renal agenesis

Kongenitale
Einzelniere rechts, welche kompensatorisch sehr groß ist.
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Infant with
prenatal diagnosis of left multicystic dysplastic kidney. Sagittal US of the left renal fossa (above) demonstrated that no left kidney was present in the left renal fossa or pelvis. Transverse ultrasound of the bladder (below) demonstrated a cystic structure adjacent to the left side of the bladder. The diagnosis was left kidney agenesis and a left seminal vesicle cyst, which is Zinner syndrome.
pediatricimaging.org • CC-by-nc-sa 4.0
Zinner
Syndrome. (a-b) showing retrovesical hypodense lesion with macrolobulated contour(star), and hypodense tubular structure was thought to be a remnant ureteric bud (arrow); absence of right kidney.
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Congenital
seminal vesicle cyst in Zinner syndrome. CT with coronal reformation showing absence of the right kidney and reduced size of the left kidney
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Congenital
seminal vesicle cyst in Zinner syndrome. The liver is shown. The right kidney is not seen in its usual location.
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Herlyn-Werner-Wunderlich
syndrome. Absence of the right kidney.
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Colonic
duplication in adult. Coronal CT view demonstrates genitourinary abnormality: left kidney absence.
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Infected
gartner duct cyst. Coronal MPR image showed a left renal agenesis and a right enlarged kidney.
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Newborn with
abnormal prenatal ultrasound. Sagittal US of the right kidney shows a lobulated renal contour along the anterior aspect of the right kidney. The left kidney was absent.The diagnosis was renal fetal lobulations in a patient with a solitary right kidney.
pediatricimaging.org • CC-by-nc-sa 4.0
Infant with
suspected congenital anomaly of the urinary tract. AP image from the nephrogram phase of a vintage intravenous pyelogram shows a dense nephrogram in the right renal fossa representing the right kidney with contrast draining down the right ureter and filling the bladder. There is no nephrogram noted in the left renal fossa.The diagnosis was agenesis of the left kidney.
pediatricimaging.org • CC-by-nc-sa 4.0
Radiopaedia • CC-by-nc-sa 3.0 • de

Renal agenesis refers to a congenital absence of one or both kidneys. If bilateral (traditionally known as the classic Potter syndrome) the condition is fatal, whereas if unilateral, patients can have a normal life expectancy.

Epidemiology

Unilateral renal agenesis affects approximately 1 in 500 live births while bilateral agenesis is less common affecting approximately 1 in 4000 live births. There may be a slightly greater male predilection.

Clinical presentation

If renal agenesis is unilateral and isolated then patients are asymptomatic. Unless identified on antenatal screening, then it is found incidentally when the abdomen is imaged for other reasons. Occasionally patients with unilateral renal agenesis, develop secondary hypertension.

Those with bilateral renal agenesis often have additional birth defects, both associated with, and a result of the absence of kidneys. With no kidneys, the fetus is unable to produce urine, which is necessary to form amniotic fluid resulting in anhydramnios. As a result, severe oligemia is present with the main resultant abnormality being pulmonary hypoplasia.

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Pathology

The etiology in many cases of renal agenesis is currently unknown but is thought to be multifactorial. An early vascular insult to the developing ureteric bud has been proposed .

Embryologically renal agenesis results from a failure of the proper development of the metanephros (the future definitive adult kidney) resulting in the complete absence of a renal structure. This is thought to occur at around early pregnancy (~6-7 weeks). Abnormalities in the mesonephros may result not only in renal agenesis (due to the absence of induction of the metanephros by the ureteral bud) but also internal genital malformations (due to the failure of the Wolffian and Mullerian duct to develop or to involute).

Associations

Renal agenesis can be associated with a number of chromosomal abnormalities including:

Unilateral renal agenesis may have other associated birth defects (most commonly, involving the genitourinary system). Such include:

Other associations with unilateral renal agenesis include:

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Radiographic features

Antenatal ultrasound

With the widespread use of antenatal ultrasound, renal agenesis can be identified in utero, although the presence of normal amounts of amniotic fluid and urine in the bladder results in the diagnosis being frequently missed, unless specifically and routinely looked for. Features include :

  • absent kidney
  • absent ipsilateral renal artery
  • compensatory hypertrophy of the contralateral (opposite) kidney
  • the term lying down adrenal sign as been ascribed to the elongated appearance of the adrenal not normally molded by the adjacent kidney
  • care must be taken not to mistake the low lying adrenal gland (large in fetuses) for a kidney
  • careful examination of the rest of the abdomen should be carried out to ensure that an ectopic kidney is not present (more common than renal agenesis) as well as of the 'single' kidney to ensure it does not represent crossed fused renal ectopia. 
  • color Doppler interrogation may aid in showing absence of renal arteries

If renal agenesis is bilateral then features are much more dramatic:

Postnatal ultrasound, CT and MRI

All imaging modalities will demonstrate the absence of a kidney, with the associated hypertrophy of the single kidney. Again, care must be taken not to misinterpret crossed fused renal ectopia for renal agenesis.

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Treatment and prognosis

Most individuals with unilateral renal agenesis lead normal lives although there is an increased risk of renal infections, nephrolithiasis, hypertension and/or renal failure. No specific treatment is necessary.

Bilateral agenesis is lethal with pulmonary hypoplasia being the most common cause of death. Bilateral renal agenesis is said to carry a recurrence risk of 3% for sporadic cases.

Differential diagnosis

It is important to differentiate between renal agenesis and a small atrophic kidney, and, of course, to ensure that the kidney is actually missing (i.e. check for a pelvic ectopic kidney or crossed fused renal ectopia).

Provided the remaining kidney is normal, and the other kidney is truly absent, then the only real differential is that of a previous nephrectomy.

Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu einseitige Nierenagenesie:
angeborene
renale Anomalien
www.eurorad.org • CC by-nc-sa-4.0
Poland-Syndrom
 
Wikipedia • CC BY-SA 4.0
Mikrodeletionsyndrom
22q11
pediatricimaging.org • CC-by-nc-sa 4.0
Rubinstein-Taybi-Syndrom
 
scoliosisjournal.biomedcentral.com • CC-by-2.0
gekreuzte
Nierendystopie mit Verschmelzung
pediatricimaging.org • CC-by-nc-sa 4.0
Wolf-Hirschhorn-Syndrom
 
Wikipedia • CC BY-SA 3.0
Zinner-Syndrom
 
www.eurorad.org • CC by-nc-sa-4.0