Imaging of urinary bladder hernias

Herniation of the urinary bladder is not rare. It is usually considered that 1–3% of all inguinal hernias involve the bladder, and Iason, in 1944, reported an incidence of 10% in men older than 50 years. Most bladder hernias involve the inguinal and femoral canals, with the latter more frequent in women, and a predilection for the right side has been reported. However, herniations through ischiorectal, obturator, and abdominal wall openings have also been described. Any portion of the bladder may herniate, from a small portion or a diverticulum to most of the bladder. In young infants, protrusion of the lateral aspect of the bladder base can be seen as an incidental finding that is normal for their age. These “bladder ears” are related to the size and position of the bladder in infants and to the persistence of a large inguinal ring. Damage to the herniated bladder during herniorrhaphy has been reported, and in the preantibiotic era, an unrecognized injury to the bladder could lead to infection, sepsis, and even death. To avoid intraoperative complications, it has been suggested that all men older than 50 years who have prostatism associated with a inguinal or femoral hernia should undergo radiographic studies to rule out involvement of the bladder within the hernia before surgical repair. In patients who do not undergo surgery, complications of herniation include possible upper tract obstruction and strangulation, infarction, and perforation of the bladder. A variety of factors can contribute to the development of bladder hernias. Among these are the presence of urinary outlet obstruction causing chronic bladder distention and contact of the bladder wall with the hernia orifices, loss of bladder tone with weakness of supporting structures, pericystitis and perivesical bladder fat protrusion, obesity, and the presence of space-occupying pelvic masses. Bladder hernias have been classified into three types according to their relationships with the peritoneum: paraperitoneal hernias, the most frequent type, in which the extraperitoneal portion of the hernia lies along the medial wall of the sac; intraperitoneal hernias, in which the herniated bladder is completely covered by peritoneum; and extraperitoneal hernias, in which the bladder herniates without any relation with the peritoneum. Anatomically, inguinal bladder hernias may be classified as indirect, entering through the internal inguinal ring and running laterally to the inferior epigastric artery, or direct, protruding through Hesselbach's triangle of the posterior wall of the inguinal canal and running medially to the vessel. Most bladder hernias are asymptomatic and discovered incidentally during surgery or during imaging studies performed for other purposes. Symptoms such as dysuria, frequency, urgency, nocturia, and hematuria have been reported; however, it is difficult to dissociate similar symptoms arising from coexisting conditions such as bladder outlet obstruction or urinary infection. Patients with large hernias may have specific symptoms, such as reduction in size of the hernia mass after micturition and two-stage micturition, a situation in which initially the patient empties the normally located bladder, then voids again after manual compression of the hernia sac.