unproductive surgery.111

Volvulus

The term volvulus indicates that a loop of bowel is twisted more than 180 degrees about the axis of its

mesentery. Volvulus has been reported for the cecum, transverse colon, splenic flexure, and sigmoid

colon. A special variant of volvulus, complicating a condition known as Chilaiditi syndrome, can occur

when redundant loops of the transverse colon slip between the liver and diaphragm and then undergo

torsion.113 Generally, the condition is asymptomatic, but when associated with volvulus must be

relieved surgically.

Table 49-4 Results of Management of Malignant Obstructions: Risk Factors for

Unfavorable Outcome

The most common site for volvulus is the sigmoid colon, accounting for 65% of cases.114 By

definition, a volvulus is a form of closed-loop obstruction of the colon. Air is always present in the colon

and rectum, and thus volvulus of any segment of the colon is associated with abdominal distention and,

usually, severe abdominal pain. As shown in Figure 49-5, the most common radiographic feature is the

“bent inner tube” appearance of the sigmoid, which is located in the upper abdomen. The preferred

method of management involves endoscopic decompression. A rigid or flexible proctosigmoidoscope is

advanced gently into the rectum until a rush of air and feces indicates that the loop has been untorsed.

A rectal tube is then advanced well into the loop as a stent to prevent retorsion. Gangrene of the colon

does not usually complicate the picture if the patient is seen and treated promptly. This conservative

approach resolves the volvulus in 85% to 90% cases and elective resection or fixation of the redundant

segment can then be planned. Following endoscopic decompression, recurrence of the volvulus is higher

than 60%.115 Thus, an operation to remove the sigmoid should be performed if the patient is fit for

surgery.116 However, a majority of these patients are elderly and infirm and approximately 15% have a

history of psychiatric disorder. As a result, the patient may present with peritoneal findings, sepsis, and

shock. In this setting, rapid resuscitation followed by urgent resection and colostomy is warranted.

Other forms of volvulus generally cannot be detorsed without operation. Fixation of the torsed segment

(e.g., via cecostomy or cecopexy) is generally a less satisfactory solution than resection of the involved

segment and is not generally recommended.114

Radiation Enteritis

After asymptomatic periods lasting at least 10 years, chronic intestinal obstruction can result. Radiation

injury elicits an underlying vasculitis and fibrosis that lead to chronic, recurring low-grade partial

obstruction of the small intestine or stricturing and bleeding in the colon and rectum. Operation is

indicated for incapacitating symptoms and obstruction not resolved by conservative management.117

Recurrence of the original tumor as a cause of obstruction should be considered and excluded. However,

the diffuse nature of the injury and pathologic responses can lead to massive resections that leave the

patient with short-bowel syndrome. Attempts to suture scarred loops can also result in chronic

inflammation and formation of interloop abscesses and fistulae. The incidence of suture line leak is

high.118 There are several experimental therapies used in the treatment and prevention of radiation

enteritis which includes pentoxifylline–tocopherol combination, sulfasalazine, methylprednisolone,

HBO, intraperitoneal octreotide, cysteine, triamcinolone, and amifostine.119,120

Role of Laparoscopy in Management of Small Bowel Obstruction

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Open surgery is the preferred method in the management of strangulating SBO after failed conservative

management but since the advent of laparoscopy for general abdominal surgery, a number of

investigators have reported the feasibility of laparoscopic approaches to small and large bowel

obstruction. Such approaches have been used, with varying degrees of success, to manage obstruction

from a number of different etiologies (Table 49-5).121–123 Laparoscopic management of bowel obstruction

provides many potential benefits including quicker recovery of bowel function, shorter hospital stay,

less postoperative pain, reduced recovery time and early return to full activity, and fewer postoperative

complications including a decreased incidence of wound infection and pneumonia. Additionally, as

suggested by both clinical and experimental studies in animal models, laparoscopy is associated with

decrease in incidence, extent and severity of intra-abdominal adhesions compared with open

surgery.124,125 Thus laparoscopic management of bowel obstruction may result in a decreased lifetime

