INTRODUCTION — Adhesive small bowel obstruction (ASBO) is a common surgical emergency, with a lifetime incidence of approximately 30 percent in patients following major abdominal and pelvic surgery. ASBO is defined as small bowel obstruction occurring in patients with a history of previous abdominal surgery and without an alternate cause for bowel obstruction, such as hernia, malignancy, or inflammation.
Oral water-soluble radiological contrast agents, most commonly diatrizoate meglumine-diatrizoate sodium (Gastrografin [GGF]), have been used to predict which patients will require surgery and which patients can be managed nonoperatively. In this context, GGF is also used therapeutically. Evidence suggests that there may be benefit in establishing an institutional protocol that utilizes GGF for the management of ASBO [1,2].
The benefits and risks of using GGF to treat ASBO are discussed in this topic as well as the proposed clinical use of GGF in this context. The diagnosis and management of ASBO is discussed separately:
●(See "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults".)
●(See "Management of small bowel obstruction in adults".)
MECHANISM OF ACTION — Diatrizoate meglumine-diatrizoate sodium (Gastrografin [GGF]) is the most commonly used water-soluble contrast medium for the treatment of adhesive small bowel obstruction (ASBO). Each 100 mL of GGF solution contains 10 grams of sodium diatrizoate and 66 grams of meglumine diatrizoate with an osmolarity of 2150 mOsm/L (approximately six times the osmolarity of extracellular fluid) [3,4].
Its main mechanism of action is by activating the movement of water into the small bowel lumen by osmosis and decreasing edema of the small bowel wall. It probably also enhances smooth muscle contractile activity. The combination of these effects is thought to generate effective peristalsis, enabling the small bowel to overcome ASBO [5].
EVIDENCE OF BENEFITS
Predicts resolution of bowel obstruction without surgery — The diagnostic benefit of Gastrografin (GGF) in adhesive small bowel obstruction (ASBO) has been demonstrated in multiple studies. A 2007 Cochrane review and meta-analysis concluded that the appearance of water-soluble contrast in the colon on an abdominal radiograph within 24 hours of its oral administration predicts clinical resolution of ASBO without surgery, with a pooled sensitivity of 97 percent and specificity of 96 percent. The area under the summary receiver operating characteristic (ROC) curve was 0.98 [3].
Timely prediction of ASBO resolution permits early feeding of patients who will not require surgical intervention, which contributes toward early discharge and a reduced length of hospital stay. (See 'Reduces length of stay' below.)
Accelerates resolution of bowel obstruction — In addition to its diagnostic and prognostic utility, GGF appears to have a specific therapeutic effect in accelerating the resolution of ASBO:
●In a randomized trial, 99 patients with 107 episodes of ASBO received either GGF or conventional therapy [5]. Patients were not blinded to treatment, and no placebo was used in the control group. Patients given GGF had more rapid resolution of ASBO than those treated with conventional therapy (6.2 versus 23.3 hours). Operative mortality and complication rates were similar between the two groups.
●A smaller double-blind randomized trial that included 35 patients reported a similar finding: complete resolution of ASBO was significantly earlier in the GGF group than in the placebo group (12 versus 21 hours) [6].
It is important to point out that GGF appears to only accelerate the resolution of ASBO in patients who would have resolved eventually without surgery, rather than increase the success rate of nonoperative management. In other words, GGF does not appear to reduce the need for surgical intervention. (See 'Does NOT consistently reduce need for surgery' below.)
Reduces length of stay — Multiple studies have associated the use of GGF with a decrease in length of stay:
●In the 2007 Cochrane review, a meta-analysis of four of the included studies showed that water-soluble contrast reduced hospital stay compared with placebo by a weighted mean difference of 1.83 days [3].
●In a randomized trial, patients given GGF spent 2.2 fewer days in the hospital [5].
●A randomized trial conducted in 2017 showed no reduction in hospital stay with GGF compared with normal saline placebo (3.8 versus 3.5 days). However, all patients underwent computed tomography on presentation and had a mandated wait period of 48 hours before any operative surgical decision could be made, both of which may have influenced the length of hospital stay results [7].
