Oral water soluble contrast for the management of adhesive small bowel obstruction

Adhesions are the leading cause of small bowel obstruction. Most adhesive small bowel obstructions resolve following conservative treatment but there is no consensus as to when conservative treatment should be considered unsuccessful and the patient should undergo surgery. Studies have shown that failure of an oral water-soluble contrast to reach the colon after a designated time indicates complete intestinal obstruction that is unlikely to resolve with conservative treatment. Other studies have suggested that the administration of water-soluble contrast is therapeutic in resolving the obstruction.

The aims of this review are:1. To determine the reliability of water-soluble contrast media and serial abdominal radiographs in predicting the success of conservative treatment in patients admitted with adhesive small bowel obstruction.2. To determine the efficacy and safety of water-soluble contrast media in reducing the need for surgical intervention and reducing hospital stay in adhesive small bowel obstruction.

The search was conducted using MeSH terms: ''Intestinal obstruction'', ''water-soluble contrast'', "Adhesions" and "Gastrografin", and combined with the Cochrane Collaboration highly sensitive search strategy for identifying randomised controlled trials and controlled clinical trials.

1. Prospective studies (to evaluate the diagnostic potential of water-soluble contrast in adhesive small bowel obstruction);2. Randomised clinical trials (to evaluate the therapeutic role).

1. Studies addressing the diagnostic role of water-soluble contrast were critically appraised and data presented as sensitivities, specificities and positive and negative likelihood ratios. Results were pooled and summary receiver operating characteristic (ROC) curve was constructed. 2. A meta-analysis of the data from therapeutic studies was performed using the Mantel -Haenszel test using both the fixed effect and random effects model.

The appearance of water-soluble contrast in the caecum on an abdominal radiograph within 24 hours of its administration predicts resolution of an adhesive small bowel obstruction with a pooled sensitivity of 0.96, specificity of 0.96. The area under the curve of the summary ROC was 0.98. Four randomised studies dealing with the therapeutic role of Gastrografin were included in the review, water-soluble contrast did not reduce the need for surgical intervention (odds ratio 1.29, P = 0.36). Meta-analysis of two studies showed that water-soluble contrast reduced hospital stay compared with placebo (weighted mean difference = - 2.58) P = 0.004.

Published literature strongly supports the use of water-soluble contrast as a predictive test for non-operative resolution of adhesive small bowel obstruction. Although Gastrografin does not cause resolution of small bowel obstruction, it does appear to reduce hospital stay.