Clinical Relevance: Congenital Abnormalities of the Kidneys
Pelvic Kidney
In utero, the kidneys develop in the pelvic region and ascend to the lumbar retroperitoneal area. Occasionally, one of the kidneys can fail to ascend and remains in the pelvis – usually at the level of the common iliac artery.
Horseshoe Kidney
A horseshoe kidney (also known as a cake kidney or fused kidney) is where the two developing kidneys fuse into a single horseshoe-shaped structure.
This occurs if the kidneys become too close together during their ascent and rotation from the pelvis to the abdomen – they become fused at their lower poles (the isthmus) and consequently become ‘stuck’ underneath the inferior mesenteric artery.
This type of kidney is still drained by two ureters (although the pelvices and ureters remain anteriorly due to incomplete rotation) and is usually asymptomatic, although it can be prone to obstruction.
Clinical Relevance - Renal Cell Carcinoma
The kidney is often the site of tumor development, most commonly renal cell carcinoma.
Due to the segmental vascular supply of the kidney it is often feasible to ligate the relative arteries and veins and remove the tumour with a safe zone of healthy surrounding parenchyma (partial nephrectomy) without removing the entire kidney or compromising its total vascular supply by ischaemia.