risk for recurrent bowel obstruction. According to a systematic review and meta-analysis, laparoscopic

adhesiolysis was associated with reduced overall complication rate with no significant difference in the

occurrence of intraoperative injury to bowel and overall mortality.126

Table 49-5 Results for Outcome of Laparoscopic Management of Intestinal

Obstruction: Favorable Attributes

In adults, the most common etiology for which laparoscopic versus open surgical management of

bowel obstruction has been evaluated is adhesive bowel obstruction.123,127–136 Studies of laparoscopic

lysis of adhesions for SBO indicate that it is feasible, with acceptable operative times, length of hospital

stay, as well as conversion and complication rates (Table 49-6). Studies directly comparing laparoscopic

to open surgical management of adhesive SBO highlight the benefits of the laparoscopic approach as

indicated by statistically significant decreases in complication rates, time to return of bowel function,

length of hospital stay, and even overall cost (Table 49-7).

Despite these benefits, laparoscopic management of bowel obstruction should be approached with

caution and individualized to specific clinical situations.137 Laparoscopy is discouraged when the

surgeon is uncomfortable with the technique or in patients presenting with peritonitis, hemodynamic

instability, severe comorbid conditions, complete and distal obstruction, or when contraindications to

pneumoperitoneum exist. Recent advancement and improvement in tools and skill in laparoscopy have

paved the way for its increased use in the surgical management of SBO. Recently, consensus guidelines

have been published emphasizing its role in selected group of patients.138 Laparoscopically assisted lysis

of adhesions may be attempted in case of first episode of SBO or anticipated single-band lesion. While it

may be problematic to use a laparoscopic approach in managing obstruction in patients who have

previously undergone extensive and open intra-abdominal procedures, it is safe to use a laparoscopic

approach in managing obstruction in patients who have previously undergone laparoscopic procedures,

especially focused procedures such as appendectomy and cholecystectomy.

Under these circumstances, success in using laparoscopy to confirm the diagnosis of obstruction is

between 60% and 100%; its success in therapeutic resolution of the obstruction is lower, perhaps 40% to

80%. The predictive factors for a successful laparoscopic adhesiolysis are less than 2 previous

laparotomies, nonmedian previous laparotomy, appendectomy as previous surgical treatment, unique

band adhesion as phatogenetic mechanism of SBO, early laparoscopic management within 4 hours from

onset of symptoms, no signs of peritonitis on physical examination, and experience of surgeon.139 There

should be a low threshold for open conversion. The usual reasons for converting to open adhesiolysis

are inadequate laparoscopic control due to intestinal distention, extensive adhesions, iatrogenic

perforations, bleeding, and resection of necrotic segments.140 Operative technique plays a paramount

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role in the success of laparoscopic approach. In obtaining laparoscopic access, an open access (Hasson)

technique, entry to the left upper quadrant and ultrasound-guided site entry were recommended.49,138

Although recent studies suggest that laparoscopic approaches are safe, effective and beneficial,

prospective randomized studies evaluating laparoscopic management of SBO are required to definitively

document its benefits over the traditional open approaches. It is also important to point out the need for

adhesion quantification in future research. Coccolini et al. proposed a peritoneal adhesion index ranging

from 0 to 30, providing a more precise and standardized system for describing findings at operation.141

Such standardization would enable integration of the results of different studies, permitting a better

understanding of circumstances where treatments may be standardized and those where

individualization is important.

Table 49-6 Outcomes and Complications of Laparoscopic Operations for

Obstruction of the Small Intestine Due to Adhesions

Table 49-7 Outcomes, Complications, and Costs in Laparoscopic Management of

Intestinal Obstruction Due to Adhesions

7 Open exploratory laparotomy is the gold standard in treating unresolved SBO, but laparoscopic

management should be considered in select group of patients. Types of intestinal obstruction that are

more likely to lead to strangulation and the need for urgent/emergent operation include closed-loop

obstructions, obstruction that occurs without a prior history of operation, and obstructions that occur

after laparoscopic procedures.

