Urinary peritonitis (the uroperitoneum) is categorized as a difficult to diagnose clinical entity due to its poor manifestations. Vesical trauma following pelvis bone fracture is the most frequently involved in the uroperitoneum aetiology, followed by spontaneous vesical rupture and intraoperative iatrogenic lesions. One of the most important and constant signs that can occur is diffuse abdominal tension, without tenderness. The imagistic procedure that sets the diagnosis is retrograde cystography showing intraperitoneal urine effusion. Vesical rupture is a surgical emergency. The uroperitoneum is a particular type of peritonitis that has hidden and misleading symptoms which can delay the diagnosis long enough to endanger the patient's life.