Bowel visualization on the lymphoscintigraphy images of a bladder cancer patient due to inadvertent injection of the tracer in the rectal wall.

The effectiveness of the sentinel lymph node mapping in patients with Urothelial carcinoma of the bladder is under investigation. Single photon emission computed tomography (SPECT/CT) and intraoperative sentinel node biopsy using gamma probe are performed to detect the exact location of the sentinel lymph node to be dissected during the surgery. In this case report, a 73-year old man with high grade urothelial carcinoma was referred to our nuclear medicine department for SPECT/CT, four hours after injection of the radiotracer through cystoscopy. SPECT/CT could not reveal any sentinel node; however, one sentinel lymph node was detected and harvested in the right external iliac region during surgery. SPECT/CT revealed unusual accumulation of tracer in large bowel which was due to severe adhesion of rectum and bladder, and inadvertent injection of the radiotracer into the rectal wall. During the sentinel lymph node procedure, the tracer should be injected with extreme caution and lymphoscintigraphy post injection may help detection of any injection failures.