●A 2019 systematic review and meta-analysis of nine trials, including the two referenced in the previous bullets, found a more modest reduction in hospital stay (weighted mean difference of -0.15 days or -3.6 hours) [8].
The reduction in length of stay is thought to be chiefly due to the prognostic ability of GGF, which allows clinicians to identify patients in whom ASBO will resolve without surgery early and subsequently discharge them early. (See 'Predicts resolution of bowel obstruction without surgery' above.)
Does NOT consistently reduce need for surgery — In randomized trials, differences in the operative rates between the placebo and GGF groups have not been consistently observed:
●In the 2007 Cochrane review, GGF did not reduce the need for surgical intervention (odds ratio [OR] 0.81, 95% CI 0.54-1.21) [3].
●A 2016 systematic review, which included both nonrandomized studies and randomized trials, suggested a decrease in requirement for surgery with GGF administered early in the clinical course [9]. The conclusion of the review was influenced by two studies. The first was a multicenter study from Italy. In that study, patients who had not resolved by 36 hours were taken to surgery. This might have biased against the control group, which may take longer to resolve than the GGF group [10]. The second study was a randomized trial from Egypt in 2008. In that study, the two groups were treated differently, with the control group offered surgery at a lower threshold than the GGF group [11].
●A randomized trial conducted in 2017 concluded that the rates of operative intervention were similar at 24 and 20 percent in the GGF and saline placebo groups, respectively [7].
●A systematic review and meta-analysis of nine randomized controlled trials in 2019 concluded that GGF did not reduce the need for surgical intervention (relative risk 0.84, 95% CI 0.533-1.339) [8].
In summary, data suggest that GGF accelerates resolution of ASBO only in patients who would have resolved eventually without surgery, rather than increasing the rate of resolution overall.
RISKS
Adverse effects — A very low rate of complications related to Gastrografin (GGF) administration in adhesive small bowel obstruction (ASBO) has been reported in the literature. GGF should not be administered to patients with a known hypersensitivity to GGF or any of its components. Rare anaphylactic reactions following GGF administration have been described, and due to its iodine content, GGF is contraindicated in patients with hyperthyroidism. Aspiration pneumonitis and pulmonary edema have been reported, which, although rare, can be fatal [12].
Other theoretical risks have been suggested, such as irritation of the gastrointestinal mucosa, leading to a risk of perforation as a result of hyperperistalsis and distension. Caution should be exercised in dehydrated patients because GGF may exacerbate dehydration by sequestration of fluid in the intestinal lumen.
Long-term effects — Compared with conventional conservative treatment for ASBO, GGF use does not appear to affect the rate of overall recurrences or recurrences requiring surgery [7,13].
CLINICAL USE — Before Gastrografin (GGF) is used, complicated small bowel obstruction and nonadhesive small bowel obstruction should be excluded (see 'Exclusions' below). After GGF is administrated, a plain abdominal radiograph should be obtained within 24 hours. The presence or absence of GGF in the colon on the radiograph informs further clinical decision making (algorithm 1).
Exclusions — Patients suspected of having complicated bowel obstruction (complete obstruction, closed-loop obstruction, bowel ischemia, necrosis, or perforation) based upon clinical and radiologic examination should undergo urgent abdominal exploration. There is no role for GGF in this setting; these patients were excluded from most randomized trials evaluating GGF.
The routine use of GGF has been endorsed by the Bologna guidelines for diagnosis and management of adhesive small bowel obstruction (ASBO) published in 2013 by the World Society of Emergency Surgery [14].
Administration — In most clinical situations, an abdominopelvic computed tomographic (CT) scan has been performed and a nasogastric tube (NGT) has been inserted when the diagnosis of ASBO is made.
Appropriate decompression by NGT should be confirmed before GGF is administered via the NGT. Although practices may vary [14], 100 mL of undiluted GGF is most often given as a one-time dose [3], and the NGT is clamped for the next two to four hours. Observational studies suggest that administering GGF within 12 hours of diagnosis improves duration of stay, complications, and mortality in nonoperative patients and shortens preoperative duration of stay in operative patients [15].
