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. This current page lists some abnormalities associated with the placenta and also provides links to other resources. (See also Week 2 Abnormalities Hydatidiform mole) |
Model of Placenta Previa |
Page Links: Introduction | Placental Abnormalities | Placenta Accreta | Placenta Percreta | Placenta Previa | Vasa Previa | Abruptio Placenta | Pre-eclampsia | Cord Abnormalities | Haemolytic Disease of the Newborn | Erythroblastosis | Placental Malaria | Placental Membranes | Placental Twins | Placental Mesenchymal Dysplasia | Placental Pathology | OMIM Database | References | Research Labs | Glossary Link | Placenta Terms |
The following represent abnormalities related to placenta, either in position or degree of implantation within the uterus: Placenta Accreta | Placenta Increta | Placenta Percreta | Placenta Previa | Abruptio Placenta | Pre-eclampsia See also WebPath images: Abnormalities of placentation, diagram |
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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. See WebPath images: Placenta accreta, microscopic References: Zaideh SM, Abu-Heija AT, El-Jallad MF. [See Related Articles] Placenta praevia and accreta: analysis of a two-year experience. Gynecol Obstet Invest. 1998 Aug;46(2):96-8. < |
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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 cases. |
Model of Placenta Previa (Italian terracotta from 1770) (More? Development History - 1770 - Obstetric Models) |
In this placenatal abnormality, the placenta overlies internal os of uterus, essentially covering the birth canal. This condition occurs in approximately 1 in 200 to 250 pregnancies. In the third trimester and at term, abnormal bleeding can require cesarian delivery and can also lead to Abruptio Placenta (More? Abruptio Placenta) Ultrasound screening programs during 1st and early 2nd trimester pregnancies now include placental localization. Diagnosis can also be made by transvaginal ultrasound. |
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References: Bhide A, Thilaganathan B. [See Related Articles] Recent advances in the management of placenta previa. Curr Opin Obstet Gynecol. 2004 Dec;16(6):447-51. Links: WebPath- Placenta previa, gross | WebPath- Placenta increta, gross | American Pregnancy Organization - Placenta Previa |
Vasa previa (vasa praevia) placental abnormality where the fetal vessels lie within the membranes close too or crossing the inner cervical os (opening). This occurs normally in 1:2500-5000 pregnancies and leads to complications similar too those for Placenta Previa.
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.
Some recent evidence of successful in utero laser ablation of type II vasa previa at 22.5 weeks of gestation.
References:
Oyelese Y, Smulian JC. Placenta previa, placenta accreta, and vasa previa. Obstet Gynecol. 2006 Apr;107(4):927-41.
Quintero RA, Kontopoulos EV, Bornick PW, Allen MH. [See Related Articles] In utero laser treatment of type II vasa previa. J Matern Fetal Neonatal Med. 2007 Dec;20(12):847-51.
Retroplacental blood clot formation, abnormal hemorrhage prior to delivery.
References
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." (see Skjaerven R. 2005)
References
Links: Australia Australian Action on Pre-eclampsia (voluntary organisation providing support and information to families who have suffered from pre-eclampsia) |
Due to a similar "grape-like" placental appearance, this rare disorder placental mesenchymal dysplasia has been mistaken both clinically and macroscopically for a partial hydatidiform molar pregnancy. (More? Week 2 - Hydatidiform mole) The disorder also has a high incidence of both intrauterine growth restriction (IUGR) and fetal death.
(More? Parveen Z, Tongson-Ignacio JE, Fraser CR, Killeen JL, Thompson KS. Placental mesenchymal dysplasia. Arch Pathol Lab Med. 2007 Jan;131(1):131-7.)
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.
Rare umbilical cord torsion, even without knot formation can also affect placental blood flow, even leading to fetal demise.
See WebPath images: umbilical cord knot 1 | umbilical cord knot 2 | Pseudoknot of umbilical cord, gross | Torsion of umbilical cord, gross | Torsion of umbilical cord, with fetal demise, gross |
References
Umbilical cord torsion
Hallak M, Pryde PG, Qureshi F, Johnson MP, Jacques SM, Evans MI. Constriction of the umbilical cord leading to fetal death. A report of three cases. J Reprod Med. 1994 Jul;39(7):561-5. Review.
This disease is also called fetal erythroblastosis
An immune problem from fetus Rh+ /maternal Rh-, leakage from fetus causes anti-Rh antibodies, which is then dangerous for a 2nd child.
Malarial infection of the placenta by sequestration of the infected red blood cells leading to low birth weight and other effects. (4 types of malaria 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).
Note also that there is also an increased susceptibility of pregnant women to malaria infection.
(More? Brown University Maternal Malaria)Review References
There are few documented abnormalities associated with fetal membranes. 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.
This relates to twins sharing a placenta (More? Twinning)
For linked information see Virtual Hospital - Twins: A Parents' Guide and the OMIM entries TWINNING, MONOZYGOTIC TWINNING, DIZYGOTIC.
Click the listed term to carry out a search of the OMIM database, all fields (number in brackets shows the number of search results Mar2005).
Chronic Villitis - 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) - maternal blood-filled space is filled with CD68-positive histiocytes and an increase in fibrin, occuring more commonly in the first trimester.
Meconium Myonecrosis - prolonged meconium exposure leads to toxic death of myocytes of placental vessels (umbilical cord or chorionic plate).
Neuroblastoma - a fetal malignancy that leads to an enlarged placenta, with tumor cells in the fetal circulation and rarely in the chorionic villi.
Thrombophilias - (protein C or S deficiency, factor V Leiden, sickle cell disease, antiphospholipid antibody) can generate an increased fibrin/fibrinoid deposition in the maternal or intervillous space, this can trap and kill villi. (Data from:
Roberts DJ. Placental pathology, a survival guide. Arch Pathol Lab Med. 2008 Apr;132(4):641-51.)
Roberts DJ. Placental pathology, a survival guide. Arch Pathol Lab Med. 2008 Apr;132(4):641-51.
Oyelese Y, Smulian JC. Placenta previa, placenta accreta, and vasa previa. Obstet Gynecol. 2006 Apr;107(4):927-41.
Quintero RA, Kontopoulos EV, Bornick PW, Allen MH. [See Related Articles] In utero laser treatment of type II vasa previa. J Matern Fetal Neonatal Med. 2007 Dec;20(12):847-51.
Victor Chang Cardiac Research Institute - Dr Sally Dunwoodie
"Dr Sally Dunwoodie has generated null mutant mouse lines for Cited1 and Cited2 (CBP/p300-Interacting Transactivators with glutamic acid (E)/aspartic acid (D)-rich carboxyl terminal domain) each of these genes is required for normal embryonic development. The predominant defect is in the placenta of the Cited1 null conceptus."
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Journal Placenta "Placenta is the international forum providing up to the minute information on all scientific and clinical investigations pertaining to placental research and their applications."
American Pregnancy Organization Placenta Previa
Brown University Maternal Malaria
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This page introduces some of the abnormalities associated with placenta development, structure and function.
The definition of ourselves as "placental mammals" shows just how important the placenta is to our own growth and development. The placenta is a multifunctional organ with both fetal and maternal origins.
Please email Dr Mark Hill if you wish to make a comment about this current project.
