Intestinal Complications after Roux-en-Y Gastric Bypass

| April 1, 2015

by Mustafa W. Aman, MD; Kimberley E. Steele, MD; Thomas H. Magnuson, MD; Anne O. Lidor, MD; Hien T. Nguyen, MD; and Michael A. Schweitzer, MD

Mustafa W. Aman, MD; Kimberley E. Steele, MD; Thomas H. Magnuson, MD; Anne O. Lidor, MD; Hien T. Nguyen, MD; and Michael A. Schweitzer, MD, are from the Department of Surgery, Johns Hopkins University School of Medicine.

Bariatric Times. 2015;12(4):14–18.


ABSTRACT
According to the most recent data from the Centers for Disease Control & Prevention, more than one-third of the U.S. adult population is obese. Obesity is associated with numerous chronic health conditions, such as diabetes, hypertension, coronary artery disease, and even certain types of cancer. Bariatric surgery has been shown to be more effective than dietary, behavioral, or pharmacological interventions for weight loss. With increasing experience in laparoscopy and improved perioperative outcomes, bariatric procedures have gained in popularity amongst patients and referring providers alike. The Roux-en-Y gastric bypass (RYGB) is highly effective in reducing excess weight and curtailing the progression of obesity-related comorbidities. In fact, the RYGB is still widely regarded today as the gold standard in weight loss surgery. There are, however, a number of short-term and long-term sequelae that may occur in RYGB patients. Herein the authors present a focused discussion of intestinal complications associated with the RYGB. The clinical management of these intestinal complications is thoroughly discussed, based upon the most recent review of the literature as well as the authors’ experience at an accredited bariatric center.

Introduction
Weight loss surgery was introduced in the United States in the early 1960s. Over the next several decades the advancement of surgical instruments and introduction of laparoscopy resulted in the Roux-en Y gastric bypass (RYGB) becoming one of the most popular and successful weight loss procedures offered to both the adult and adolescent populations.[1] The RYGB has been shown to result in 50 to 75 percent excess weight loss (EWL) and there is an abundance of long-term follow-up data in the literature.[2] In particular, among obese patients with diabetes or gastroesophageal reflux disease (GERD) RYGB has been shown to have excellent long-term outcomes. Despite its overall benefit, however, there are numerous complications associated with the RYGB, including leaks, internal hernias, gastric ulcers, strictures, bowel obstructions, pulmonary emboli, postoperative bleeding, and malabsorptive complications, such as vitamin and nutrient deficiencies. A thorough discussion of the aforementioned early and late complications of the RYGB is beyond the scope of this article. Here, we present a focused discussion of select intestinal complications of the RYGB that highlight pearls of management based upon a thorough review of the literature and our own bariatric center experience.

INTERNAL HERNIA
An internal hernia is defined as herniation of bowel through a mesenteric defect.[5] The RYGB, regardless of whether performed laparoscopically or open, may be constructed in either an antecolic or retrocolic configuration. By dividing the small bowel mesentery and making two new anastomoses, at least two potential defects are created—the Petersen space and the jejuno-jejunostomy mesenteric defect. The Petersen defect, first described by German surgeon Walther Peterson in 1900, is bordered by the Roux limb mesentery, the retroperitoneum, and the transverse mesocolon. The original definition of the Petersen defect referred to the potential internal hernia space created under the Roux limb from a retrocolic gastrojejunostomy, although it is commonly understood today to include the mesenteric defect under the Roux limb from an antecolic gastrojejunostomy as well. When the gastrojejunostomy is constructed through a retrocolic approach, an additional potential hernia site is created at the transverse mesocolon window (Figure 1). Each of these potential spaces increases the risk of bowel entrapment leading to possible incarceration, closed loop obstruction, ischemic necrosis, sepsis, and ultimately the patient’s demise. In fact, a 2007 review of over 3,400 gastric bypasses performed at the Cleveland Clinic, Cleveland, Ohio, found that internal hernia was the single most common cause of bowel obstruction in this patient population, accounting for 41 percent of cases.[6,7]

