Bilateral Kidney Malrotation: Congenital Origin
Yes, malrotation of bilateral kidneys is definitively a congenital finding that occurs during embryonic kidney development. 1
Embryological Basis
Renal malrotation represents a failure of the normal 90-degree medial rotation that kidneys undergo during their ascent from the pelvis to the lumbar region during fetal development. 2 This developmental anomaly occurs in utero and is present at birth, making it by definition a congenital malformation.
- Congenital anomalies of the kidney and urinary tract (CAKUT) encompass malrotation as part of their spectrum and represent approximately 30% of all prenatally diagnosed malformations. 1
- Malrotation can occur unilaterally or bilaterally and may be isolated or associated with other renal positional anomalies such as ectopia. 3, 4
Clinical Significance and Associated Risks
While congenital in origin, bilateral malrotation carries important clinical implications:
- Increased susceptibility to recurrent urinary tract infections due to altered drainage patterns and potential urinary stasis. 3
- Higher risk of vesicoureteral reflux and subsequent kidney infection. 3
- Predisposition to recurrent renal stones from impaired urinary drainage. 3
- Increased vulnerability to renal injury due to abnormal positioning. 3
Diagnostic Considerations
- Malrotation is frequently discovered incidentally during imaging for unrelated conditions, as many cases remain asymptomatic. 4
- Recurrent urinary tract infections without apparent cause should prompt investigation for underlying renal anomalies including malrotation. 3
- Ultrasound or CT imaging can definitively diagnose malrotation by demonstrating abnormal orientation of the renal pelvis (often facing anteriorly, laterally, or superiorly rather than medially). 3, 2
Associated Anomalies
Bilateral malrotation may occur in isolation or as part of more complex congenital patterns:
- Can coexist with renal ectopia, lobulated kidneys, and vascular variants (multiple renal arteries). 4, 2
- May be associated with other CAKUT manifestations or, rarely, with non-renal congenital anomalies. 1, 5
- The presence of bilateral malrotation warrants comprehensive evaluation for other urogenital and systemic anomalies. 6, 7
Critical Clinical Pitfall
Do not dismiss recurrent urinary symptoms in patients with known or suspected renal malrotation as simple infections. Early recognition and appropriate imaging can prevent progression to end-stage renal failure, which carries higher risk in patients with congenital renal anomalies. 3