Moglabey, R Kircheisen, M Seoud, N El Mogharbel, I Van den Veyver, R Slim Genetic mapping of a maternal locus responsible for familial hydatidiform moles. Hum. Mol. Genet.: 1999, 8(4);667-71 PubMed 10072436
  36. Benjamin Piura, Alex Rabinovich, Relly Hershkovitz, Ester Maor, Moshe Mazor Twin pregnancy with a complete hydatidiform mole and surviving co-existent fetus. Arch. Gynecol. Obstet.: 2008, 278(4);377-82 PubMed 18273627
  37. Juliana Rocha, Joana Carvalho, Fernanda Costa, Isabel Meireles, Olímpia do Carmo Velamentous cord insertion in a singleton pregnancy: an obscure cause of emergency cesarean-a case report. Case Rep Obstet Gynecol: 2012, 2012;308206 PubMed 23243528 | PMC3517836 | Case Rep Obstet Gynecol.
  38. J Hasegawa, R Matsuoka, K Ichizuka, A Sekizawa, A Farina, T Okai Velamentous cord insertion into the lower third of the uterus is associated with intrapartum fetal heart rate abnormalities. Ultrasound Obstet Gynecol: 2006, 27(4);425-9 PubMed 16479618
  39. L M Hill, A Mills, C Peterson, D Boyles Persistent right umbilical vein: sonographic detection and subsequent neonatal outcome. Obstet Gynecol: 1994, 84(6);923-5 PubMed 7970470
  40. J Weichert, D Hartge, U Germer, R Axt-Fliedner, U Gembruch Persistent right umbilical vein: a prenatal condition worth mentioning? Ultrasound Obstet Gynecol: 2011, 37(5);543-8 PubMed 20922781
  41. Brianna Lide, William Lindsley, Margaret J Foster, Richard Hale, Sina Haeri Intrahepatic Persistent Right Umbilical Vein and Associated Outcomes: A Systematic Review of the Literature. J Ultrasound Med: 2015; PubMed 26635256
  42. M Hallak, P G Pryde, F Qureshi, M P Johnson, S M Jacques, M I Evans Constriction of the umbilical cord leading to fetal death. A report of three cases. J Reprod Med: 1994, 39(7);561-5 PubMed 7966052
  43. Mehmet Tunç Canda, Namık Demir, Latife Doganay Velamentous and Furcate Cord Insertion with Placenta Accreta in an IVF Pregnancy with Unicornuate Uterus. Case Rep Obstet Gynecol: 2013, 2013;539379 PubMed 24455351
  44. Mariantonietta Di Stefano, Maria Luisa Calabrò, Iole Maria Di Gangi, Santina Cantatore, Massimo Barbierato, Elisa Bergamo, Anfumbom Jude Kfutwah, Margherita Neri, Luigi Chieco-Bianchi, Pantaleo Greco, Loreto Gesualdo, Ahidjo Ayouba, Elisabeth Menu, Josè Ramòn Fiore In vitro and in vivo human herpesvirus 8 infection of placenta. PLoS ONE: 2008, 3(12);e4073 PubMed 19115001
  45. C Sinzger, H Müntefering, T Löning, H Stöss, B Plachter, G Jahn Cell types infected in human cytomegalovirus placentitis identified by immunohistochemical double staining. Virchows Arch A Pathol Anat Histopathol: 1993, 423(4);249-56 PubMed 8236822
  46. Liu Tao, Chen Suhua, Chen Juanjuan, Yin Zongzhi, Xiao Juan, Zhang Dandan In vitro study on human cytomegalovirus affecting early pregnancy villous EVT's invasion function. Virol. J.: 2011, 8;114 PubMed 21392403
  47. M Gantert, J V Been, A W D Gavilanes, Y Garnier, L J I Zimmermann, B W Kramer Chorioamnionitis: a multiorgan disease of the fetus? J Perinatol: 2010, 30 Suppl;S21-30 PubMed 20877404
  48. Chong Jai Kim, Roberto Romero, Juan Pedro Kusanovic, Wonsuk Yoo, Zhong Dong, Vanessa Topping, Francesca Gotsch, Bo Hyun Yoon, Je Geun Chi, Jung-Sun Kim The frequency, clinical significance, and pathological features of chronic chorioamnionitis: a lesion associated with spontaneous preterm birth. Mod. Pathol.: 2010, 23(7);1000-11 PubMed 20348884 | Mod Pathol.
  49. Drucilla J Roberts Placental pathology, a survival guide. Arch. Pathol. Lab. Med.: 2008, 132(4);641-51 PubMed 18384216