Confirming the diagnosis of an internal hernia in a gastric bypass patient can be challenging. Patients may report recurrent nonspecific, colicky mid-epigastric or peri-umbilical pain.[5] Occasionally, the pain may radiate to the back. Patients may report leaning forward to alleviate the pain, a maneuver felt to decrease compression on entrapped bowel.[6] In many cases, however, the physical exam may be normal with no signs of abdominal distention or peritonitis. Routine laboratory studies, such as complete blood count and basic metabolic profile, may not reveal any abnormalities. In these patients the diagnosis is frequently delayed or even missed altogether as the patient’s symptoms may be erroneously attributed to biliary pathology, peptic ulcer disease, pancreatitis, or other more common conditions, such as gastroenteritis. Internal hernias most frequently present between 6 to 24 months after RYGB;[5] however, they can occur at any time after the operation. It is very important to maintain a high index of suspicion for internal hernia in any RYGB patient who presents with the aforementioned symptoms. This is especially true if the symptoms (crampy abdominal pains) continue to reoccur or crescendo over time.

Routine imaging studies in bariatric patients, such as upper gastrointestinal (UGI) series and computed tomography (CT) scans, unfortunately do not have high yield in diagnosing internal hernias. Goudsmedt et al[8] demonstrated that there was a high degree of inter-observer variability even among experienced radiologists trained in identifying 10 radiologic signs of an internal hernia. Multiple studies have reported the presence of a mesenteric swirl to be the best predictor of an internal hernia, with sensitivity ranging between 68 and 89 percent and specificity between 80 and 90 percent.[8,9] Other findings on CT include clustered loops of bowel on the left side, location of the jejunojejunostomy on the right side of the abdomen, and loops of small bowel posterior to the superior mesenteric artery (SMA).[8,9] UGI studies in patients with true internal hernias may be normal. It is imperative to recognize that the presence of normal imaging studies does not exclude the diagnosis of an internal hernia. Even patients with severe intestinal ischemia may have normal imaging studies.[6,8] Due to the difficulty in confirming the diagnosis and the significant sequelae of a missed internal hernia, these patients should be offered a diagnostic laparoscopy to definitively rule out an internal hernia in cases where the patient’s pain continues to reoccur over time.

In our practice, we routinely perform the laparoscopic RYGB in an antecolic, antegastric fashion if the mesentery is long enough for a tension-free gastrojejunostomy anastomosis. This avoids any possibility of creating an internal hernia through a transverse mesocolon defect and possibly decreases the overall internal hernia rate. A retrospective analysis of 274 retrocolic bypasses and 205 antecolic bypasses performed at our institution between 2001 and 2005 found that there was a 2.6 percent internal hernia rate in the retrocolic group as compared to a zero percent incidence in the antecolic cohort.[5] Therefore, unless it is not technically feasible, we routinely perform all laparoscopic gastric bypass operations in antecolic, antigastric fashion. We also carefully close the mesenteric defect at the jejunojejunostomy and close together Roux limb mesentery to transverse colon mesentery with retroperitoneum included to decrease the risk of an internal hernia.

OBSTRUCTION OF THE BILIOPANCREATIC LIMB
Among the commonly performed bariatric procedures today, one of the complications unique to malabsorptive procedures, such as the RYGB, is obstruction of the biliopancreatic limb (BP). A common cause of BP limb obstruction is an internal hernia, however, the obstruction may occur due to a number of other causes, such as adhesions, strictures, volvulus, or other complications at the jejunojeunostomy.[6,7,10] In the immediate postoperative period the jejunojejunostomy may be temporarily partially or fully obstructed by edema or a hematoma. Unlike the general surgery patient with the more common nonclosed loop bowel obstruction, these patients may not have nausea, vomiting, or obstipation. They may present with left upper quadrant fullness, hiccoughs, or unexplained tachycardia. They may also have shoulder pain as a result of a distended remnant stomach causing diaphragmatic irritation. Physical exam is typically normal. Recognizing BP limb obstruction early is critical, as a delay in diagnosis can lead to perforation and significant morbidity to the patient.

