Wall maturation in necrotic collections in acute pancreatitis: a computed tomography based evaluation

Aim: To systematically investigate the timing of encapsulation of necrotic collections in acute necrotizing pancreatitis (ANP) using contrast-enhanced computed tomography (CECT).

Methods: This retrospective study comprised consecutive patients of ANP who underwent CECT of the abdomen between the second and fourth weeks of illness. Number and site of collections and presence and completeness of the wall (defined as a thin smooth enhancing rim more than 1 mm in thickness) were documented.

Results: A total of 195 patients of ANP were included. Seven hundred seventy-three collections were evaluated in 284 CECT scans. The most common site of the collection was anterior pararenal space (n=290, 37.5%). The mean maximum dimension of the collection was 8.1 cm (range, 3.1-16 cm). Two hundred twentytwo (28.7%) collections had a complete wall. The mean interval to complete wall maturation was 18 days (range, 8-28). Overall, 13.3%, 37.1%, and 56.2% of the collections showed complete encapsulation in the second, third, and fourth weeks, respectively.

Conclusions: Our study suggests that a significant proportion of necrotic collections show complete encapsulation within 4 weeks of the onset of ANP.

Keywords: acute necrotizing pancreatitis, acute necrotic collection, walled off necrosis, encapsulation, multidetector computed tomography.