Gali Garmi, Raed Salim Epidemiology, etiology, diagnosis, and management of placenta accreta. Obstet Gynecol Int: 2012, 2012;873929 PubMed 22645616

| Obstet Gynecol Int. Khaled M Elsayes, Andrew T Trout, Aaron M Friedkin, Peter S Liu, Ronald O Bude, Joel F Platt, Christine O Menias Imaging of the placenta: a multimodality pictorial review. Radiographics: 2009, 29(5);1371-91 PubMed 19755601

J S Abramowicz, E Sheiner In utero imaging of the placenta: importance for diseases of pregnancy. Placenta: 2007, 28 Suppl A;S14-22 PubMed 17383721


A Messerschmidt, A Baschat, N Linduska, G Kasprian, P C Brugger, A Bauer, M Weber, D Prayer Magnetic resonance imaging of the placenta identifies placental vascular abnormalities independently of Doppler ultrasound. Ultrasound Obstet Gynecol: 2011, 37(6);717-22 PubMed 21105016

B Hargitai, T Marton, P M Cox Best practice no 178. Examination of the human placenta. J. Clin. Pathol.: 2004, 57(8);785-92 PubMed 15280396

J F Yetter Examination of the placenta. Am Fam Physician: 1998, 57(5);1045-54 PubMed 9518951

Search PubMed

Search Pubmed: Placenta Abnormalities | Placenta Accreta | Placenta Increta | Placenta Percreta | Placenta Previa | Vasa Previa

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.