Two of the important lab assays in the workup of RYGB patients presenting with abdominal pain are serum amylase and lipase levels. An elevation of these labs in post-gastric bypass patients with abdominal pain has been shown to correlate with obstruction of the BP limb.10 Liver function tests may also be elevated, especially in cases of chronic obstruction. Frequently, these patients are misdiagnosed with pancreatitis or biliary disease, and surgical consultation is often delayed. As a result, they may be treated nonoperatively with resultant worsening obstruction and possible gastric perforation or bowel ischemia. Spector et al[10] reviewed 99 cases of surgically treated small bowel obstruction following RYGB. The authors found that among RYGB patients diagnosed intra-operatively with an obstructed BP limb, the serum amylase and lipase levels were elevated. Furthermore, they noted that the levels were not exceedingly high. The highest reported amylase and lipase levels in their study were 328 international units per liter (IU/L) and 148 IU/L, respectively. The authors concluded that this is significant because it can help distinguish BP limb obstruction from pancreatitis, as in the latter condition the lipase level would typically be in the thousands. Given that these blood tests are rapid, readily available, and inexpensive, we recommend that all RYGB patients presenting to the emergency department with abdominal pain have these labs drawn as part of the standard initial workup. Although a CT scan can certainly confirm the diagnosis, plain abdominal radiographs alone may show a massively dilated remnant stomach and, therefore, can be used to help make the diagnosis.[15]

The primary objectives in the treatment of acute biliopancreatic limb obstruction are twofold—decompression and definitive surgical intervention. It is worth noting that unlike an obstructed afferent loop after Billroth II reconstruction, the most proximal aspect of the BP limb in RYGB patients is the excluded stomach rather than the duodenum. Since the stomach can accommodate a much greater volume of fluid than the duodenum, an obstructed BP limb after RYGB may not manifest with symptoms initially until the stomach becomes fully distended. A percutaneous or surgical gastrostomy is an excellent means of achieving immediate decompression of the obstructed biliopancreatic limb.[6] Although this may temporize the acute problem, definitive surgical exploration to identify and treat the etiology of the obstruction may be necessary if internal hernia is suspected or other causes that do not resolve with decompression alone.

ANASTOMOTIC COMPLICATIONS
There are a number of complications that can occur at either the gastrojejunostomy or jejunojejunostomy. These include anastomotic leaks, obstructions, bleeding, ulcers, strictures, and other complications. The timing of such complications varies between patients, but in general, early complications include a leak, bleeding, and postoperative edema. These tend to be more common in the first two weeks after RYG. Strictures, ulcers, and internal hernias tend to occur later than two weeks after the operation.[19]
The most significant early intestinal complication of the RYGB is an anastomotic leak. This may manifest with significant tachycardia (heart rate over 120 beats per minute), increasing abdominal pain, chest pain, prolonged fever, and/or evidence of physiologic derangement.  When performing the RYGB it is important to inspect all anastomoses intraoperatively to ensure that they are tension free and that they have an excellent blood supply. UGI series and contrast enhanced CT scans are considered the diagnostic modalities of choice in any RYGB patient being evaluated for a leak. Drainage and attempted repair is the treatment for most but not all very early leaks, whereas, delayed leaks may be managed with drainage of intra-abdominal fluid collections by interventional radiology, antibiotics, and parenteral nutrition. A gastrostomy tube in the distal stomach can be helpful to feed the patient while a gastrojejunostomy leak heals. Transoral stenting, clipping, or suturing may or may not aid in the closure of a leak. Based on the clinical picture of the patient, some early leaks may be managed without surgical intervention and some late leaks may require surgical intervention if the patient is not improving with nonoperative interventions.

Another intestinal complication of the gastric bypass is obstruction at the enteroenterostomy. These patients typically have intolerance to oral intake, nausea, and occasionally emesis as well. Imaging studies show delayed transit of contrast through the small intestine. Bowel rest, hydration, and short-term parenteral nutrition are first line treatments. Patients presenting with any signs of peritonitis or sepsis require immediate surgical exploration. Patients who present with delayed obstruction at the jejunojejunostomy may have a number of possible etiologies for the obstruction, such as strictures, adhesions, or other etiologies. In most cases, a leak at the enteroenterostomy will require surgical repair.

