Renal System - Abnormalities

Embryology - 18 Apr 2024        Expand to Translate
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Introduction

Obstructive Defect of the Renal Pelvis

There are many different forms of renal development abnormalities associated with kidney, ureters, bladder and urethra. There are many genetic disorders associated with failure or abnormal renal development. Prenatal diagnosis of obstructive and renal agenesis/dysgenesis disorders are also important for early reproductive decisions by the parents. For example, with bilateral renal agenesis, failure of both kidneys to development, is not compatible with fetal/neonatal survival.

Because of their close developmental association, often described as the urogenital system, there can be an associated genital abnormalities.

There are also a range of branchiootorenal spectrum disorders (branchiootorenal syndrome and branchiootic syndrome) where both renal and auditory development are affected (for review see ).

Some Recent Findings

Trisomy 21 newborn

Congenital urological anomalies diagnosed in adulthood "Despite worldwide availability of prenatal ultrasound, many patients are diagnosed in adult life with congenital anomalies such as ureteropelvic junction obstruction (UPJO), undescended testicle (UDT), ureterocele, hypospadias, vesicoureteral reflux (VUR) and primary obstructing megaureter (POM)." Etv4 and Etv5 are required downstream of GDNF and Ret for kidney branching morphogenesis "Mice lacking both Etv4 alleles and one Etv5 allele show either renal agenesis or severe hypodysplasia, whereas kidney development fails completely in double homozygotes. We identified several genes whose expression in the ureteric bud depends on Etv4 and Etv5, including Cxcr4, Myb, Met and Mmp14. Thus, Etv4 and Etv5 are key components of a gene network downstream of Ret that promotes and controls renal branching morphogenesis."

More recent papers

This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on 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. More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Abnormal Development Renal <pubmed limit=5>Abnormal Development Renal</pubmed>

Australian Statistics

Statistics - Top Ten

Australian Data 1981-92

The ten most frequently reported birth defects in Victoria between 2003-2004.

1. Hypospadias
2. Obstructive Defects of the Renal Pelvis or Obstructive Genitourinary Defects
3. Ventricular Septal Defect
4. Congenital Dislocated Hip
5. Trisomy 21 or Down syndrome
6. Hydrocephalus
7. Cleft Palate
8. Trisomy 18 or Edward Syndrome - multiple abnormalities of the heart, diaphragm, lungs, kidneys, ureters and palate 86% discontinued.
9. Renal Agenesis/Dysgenesis - reduction in neonatal death and stillbirth since 1993 may be due to the more severe cases being identified in utero and being represented amongst the increased proportion of terminations (approximately 31%).
10. Cleft Lip and Palate - occur with another defect in 33.7% of cases.

International Classification of Diseases

The International Classification of Diseases (ICD) World Health Organization's classification used worldwide as the standard diagnostic tool for epidemiology, health management and clinical purposes. This is not a full listing of the renal abnormality classifications, only the major sub-headings that relate to development, use the Q60-Q64 links to see additional sub-sub-headings. Close association with the genital system abnormalities (Q50-Q56) means that the two can be related. Pre-existing maternal conditions (O10-O16) such as oedema, proteinuria and hypertensive disorders in pregnancy, can also impact upon development.

Links: Q60-Q64 Renal Detailed | Perinatal Period | Q50-Q56 Genital Detailed | ICD-10

Congenital malformations of the urinary system (Q60-Q64)

Links: Q60-Q64 Detailed

• Q60 Renal agenesis and other reduction defects of kidney Incl.: atrophy of kidney: congenital infantile congenital absence of kidney
• Q61 Cystic kidney disease Excl.: acquired cyst of kidney (N28.1) Potter's syndrome (60.6)
• Q62 Congenital obstructive defects of renal pelvis and congenital malformations of ureter
• Q63 Other congenital malformations of kidney Excl.: congenital nephrotic syndrome (N04.-)
• Q64 Other congenital malformations of urinary system

P00 Fetus and newborn affected by maternal conditions that may be unrelated to present pregnancy

Excl.: fetus and newborn affected by: maternal complications of pregnancy (P01.-) maternal endocrine and metabolic disorders (P70-P74) noxious influences transmitted via placenta or breast milk (P04.-)

• P00.0 Fetus and newborn affected by maternal hypertensive disorders Fetus or newborn affected by maternal conditions classifiable to O10-O11, O13-O16
• P00.1 Fetus and newborn affected by maternal renal and urinary tract diseases Fetus or newborn affected by maternal conditions classifiable to N00-N39

P96 Other conditions originating in the perinatal period

• P96.0 Congenital renal failure Uraemia of newborn

Links: Q60-Q64 Renal Detailed | Perinatal Period | Q50-Q56 Genital Detailed

Obstructive Renal Pelvis Defect

Renal outflow obstruction

Obstructive Renal Pelvis Defect (obstructive defects of the renal pelvis, uteropelvic junction obstruction, pelvo-uterero junction obstruction) is a term describing a developmental renal abnormality due to partial or complete blockage of the drainage of the kidney pelvis requiring surgical correction.

The blockage during development can be due to failure of recanalization of the outflow tract.