If an NGT is not placed, the same volume of GGF can be administered orally [14].
Prior administration of undiluted GGF is not a contraindication to performing a subsequent CT scan. In the rare occasion where a CT scan is required after GGF administration, the radiologist should be made aware that concentrated oral contrast has been administered so the interpretation can be made in the correct context.
Follow-up abdominal imaging — A plain abdominal radiograph (ie, Kidney-Ureter-Bladder [KUB]) should be obtained in 6 to 24 hours after the administration of GGF. A radiograph taken after GGF administration early in the hospital course aids the clinical decision to operate or feed early, thus combining the diagnostic/triage and therapeutic functions of GGF:
●Evidence of GGF reaching the colon on the radiograph is highly predictive of the resolution of ASBO without surgical intervention [9] and should inform the clinical decision to advance the patient's diet.
●Failure of GGF to reach the colon on the radiograph by 24 hours after administration of GGF should influence, but not dictate, the decision to operate. (See 'Clinical decision making' below.)
The optimal timing to perform the plain abdominal radiograph is debated. There seems to be no advantage in waiting longer than eight hours after the administration of GGF, and the radiograph should not be performed later than 24 hours after administration of GGF. Within the window of 6 to 24 hours, however, the timing of the radiograph is flexible, which allows it to be taken at a time that is convenient for both the patient and surgical team.
Clinical decision making — As stated above, GGF accelerates the resolution of ASBO in patients who would have resolved without surgery but does not reduce the need for surgery. Thus, failure of GGF to reach the colon in 24 hours should only influence, but not dictate, surgical decision making.
Although some investigators have recommended surgery to be conducted as soon as practical if GGF is not present in the colon on plain abdominal radiograph by 24 hours, several studies have shown that up to 30 percent of such patients can still be managed nonoperatively [3]. However, response to GGF does not identify which patients will or will not respond to continued nonoperative management. Therefore, subsequent management in nonresponders to GGF should be dictated by clinical judgement.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Bowel obstruction".)
SUMMARY AND RECOMMENDATIONS
●Adhesive small bowel obstruction (ASBO), defined as small bowel obstruction occurring in patients with a history of previous abdominal surgery and without an alternate cause for bowel obstruction, such as hernia, malignancy, or inflammation, is a common surgical emergency. (See 'Introduction' above.)
●Water-soluble radiological contrast agents, such as Gastrografin (GGF), have been used for diagnosis and therapeutically to treat ASBO by virtue of their high osmolality. (See 'Mechanism of action' above.)
●Evidence from randomized trials suggests that GGF can predict clinical resolution of ASBO without surgery, reduce the length of hospital stay, and accelerate the resolution of ASBO in patients who would have resolved without surgery. However, GGF does not reduce the need for surgical intervention. (See 'Evidence of benefits' above.)
●Before GGF is used, complicated small bowel obstruction (complete obstruction, closed-loop obstruction, bowel ischemia, necrosis, or perforation) and alternate causes of small bowel obstruction (internal hernia, malignancy, or inflammation) should be excluded. GGF has not been evaluated in patients with complicated or nonadhesive causes of small bowel obstruction (algorithm 1). (See 'Exclusions' above.)
●For all patients with uncomplicated ASBO, we suggest nasogastric tube or oral administration of 100 mL of undiluted GGF (Grade 2B). (See 'Administration' above.)
●After GGF administration, a plain abdominal radiograph should be obtained within 6 to 24 hours to document the progression of GGF into the colon (see 'Follow-up abdominal imaging' above):
•Evidence of GGF reaching the colon on plain abdominal radiograph is highly predictive of the resolution of ASBO without surgical intervention and should inform the clinical decision to advance the patient's diet.
•Failure of GGF to reach the colon on plain abdominal radiograph by 24 hours after administration of GGF should influence, but not dictate, the decision to operate. Further management requires clinical judgment. (See 'Clinical decision making' above.)
