This study aims to investigate the natural clinical course, diagnostic possibilities and treatment modalities in moderately severe (MSAP) and severe acute pancreatitis (SAP). The management of severe acute pancreatitis varies with the severity and depends on the type of complication that requires treatment. Although no universally accepted treatment algorithm exists, the step-up approach using close monitoring, percutaneous or endoscopic drainage, followed by minimally invasive video-assisted retroperitoneal debridement has demonstrated to produce superior outcomes to traditional open necrosectomy and may be considered as the reference standard intervention for this disorder.

Despite overall reduced mortality in the last decade, MSAP and SAP are devastating diseases associated with mortality ranging from less than 10% to as high as 85%, according to various studies. The management of SAP is complicated because of the limited understanding of the pathogenesis and multi-causality of the disease, uncertainties in outcome prediction and few effective treatment modalities. Generally, sterile necrosis can be managed conservatively in the majority of cases with a low mortality rate (12%). However, infection of pancreatic necrosis can be observed in 25%-70% of patients with necrotizing disease; it is generally accepted that the infected non-vital tissue should be removed to control the sepsis. Laparotomy and immediate debridement of the infected necrotic tissue have been the gold standard treatment for decades. However, several reports have shown that early surgical intervention for pancreatic necrosis could result in a worse prognosis compared to cases where surgery is delayed or avoided. Therefore, several groups worldwide have developed new, minimally invasive approaches for managing infected necrotizing pancreatitis. The applicability of these techniques depends on the availability of specialized expertise and a multidisciplinary team dedicated to the management of SAP and its complications.

Inclusion Criteria:

1. fluid collections within two weeks of disease onset;
2. single- or multi-organ failure;
3. CTSI > = 7 (initial CT performed within 7 days after the onset of disease.); and (4) acute physiology and chronic health evaluation (APACHE) II score > = 8.

Exclusion Criteria:

1. patients without APD interventions;
2. patients who underwent necrosectomy directly after APD without PCD as a bridge therapy;
3. previous percutaneous drainage or surgical necrosectomy during the episode of pancreatitis;
4. previous exploratory laparotomy for acute abdomen and intraoperative diagnosis of AP.