A marginal ulcer, also referred to as a stomal ulcer or anastomotic ulcer, is defined as an ulcer that arises at or near the gastrojejunostomy. It is almost always located on the jejunal side of the anastomosis.[19] Patients usually present with burning epigastric pain, however, it is not uncommon to find concomitant ulcers after other complications, such as leaks, internal hernia, obstruction, and even cholelithiasis. Complicated or long-standing marginal ulcers may result in massive hematemesis or perforation of the gastrjojejunostomy. Coblijn et al[15] conducted a systematic review on marginal ulcers, with a total of 41 studies analyzed encompassing 16,987 patients. They found that the incidence varies widely in the literature from 0.6 percent to as high as 25 percent of RYGB patients. Time to presentation ranged from one month to six years following surgery. Technical risk factors include creation of a large gastric pouch, possible use of nonabsorbable suture material, and ischemia. Smoking and non-steroidal anti-inflammatory drug (NSAID) use have been shown to be independent predictors for development of marginal ulcers.[15] The role of Helicobacter pylori (H.pylori) infection in marginal ulcer formation remains debated. The majority of marginal ulcer cases can be treated with proton pump inhibitors (PPIs), sucralfate and conservative therapy. In cases of complicated marginal ulcer (perforation or bleeding) surgical intervention may be warranted.

Bleeding from either the gastrojejunostomy or enteroenterostomy in RYGB patients has been well described in the literature.[14] Depending on the severity and duration of the bleed, a repeat trip to the operating room may be required. Upper endoscopy may be used for gastrojejunal bleeding where the use of clips, cautery, argon beam coagulation, or injection of epinephrine may be used to stop the bleeding. The initial management of these patients is establishing adequate intravenous (IV) access, prompt resuscitation with fluid and blood products, holding anti-coagulation, carefully monitoring hemodynamic parameters, following hemoglobin and hematocrit levels, and carefully assessing the patient’s response. Those who fail to respond with these measures usually require surgical intervention. In some patients, a slow rate of bleeding can occur over a period of time and result in a large organized blood clot at the anastomosis that becomes an obstructing bezoar. The reported incidence of blood clot obstructions at the jejunojejunostomy in the literature ranges from 0.6 to 3.7 percent.[14]

INTUSSUSCEPTION
Small bowel intussusception after RYGB is a rare but important complication to consider. In the nonbariatric adult population, small bowel intussusception is almost always due to a pathologic lead point. The lead point may be a polyp or mass that moves with peristalsis and causes invagination of proximal bowel into the distal segment (antegrade intussusception). Due to presumed presence of a neoplastic process, reduction and resection of the involved bowel with broad inclusion of the small bowel mesentery is typically the treatment of choice.

Intussusception in RYGB has several unique features that distinguish it from intussusception seen in the adult general surgery population. In 2011, Daellenbach et al[17] published a thorough review of the literature on intussusception in post-gastric bypass patients. They identified a total of 62 reported cases worldwide, with all but one of those cases occurring in women. The reported prevalence of this condition was between 0.07 and 0.6 percent of all gastric bypass patients, and most cases occurred at a mean of 3.6 years following surgery. Unlike other types of intussusception, intussusception in the RYGB patient population most frequently occurred in retrograde fashion (69.8% of cases) rather than antegrade. Although any limb of bowel can be affected, the most common form observed was intussusception of the common channel into the jejunojejunostomy (Figure 2). Clinical findings on presentation were typical of bowel obstruction—abdominal pain, nausea, and vomiting being the most frequent complaints.[16,17] Physical exam and lab findings were typically unremarkable. Imaging studies demonstrated dilated loops of bowel and air-fluid levels. A “target sign” on CT scan was found in 81 percent of cases. Unlike other types of intussusception, when this condition occurs in post-gastric bypass patients there is almost never a “lead point” (only one patient out of 62 had a lead point—ectopic pancreatic tissue). Rather, the pathophysiology is felt to be related to a disturbance in the normal motility pattern of small bowel that occurs with division of the jejunum and construction of an enteroenterostomy.

There is broad consensus that the treatment of intussusception in post-gastric bypass patients is usually surgical exploration. The type of procedure that should be performed intra-operatively, however, is less well defined. The reported surgical interventions in the literature include simple manual reduction, reduction with small bowel plication, and surgical resection. In the aforementioned review, which to our knowledge represents the largest review of published data on this rare entity to date, the authors found a statistically higher recurrence rate in patients treated with bowel-conserving surgeries (reduction with our without plication) as compared to resection of the involved segment with reconstruction of the jejunojejunostomy (33.3% versus 7%. P= 0.02).[17] Based on this finding the authors concluded that resection of the invaginated segment is the treatment of choice. In this series, the jejunojejunostomy was the most commonly affected site.

