Unsuccessful foley catheterization had an unexpected explanation.

Background: Foley catheterization is a simple procedure routinely performed during many obstetric and gynecologic procedures. Failure to adequately drain the bladder with catheter insertion should prompt further investigation to minimize morbidity to the patient.

Case: After repeated attempts to place a Foley catheter during a cesarean section, the urinary bladder did not drain. Postoperatively, it was found that the catheter was positioned inside the left ureter, and cystoscopy confirmed an ectopic ureter inserting into the proximal urethra.

Conclusions: This case presents an unusual cause of oliguria in an operative patient requiring Foley catheterization. An ectopic ureteral orifice should be considered in the differential diagnosis of a patient presenting with unexplained oliguria or anuria and failure to decompress the bladder with catheter placement.