False-Positive Results of a Gastrointestinal Bleeding Study Caused by an Ectopic Kidney

A 64-year-old woman with a history of repeated bleeding episodes in the previous 4 years had several days of lower gastrointestinal bleeding and a low hematocrit concentration. Despite intensive searching (colonoscopy, arteriography, and upper gastrointestinal tract endoscopy), the site of the bleeding was not identified, and Tc-99m–labeled RBC scintigraphy was performed. Immediately after injection of the radiopharmaceutical, significant activity was visualized in the upper abdomen. Subsequent Tc-99m MAG3 renal scintigraphy showed that the activity was secondary to an ectopic right kidney, which was confirmed by ultrasound.