**4. General considerations for surgical management**

Surgical management may be minimally-invasive or open, but has the same two primary goals: obtaining source control by removing as much necrotic tissue as possible and providing access for irrigation and drainage. As a general principle, minimally-invasive approaches are preferred to open necrosectomy as first-line treatment. The improved outcomes of minimally-invasive technique lead to development of the "step-up" approach to management, which begins with percutaneous or endoscopic intervention, followed by a progression to surgical intervention as indicated by unresolved disease. However, the final treatment decision is dictated by the patient, surgeon, and available resources. A second principle is that surgical intervention should be delayed as long as possible in order to improve outcomes. Operating during the early, acute phase of pancreatitis, especially in the presence of ANC, rather than WON, is associated with higher morbidity and mortality regardless of surgical approach. A third principle is that long-term nutritional access, through a gastrostomy or gastrojejunostomy tube, should be obtained prior to concluding the procedure if no other method for enteral feeding has been established. Fourth, a cholecystectomy may also be performed if gallstones were implicated in the etiology of pancreatitis, provided the patient is adequately stable to undergo an additional procedure (**Figure 1**).

## **5. Minimally-invasive necrosectomy**

VARD is a technique, used as the final phase of the step-up approach, where the retroperitoneum is accessed through a previously established, left flank, percutaneous drainage tract (**Figure 2**). The tract is then serially dilated, in order to accommodate progressively larger drainage catheters. At the time of surgery, in order to facilitate introduction of laparoscopic instruments, a small, 4–6 centimeter incision is made where the tract exits the skin. After confirming entry into the WON with a probe, tissue and fluid are removed with suction. The laparoscope is then inserted, with or without CO2 insufflation, for continued debridement under direct visualization, using blunt laparoscopic forceps. Following debridement, again under direct visualization, large drainage catheters or chest tubes, 28-French or greater, are placed. After surgery, these catheters are used for repeated lavage as well as for drainage [31].

The superiority of VARD, and the step-up approach, compared to surgery for the treatment of necrotizing pancreatitis was first published in the Minimallyinvasive Step-up Approach Versus Maximal Necrosectomy in Patients with Acute Necrotizing Pancreatitis (PANTER) Trial. In this study, 35% of the patients assigned to the step-up arm were successfully treated with percutaneous drainage alone. When comparing the step-up and surgical groups, the step-up group was less likely to have new-onset organ failure, less likely to develop an incisional hernia, and had an overall lower rate of endocrine insufficiency. However, the mortality rate was not significantly different, 19% in the step-up group versus 16% in surgery group [31].

A similar procedure, percutaneous endoscopic necrosectomy (PEN), can be performed utilizing a previously established percutaneous drainage tract. Unlike VARD, PEN utilizes a flexible endoscope, as compared to a rigid laparoscope. Because the endoscope has working ports, in addition to irrigation and suction, an additional incision around the tract is not needed. Also unlike VARD, PEN can be performed at bedside, with conscious sedation [32].

PEN was shown to be effective in a large, prospective study of 171 patients with infected pancreatic necrosis. The primary outcome investigated was control of sepsis and resolution of the infected collection. In this study, 18 of 26 (69%) patients with infected ANC and 23 of 27 (85%) with infected WON who underwent PEN were successfully treated, while the remainder required surgical necrosectomy. Predictors of failure included >50% parenchymal necrosis and early organ failure. ANC was not predictive. The overall mortality rate for this study was 38% [32, 33]. Although this technique has not been directly compared to surgery, VARD, or transmural endoscopy, this study demonstrated the safety and utility of PEN in patients with infected pancreatic necrosis.

Regardless of the type of minimally-invasive drainage, VARD or PEN, it has been shown that the "step-up approach," beginning with drainage and progressing to debridement, is superior to upfront surgical approaches in terms of mortality, rates of pancreaticocutaneous fistula formation, and long-term morbidity [25, 30, 34].

### **6. Transgastric necrosectomy**

In addition to utilizing a percutaneous drainage tract for necrosectomy, access can also be gained through the stomach. By entering the abdomen and opening the anterior wall of the stomach and then opening the posterior aspect of the stomach, access to the lesser sac and underlying pancreas is achieved (**Figure 2**). An aperture between the WON and posterior wall of the stomach is then created, either with sutures or by stapling, providing a definitive drainage tract. This tract is then used for necrosectomy following the same principles as DEN.

This approach is most well suited for WON limited to the lesser sac. When there is extensive necrosis extending to the retroperitoneum or paracolic gutters, VARD or traditional necrosectomy are more appropriate, due to the limited exposure with this method. These limitations are counterbalanced by the minimal amount of mobilization required to enter the lesser sac by the transgastric method [35].

When performed laparoscopically, five ports are typically placed; in addition to an umbilical port, two ports are placed in the right upper quadrant, one port is placed in the left upper quadrant, and one port in the epigastrium. After entering the abdomen and creating the anterior gastrotomy, an ultrasound is used to identify the necrosis and plan the locations of the posterior gastrotomy. Ultrasound is adjunctive to preoperative imaging, which is also essential to surgical planning.

### *Surgical Management of Necrotizing Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.96044*

Both anterior and posterior gastrotomies should be made after placement of stay sutures. Upon entering the lesser sac, necrosectomy should be performed with blunt instruments, such as a ring forceps, taking great care to remove only loose material and avoid avulsing adherent tissue or vessels that may be bridging the area of necrosis. Following necrosectomy, a cystogastrostomy is created with an endoscopic stapler, or suture. The anterior gastrotomy is then closed with sutures or with a stapler [36].

When performed open, an upper midline incision is made, and the procedure proceeds in the same fashion as in the laparoscopic procedure. One difference in the open procedure is that many surgeons elect to use digital dissection for the necrosectomy, as opposed to instruments [37].

Open and laparoscopic approaches to transgastric drainage have been shown to have similar outcomes. In a recent retrospective review of patients from three tertiary referral centers, rates of morbidity, including rates of reoperation and hemorrhage, and mortality were not significantly different. However, the patients who underwent laparoscopic drainage had a higher rate of readmission. It should be noted that the overall mortality in this study was 2% at an average follow-up of 21 months, significantly less than reported elsewhere in the literature. The overall morbidity rate of 38% is in alignment with commonly reported rates elsewhere in literature [38].

Although surgical transgastric necrosectomy is relatively well tolerated, outcomes favor endoscopic transgastric drainage. Meta-analysis comparing the two show lower rates of overall major complications, pancreatic fistula formation, post-procedural organ failure, and hernia with an endoscopic approach. However, the overall rate of clinical resolution, post-operative bleeding, endocrine dysfunction, exocrine insufficiency, and mortality were not significantly different [39]. Thus, surgical transgastric necrosectomy is a valid alternative to other approaches of necrosectomy in the absence of an experienced endoscopist or at a center without access to advanced endoscopic tools.
