**2.2 Endoscopic management of acute pancreatitis associated with congenital variants**

### *2.2.1 Pancreas divisum*

Pancreas divisum (PD) represents the most frequent congenital pancreatic malformation, resulting from a failure of the fusion between dorsal and ventral pancreatic ducts during the second month of fetal life, with preferential pancreatic juice outflow via the dorsal pancreatic duct through the minor papilla. PD is defined as complete if no communication between the ventral and dorsal ducts is visible, incomplete if communication remains. The prevalence of PD in caucasian population is about 5–10%, and more than 95% of these patients are asymptomatic, with incidental diagnosis on abdominal imaging [11].

PD has long been regarded as a predisposing factor to AP, but studies conducted on individuals with recurrent AP showed that the comparable AP incidence between patients with PD and those with normal ductal anatomy. PD is, infact, a co-factor which in association with certain genetic mutations of serine protease inhibitor Kazal type 1 (SPINK1) gene, cystic fibrosis transmembrane conductance regulator (CFTR) gene, and chymotrypsin C (CTRC) gene increases the risk of AP [12]. Other additional factors that can determine AP in PD are the presence of stenosis of the minor papilla or santorinicele, which consists in cystic dilatation of the distal dorsal duct just proximal to the minor papilla [13].

ERCP is the gold standard for diagnosis of PD, but it is not used as a diagnostic method, given its invasiveness and the high accuracy of magnetic resonance pancreatography after secretin injection (s-MRCP) [14]. EUS shows also a high diagnostic accuracy for PD with a sensitivity of 87–95%, with absence of a "stack sign," i.e., the parallel alignment of distal CBD, ventral pancreatic duct and portal vein, presence of a "crossed duct sign," which is given by the crossing of dorsal pancreatic duct over the bile duct anteriorly and superiorly [15].

In asymptomatic patients with incidental diagnosis of PD therapeutic measures are not required, reserving them for those with recurrent attacks of AP, even if of mild entity, or those who had one attack of severe AP in absence of other identifiable causal factors. Also the presence of santorinicele with large main pancreatic duct could be an indication for treatment. Endoscopic therapy includes minor papilla endoscopic sphincterotomy (mPES) and minor papilla orifice balloon dilation. Given the high risk of post-ERCP AP associated with both these procedures, placement of a prophylactic temporary pancreatic stent is advisable [16].

### *2.2.2 Other congenital variants*

Anomalous pancreatobiliary union (ABPU) affects 1.5–3% of individuals, and it consists in the union of the pancreatic and bile ducts outside the duodenal wall, resulting in a longer common channel (more than 15 mm proximal to the duodenum) that promotes reflux of bile and pancreatic juice into the alternative duct. Therefore, stones, protein plugs, or sphincter of Oddi dysfunction can cause temporary obstruction to pancreatic flow. All these factors determine an increase of pancreaticobiliary intraductal pressure, leading to AP [17]. AP is reported in 3–31% of APBU patients, and it is generally mild and self-limiting. Endoscopic sphincterotomy may decrease the risk of AP in these patients [18].

Choledochocele is a rare congenital or acquired condition, consisting in dilatation of the intraduodenal segment of the CBD. In these patients, AP occurs when the cystic dilatation or its content (sludge or stones) causes obstruction of the pancreatic duct outflow. Endoscopic sphincterotomy in order to unroof the choledochocele is recommended [19].

### **2.3 Endoscopic management of acute idiopathic pancreatitis**

Recurrent AP is defined by the occurrence of two or more episodes of AP. Etiological diagnosis of AP is achieved in 70–90% of cases. Minimal diagnostic workup during a first episode of acute pancreatitis is suggested by guidelines and includes detailed personal history, family history, physical examination, laboratory tests (i.e. liver enzymes, calcium, and triglycerides), and transabdominal ultrasound (US) [20]. If etiology cannot be determined using this workup, AP is defined idiopathic, and this occurs in around 10–30% of cases [21].

There are several causes of AP that may be missed with this workup, and thus further diagnostic modalities, such as MRCP and computed tomography (CT), should be *Endoscopic Management of Acute and Chronic Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.105930*

considered to rule out the presence of ductal adenocarcinoma or intraductal papillary mucinous tumors, or autoimmune pancreatitis. EUS may identify an etiology in 61% idiopathic AP, mainly represented by microlithiasis or sludge [22]. Also early chronic pancreatitis could be diagnosed with EUS, as possible cause of recurrent AP. When no etiologic factors are identified, sphincter of Oddi dysfunction should be suspected. ERCP with sphincter of Oddi manometry is the gold standard diagnostic test, but it is associated with significant morbidity [23]. At present, ERCP with sphincterotomy represents the treatment of choice for patients with structural or functional stenosis of the sphincter of Oddi, with reports of 70–90% resolution of symptoms [24].

