Renal agenesis can develop as a component of a syndrome or as an isolated anomaly [1]. This congenital disorder is classified as unilateral or bilateral.

Unilateral renal agenesis

Renal agenesis is commonly unilateral with a predilection for males [2]. Individuals with only one kidney will likely remain asymptomatic [3] and achieve a normal life expectancy. Typically, the sole kidney enlarges to compensate for the absent kidney. This disorder is usually discovered incidentally.

Among the various urologic pathologies that are observed in patients with unilateral renal agenesis, contralateral vesicoureteral reflux is most frequent [4].

Bilateral renal agenesis

Babies with this type of renal agenesis will die in utero or within a few hours of life due to immature lungs and consequently respiratory failure [5]. These patients lack the complete development of kidneys and ureters and hence manifest with the interrelated complications of pulmonary hypoplasia and oligohydramnios.

Regarding the clinical presentation, patients exhibit the Potter sequence, which is characterized by extrarenal features such as wide-set eyes, epicanthal folds, flat nose, large low-set ears with absent cartilage, receding chin, and limb defects [6] [7]. Furthermore, there may be other systems that are involved in Potter syndrome. Among these are cardiac malformations [8] and abnormalities of the gastrointestinal [5] and genitourinary [9] tracts.

Pregnancy complications

A fetus with renal agenesis is at risk for intrauterine growth retardation (IUGR), breech presentation, and premature delivery.

• Periorbital Edema

  Homozygotes for this allele (hereafter, greb1l mutants) were readily recognized at 3 dpf by periorbital edema and pericardial effusions, consistent with a defect in ion and fluid homeostasis (16 embryos in a clutch of 109 embryos showed this phenotype [doi.org]

• Skin Lesion

  Although renal agenesis, hemihypertrophy and hyperpigmented macular skin lesions (skin naevuses) may be incidental findings, together they may form a variant of Klippel-Trenaunay-Weber syndrome, as in our case. [ncbi.nlm.nih.gov]

• Vaginal Bleeding

  A 27 year old female presented with two months history of continuous vaginal bleeding. [ncbi.nlm.nih.gov]

Routine widespread use of prenatal ultrasonography improves detection of renal agenesis and other conditions associated with it. Findings are likely to include oligohydramnios, absent kidney(s), absent bladder (particularly in bilateral renal agenesis), hypertrophy of the solitary kidney secondary to compensation (in a fetus with unilateral renal agenesis), and other abnormalities. Moreover, color doppler ultrasonography demonstrates the presence of the renal artery(ies) [10]. The presence of an ectopic kidney should be considered and ruled out [11].

Prenatal magnetic resonance imaging (MRI) may be useful for confirmation of bilateral renal agenesis when ultrasonography is not definitive [12].

A special procedure known as amnioinfusion can be used to evaluate low levels of amniotic fluid [13].

Postnatal tests

Neonatal laboratory studies include serum electrolyte measurements, renal function tests, complete blood count (CBC), and urinalysis. Additionally, levels of urine sodium, creatinine,and osmolality may be warranted.

Various imaging modalities such as abdominal ultrasonography, MRI, and computed tomography (CT) can be performed on the neonate to confirm the congenital defects identified prenatally. Procedures such as voiding cystourethrography and nuclear renal scanning are used to evaluate the genitourinary tract. Additionally, a chest x-ray is used to assess pulmonary hypoplasia.

Genetic tests

All pregnant women carrying fetus(es) with congenital defects should undergo genetic counseling and possibly testing. The family history is a significant component of the workup.

Very importantly, chromosomal analysis for various trisomies and conditions are indicated in infants with a clinical picture suggestive of a genetic disorder [1].

• Small Kidney

  MATERIAL AND METHODS: In this single center, cross-sectional study, a total of 55 patients (39 (% 70.9) with unilateral small kidney and 16 (%29.1) with renal agenesis) were included. The median age was 35 (21-50) years. [ncbi.nlm.nih.gov]

  A small kidney may produce arterial hypertension or chronic urinary tract infection or even possibly result in a renal neoplasm. Two other points should be remembered in assisting one in making the correct diagnosis. [fetalsono.com]

• Unilateral Small Kidney

  MATERIAL AND METHODS: In this single center, cross-sectional study, a total of 55 patients (39 (% 70.9) with unilateral small kidney and 16 (%29.1) with renal agenesis) were included. The median age was 35 (21-50) years. [ncbi.nlm.nih.gov]

• Pericardial Effusion

  Homozygotes for this allele (hereafter, greb1l mutants) were readily recognized at 3 dpf by periorbital edema and pericardial effusions, consistent with a defect in ion and fluid homeostasis (16 embryos in a clutch of 109 embryos showed this phenotype [doi.org]

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3. Woolf AS, Hillman KA. Unilateral renal agenesis and the congenital solitary functioning kidney: developmental, genetic and clinical perspectives. BJU Int. 2007; 99(1):17–21.
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5. Khatemi F. Potter's Syndrome: A Study of 15 patients. Arch Iranian Med, 2004; 7(3):186-9.
6. Potter E. Bilateral renal agenesis. J Pediatr. 1946;26:68–76.
7. Potter E. Bilateral absence of ureter and kidney. Obstetrics and Gynecology. 1965; 25: 3-12.
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11. Uematsu M, Sakamoto O, Nishio T, et al. A case surviving for over a year of renal tubular dysgenesis with compound heterozygous angiotensinogen gene mutations. Am J Med Genet A. 2006; 140(21):2355-60.
12. Gęca T, Krzyżanowski A, Stupak A, et al. Complementary role of magnetic resonance imaging after ultrasound examination in assessing fetal renal agenesis: a case report. J Med Case Rep. 2014;8(1):96.
13. Fisk NM, Ronderos-Dumit D, Soliani A, et al. Diagnostic and therapeutic transabdominal amnioinfusion in oligohydramnios. Obstet Gynecol. 1991; 78(2):270-8.