with or without duodenal switch. Band slippage can occur in 15% to 20% of patients and typically

presents with a history of upper abdominal symptoms of reflux, regurgitation, and dysphagia. Upper GI

study is the preferred method of diagnosing band slippage showing the evidence of malposition of the

band and proximal pouch dilatation with obstruction. The initial management is urgent band deflation

using Huber needle and if this is unsuccessful or patient is acutely unwell, necrosis, abscess, or erosion

must be considered which may require surgery. Intestinal obstruction occurs in 4.4% after roux-en-y

gastric bypass. The etiology of obstruction includes internal hernia (53%), roux limb compression due to

scarring (20%), adhesion (14%), stricture at gastrojejunal anastomosis, kinking of the alimentary limb,

incisional hernia, and intestinal intussusception. The most common site of internal herniation is

mesojejunal mesenteric window, followed by Petersen window and the mesocolic window.93 It is

paramount to differentiate bariatric from nonbariatric patients presenting with SBO since there are

significant differences in their management. Nonoperative management was successful in 72% of nonpostbariatric patients but surgery was performed in about 62% of postbariatric surgery patients with

SBO. Also, the bariatric group is most likely to undergo laparoscopy (5% vs. 2%), abdominal wall

reconstruction (38% vs. 9%) and is less likely to require colostomy (1% vs. 13%). The bariatric group

underwent surgery sooner within an average of 24 hours compared to 3.3 days in non-postbariatric

patients.94

Algorithm 49-2. Approach to the management of malignant bowel obstruction.

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Figure 49-7. Computed tomography images of an inguinal hernia. Axial (A) and coronal (B) CT scan images showing incarcerated

right inguinal hernia with air- and fluid-filled loop of small bowel (arrowhead) in the right inguinal canal (arrow) causing small

bowel obstruction with dilated loops of proximal small bowel (B).

Hernia

Hernias of all types are second only to adhesions as the most frequent causes of obstruction in Western

countries. External hernias such as inguinal (Fig. 49-7) or femoral hernias may present with the

symptoms of obstruction and will not be diagnosed unless sought.95 Femoral hernias are particularly

prone to incarceration and bowel necrosis due to the small size of the hernia inlet.95 Other hernias such

as umbilical, incisional, paracolostomy, or lumbar hernias are obvious. Still others, such as internal

hernias are usually diagnosed at laparotomy for obstruction. These include obturator hernias,

paraduodenal hernias (Fig. 49-8), and hernias through the foramen of Winslow or mesenteries. When

hernia has been identified as the cause of the obstruction, the patient is quickly resuscitated, given

antibiotics, and taken to the operating room. The hernia is then reduced and the viability of the bowel

assessed. If viable, the bowel is left alone; if not, it is resected. The hernia defect is then repaired. One

important consideration is the Richter hernia (Fig. 49-9).96 In this variant, only a portion of the wall of

the bowel is incarcerated and thus incarceration and strangulation may not be associated with complete

obstruction. These most frequently occur in association with femoral or inguinal hernias. Complete

obstruction can occur if more than half of the bowel circumference is incarcerated.

For external (abdominal wall) hernias, it may be possible to perform taxis, that is, the manual

reduction of an incarcerated/irreducible hernia. Reduction (taxis) of the hernia is usually successful.

Occasionally taxis results in reduction of the contents of the hernia sac en mass (still obstructed),

reduction of strangulated bowel resulting in generalized peritonitis, or reduction of an obstructed

Richter hernia.97–101 This is one reason for using circumspection in relying on taxis as a mode of

treatment for incarcerated inguinal, femoral, and incisional hernias. In general, taxis should be followed

expeditiously by operative repair.

Gallstone Ileus

As a result of intense inflammation surrounding a gallstone, a fistula may develop between the biliary

tree and the small or large intestine. Most fistulae develop between the gallbladder fundus and

duodenum. If the stone is greater than 2.5 cm in diameter, it can lodge in the narrowest portion of the

terminal ileum, which is just proximal to the ileocecal valve. This complication is rare, accounting for

less than 6 in 1,000 cases of cholelithiasis and no more than 3% of cases of intestinal obstruction.

Typically, the patient is elderly female and presents with intermittent symptoms over several days, as

the stone tumbles distally toward the ileum. The classic findings on plain radiographs include those of

intestinal obstruction, a stone lying outside the right upper quadrant, and air in the biliary tree (Fig. 49-

10). Treatment includes removal of the stone and resection of the obstructed segment only if there is

evidence of tissue necrosis. The risk of a recurrent gallstone ileus is about 5% to 10%.102,103 Such

recurrences usually occur within 30 days of the initial episode and are usually due to stones in the small

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intestine that were missed at the original operation.

