Natural History of Asymptomatic Walled-off Necrosis in Patients With Acute Pancreatitis.

Background and objectives Studies on the natural history of asymptomatic walled-off necrosis (WON) in acute pancreatitis (AP) are scarce. We conducted a prospective observational study to look for the incidence of infection in WON. Material and methods In this study, we included 30 consecutive AP patients with asymptomatic WON. Their baseline clinical, laboratory, and radiological parameters were recorded and followed up for three months. Mann Whitney U test and unpaired t-tests were used for quantitative data and chi-square and Fisher's exact tests were used for qualitative data analysis. A p-value <0.05 was considered significant. Receiver operating characteristic curve (ROC) analysis was done to identify the appropriate cutoffs for the significant variables. Results Of the 30 patients enrolled, 25 (83.3%) were males. Alcohol was the most common etiology. Eight patients (26.6%) developed an infection on follow-up. All were managed by drainage either percutaneously (n=4, 50%) or endoscopically (n=3, 37.5%). One patient required both. No patient required surgery and there was no mortality. Median baseline C-reactive protein (CRP) was higher in infection group 76 (IQR=34.8) mg/L vs asymptomatic group, 9.5 mg/dl (IQR=13.6), p<0.001. IL-6 and tumor necrosis factor (TNF)-alpha was also higher in the infection group. The size of the largest collection (157.50±33.59 mm vs 81.95±26.22 mm, P<0.001) and CT severity index (CTSI) (9.50±0.93 vs 7.82±1.37, p<0.01) were also higher in infection group as compared to the asymptomatic group. ROC curve analysis of baseline CRP (cutoff 49.5mg/dl), size of WON (cutoff 127mm) and CTSI (cutoff of 9) showed AUROC (area under ROC) of 1, 0.97, and 0.81 respectively for the future development of infection in WON. Conclusion Around one-fourth of asymptomatic WON patients developed an infection during three-months follow-up. Most patients with infected WON can be managed conservatively.