Direct bladder hernia after indirect hernia repair in extremely low birth weight babies: two case reports and a review of the literature

Cadaveric and radiographic studies have indicated that transitory extraperitoneal herniation of the bladder, a phenomenon known as “bladder ears,” may occur in significant numbers of babies, children, and even adults [13]. According to these observations, the bladder may herniate into the internal ring, and the bladder’s grade of protrusion depends on bladder filling.

Among adults, the incidence of bladder involvement in low abdominal hernias reportedly ranges from 1 to 10% [6]. Direct and indirect hernias are involved with equal frequency, with hernias predominantly occurring on the right side [6].

The rate of bladder involvement during indirect inguinal hernia repair is not well known. Shaw and Santulli used a flap technique to repair sliding hernias with involvement of the urinary bladder in 27 female patients [1]. Several additional case series describe bladder involvement during pediatric hernia repair. Six cases with recognized bladder involvement and one case involving unrecognized bladder injury were reported by Colodny [2]. In contrast, in a large single-surgeon series of 6361 cases, only two patients (0.03%) had sliding bladder hernias [9].

Reports on pediatric bladder hernias and certain near-catastrophic iatrogenic urinary bladder injuries are collected in Table 2. Eight out of the nine presented cases involved male patients. Bladder hernias affected the left side in three cases and the right side in two cases. In three cases, the affected side was not reported, and in one extraordinary case, a median protrusion occurred. No patients in the presented series had previously undergone surgery for inguinal hernia repair. Injuries of the bladder occurred due to either the prolapse of the bladder into the indirect hernia sac or a misplaced approach medial to the inguinal canal.

F female, M male, mo. months, wk. weeks, yr. year

In contrast with the observations above, bladder herniation occurred in our patients as a relapse after the primary repair of indirect inguinal hernias. In both cases, the bladder wall was prolapsed directly through an opening in the prevesical abdominal wall. The medial margin of this opening was lined by the lateral border of the rectus sheath (Hesselbach’s triangle) [17].

In general, hernia recurrence rates of 0.8 to 3.8% have been reported following open hernia repairs in children [11]. An increased incidence of direct herniation after the repair of congenital indirect hernias is a well-known phenomenon. In a previous series, 20 out of 62 children had direct hernias [11]. In another series of over 1600 inguinal hernias, six patients presented with nine recurrent hernias [18].

Several factors that may predispose patients to indirect inguinal hernia recurrence have been reported. Hernia recurrence in otherwise healthy children may be caused by inadequate surgical technique (failure to ligate the sac sufficiently high and inadvertent tearing of the sac) [18]; injury to the floor of the inguinal canal due to operative trauma; the inherent weakness or friability of tissues; and postoperative wound infection or hematoma [11]. In the two presented cases, the primary surgery and the repair of the relapse were performed by the first author (RBT). The applied technique was a modified “classical” hernia repair, as described in detail by Ladd and Gross [8]. For both babies, during relapse surgery, surgical exploration through the previously used inguinal access revealed a right extraperitoneal bladder hernia. This predilection for the right side may be supported by the fact that 59% of indirect hernias occur on the right side [9].

Laparoscopy was an important tool for specifically localizing the type of relapsed hernia in Case 1; however, laparoscopy was not used in our second case. In both cases, direct bladder herniation occurred extraperitoneally in the form of a direct hernia.

In both reported cases, the family history was unremarkable, and there were no clinical signs of relevant neurological impairment. Prematurity and multimorbidity might have contributed to the development of secondary bladder herniation. Increased intra-abdominal pressure due to CPAP ventilation and repeated squeezing of the immature intestine are additional predisposing factors. In our cases, the role of the primary surgical technique remains debatable. The narrowing of the enlarged inguinal canal by placing a suture at the margin of the internus muscle and the aponeurosis of the obliquus externus might have contributed to weakening the medial portion of the inferior abdominal wall.