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An ectopic kidney, also known as renal ectopia, is a congenital renal anomaly characterized by the abnormal location of one or both of the kidneys.
They can occur in several forms:
The estimated incidence of an ectopic kidney varies by location:
- one normal and one pelvic kidney - 1 in 3,000
- crossed renal ectopia - 1 in 7,000
- ectopic thoracic kidney - 1 in 13,000
- solitary pelvic kidney - 1 in 22,000
Patients are most often asymptomatic. Normal pathology (e.g. infection, calculus) can affect ectopic kidneys, leading to non-classical abdominal pain. Ectopic kidneys are also prone to traumatic injury due to their abnormal location in the lower abdomen, pelvis or thorax.
During normal embryological development, there is cephalic migration of the kidneys to their normal retroperitoneal location and an ectopic location is a result of arrested migration.
The kidney during its normal ascent has multiple aortoiliac branches, which degenerate when the kidney reaches its normal location. Here they develop new renal branches from the aorta. However, during an arrested ascent the ectopic kidney tends to retain some of the older aortoiliac vessels.
- multicystic dysplasia in a fused or unfused crossed kidney
- patent urachus
- ectopic ureteral orifice
- vesicoureteric reflux
- vaginal agenesis
- pelviureteric junction obstruction
- multicystic dysplasia
- variations may be in the number, position, shape and size or the rotation of kidney(s), calyces, ureter(s) or bladder
- may be associated with anomalies of the vertebral column, lower gastrointestinal tract, genital tract or spinal cord and meninges
This is frequently the first modality to diagnose the ectopic kidney, which most often is incidentally detected.
Contrast-enhanced CT scan depicts the vascular and non-vascular anatomy
IVP and MRI
May additionally help in the functional and structural assessment
Treatment and prognosis
Treatment options vary based on whether there are symptoms or complications. If an obstruction is present, surgery may be required for correction of the position of the kidney to allow better drainage of urine. In presence of extensive renal damage, nephrectomy is indicated.
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