Transitory Extraperitoneal Hernia of the Bladder in Infants (Bladder Ears)

For several years lateral protrusions of the urinary bladder have been observed by us during intravenous urography and cystography in infants. These are more than the usual posterior extensions of the partially filled bladder. Further study has shown them to be extraperitoneal herniations through the internal inguinal ring into the inguinal canal (Fig. 1). Almost all of the patients have been infants under six months of age, although the finding has been observed in both older children and in adults. Clinical inguinal hernia is present in a higher incidence in this group than is normally expected. This suggests a relationship to persistence of a large internal inguinal ring. It is the purpose of this study to elaborate and illustrate the findings in such herniations of the bladder. Anatomy and Etiology The urinary bladder is a hollow neuromuscular organ that, in the infant, lies in a relatively high position in the pelvis and is proportionately large in relation to the abdominal cavity (1, 15). This position places the lateral base closer to the internal inguinal ring than in the adult. With increasing age, the bladder becomes almost completely a true pelvic structure except when distended (5). It is covered by peritoneum in its superior and posterior portions, while laterally and anteriorly it consists of only loose areolar tissue. There are three types of herniation of the bladder: extraperitoneal, in which the bladder protrudes through the inguinal ring, remaining entirely outside the peritoneum; paraperitoneal, which is also an extraperitoneal protrusion with an adjacent peritoneal hernia; and intraperitoneal, in which a more superior portion of the bladder carries its peritoneal covering into the inguinal ring (9, 19) (Figs. 1 and 2). Wakeley states that the paraperitoneal type is twice as common as the intraperitoneal and that extraperitoneal hernias are rare (20). The proximity of the lateral extraperitoneal portion of the bladder to the inguinal ring makes movement in a lateral direction unrestricted and facilitates the protrusion of part of the bladder through the internal inguinal ring, still extraperitoneally (3). Karewski clearly demonstrated this close connection in cadavers (2). Studies of the normal cystogram by Braasch and Emmett revealed the great variability in size of the urinary bladder, with the longest axis frequently in the transverse plane, particularly in females (4). Persistent patency of the processus vaginalis with its associated wide inguinal ring may further predispose such patients to bladder herniation (11, 14, 17). Watson lists other contributing factors, such as prematurity, poorly developed musculature, prolonged crying, colic, flatulence, bronchitis, and whooping cough (21). Localized causes may include congenital malformations of the bladder as well as bladder-outlet obstructions (6).