**4. Management off infection of pancreatic necrosis**

We present the management of acute pancreatitis with signs of infected necrosis. For this we will describe each of the therapeutic options in the philosophy of step up approach (Algorithm 1).

### **4.1 Antibiotic therapy**

The first step is the administration of broad- spectrum antibiotic therapy [16]. The germs most involved are *E. coli*, *Enterobacter cloacae*, *Enterococcus faecalis* and Bacteriodes fragilis, and the antibiotic of choice for empirical treatment in these cases would be carbapenemics. In cases of allergy, quinolones would be used.

Recommended empirical therapy:


Once the final result of the cultivation is obtained, the anti-biotherapy will be adapted. A small proportion of patients can be managed with supportive care and antibiotics alone, without the need for additional invasive interventions [17].

### **4.2 The step-up approach**

Open surgery in the treatment of infected pancreatic necrosis has been replaced by the minimally invasive approach. The multi-centre randomized clinical trial PANTER [18] showed that step up approach treatment of necrotising pancreatitis reduces patient mortality, multiorgan failure, costs and late surgical complications. The step-up approach consists of percutaneous catheter drainage or endoscopic transluminal drainage, followed by minimally invasive necrosectomy only when clinically required, is the current standard treatment [19].

### *4.2.1 Percutaneous catheter drainage*

Secondary infection of pancreatic or peripancreatic necrosis can occur in the first 3 weeks after onset of disease, and long-term administration of antibiotics might lead to increased incidence of fungal infections and antibiotic resistance [15, 20]. The benefit of early drainage has been demonstrated, although its indication has to be established after confirmation of infection, otherwise we could be infecting a sterile collection. The ideal percutaneous drainage would be via the retroperitoneal route and on the left side, which would facilitate subsequent minimally invasive surgical access if necessary. Current evidence shows that 35% of patients treated with percutaneous drainage in this phase will not require additional surgical necrosectomy and that up to 50% in series where a progressive increase in the diameter of the drainage catheter is used [19]. Once the radiological drainage was carried out, the therapeutic sequence would be as follows:

if poor evolution persists after 48 hours and the patient's conditions permit it, a new drainage with a larger diameter would be attempted.

if the poor clinical condition is maintained, despite the use of larger drains, surgical drainage should be carried out.

The current tendency is to be as non-invasive as possible. Several techniques have been described that will be developed in our service gradually, such as video assisted retroperitoneal access that presents significantly lower rates of abdominal complications than the most classic techniques. This technique uses radiological drainage as a guide to the collection, hence the importance of placing it on the left side as long as possible (**Figure 3**).

After 4 weeks, in addition to percutaneous radiological drainage in case of infection as mentioned above, endoscopic drainage could be evaluated. Generally, at this stage an inflammatory wall would already be formed consistent enough to withstand transgastic endoscopic drainage (walled-off necrosis).

### *4.2.2 Transgastric endoscopic drainage*

The step-up approach can be done both surgically and endoscopically. The two different approaches have been compared with each other in two randomized trials. The first is the TENSION trial that concluded that the endoscopic step-up approach was not superior to the surgical step-up approach in reducing major complications or death but the rate of pancreatic fistulas and length of hospital stay were lower in the endoscopy group [21]. The second trial is MISER [22] randomizade controlled trial showed that an endoscopic transluminal approach for infected necrotizing pancreatitis, compared with minimally invasive surgery, significantly reduced major complications, lowered costs, and increased quality of life.

In short, the endoscopic staggered approach has become the approach of choice according to recent studies for the management of infected necrotizing pancreatitis [23–27]. However it could not be feasible in all patients. It depends

### **Figure 3.**

*CT scan image showing left retroperitoneal collection with easy access for percutaneous drainage. And it will allow a retroperitoneal laparoscopic approach.*

on the anatomical location of the infected necrotic collections, availability of technique and experience of the center and trained personnel (**Figure 4**). The option of combined endoscopic transluminal and percutaneous catheter drainage, which is also known as dual-modality drainage, should not be overlooked in patients with large collections extending into the paracolic gutters or the pelvic region.

Currently, the stents placed between gastric light and the infected collection are metallic (**Figure 5**). They were created in 2011 and replaced with plastic stents. These stents provide wider light that allows better drainage and facilitates transluminal necrosectomy. The best available evidence comes from a randomized trial

### **Figure 4.**

*CT scan image showing infected acute necrotic collection of retrogastric location. We can see metallic stent drainage inside the collection.*

### **Figure 5.** *Endoscopy image showing metallic stent that communicates the gastric camera and the acute necrotic collection.*

that compared the efficacy of metal and plastic stents in the drainage of infected pancreatic necrosis. The study found no differences in the median number of procedures, readmissions, and length of hospital stay [28]. Although endoscopic treatment with metal stents was associated with higher procedure costs. In addition, adverse effects such as stent migration were observed. Therefore, the latest consensus guidelines recommend metal stents or double pigtail plastic stents for endoscopic transluminal drainage and removal after 4 weeks to minimize the risks of complications [28, 29].

### *4.2.3 Surgical necrosectomy*

Between 23–47% of patients will improve only with percutaneous or endoscopic drainage. But in those patients with persistent disease, surgery is the next step [18, 30, 31]. Objectives of surgical debridement are to control the source of infection and reduce the burden of necrosis, while minimizing the proinflammatory damage of the intervention itself on the weakened patient. The current trend is to be as non-invasive as possible. We will start with a videoassisted retroperitoneal approach and if it is not enough we will perform necrosectomy by open approach [32].