Placenta Terms (expand to view) 
  • after-birth - term used to describe the delivery of placenta and placental membranes following birth of the child.
  • allantois - An extraembryonic membrane, endoderm in origin extension from the early hindgut, then cloaca into the connecting stalk of placental animals, connected to the superior end of developing bladder. In reptiles and birds, acts as a reservoir for wastes and mediates gas exchange. In mammals is associated/incorporated with connecting stalk/placental cord fetal-maternal interface.
  • anastomosis - Term used to describe the connection between two tubes. Applied to describe the connection between peripheral blood vessels without an intervening capillary bed.
  • anchoring villi - (stem villi) describes the placental villi (embryonic) that attach to the decidua (maternal) tissue. The tip of the villi consists of a column of trophoblast cells attached to an epithelial plaque.
  • angioblasts form clusters or blood islands on surface of yolk sac.
  • angiogenesis - Term describing the development of new vessels from already existing vessels, this process is secondary to vasculogenesis which is the initial formation of first blood vessels by differentiation of pluripotent mesenchymal cells (extraembryonic mesoderm).
  • capsularis - portion of maternal decidua that covers the conceptus facing towards the uterine cavity.
  • chorioamnionitis - (CA) An intraamniotic puerperal infection described as having 3 forms: histologic, clinical (clinical chorioamnionitis, IAI), and subclinical. Intraamniotic infection is a common (2-4%) event in labor and the systemic inflammatory response can also lead to preterm birth and neonatal complications.
  • chorion - The extraembryonic membrane generated from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange.
  • chorionic cavity - The fluid-filled extraembryonic coelom (cavity) formed initially from trophoblast and extraembryonic mesoderm that forms placenta. chorion and amnion are made by the somatopleure. The chorion becomes incorporated into placental development. The avian and reptilian chorion lies beside the egg shell and allows gas exchange. In humans, this cavity is lost during week 8 when the amniotic cavity expands and fuses with the chorion.
  • chorion frondosum - (frondosum = leafy) The chorion found on conceptus oriented towards maternal blood supply where the majority of villi form and proliferate, will contribute the fetal component of the future placenta.
  • chorion laeve - (laeve = smooth) The smooth chorion found on conceptus away from maternal blood supply (towards uterine epithelium and cavity) with very few villi present.
  • chorionic gonadotropin - (CG, human chorionic gonadotropin, hCG) A hormone see human chorionic gonadotropin.
  • chorionic somatomammotropin - (CSH, human lactogen) A hormone synthesized within the placenta by syncytiotrophoblast cells. This protein hormone (190 amino acid) has a structure is similar to pituitary growth hormone.
  • chorionic villus sampling - (CVS) The taking a biopsy of the placenta, usually at the end of the second month of pregnancy, to test the fetus for genetic abnormalities.
  • coelocentesis - A sampling of extracoelomic fluid usually for an early prenatal diagnostic technique.
  • connecting stalk - the original extra-embryonic mesoderm structure attaching the embryonic disc to the chorion. The placental blood vessels form within this structure.
  • cord blood - (human umbilical cord blood, HUCB) A term used to describe blood collected from the placenta usually after birth. Has been identified as a source of stem cells with potential therapeutic uses and is stored in Cord Blood Banks throughout the world.
  • cord knotting Term describing umbilical or placental cord knotting. This occurs in about 1% prevents the passage of placental blood, pseudoknots also occur usually with no effect.
  • cord presentation - A term used to describe at birth the presence of the umbilical cord between the fetal presenting part and the cervix, with or without membrane rupture.
  • cord prolapse - A term used to describe at birth the descent of the umbilical cord through the cervix alongside (occult) or past (overt) the presenting part in the presence of ruptured membranes (incidence of 0.1% to 0.6%).
  • cotyledon - (Greek, kotyle = a deep cup) In the embryos of seed plants, the "seed leaves," in which nutrients are stored for use after germination. In placental animals, the term is also to describe the leaf-like structure of the placenta surface.
  • cytotrophoblast - The "cellular" trophoblast layer surrounding (forming a "shell") the early implanting conceptus. Beginning at uterine adplantation, proliferation and fusion of these cells is thought to form a second outer trophoblast layer, the syncytiotrophoblast. The cytotrophoblast layer contributes to formation of the placental villi, the functional component of the fetal placenta.
  • decidua basalis - The term given to the uterine endometrium at the site of implantation where signaling transforms the uterine stromal cells (fibroblast-like) into decidual cells. This forms the maternal component of the placenta, the decidualization process gradually spreads through the remainder of the uterus, forming the decidua parietalis.
  • decidua basalis reaction - Term describing the maternal endometrial changes that occur initially at the site of, and following, blastocyst implantation. Seen as a deposition of glycogen, fibrin and proliferation of blood vessels. See also decidualization.
  • decidua capsularis - The term given to the uterine endometrium which has been converted to decidua surrounding the conceptus on the smooth chorion side.
  • decidua parietalis - The term given to the remainder of the uterine endometrium, away from the site of implantation, that gradually becomes comverted to decidua.
  • decidual cell - The uterine stromal cells (fibroblast-like) that differentiate in response to both steroid hormones (progesterone) and embryonic signals. These cells then alter uterine environment to support further embryonic development as well as producing cytokines related to prolactin (PRL) and have an innate immune function.
