Menstruation Confounding the Correct Interpretation of 99m Tc-RBC Bleeding Scan

99m Tc-RBC bleeding scan in a 17-year-old adolescent girl showed an increased focal activity in the pelvis. However, SPECT/CT showed that this activity was located in the uterus, which was considered a normal variant considering that the patient was in her fourth day of the menstrual period. Subsequent 99m TcO 4- Meckel scan showed the typical characteristic of ectopic gastric mucosa in the small bowel. Postsurgical pathology confirmed the diagnosis of ectopic gastric mucosa. This case suggested the menstrual period uterus should be included as differential diagnosis of 99m Tc-RBC scan.