The blockage can have several anatomical causes including:

1. ureter twisting or bending
2. ureter compression by a blood vessel
3. malformations of the muscular wall

The blockage leads to an accumulation of urine in the affected region, with several potential effects: nephron damage from compression (hydronephrosis); decreased urine output leading to lack of amniotic fluid (oligohydramnios); respiratory development effects due to the lack of amniotic fluid. The most common type of obstruction is at the uteropelvic junction (UPJ), between the junction of the ureter and the kidney. Blockage lower as the ureter enters the bladder, the ureterovesicular junction (UVJ), usually involves only one kidney and the back flow enlarges the affected ureter (megaureter).

Renal Agenesis or Dysgenesis

Renal agenesis. DTPA scan shows agenesis of the right kidney.

Unilateral renal absence is relatively common and may be asymptomatic. In the complete form, bilateral absence, the child is not viable and dies within a few days of birth.

Features associated with this anomaly are:

• Oligohydramnios
• Amnion nodosum (small warty amnion with accretions of squamous cells on the inner wall). This is tangible evidence for oligohydramnios.
• Facial deformities: This results from uterine moulding around the head. The ears are low slung and simple, the mandible is small, the nose flattened and the eyes exhibit Pre-epicanthic folds. This is a horseshoe shaped flap of skin from the upper lid to the cheek in front of the epicanthus. (Downs syndrome has an epicanthic fold). Note that the genesis is occasionally incomplete allowing survival (e.g.) Causal factors are largely unknown although there is some familial predisposition. There has been described a mutation in the enzyme, heparan sulfate 2-sulfotransferase, that generates a similar phenotype in the mouse.

Note that upper G.I.T. obstruction is associated with POLYHYDRAMNIOS whereas failure of fetal micturition is associated with OLIGOHYDRAMNIOS with consequent firm uterine moulding on the fetus, leading to facial, locomotor and palatal deformities.

Renal agenesis. I.V. pyelography showing right renal agenesis (or dysplasia) (>). The right hip dysplasia is also shown (>>).

Links: OMIM - UROGENITAL ADYSPLASIA, HEREDITARY

Renal Fusion

Renal fusion (pathology specimen)

A Horseshoe.

Also described as Horseshoe kidney.

• fusion of the lower poles of the kidney.
• During migration from the sacral region the two metanephric blastemas can come into contact, mainly at the lower pole.
• The ureters pass in front of the zone of fusion of the kidneys.
• The kidneys and ureters usually function adequately but there is an increased incidence of upper urinary tract obstruction or infection.
• Some horseshoe variations have been described as having associated ureter abnormalities including duplications.

Renal-Adrenal Fusion

A rare anomaly of the upper pole of the kidney historically first described by Rokitansky in 1855. Intrarenal ectopic adrenal tissue can also occur and in such instances consist of adrenal cortical tissue with no adrenal medullary tissue. Other organ fusions can occur with splenogonadal fusion the most commonly reported.

Triad Syndrome

Also described as Prune Belly Syndrome.

The Triad is:

1. Agenesis of abdominal wall muscles
2. Bladder outflow obstruction
3. Bilateral undescended testes

The condition was first described by Frolichand then called "prune belly syndrome" as a descriptive, because the intestinal pattern is evident through the thin protruding abdominal wall in the infant.

Survival of the prune belly child depends on the number of functioning remaining nephrons at birth and the operability of the obstruction.

In some cases there are vestiges of muscle in the abdominal wall and it is not known whether this represents (a) destruction of muscle, or (b) failure of development of muscle. The causes of this malformation are little known, but maternal therapy with estrogens in the first trimester has been implicated frequently.

• 

  Hydronephrosis

• 

  Renal outflow obstruction

• 

  Prune belly

Polycystic Kidney Disease

Multicystic kidney

Multicystic kidney and histology

• diffuse cystic malformation of both kidneys
• cystic malformations of liver and lung often associated, Often familial disposition
• Two types
  • Infantile (inconsistent with prolonged survival)
  • Adult (less severe and allows survival)
• Autosomal dominant PKD disease - recently identified at mutations in 2 different human genes encoding membrane proteins (possibly channels)

Defects in the genes encoding PC1 or PC2 lead to aberrant gene transcription, cell proliferation, and ion secretion, which in turn result in the formation of fluid-filled cysts. As cysts balloon out from individual nephrons, their collective effect leads to the displacement of the normal renal parenchyma and the formation of a cyst-filled kidney with reduced functional capacity.

Cyst formation at the level of the cell, nephron, and kidney

Nephroblastoma (Wilms' Tumor)

Wilms tumor

• (nephroblastoma) Named after Max Wilms, a German doctor who wrote first medical articles 1899
• most common type of kidney cancer children
• WT1 gene - encodes a zinc finger protein
• Both constitutional and somatic mutations disrupting the DNA-binding domain of WT1 result in a potentially dominant-negative phenotype
• some blastema cells (mass of undifferentiated cells) persist to form a ‘nephrogenic rest’
• Most rests become dormant or regress but others proliferate to form hyperplastic rests
• any type of rest can then undergo a genetic or epigenetic change to become a neoplastic rest
• can proliferate further to produce a benign lesion (adenomatous rest) or a malignant Wilms’ tumour

Renal Cysts

The Bosniak classification system (I - IV) was designed to separate identified cystic renal masses by analysis of computed tomography (CT) features into surgical and nonsurgical categories. Named after Morton Bosniak, Yale University School of Medicine, the developer of this classification system.

