Suspected microscopic ureteral injury detected by time-dependent CT attenuation elevation in ascites: A novel diagnostic insight from ultra-late dynamic imaging.

Purpose: To report a case of suspected ureteral injury following gynecologic surgery, in which a temporal increase in computed tomography (CT) attenuation values of ascitic fluid in the pouch of Douglas observed during the ultra-late phase of dynamic CT imaging aided in diagnosis. Case: A woman in her 40s, gravida 0, para 0, with a history of total laparoscopic hysterectomy, bilateral oophorectomy, and left ovarian cystectomy performed two years earlier at another institution for uterine fibroids, presented to our department with severe lower abdominal pain. Imaging with CT and MRI revealed a 10 cm pelvic mass and hemoperitoneum, prompting emergency laparoscopic surgery. Intraoperatively, a ruptured right ovarian endometriotic cyst was identified, and a right oophorectomy was performed. On postoperative day five, transvaginal ultrasonography demonstrated an accumulation of ascites in the pouch of Douglas. Dynamic contrast-enhanced CT revealed a progressive increase in CT attenuation values of this fluid during the ultra-late phase, suggestive of a microscopic ureteral injury. Although retrograde pyeloureterography showed no definitive injury, the suspicion of subclinical ureteral damage led to the prophylactic placement of a right ureteral stent. Subsequently, the ascitic fluid resolved spontaneously. The stent was removed after 1.5 months, and the patient remained asymptomatic. Discussion: A progressive increase in CT attenuation of Douglas pouch ascites in the ultra-late phase of dynamic imaging may indicate subtle ureteral injury. Ureteral stenting can be considered a feasible intervention in such cases.