  • decidualization - (decidualisation) The process by which uterine stromal cells differentiate in response to both steroid hormones and embryonic signals into large epitheliod decidual cells. This process is essential for the progress of implantation and establishing fetal-maternal communication.
  • fetal drug addiction - occurs when drugs used maternally cross the placental barrier and can establish addiction in the unborn fetus.
  • fetal erythroblastosis - (Haemolytic Disease of the Newborn) A clinical term describing an immune response between fetal and maternal blood groups; from fetus Rh+ / maternal Rh-. The leakage of blood from fetus, particularly at birth, causes maternal anti-Rh antibodies, which is then dangerous for a 2nd or future pregnancies.
  • fibrinoid layer - (Nitabuch's layer) A layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
  • floating chorionic villi - Term used to describe the placental microanatomy structure of chorionic villi that are not attached to the maternal decidua and float in the maternal blood-filled space (lacunae). Structurally the same as anchoring chorionic villi conceptus side that are attached to the maternal decidua.These villi go through the same stages of development: primary, secondary and tertiary villi.
  • hemotrophic nutrition - Term used to describe in late placenta development the transfer of blood-borne nutrition from maternal to embryo/fetuscompared to early histiotrophic nutrition.
  • histiotrophic nutrition - Term used to describe in early placenta development the intital transfer of nutrition from maternal to embryo (histiotrophic nutrition) compared to later blood-borne nutrition (hemotrophic nutrition). Histotroph is the nutritional material accumulated in spaces between the maternal and fetal tissues, derived from the maternal endometrium and the uterine glands. This nutritional material is absorbed by phagocytosis initially by blastocyst trophectoderm and then by trophoblast of the placenta. in later placental development nutrition is by the exchange of blood-borne materials between the maternal and fetal circulations, hemotrophic nutrition.
  • Hofbauer cells - Cells found within placental villi connective tissue. Have a role as macrophages of mesenchymal origin with potentially additional functions (remodeling, vasculogenesis, regulation of stromal water content).
  • Human chorionic corticotropin - (hCACTH) placental derived hormone equivilant to corticotropin (ACTH) from the pituitary.
  • Human chorionic gonadotrophin - (hCG) like leutenizing hormone, supports corpus luteum, originally secreted by trophoblast cells.
  • Human chorionic somatommotropin - (hCS, placental lactogen) hormone level increases in maternal blood through pregnancy, decreases maternal insulin sensitivity (raising maternal blood glucose levels and decreasing maternal glucose utilization) aiding fetal nutrition.
  • hydatiform mole - A uterine tumour with "grape-like" placenta appearance without enclosed embryo formation, arises mainly from a haploid sperm fertilizing an egg without a female pronucleus. It is one form of gestational trophoblastic disease(GTD), a number of abnormalities including hydatiform mole, invasive mole, choriocarcinoma and placental site trophoblastic tumor (PSTT).
  • hysterectomy – clinical term for the surgical removal of the uterus.
  • Langhans layer - cytotrophoblast cell layer.
  • maternal antibodies - antibodies from the mother's immune system that are capable of crossing placental barrier. They can provide immune protection to the embryo, but may also participate in immune disease (fetal erythroblastosis).
  • maternal sinusoids - placental spaces around chorionic villi that are filled with maternal blood. This is the closest maternal/fetal exchange site.
  • Nitabuch's layer - (fibrinoid layer) The layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
  • Morbidly adherent placenta (MAP) A general clinical term used to describe the different forms of abnormal placental implantation (Accreta, Increta and Percreta).
  • persistent right umbilical vein - (PRUV) A placental cord abnormality associated with fetal abnormalities and poor neonatal prognosis. The estimated incidence of persistent right umbilical vein in a low-risk population is 1 : 526. PMID: 12047534
  • placenta - (Greek, plakuos = flat cake) The developmental organ formed from maternal and fetal contributions in animals with placental development. In human, the placenta at term is a discoid shape "flat cake" shape; 20 cm diameter, 3 cm thick and weighs 500-600 gm. Placenta are classified by the number of layers between maternal and fetal blood (Haemochorial, Endotheliochorial and Epitheliochorial) and shape (Discoid, Zonary, Cotyledenary and Diffuse). The placenta has many different functions including metabolism, transport and endocrine.
  • placenta accreta - The abnormal placental adherence, either in whole or in part of the placenta with absence of decidua basalis, leading to retention as an after-birth to the underlying uterine wall. The incidence of placenta accreta also significantly increases in women with previous cesarean section compared to those without a prior surgical delivery.
  • placental arteries - (umbilical arteries) In placental animals, the blood vessels which develop within the placental cord carrying relatively deoxygenated blood from the embryo/fetus to the placenta. In humans, there are two placental arteries continuous with the paired internal iliac arteries (hypogastric arteries) arising off the dorsal aortas. At birth this vessel regresses and form the remnant medial umbilical ligament.
  • placental cord - (umbilical cord) The placental cord is the structure connecting the embryo/fetus to the placenta. It is initially extra-embryonic mesoderm forming the connecting stalk within which the placental blood vessels (arteries and veins) form. In human placental cords the placental blood vessels are initially paired, later in development only a single placental vein remains with a pair of placental arteries. This structure also contains the allantois, an extension from the hindgut cloaca then urogenital sinus. Blood collected from the placental cord following delivery is a source of cord blood stem cells.)