### **2.4 Endoscopic management of acute pancreatitis complications**

### *2.4.1 Pancreatic fluid collections*

Pancreatic fluid collections (PFCs) are a frequent complication of AP, and their correct classification is important to guide the management. In 2012, an international working group has modified the Atlanta classification for AP, introducing new terminology for PCFs, which are classified according to the time elapsed since the collection was formed and to the presence or absence of necrosis. Acute collections in the first 4 weeks are called acute necrotic collections (ANCs) if necrosis is present or acute peripancreatic fluid collections (APCs), in absence of necrosis. After 4 weeks, when a capsule develops, persistent acute peripancreatic fluid collections are called pseudocysts and acute necrotic collections are called walled-off necrosis (WON) (**Figure 1**) [25]. The majority of APC resolve spontaneously and only a 5–15% of them transform into pseudocyst. On the contrary, half of ANC become WON. 16–47% of pancreatic necrosis get infected [26, 27].

PFCs drainage is recommended in presence of symptoms and/or complications such as abdominal pain, gastrointestinal obstruction, vascular compression, biliary obstruction, or infection. Size alone is not an indication for treatment. Historically, drainage has been performed via surgical techniques. However, in the last decade,





**Figure 1.** *Pancreatic fluid collections.* thanks to new and advanced endoscopic tools and expertise and consequent reduction in health care costs, minimally invasive endoscopic drainage has become the preferable approach [28].

The first conventional endoscopic transmural drainage of PFCs consisted of endoscopic visualization of PFC bulge in the gastric wall, creation of a fistulous tract between PCF and gastric lumen with a seldinger technique, insertion of a guidewire into the PFCs cavity, dilation of the tract, and, finally, deployment of one or more plastic stents to secure apposition of the lumens and continuous drainage [29]. A nasocystic catheter was generally performed to promote liquefaction of the debris and improve drainage. Infusion of hydrogen peroxide (H2O2) facilitated dislodgement and removal of necrotic debris. Adverse events, even if rare, such as bleeding, perforation, and self-limited pneumoperitoneum, have been reported [30]. To remedy the suboptimal drainage efficiency of plastic stents, especially in WON, covered biliary metal stents were used for this purpose. However, they were associated with complications, such as migration, erosions, or ulceration over gastric or retroperitoneal side and difficulty in performing necrosectomy [31].

Recently, a new dedicated bi-flanged lumen apposing metal stent (LAMS) has been introduced for EUS drainage of PFCs. LAMS has been specifically designed to create an anastomosis between the cyst cavity and the gut lumen. At first, the insertion of a guidewire inside the collection by a standard 19G FNA needle was necessary to release the stent. Subsequently, a new device in which the LAMS is equipped with an electrocautery-enhanced delivery system avoided the use of multiple accessories to achieve the drainage. Different diameters are available for these stents [32]. Published data report that, compared to plastic stents and fully covered metal biliary stents, LAMS determines an earlier resolution of PFCs. They are associated with increased costs and, in the first published series, with increased risk of adverse events, in particular pseudoaneurysm-related bleeding [33]. Recent studies have shown that earlier removal of LAMS, within 3 weeks from stent placement, significantly reduces the frequency of bleeding complications, with same rate of adverse events of plastic stents. Finally, recent scientific literature supports the use of LAMS for drainage of PFCs, mostly because they make possible to access the WOPN cavity with a standard gastroscope, after dilatation of the cysto-gastric tract with a balloon, to perform lavage and direct endoscopic necrosectomy (DEN) [34]. Hydrogen peroxide plus normal saline is used for the lavage of the cavity, and then necrotic debris is removed under direct vision using snares or baskets. Several sessions may be necessary to achieve complete DEN.

### *2.4.2 Disconnected pancreatic duct syndrome*

In severe AP, necrosis of the pancreatic parenchyma may cause loss of integrity of the pancreatic duct, determining duct disruption, i.e., a partial interruption of the duct integrity, or its disconnection, i.e., a circumferential interruption of the duct. This leads to extraductal and extrapancreatic leakage, which can be complicated by recurrent PCFs and their possible infection, or pancreatic fistulas [35].

The diagnosis of disconnected pancreatic duct syndrome (DPDS) is usually delayed, given a lack of awareness on the topic, resulting in increased morbidity, cost of treatment, and duration of hospital stay. Surgery has been for long time the best approach for the management of DPDS, consisting of either resection or internal drainage procedures. Anyway, in the setting of a severe AP, surgery is often difficult due to presence of local inflammation and vascular alterations, as extensive venous collaterals consequent to splenic vein thrombosis [36]. With recent advancements, endoscopy offers new

### *Endoscopic Management of Acute and Chronic Pancreatitis DOI: http://dx.doi.org/10.5772/intechopen.105930*

minimally invasive therapeutic options for the management of DPDS. When a co-existent PFC is present, endoscopic approach consists of EUS-guided transmural drainage. In DPDS without a co-existing PFC, surgery is the best option as endoscopy cannot ensure internal drainage of the secretions of disconnected pancreas. Transpapillary drainage in patients with is effective only in patients with partial pancreatic duct disruption that can be bridged with the positioning of a stent. In complete disruption of pancreatic duct, bridging with pancreatic stent is often not feasible [37].
