**Abstract**

Acute pancreatitis (AP) is a inflamatory condition of the pancreatic gland with or without involvement of peripancreatic tissues and distant organs. The incidence of AP is 20–35 cases per 100,000 inhabitants per year, with an overall mortality of 2–10%. In recent decades the incidence of AP has increased globally. Most cases follow a mild, self-limiting course, but 10–20% of patients develop a severe form with systemic and local life-threatening complications of pancreatic and peripancreatic necrosis come about 20–40% of patient with severe AP and aggravate organ functions. The traditional approach to the treatment of necrotizing pancreatitis with secondary infection of necrotic tissue is open necrosectomy to remove the infected necrotic tissue. But this is associated with high rates of complications, death and pancreatic insufficiency. The benefits of sequential treatment in cases of infected necrosis ("Step an approach") compared to traditional open necrosectomy, showing less morbidity and lower costs. The sequential treatment is an alternative to open necrosectomy, including percutaneous drainage, endoscopic (transgastric) drainage, and minimally invasive retroperitoneal necrosectomy. With this approach, up to 35% of patients can be treated only with drainage, to avoid necrosectomy and to reduce the percentage of complications. In this chapter we present the step-by-step approach.

**Keywords:** necrotizing pancreatitis, step up approach, acute pancreatitis, percutaneous, endoscopic, necrosectomy

### **1. Introduction**

Acute pancreatitis (AP) is a inflamatory condition of the pancreatic gland with or without involvement of peripancreatic tissues and distant organs [1]. The incidence of AP is 20–35 cases per 100,000 inhabitants per year, with an overall mortality of 2–10%. In recent decades the incidence of AP has increased globally and is expected to increase even more. The most common cause is biliary lithiasis, which accounts for about 40–50%. The alcohol, predominantly in males, is the second most common cause, at over 30% and 10–25% the cause is unknown.

Most cases follow a mild, self-limiting course, but 10–20% of patients develop a severe form with systemic and local life-threatening complications of pancreatic and peripancreatic necrosis come about 20–40% of patient with severe AP and aggravate organ functions [2–6]. Infected necrotic tissue is defined as a gram positive of pancreatic or peripancreatic necrotic tissue obtained by means of

fine-needle aspiration or from the first drainage procedure or operation, or the presence of gas in the fluid collection on contrast-enhanced computer tomography (CT). Suspected infected necrosis is defined as persistent sepsis or progressive clinical deterioration in the intensive care unit without documentation of infected necrosis. Failure of one or more organs occurs in 40% of these patients with pancreatic necrosis and on rare occasions it can also occur in cases without necrosis. Mortality amounts to 30% when infection of the pancreatic and/or peripancreatic necrosis is present [7].

The traditional approach to the treatment of necrotizing pancreatitis with secondary infection of necrotic tissue is open necrosectomy to remove the infected necrotic tissue. But this is associated with high rates of complications, death and pancreatic insufficiency. The studies show that death rates from open pancreatic necrosectomy are between 10–40% [8–10]. The management of AP has evolved greatly in recent years thanks to a better understanding of pathophysiology, the improvement of the therapeutic arsenal of intensive care units, nutritional support, conventional and interventional radiology techniques and surgical treatment. Recently, a randomized trial called "PANTER" very well designed study by the Dutch Pancreatitis Study Group, demonstrated the benefits of sequential treatment in cases of infected necrosis ("Step an approach") compared to traditional open necrosectomy, showing less morbidity and lower costs [7]. The sequential treatment is an alternative to open necrosectomy, less invasive techniques, including percutaneous drainage, endoscopic (transgastric) drainage, and minimally invasive retroperitoneal necrosectomy. The importance of step up approach is that the first step is percutaneous or endoscopic drainage of the collection of infected fluid to mitigate sepsis and this step may postpone or even obviate surgical necrosectomy. If the drainage does not take to clinical recovery, the next step is minimally invasive retroperitoneal necrosectomy. With this approach, up to 35% of patients can be treated only with drainage, to avoid necrosectomy and to reduce the percentage of complications [7].
