The Sentinel Clot Sign: a Useful CT Finding for the Evaluation of Intraperitoneal Bladder Rupture Following Blunt Trauma

OBJECTIVE: To evaluate the frequency and relevance of the "sentinel clot" sign on CT for patients with traumatic intraperitoneal bladder rupture in a retrospective study. MATERIALS AND METHODS: During a recent 42-month period, 74 consecutive trauma patients (45 men, 29 women; age range, 12-84 years; mean age, 50.8 years) with gross hematuria were examined by the use of intravenous contrast-enhanced CT of the abdomen and pelvis, followed by retrograde cystography. Contrast-enhanced CT scanning was performed by using a helical CT scanner. CT images were retrospectively reviewed in consensus by two radiologists. The CT findings including the sentinel clot sign, pelvic fracture, traumatic injury to other abdominal viscera, and the degree of intraperitoneal free fluid were assessed and statistically analyzed using the two-tailed χ(2) test. RESULTS: Twenty of the 74 patients had intraperitoneal bladder rupture. The sentinel clot sign was seen for 16 patients (80%) with intraperitoneal bladder rupture and for four patients (7%) without intraperitoneal bladder rupture (p < 0.001). Pelvic fracture was noted in five patients (25%) with intraperitoneal bladder rupture and in 39 patients (72%) without intraperitoneal bladder rupture (p < 0.001). Intraperitoneal free fluid was found in all patients (100%) with intraperitoneal bladder rupture, irrespective of an associated intraabdominal visceral injury, whereas 19 (35%) of the 54 patients without intraperitoneal bladder rupture had intraperitoneal free fluid (p < 0.001). CONCLUSION: Detection and localization of the sentinel clot sign abutting on the bladder dome may improve the accuracy of CT in the diagnosis of traumatic intraperitoneal bladder rupture, especially when the patients present with gross hematuria.