Persistent Colonic Activity on 99mTc-MDP Whole Bone Scintigraphy Revealing a Complex Ureterorectal Fistula.

Yu, Chang-Ching; Teng, Hui-Chung; Shen, Daniel Hueng-Yuan; Lee, Ming-Chan; Chan, Hung-Pin · Clin Nucl Med · 2026

case_report · Level V

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Abstract

Intense bowel activity on 99mTc-MDP bone scintigraphy is often dismissed as urinary contamination or radiopharmaceutical instability, but persistent uptake should prompt an anatomic search. A 68-year-old woman with metastatic cervical squamous cell carcinoma after radical pelvic surgery underwent bone scintigraphy for suspected left-foot metastasis. Images showed sacral/pelvic metastases, benign-appearing calcaneal uptake, and organized colonic activity. Contrast-enhanced CT revealed a complex fistulous tract connecting the left distal ureter, vaginal stump, rectum, and sigmoid colon. Follow-up pelvic SPECT/CT localized persistent activity to the rectosigmoid lumen, confirming fistula-related intraintestinal urine. Recognition redirected interpretation from artifact to actionable urinary-enteric fistula with clinical implications.