Natural Course of Asymptomatic Walled-off Necrosis due to Acute Pancreatitis

Walled-off necrosis (WON) is a well-developed, enclosed accumulation of fluid, comprising a mixture of solid and liquid necrotic material, located within the pancreas and its surrounding area. Managing patients with asymptomatic WON is controversial due to limited information available about its natural history. The study aimed to determine the long-term natural course of WON in acute pancreatitis (AP) patients who remained asymptomatic and did not undergo any interventional treatment upon initial diagnosis.

Acute pancreatitis patients who were followed between June 2016 and December 2019 were retrospectively evaluated. Among them, patients who developed WON after the AP attack and did not undergo any therapeutic intervention upon initial diagnosis due to their asymptomatic course were enrolled in the study.

The asymptomatic WON patients (n = 31) were followed up for a mean duration of 25.6 ± 17.3 months. During the follow-up, 10 (32.3%) patients required interventional treatment within an average of 124.9 ± 189.5 days. Two patients died while under asymptomatic follow-up. In 12 patients (38.7%) WON disappeared; and in 7 (22.5 %) patients, mean size of the largest WON decreased from 64.7 ± 34.2 to 29.8 ± 27.4 mm. The extent of necrosis and the initial WON size were significantly higher in those requiring interventional treatment [AUC (area under the curve) were 0.844 and 0.733, respectively].

The management of WON usually includes close monitoring of the patient. The initial characteristics of WON (e.g., extent of necrosis, size, etc.) may aid in determining the necessity for drainage during the follow up of asymptomatic patients.