Abstract Background Selection of patients for open abdomen (OA) treatment in severe acute pancreatitis (SAP) is challenging. Treatment related morbidity and risk of adverse events are high; however, refractory abdominal compartment syndrome (ACS) is potentially lethal. Factors influencing the decision to initiate OA treatment are clinically important. We aimed to study these factors to help understand what influences the selection of patients for OA treatment in SAP. Methods A single center study of patients with SAP that underwent OA treatment compared with conservatively treated matched controls. Results Within study period, 47 patients treated with OA were matched in a 1:1 fashion with conservatively treated control patients. Urinary output under 20 ml/h (OR 5.0 95% CI 1.8-13.7) and ACS (OR 4.6 95% CI 1.4-15.2) independently associated with OA treatment. Patients with OA treatment had significantly more often visceral ischemia (34%) than controls (6%), P = 0.002. Mortality among patients with visceral ischemia was 63%. Clinically meaningful parameters predicting developing ischemia were not found. OA treatment associated with higher overall 90-day mortality rate (43% vs 17%, P = 0.012) and increased need for necrosectomy (55% vs 21%, P = 0.001). Delayed primary fascial closure was achieved in 33 (97%) patients that survived past OA treatment. Conclusion Decreased urine output and ACS were independently associated with the choice of OA treatment in patients with SAP. Underlying visceral ischemia was strikingly common in patients undergoing OA treatment, but predicting ischemia in these patients seems difficult.