The difficult decisions in management of gallstone ileus focus on the fistula. The arguments in favor

of disconnecting the fistula and removing the gallbladder have been the possibility of recurrence of

gallstone ileus and the risk of cholangitis due to reflux of intestinal content into the biliary tree. When

the latter operation is included, the mortality may be doubled as compared to simple removal of the

gallstone. It is used selectively in good-risk patients. The long-term incidence of biliary tract infections

has not been common enough to warrant the more aggressive approach at the initial operation. Some

authors have advocated cholecystectomy at a second operation, especially if the patient is young and fit.

The consensus is that cholecystectomy should not be performed at the initial operation for gallstone

ileus, except in highly selected patients. A careful search of the entire intestine should be performed to

exclude the possibility of additional large stones which can occur in up to 25% of patients.102–104

Figure 49-8. Paraduodenal hernia. A: Plain film of closed-loop obstruction with neck of the closed loop in the right upper

abdomen. B: Computed tomography scan showing slippage of the jejunum behind the stomach, with dilatation and obstruction of

the duodenum. C: Schematic diagram showing relationships of the paraduodenal fossa and transverse mesocolon.

Figure 49-9. Richter hernia. A: Computed tomography scan showing contrast and air in the incarcerated segment within the left

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groin. B: Schematic diagram showing Richter hernia, in which the antimesenteric border (but not the whole wall) of the intestine

is incarcerated.

Figure 49-10. A: Plain radiograph of a patient with gallstone ileus, showing obstructed loops of small intestine (black arrow) in the

abdomen and a gallstone (white arrow) in the pelvis (gallstone was initially misinterpreted as an EKG lead [black arrow]). B:

Computed tomography (CT) scan showing a cholecystoduodenal fistula (black arrow) with air in the biliary tree (D, duodenum). C:

CT scan showing gallstone (white arrow) in the distal ileum and fecalization of luminal content adjacent to the stone.

Intussusception

About 5% of intussusceptions occur in adults. An intussusception occurs when one segment of bowel

telescopes into an adjacent segment, resulting in obstruction and ischemic injury to the intussuscepting

segment (Fig. 49-11) and the obstruction may become complete, particularly if tissue inflammation and

necrosis occur. Of adult cases, 90% are associated with pathologic processes.105,106 Tumors, benign or

malignant, act as the lead point of intussusception in more than 65% of adult cases. A significant

proportion of cases have been reported to occur after abdominal surgery for lesions other than

neoplasm. In cases not associated with neoplasm, Sarr et al.106 reported that approximately 20% were

related to the suture line, approximately 30% to adhesions, and approximately 60% to intestinal tubes.

Intussusception related to long tubes can occur when the tube is withdrawn, but most frequently occurs

with the tube in place. Perioperative intussusception frequently subsides without intervention.

Four types of intussusception are recognized: enteric (Fig. 49-12), ileocolic, ileocecal, and colonic. In

the ileocolic form, the ileum telescopes into the colon past a fixed ileocecal valve. In the ileocecal form,

the valve itself may be the lead point of the intussusception. Radiographic features of intussusception

are not specific. Plain films reveal evidence of partial or complete obstruction. Occasionally, a sausageshaped soft tissue density will be seen, outlined by two strips of air. Recently, in both pediatric and

adult cases, it has been suggested that sonography may be useful in diagnosis. Nevertheless, the

mainstays of diagnosis are contrast studies or CT scan. Because of the high incidence of tumors, surgery

has generally been recommended. Reduction by hydrostatic pressure, which is the standard of care in

pediatric cases, is not usually attempted in adults. Honjo et al. described preoperative reduction in

31.8% and 31.8% intraoperative reduction of adult intussusceptions. Preoperative reduction serves

several functions including avoidance of emergency surgery, allowing radical surgery for cancer,

reducing the extent of intestinal resection, and allows time for preoperative predation of the bowel.

This may shift the paradigm in management of adult intussusception.107 Clear indications for operation

include long length and wide diameter of the intussusception, presence of a lead point, or evidence of

bowel obstruction.105 Recent studies have called into question the need to operate in all cases detected

on sensitive imaging studies such as CT scan, arguing that a number of these patients can be safely

managed without operation.105 However, in the opinion of these authors, it is difficult to advise

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expectant management except in unusual circumstances.

Figure 49-11. Anatomy of intussusception. The intussusceptum is the segment of bowel that invaginates into the intussuscipiens.

