Learning Objectives: Review normal kidney development and embryology Understand spectrum of renal fusion abnormalities, associated genitourinary abnormalities, and their clinical manifestations Recognize imaging findings and important associations Kidney Development and Abnormalities: The metanephric blastema becomes the functioning kidney and the ureteric bud develops into the ureters and upper collecting system. Typical kidney development begins at 4 weeks gestation. Over 4-7 weeks gestations, the developing kidneys rise from the sacrum to the abdomen moving apart from each other and rotating medially with final positioning at week 9. Renal positioning defects include malrotation which is abnormal rotation of the kidney along its long axis. The hilum often faces anteriorly, as the kidney fails to medially rotate during ascent. Ectopic kidneys are position defects where the kidneys are not located in the renal fossa. Renal ectopia can be simple, wherein the kidney remains ipsilateral, or crossed, wherein the kidney is located contralateral to the distal ureter insertion. Pelvic kidney is the most common simple ectopia. Ectopic kidneys may coexist with fusion defects. Associated symptoms include vesicoureteral reflux, increased urinary tract infections, and renal calculi formation. The horseshoe kidney is the most common congenital partial renal fusion abnormality (1/400 live births with male predilection). Case Report: Our case report had a prenatal diagnosis of absent left kidney and postnatal diagnosis of imperforate anus. Ultrasound revealed left to right crossed fused renal ectopia. Voiding cystourethrogram demonstrated additional abnormalities in the genitourinary tract, including a fistulous connection between the bladder and uterine segment/vagina and bifid appearance of the uterus with bilateral grade II vesicoureteral reflux. MRI redemonstrated left-to-right crossed fused renal ectopia and vesicovaginal/rectovaginal fistulas. Conclusion Cross fused renal ectopia is part of a spectrum of congenital genitourinary abnormalities and are common in prenatal assessment. Read More

Meeting name: SPR 2022 Annual Meeting & Postgraduate Course , 2022

Authors: Kariher Julia, Duden Peter, Clark Meghan, Hook Marcus

Keywords: Cross fused renal ectopia, Renal, Embryology