Water-soluble contrast agents in adhesional small bowel obstruction: meta-analysis and PRECIS-2 assessment of trials

Background: Adhesional small bowel obstruction is a common presentation to acute general surgical services. Initial management is typically conservative and includes the use of water-soluble contrast agents. Current trials assessing water-soluble contrast agents are limited by sample size and demonstrate contrasting results. The aim of this review was to systematically appraise the use of water-soluble contrast agents in adhesional small bowel obstruction.

Methods: This systematic review and meta-analysis was registered with PROSPERO (CRD42024573136) and conducted in line with PRISMA guidelines. Searches of Medline, Embase and Central databases were undertaken to include randomized clinical trials reporting the use of water-soluble contrast agents in adhesional small bowel obstruction. Searches were last updated on 26 July 2024. The primary outcome was the need for operative intervention. Secondary outcomes included the rate of intestinal ischaemia, the need for bowel resection, and mortality. A random-effects meta-analysis was conducted for outcomes reported in three or more studies. Risk of bias was assessed using the Cochrane Risk-of-Bias tool, and trial methods were appraised using the PRagmatic Explanatory Continuum Indicator Summary (PRECIS-2) tool.

Results: In all, 11 randomized controlled trials were included with a median sample size of 88 (range 26-242), nine of which were single-centre studies; only one study used computed tomography imaging to diagnoses adhesional small bowel obstruction. Meta-analysis revealed no significant difference in operative intervention (odds ratio 0.63, 95% confidence interval 0.39 to 1.01; P = 0.053), small bowel ischaemia, small bowel resection, or mortality. Risk of bias raised concerns in several domains. PRECIS-2 assessment showed trials were pragmatic rather than explanatory designs.

Conclusion: This review does not support the use of therapeutic water-soluble contrast agents in adhesional small bowel obstruction. Further adequately powered trials are needed. Standardization of diagnostic modality and consideration of explanatory designs should be considered.