Figure 49-12. Axial (A) and coronal CT scan (B) images of an ileocolic intussusception secondary to colon carcinoma (M) as a lead

point. Intussusceptum (long arrows) and intussuscipiens (arrowhead). Mesenteric vessels and fat (white arrowhead) accompany the

intussusceptum.

Crohn Disease

Indications for surgery in Crohn disease are discussed elsewhere in this book. In this disease, obstruction

occurs under two different sets of circumstances.108 When the disease has flared acutely, the lumen may

be narrowed by a reversible inflammatory process. The result is an open-loop obstruction that may

respond, first to intravenous hydration and nasogastric decompression, and ultimately to therapy with

corticosteroids or other anti-inflammatory regimens. Alternatively, obstruction may occur in the setting

of a chronic stricture. Such strictures will not respond to conservative measures and, once diagnosed,

operative therapy should not be delayed. One important clinical point is that about 7% of strictures in

the colon, and an uncertain proportion of those in the small intestine, are malignant.108 Extent of

resection is thus based on intraoperative findings, that is, to margins beyond visibly diseased bowel and

does not necessarily include enlarged lymph nodes in the mesentery. If there is suspicion for

malignancy, a lymphadenectomy is performed.

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A second clinical point is that Crohn-affected bowel may not be dilated proximal to the obstruction

but can be complicated by a small perforation. Such a microperforation may not be large enough to be

associated with free air on plain films. The patient may thus present with significant abdominal pain and

tenderness. A CT scan is likely to be the most sensitive imaging modality for obtaining evidence that

differentiates conditions that require immediate surgery (closed-loop obstruction and microperforation)

from simple obstruction that would otherwise be observed. In the absence of clinical progression of

symptoms and signs, however, extended conservative management is warranted before the patient is

committed to surgery.

Malignant Obstruction

Obstruction can complicate malignancies of the small and large bowel in a number of settings. Studies

have documented that 10% to 28% of patients with colorectal cancer and 20% to 50% of patients with

ovarian cancer will present with a malignant bowel obstruction at some point during the course of their

disease.109 Most commonly, a primary lesion such as an adenocarcinoma or lymphoma will enlarge until

the lumen of the intestine is blocked. The lesion then presents with symptoms and signs associated with

the level of obstruction and are managed accordingly.

A second setting involves a patient who previously has undergone surgery for malignancy and now

returns with evidence of bowel obstruction. The likelihood that the obstruction is due to recurrent

disease is based on several factors, including the origin of the primary malignancy, the stage of the

primary malignancy, and the designation of the original surgery as curative or palliative. Gastric and

pancreatic carcinomas often present with or are subsequently complicated by peritoneal carcinomatosis

and thus the subsequent obstruction is most likely due to malignancy. With respect to colon and rectal

carcinomas, as many as 50% of cases presenting with obstruction after resection of the primary may be

due to adhesions and not recurrent malignancy.109,110 In addition, even if the obstruction is now due to

unresectable disease, significant palliation can be obtained through bypass or enterostomy in up to 75%

of patients (Fig. 49-13). However, the underlying diagnosis of cancer in this patient population

mandates careful attention be paid to patient selection prior to any surgical intervention and risk factors

for poor outcome (Table 49-4, Algorithm 49-2). In patients presenting with gastroduodenal and

colorectal obstructing lesions who are not candidates for surgical bypass or enterostomy, endoscopic

management options including percutaneous endoscopic gastrostomy (PEG) tube placement and selfexpanding metallic stent (SEMS) placement, are available (Algorithm 49-2). These options have been

associated with symptomatic relief in greater than 75% of patients.109

Figure 49-13. Significant palliation can be achieved in a patient with obstructing but unresectable malignancy. Enteroenterostomy

is performed to bypass the obstructing segment.

Management of incurable malignant obstruction may require an approach that moves away from

classical surgical teaching of nil by mouth, nasogastric tube, intravenous fluids, and serial

radiographs.111 Patients with advanced malignant obstruction in the absence of a solitary or correctable

obstructing lesion are generally managed without surgery (Algorithm 49-2). Patients are managed

without a nasogastric tube if possible. They are encouraged to eat as soon as obstructive symptoms

resolve using a low-fiber diet. Antiemetics and opioids via continuous subcutaneous infusions are used

to manage nausea, vomiting, and colic, respectively. In addition, octreotide, a somatostatin analog, is

used in palliation of refractory malignant intestinal obstruction by improving intestinal mucosal

absorption, improving motility, reducing gastrointestinal hormone levels and intestinal secretions, and

having a direct antineoplastic effect on the obstructing tumor.112 This allows true palliative care outside

a hospital setting saving patients the pain, discomfort, and complications of hospitalization and

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