1. Category I lesions are simple benign cysts showing homogeneity, water content, and a sharp interface with adjacent renal parenchyma, with no wall thickening, calcification, or enhancement.
2. Category II consists of cystic lesions with one or two thin (<=1 mm thick) septations or thin, fine calcification in their walls or septa (wall thickening > 1 mm advances the lesion into surgical category III) and hyperdense benign cysts with all the features of category I cysts except for homogeneously high attenuation. A benign category II lesion must be 3 cm or less in diameter, have one quarter of its wall extending outside the kidney so the wall can be assessed, and be nonenhancing after contrast material is administered.
3. Category IIF consists of minimally complicated cysts that need followup. This is a group not well defined by Bosniak but consists of lesions that do not neatly fall into category II. These lesions have some suspicious features that deserve followup to detect any change in character.
4. Category III consists of true indeterminate cystic masses that need surgical evaluation, although many prove to be benign. They may show uniform wall thickening, nodularity, thick or irregular peripheral calcification, or a multilocular nature with multiple enhancing septa. Hyperdense lesions that do not fulfill category II criteria are included in this group.
5. Category IV lesions with a nonuniform or enhancing thick wall, enhancing or large nodules in the wall, or clearly solid components in the cystic lesion. Enhancement was considered present when lesion components increased by at least 10 H.

Urorectal Septum Malformation

Urorectal septum malformation thought to be a deficiency in caudal mesoderm which in turn leads to the malformation of the urorectal septum and other structures in the pelvic region. Recent research has also identified the potential presence of a persistent urachus prior to septation of the cloaca (common urogenital sinus).

Clinically the condition is described as a urorectal septum malformation sequence (URSMS): female disorder of sexual development; ambiguous external genitalia; imperforate anus, vagina, and urethra; renal, colonic, and lumbosacral anomalies.

Renal Vascular Anomalies

There is an excellent recent 2010 review of renal vascular anomalies shown in adults using computed tomography. The images below are from that review.

Renal Arteries

Multiple renal arteries	Accessory renal artery

Renal Veins

Supernumerary right renal vein	Supernumerary right renal vein
Multiple right renal veins	Multiple right renal veins

Renal Vascular Anomalies: Multiple renal arteries | Accessory renal artery | Supernumerary right renal vein 1 | Supernumerary right renal vein 1 | Multiple right renal veins 2 | Multiple right renal veins 2 | Cardiovascular System Development

Bladder Exstrophy

Bladder_Exstrophy

• developmental abnormality associated with bladder development.
• origins appear to occur not just by abnormal bladder development, but by a congenital malformation of the ventral wall of abdomen (between umbilicus and pubic symphysis).
• There may also be other anomolies associated with failure of closure of abdominal wall and bladder (epispadias, pubic bone anomolies).

Bladder

• absent or small bladder - associated with renal agenesis.

Ureterocele

The distal ureter balloons at the opening into the bladder and forms a sac-like pouch. Often associated with other ureter abnormalities.

Ureter and Urethra

Ureteral duplication. Frontal radiograph from an intravenous urogram study shows bilateral complete ureteral duplication.

• Ureter - Duplex Ureter, ectopic ureter

• Urethra - Urethral Obstruction and Hypospadias

Ectopic and dilated left ureter (small arrows) inserting ectopically into the obstructed left hemivagina (asterisk) on MR imaging in a 17-year-old girl.

See also Genital System - Abnormalities

References

Search Pubmed

Search Pubmed: Obstructive Renal Pelvis Defects | Renal Agenesis | hydronephrosis | Ureterocele

Terms

• bilateral renal agenesis - (BRA) failure of both kidney development and is not compatible with life and is associated with oligohydramnios and pulmonary hypoplasia.
• cystic dysplasia - term used in renal dysplasia if cysts are present.
• renal agenesis - term for a complete absence of renal development.
• renal dysgenesis - term for several forms of abnormal kidney development, which includes aplasia, hypoplasia, dysplasia, and cystic disease.
• renal aplasia - term for a rudimentary kidney without any functional nephrons.
• renal hypoplasia - term for a small non-dysplastic kidney that has less than the normal number of calyces and nephrons.
• renal dysplasia - term for focal, diffuse, or segmentally arranged primitive structures, specifically primitive ducts, resulting from abnormal metanephric differentiation. There can also be non-renal elements present.
• renal adysplasia - term is used when aplasia and severe dysplasia are aspects of phenotypic spectrum.
• unilateral renal agenesis - (URA) failure of a single kidney development, often asymptomatic if not detected by prenatal screening.

Glossary Links

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Cite this page: Hill, M.A. (2024, April 18) Embryology Renal System - Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Renal_System_-_Abnormalities

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G