Utility of contrast enema to assess anastomotic integrity and the natural history of radiological leaks after low rectal surgery: systematic review and meta-analysis

There is no clear consensus on how to assess low rectal anastomotic integrity and patency prior to reversal of de-functioning stoma. The aim of this systematic review was to assess the utility of contrast enema (CE) in this context and to clarify the natural history of radiological leaks. Keyword search of electronic databases (Embase, MEDLINE, Cochrane Library, Google Scholar) and bibliographic cross-referencing were performed to identify appropriate studies. Data extraction and synthesis was performed with the primary outcomes being the sensitivity and specificity of CE for detecting clinically significant abnormalities. Statistical analysis was performed using Open Meta-Analyst software. Narrative review of outcomes including those of clinical and radiological leaks was also undertaken. A total of 1,142 CE from 11 articles were included in the final meta-analysis. CE had high specificity (95.4; 95 % confidence interval = 92.0-97.4) and negative predictive value (98.4; 97.4-99.1) and moderate sensitivity (79.9; 63.9-89.9) and positive predictive value (64.6; 55.5-72.9) for the detection of clinically significant anastomotic problems. There was a high degree of correlation between CE and clinical examination findings (96.7 %). Occult radiological leaks were seen in 5.7 % of CE, and all but one (97 %) eventually underwent successful reversal. Only three quarters of patients with clinical leak underwent successful reversal. CE is effective at excluding clinically significant anastomotic problems, especially after clinical anastomotic leaks. However, false positive results can be observed in asymptomatic patients, and it is unclear how much additional information CE provides over clinical assessment in the low uncomplicated anastomosis.