The purpose of this review is to evaluate the incidence and management of internal hernias (with or without SBO) after LGBP.
Laparoscopic Roux-en-Y gastric bypass (LGBP) has been shown to be an effective treatment for morbid obesity, both in terms of weight loss and improvement in multiple comorbidities. While the laparoscopic approach offers many advantages to the patient in terms of fewer wound complications, decreased length of hospital stay, and decreased postoperative pain, certain complications of this operation continue to pose difficult clinical problems as the number of procedures performed increases. One such complication is internal hernia through one of the mesenteric defects, which can result in small bowel obstruction, ischemia, or infarction and often requires reoperation.
An internal hernia is defined as a protrusion of intestine through a defect within the peritoneal cavity, as opposed to an external (or incisional) hernia that protrudes through all layers of the abdominal wall. Internal hernias almost always occur through iatrogenic defects created surgically.
Incisional hernias occur at a higher incidence after open gastric bypass (GBP) at a rate of about 20 percent. LGBP has a lower rate of incisional hernias. A recent study by Rosenthal, et al., showed a 0.2-percent rate of port site hernias in 849 patients using blunt-tip trocars at 3,744 port sites. Internal hernias, on the other hand, occur more frequently in LGBP than in the open procedure. This is a significant clinical problem, since internal hernia is the most common cause of small bowel obstruction (SBO) after LGBP. Retrospective reviews have found the incidence of SBO after LGBP to be between 1.8 and 9.7 percent. The incidence of internal hernia after LGBP is between 0.2 and 8.6 percent based on multiple studies.
This incidence is higher than that seen with open GBP, and this is presumably due to decreased adhesion formation after laparoscopic surgery compared to open surgery. The creation of potential space as a result of weight loss may also be a contributing factor in the etiology of internal hernias, which often present in a delayed fashion. In addition, the particular case of pregnancy— with the mass effect of an enlarging uterus—may predispose to this condition, as there have been three case reports in the literature of internal hernia during pregnancy, one of which resulted in intestinal ischemia and fetal demise. Due to the increasing scope of this problem and its potentially devastating consequences, surgeons should have a high clinical suspicion for internal hernia after LGBP.
An internal hernia can potentially occur through either two or three defects, depending on whether a retrocolic or antecolic technique is used for the Roux limb. Petersen’s defect is defined as the space between the Roux limb and the transverse mesocolon. A defect is also present between the biliopancreatic and Roux limbs at the jejunojejunostomy. If a retrocolic approach is used, a third defect in the transverse mesocolon is created. This is the most common site of internal hernia in most reports, which has prompted many surgeons to adopt an antecolic technique in order to eliminate this defect. Higa’s study of 2,000 patients showed an internal hernia distribution of 67 percent mesocolic, 21 percent jejunal, and 7.5 percent Petersen. However, some centers experience a higher rate of hernia in the jejunal or Petersen’s defects, despite the use of a retrocolic approach.
Patients with internal hernia most commonly present with abdominal pain, and may also have symptoms of small bowel obstruction. The time of presentation varies greatly and may occur within one week of the initial operation or up to three years postoperatively. However, the majority of cases occur between 6 and 24 months postoperative. Radiographic diagnosis of internal hernia presents a challenge since the characteristic findings on computed tomography (CT) scan are often missed.
Features suggestive of an internal hernia include small bowel loops in the upper quadrants; evidence of small bowel mesentery crossing the transverse mesocolon; presence of the jejunojejunostomy superior to the transverse colon; signs of small bowel obstruction; or twisting, swirling, crowding, stretching, or engorgement of the main mesenteric trunk and according to one study, the sensitivity and specificity of CT is 63 percent and 76 percent, respectively.
Another study showed that although the diagnosis was only made prospectively by CT scan in 64 percent of cases, a retrospective review of the images showed that diagnostic abnormalities were present in 97 percent of cases. A report of five cases of internal hernia by Onopchenko found that only one was diagnosed preoperatively by radiological reading, even though all five had findings suggestive of internal hernia to the bariatric surgeon. These findings emphasize the need for communication with the radiologist, careful attention to patient history, and high clinical suspicion for internal hernias. In rare cases, closed loop obstruction and extensive bowel ischemia and infarction can occur. This dreaded complication underscores the necessity of making a rapid diagnosis. If the patient has significant symptoms but radiologic studies are negative, a diagnostic laparoscopy is warranted to rule out internal hernia.
PREVENTION AND TREATMENT
Given the prevalence of internal hernias and the increasing popularity of bariatric surgery, it is important to prevent or minimize this complication at the time of the initial operation. Although there have been no randomized, controlled trials comparing different techniques of LGBP, some authors have anecdotally reported lower rates of internal hernia after modifying their technique from a retrocolic to antecolic approach. Champion and Williams reported a significant decrease in small bowel obstruction after changing to an antecolic position, and Felsher and colleagues found no internal hernias in their study after adopting the antecolic approach.
However, other studies support careful defect closure as the most important factor in reducing hernia rates. Dresel and colleagues report no internal hernias after modifying their technique to include closure of Petersen’s defect. Carmody and colleagues report a decreased hernia incidence when closing all defects, even with a retrocolic approach. DeMaria’s study reports anecdotal improvement after closing mesenteric defects in two layers, on the medial and lateral aspects of the defect.
The majority of internal hernias can be successfully treated laparoscopically, with reduction and defect closure. The laparoscopic approach is usually successful; however, because of the lack of adhesion formation after laparoscopy, Capella, et al., suggest laparotomy for patients who experience a second episode of bowel obstruction due to recurrent internal hernia after laparoscopic repair. The greater adhesion formation after laparotomy may help prevent future internal hernia formation.
One of the benefits of laparoscopy, decreased adhesion formation, is likely also responsible for the increasing prevalence of internal hernia as a complication following laparoscopic gastric bypass. Although it has not been borne out in randomized clinical trials, anecdotal evidence and expert opinion suggest that Roux limb position and mesenteric defect closure at the time of initial operation are important factors in ultimate rates of hernia formation. Careful attention must be paid to individual surgical techniques in order to prevent this potentially devastating complication. The benefits of LGBP are maximized when there is a low incidence of postoperative hernias and resultant obstruction.