ANSWER: Intraperitoneal bladder rupture:
EXPLANATION:
CT cystogram demonstrates a focal defect (blue arrow) in the wall of the dome of the bladder with extraluminal contrast. The extraluminal contrast is seen accumulating in the mesentery around bowel loops and in the paracolic gutters (yellow arrows). This is compatible with an intraperitoneal bladder rupture.
Bladder ruptures can be classified as intraperitoneal or extraperitoneal. Intraperitoneal ruptures commonly occur at the dome of the bladder. A typical story is a motor vehicle crash resulting in sudden increase in pressure against a full bladder causing a blowout at the dome. Other causes include deep bladder biopsy and tumor resection as well as traumatic catheterizations. Intraperitoneal bladder ruptures are typically managed surgically and are diagnosed by accumulation of urine/contrast in the peritoneal cavity, classically seen outlining bowel loops and extending into the paracolic gutters.
Extraperitoneal bladder ruptures comprise approximately 80% of bladder ruptures and manifest as accumulation of urine/contrast in the perineum, upper thighs and/or anterior and lateral to the bladder including the space of Retzius. Accumulation of contrast in the anterior and lateral perivesical spaces gives rise to the "molar tooth sign" as the configuration of the extravasated contrast can loosely mimic the appearance of a molar tooth. Extraperitoneal ruptures are often associated with pelvic fracture and are often managed non-surgically with Foley catheter placement.