ILEUS AND PSEUDO-OBSTRUCTION

Ileus

Etiologic Factors

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8 An ileus or “eileos” (Greek for “twisting”) reflects a loss of forward peristalsis and coordination of the

motility of the different regions of the gastrointestinal tract causing a functional obstruction.142

Clinically, bowel sounds, passage of flatus, and bowel movements have been used to signal the return of

bowel function and coordination of peristalsis. Liquid contrast and radiolabeled marker studies suggest

that effective duration of ileus varies in different regions of the alimentary tract.143,144 A POI may last

for 0 to 24 hours in the small intestine, 24 to 48 hours in the stomach, and 48 to 72 hours in the large

bowel.145,146 The type of surgery and the wide variety of endpoints used to measure gut recovery often

decide the duration of ileus. There is no consensus as to which one is most clinically meaningful.

Duration of ileus is therefore primarily dependent on the return of colonic motility and its coordination

with other regions of the gastrointestinal tract. A typical period of ileus is thus self-limited and easily

tolerated. Factors implicated in ileus (Table 49-6) are outlined below:

Neurohumoral Peptides. Increases in endogenous neuromuscular inhibitors of the bowel include

norepinephrine, corticotropin-releasing hormone (CRH), nitric oxide, somastostatin, glucagon, gastric

inhibitory peptide, opioids and other peptides such as calcitonin gene-related peptide, motilin, substance

P, VIP_ and substance P, have all been established as inhibitory neurotransmitters in the intrinsic gut

nervous system. Antagonists to VIP, substance P and inhibitors of NO synthesis improve postoperative

bowel motility.147,148 Calcitonin gene–related peptide inhibits postoperative gastric emptying and

gastrointestinal transit.149,150 The use of anticholinergic medications delays recovery of an ileus.151

One group of neurohumoral substances that are particularly important in this regard are the opioids,

both synthetic and endogenous. Opioids are established neurotransmitters in central and peripheral

nervous systems, and it is well established that their use delays gastric emptying and promotes

nonpropulsive smooth muscle contraction with an increase in intraluminal pressure throughout the

entire gastrointestinal tract.152,153 Over the years, a series of experimental studies have indicated that

recovery of ileus is accelerated during administration of specific antagonists to kappa or mu opioid

receptors,154,155 suggesting that endogenous opioid release modulates recovery from ileus.

Inflammation. A relatively recent series of experimental and clinical investigations have focused

attention on the role of inflammatory cells and mediators of inflammation in the development of

prolonged ileus. Surgical intervention results in elevated levels of interleukin-6 (IL-6), cyclooxygenase

isoform COX-2, and inducible nitric oxide synthetase (iNOS), all mediators of inflammation from

macrophages.156,157 In experimental animals, focal manipulation of the bowel may result in a panenteric inflammation and ileus.157 In experimental animals and human subjects, activated macrophages

have been found in the muscularis of the small bowel, as early as 3 hours after laparotomy.158 Increased

COX-2 expression leads to prostaglandin release. Jejeunal contractility appears to be impaired, an effect

blocked in COX-2 knockout mice and by the administration of selective COX-2 inhibitors. In related

studies both in experimental animals and human subjects, Kalff et al. found that NO synthesis is

stimulated in activated macrophages in the muscular layer of the small intestine following surgical

intervention. More recently, degranulation of mast cells has also been implicated in the pathogenesis of

ileus after laparotomy. In this regard, it has been shown that surgical manipulation of intestines

activates quiescent macrophages as well as mast cells, and that mast cell destabilizers can prevent

mechanically induced intestinal inflammation and dysmotility.159,160 Bowel wall edema from

inflammation or intravenous fluid overload is another mechanism of impairment of GI motility.161