VOLVULUS
One of the intestinal complications that has been described following RYGB is bowel obstruction secondary to a volvulus. Patients may present with abdominal pain, distention, and dry heaves. While plain abdominal films could be obtained to assess for presence of air fluid levels and to rule out perforation, CT scan of the abdomen and pelvis is the imaging modality of choice. This imaging study can provide detailed information regarding the patient’s anatomy and define which limb of small bowel is involved (biliopanceatic limb, Roux limb, or common channel).

One of the intra-operative factors known to cause volvulus is the placement of a Roux-limb stabilization suture. Marr et al[18] performed a retrospective analysis of 199 cases of RYGBs performed by a single surgeon over a period of three years. Four cases of Roux limb volvulus were identified, and in all four of these cases a stitch had been placed between the Roux limb and the excluded stomach in an attempt to stabilize the Roux limb and prevent kinking at the gastrojejunostomy anastomosis. This caused a volvulus of the Roux limb, and cutting this stitch in the operating room relieved the obstruction. After abandoning this practice, a follow-up analysis of the next 250 RYGBs performed at this institution found no further cases of Roux limb volvulus. Any gastric bypass patient presenting with signs or symptoms concerning for volvulus should be surgically explored to avoid sequelae of ischemic bowel.

TROCAR SITE HERNIA
Trocar site hernias are considered relatively uncommon complications after laparoscopic surgery, with an overall reported incidence in the literature of 0.65 to 2.8 percent.[12,13] A recent review, however, demonstrated that the risk of trocar site hernias may be higher in patients with elevated body mass indices (BMIs) undergoing laparoscopic surgery.[11] This is of concern as patients may develop incarcerated or strangulated bowel (Richter’s Hernia) in these port sites without being quickly recognized due to the large body habitus.

A recent retrospective review of 3,735 radially expanding 12mm and 5mm trocar sites that were not closed in 747 laparoscopic gastric bypass patients demonstrated a zero percent hernia rate at two years follow up.[13] The authors of this study claim that since these trocars do not cut tissue, they result in less postoperative pain, less tissue damage, fewer wound complications, minimal port-site bleeding, and no port-site hernias despite leaving the fascial defect unclosed.[13] It is also important to inspect the fascial defect upon removal of the port to ensure that the defect remains small.

In cases where bladed trocars are used, we recommend routine closure of any port site greater than 10mm in size to decrease the risk of a postoperative hernia. We employ use of a suture passer to close the fascial defects laparoscopically under direct vision. This technique is particularly important in the bariatric population as their fascia may be several centimeters deep to the skin, thereby making primary closure from above the skin very challenging. This technique is also useful in controlling bleeding from a port site.

CONCLUSION
The RYGB has long been considered the most effective and durable solution for achieving and maintaining weight loss. It is still widely regarded as the gold standard operation against which all other bariatric procedures are compared. The RYGB not only yields excellent sustained long-term weight loss, but also results in improvement or complete resolution of many obesity-related comorbidities. Although the RYGB offers numerous advantages to patients, there are a number of early and late complications associated with this procedure. With the worsening obesity epidemic and the rising number of RYGB procedures performed nationwide, one can reasonably expect that these complications will be seen with increasing frequency in the future. A thorough understanding of intestinal complications that may arise in the RYGB patient is integral to the successful management of these complications by surgeons and nonsurgeon providers alike.

References
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14.    Mala T, Søvik TT, Schou CF, Kristinsson J. Blood clot obstruction of the jejuno-jejunostomy after laparoscopic gastric bypass. Surg Obes Relat Dis. 2013;9(2):234–237.
15.    Surgerman H. Morbid obesity. In: ACS Surgery: Principles and Practice. New York, New York: Webmd Professional Publishing, 2003.
16.    Bocker J, Vasile J, Zager J, et al. Intussusception: an uncommon cause of postoperative small bowel obstruction after gastric bypass. Obes Surg. 2004; 14(1): 116–119.
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18.    Marr B, Yenumula P. Roux limb volvulus in laparoscopic Roux-en-Y gastric bypass due to Roux limb stabilization suture: case series. Obes Surg. 2012;22(1):4–7.
19.    Coblijn UK, Goucham AB, Lagarde SM, et al. Development of ulcer disease after Roux-en-Y gastric bypass—Incidence, risk factors, and patient presentation: a systematic review. Obes Surg. 2014;24 (2):299–309.

FUNDING: No funding was provided.

DISCLOSURES: The authors report no conflicts relevant to the content of this article.

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