  • placental diameter - is measured in the transverse section by calculating the maximum dimensions of the chorionic surface.
  • placental growth factor - (PlGF) A growth factor of the vascular endothelial growth factor (VEGF) family, released from the placental trophoblast cells and other sources that stimulates blood vessel growth.
  • placental malaria - The malarial infection of the placenta by sequestration of the infected red blood cells. This condition can be common in regions where malaria is endemic with women carrying their first pregnancy (primigravida).
  • placenta membranacea - rare placental abnormality characterized by the presence of chorionic villi directly attached to and covering the fetal membranes. Placenta Membranacea
  • placenta percreta - abnormal placentation where the villi penetrate myometrium.
  • placenta previa - placenta overlies internal os of uterus, abnormal bleeding, may require cesarian delivery.
  • placental thickness - is measured at its mid-portion from the chorionic plate to the basilar plate, on a longitudinal plane (less than 4 cm at term). Excludes any abnormalities (fibroids, myometrial contractions, or venous lakes). The placental thickness approximates in millimeters to the weeks of gestation.
  • placental vein - (umbilical vein) In placental animals, the blood vessels which develop within the placental cord carrying relatively oxygenated blood from the placenta to the embryo/fetus. In humans, there are initially two placental veins which fuse to form a single vein. The resence of paired veins in the placental cord can be indicative of developmental abnormalities.
  • placentophagia - Term used to descrbe the maternal ingestion of afterbirth materials (placental membranes and amniotic fluid) that can occur following mammalian parturition (birth).
  • primary villi - (primary chorionic villi) Term describing the earliest stage of embryonic placenta development. In humans, the conceptus during week 2 this first stage of chorionic villi development consists of only the trophoblastic shell cells (syncitiotrophoblasts and cytotrophoblasts) forming finger-like extensions into maternal decidua. Initially these finger-like projections cover the entire surface of chorionic sac and later become restricted to the placental surface. The villi stages are ongoing as the placenta continues to grow through both the embryonic and fetal development.
  • pre-eclampsia - During pregnancy a combination of high blood pressure, protein in urine and fluid retention resulting in maternal sudden excessive swelling of the face, hands and feet. Eclampsia is the subsequent development of convulsions, kidney failure, liver failure, clotting problems or mortality.
  • secondary villi - (secondary chorionic villi) Term describing the second stage of embryonic placenta development. In humans, the conceptus during week 3 onward this stage of chorionic villi development consists of the trophoblastic shell cells (syncytiotrophoblast and cytotrophoblasts) filled with extraembryonic mesoderm forming finger-like extensions into maternal decidua. Initially these finger-like projections cover the entire surface of chorionic sac and later become restricted to the placental surface. The villi stages are ongoing as the placenta continues to grow through both the embryonic and fetal development. Placental villi stages: primary villi - secondary villi - tertiary villi
  • syncytiotrophoblast - A multinucleated cell currently thought to form by the fusion of another trophoblast cell the cytotrophoblasts, within the trophoblast layer (shell) of the implanting conceptus. In early development, these cells mediate implantation of the conceptus into the uterine wall and secrete the hormone (human Chorionic Gonadotrophin, hCG) responsible for feedback maintainance of the corpus luteum (in maternal ovary) and therefore maintaining early pregnancy.
  • trophoblast - (trophectoderm, Greek, trophe = "nutrition" and blast = a primordial cell) cells that firstly support adplantation, implantation and endocrine support of pregnancy. Contribute to the extraembryonic tissues, fetal placenta and membranes. Initially form 2 populations individual cytotrophoblast cells and their fused multinucleate syncytiotrophoblast cells.
  • umbilical cord (placental cord) fetal attachment cord 1-2 cm diameter, 30-90cm long, covered with amniotic attached to chorionic plate, umbilical vessels (artery, vein) branch into chorionic vessels. Vessels anastomose within the placenta.
  • vasculogenesis - formation of first blood vessels by differentiation of pluripotent mesenchymal cells (extraembryonic mesoderm) followed by angiogenesis which is the development of new vessels from already existing vessels.
  • villi - Plural of villus, which is a thin projection from a surface. The term in development is used to describe the individual functional units together of the fetal placenta.
  • virus - small infectious agents that may cross the placental barrier. Can infect embryo and/or placenta and cause developmental abnormalities. (e.g. cytomegalovirus, rubella, measles).
  • Wharton's jelly - Placental cord (umbilical cord) gelatinous connective tissue composed of myofibroblast-like stromal cells, collagen fibers, and proteoglycans. Increases in volume (myxomatous, connective tissue embedded in mucus) at parturition (birth) to assist closure of placental blood vessels. Matrix cells from Wharton's jelly have recently been identified as a potential source of mesenchymal stem cells (MSC), also called mesenchymal stromal cell. This placental cord substance is named after Thomas Wharton (1614-1673) an English physician and anatomist who first described this placental tissue.
Other Terms Lists  
Terms Lists: ART | Birth | Bone | Cardiovascular | Cell Division | Gastrointestinal | Genetic | Hearing | Heart | Immune | Integumentary | Neural | Oocyte | Palate | Placenta | Renal | Respiratory | Spermatozoa | Ultrasound | Vision | Historic | Glossary

Glossary Links

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols

Cite this page: Hill, M.A. 2018 Embryology Placenta - Abnormalities. Retrieved January 18, 2018, from

What Links Here?
© Dr Mark Hill 2018, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G