Table 49-8 Etiologies of Prolonged Ileus After Abdominal Operations

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Inhibitory Neural Reflexes. Noxious spinal afferent signals are thought to increase inhibitory

sympathetic activity in the gastrointestinal tract.162 Blockade of spinal afferents with epidural local

anesthetics or with topical capsaicin has been shown to accelerate resolution of ileus in experimental

studies.149,150 In clinical studies of patients undergoing complex abdominal operations through

conventional laparotomy incisions, it appears that conventional intramuscular injections are less likely

to be associated with prolonged ileus than strategies utilizing patient-controlled intravenous

injection.163,164 Moreover, utilization of epidural analgesia tends to decrease recovery times from ileus

in this group of patients,165–167 suggesting that autonomic pathways coursing through spinal cord may

serve as control points for ileus. Recent studies also provide evidence that carbon monoxide, derived

from the activity of heme oxygenase-2 in myenteric plexus of the intestine, may play a role in

modulating smooth muscle activity and its regulation by enteric nervous system.168–170

Central responses have also been observed as a result of laparotomy162 and have been linked to

activation of afferent pathways in the vagus nerve and a general response of the organism to stress and

release of corticotrophin-releasing factor.171 Very recently, the efferent pathways in the vagus have also

been implicated as possible modulators or control points for the inflammatory response. A series of

experimental studies

172,173 has suggested that the vagus participates in suppression of certain

macrophage activities, leading to earlier resolution of intestinal ileus.173 These observations offer the

possibility of a multidimensional understanding of ileus, both in individuals who are recuperating

normally and in those who have protracted ileus but no specific risk factors for it (e.g., undrained

sepsis, overuse of narcotics, spinal cord injury, severe pelvic fractures, and retroperitoneal

inflammation).

Diagnosis

It is important to distinguish between a normal POI and a paralytic ileus. The distinction is

predominantly one of time since operation and based on circumstance. POI is less severe, self-limiting

(lasts 2 to 3 days vs. 3 to 5 days) and is usually an indicator of colonic dysmotility rather than a

paralytic ileus which represents inhibition of small bowel activity. A prolonged POI (PPOI) occurs with

protracted signs or symptoms of abdominal distention, bloating, diffuse and persistent abdominal pain,

nausea, vomiting, and inability to pass flatus or tolerate an oral diet.

It is also important to distinguish between a PPOI from a mechanical SBO. Clinically, the presence of

intense colicky pain, feculent emesis, or rapidly progressing pain or distension is more suggestive of

SBO than PPOI. Localized tenderness, fever, tachycardia, and peritoneal signs suggest bowel ischemia or

perforation, necessitating emergent surgical intervention.10

A variety of clinical circumstances and laboratory tests may also increase suspicion for prolonged

ileus and lessen concern for mechanical obstruction and associated complications. In addition to opiates,

a number of medications have been associated with slow recovery of intestinal motor function (Table

49-8). Isolated metabolic disturbances such as ketoacidosis, hypomagnesemia, hypercalcemia, and

hypokalemia can prolong ileus. Ileus can be caused and perpetuated by systemic inflammatory

responses to sepsis, abscess, pneumonia, and pancreatitis.

9 When the patient’s POI has extended beyond the expected period, plain films of the abdomen

reveals gas in segments of both small and large bowel (Fig. 49-14). At this point, the patient may begin

to experience some discomfort and distention, as swallowed air fills loops that do not have effective

peristalsis. Bowel sounds may be present, if hypoactive. The differential diagnosis now includes the

possibility of mechanical obstruction from early postoperative adhesions (see earlier). To differentiate

early postoperative obstruction from ileus, contrast studies or CT scans are helpful. The latter may be

useful if other abdominal pathology such as an abscess could be contributing to the clinical picture. CT

with oral contrast has a sensitivity and specificity of 90% to 100% in distinguishing ileus from a complete

postoperative SBO.174 However, it is less reliable in distinguishing ileus from a partial SBO.174 If the

diagnosis is uncertain after CT, upper GI contrast studies (enteroclysis) with water-soluble radio-opaque

contrast material (e.g., Gastrograffin) are especially helpful in distinguishing ileus from partial SBO

(which more closely mimics ileus than complete SBO) and in identifying the severity of partial

obstruction.174

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