An Unusual Case of Flank Pain Late in Life: A Case Report.

Abnormalities in renal fusion represent a subset of congenital anomalies of the kidneys and urinary tract (CAKUT). Horseshoe kidneys (HSKs) are the fusion of kidneys at their lower poles. It is the most common form of CAKUT. Symptoms are usually subtle. The diagnosis is usually made incidentally during childhood. Rarely does an HSK become symptomatic later in life. We present the case of an 88-year-old female with a history of HSK who presented to the emergency department (ED) with a three-week history of left-sided flank pain, intermittent nausea, and reduced urine output. Her inpatient workup included imaging that revealed an HSK and bilateral hydronephrosis, which was more prominent on the left. The onset of symptoms for an HSK late in life is extremely rare.