Necrosectomy procedures are performed in patients with severe acute pancreatitis and infected necrosis. To date, necrosectomy is used a last resort, after failure of less invasive techniques (such as percutaneous drainage of pancreatic necrosis). This “step-up” approach has proven to be superior to the “step-down” approach in which open necrosectomy plays a primary role, with less invasive methods used for residual or subsequent collections.
The principle of necrosectomy is minimization of injury to viable tissues and maximization of postoperative removal of exudative fluid and extravasated pancreatic exocrine secretions from the operative bed. It may be a very difficult procedure, associated with an increased risk of bleeding.
Open necrosectomy is traditionally performed via a midline or a subcostal laparotomy. Once the focus of necrosis is exposed, debridement is carried out bluntly. After all loose debris has been removed, the retroperitoneal cavity is irrigated with normal saline solution. After necrosectomy, four different techniques are used to provide exit channels for further slough and infected debris:
- Open packing (The abdomen is left open, continuous reoperations with open lavage of necrotic areas are performed)
- Planned staged relaparotomies with repeated lavage (The abdomen is closed, continuous relaparotomies with open lavage of necrotic areas are performed)
- Closed continuous lavage of the lesser sac and retroperitoneum (the abdomen is closed over drains for contained postoperative lavage of the lesser sac and involved retroperitoneum)
- Closed packing (the abdomen is closed, reabsorbable sponges are used for packing)
Prof. Perderzoli and Prof. Bassi from Verona were among the first to describe in 1990 the procedure of open necrosectomy with continuous lavage of the lesser sac and retroperitoneum (Figure 1).
Figure 1. Open necrosectomy and continuous lavage of the lesser sac and retroperitoneum,
as described by Pederzoli and Bassi in 1990.
as described by Pederzoli and Bassi in 1990.
MINIMALLY INVASIVE NECROSECTOMY
Minimally invasive necrosectomy encompasses radiological, endoscopic and percutaneous techniques. Minimally invasive necrosectomy techniques had been initially proposed as an alternative to open necrosectomy, with the aim of reducing the surgical trauma. However, a number of studies showed that open necrosectomy often makes patients sicker and that outcome may be improved when necrosectomy is delayed or when it is used a last resort, after failure of minimally invasive techniques.
However, these results may be influenced by variation in expertise with minimally invasive techniques, and in the definitions of target lesions. Variations in the target lesions (location of necrosis, fluid/mixed/solid nature, early/late procedure, sterile/infected necrosis, single/multiple areas, wall thickness) and in the patients (co-morbidity, degree of organ dysfunction) require an individually tailored approach to the treatment of pancreatic necrosis.
As reported by Windsor, minimally invasive techniques can be classified by the type of scope used (flexible endoscope, laparoscope, nephroscope) and the route of access (transperitoneal, transgastric, retroperitoneal).
The two approaches that have risen to favour are the endoscopic transgastric and nephroscopic retroperitoneal routes.
Endoscopic transgastric necrosectomy involves include endoluminal ultrasonographically guided transgastric puncture of the necrotic area, balloon dilatation of the track, insertion of multiple stents, direct basket extraction of necrosum, and transpapillary stenting of the pancreatic duct. The endoscopic transgastric procedure avoids peritoneal contamination and external pancreatic fistula formation, but it may not be possible if there is no abutment of the lesion against the stomach or duodenal wall.
The nephroscopic retroperitoneal procedure has been advocated by the Glasgow group and appears now to be the most popular minimally invasive necrosectomy approach. The various techniques described may use a small retroperitoneal incision or rely on dilatation of a drain-track. The majority utilize contrast-computed tomography (CT) or image itensifier to guide the placement of small-calibre percutaneous drains into retroperitoneal collections. The drain-track is then dilated using the Seldinger technique and a nephroscope is placed into the cavity and semi-solid necrotic tissue removed piecemeal. This is achieved using various accessories, including biopsy forceps and baskets.