**11. Therapeutic role of ERCP and EUS in chronic pancreatitis**

Chronic pancreatitis is a long standing painful inflammatory condition leading to progressive and irreversible pancreatic parenchymal damage and if not treated may result in either exocrine, endocrine insufficiency or both. This condition can be debilitating and severely affect the quality of life of these patients since most of them are either in and out of hospital, are on pain relieving medications, some may need enzyme supplementation and those that ultimately develop diabetes mellitus will

have to be on oral hypoglycemic medications or insulin injections for life. Chronic pancreatitis may lead to stricture formation at the ampullary region leading to upstream dilatation of both the CBD and main pancreatic duct [57].

This ampullary strictures can also lead to both choledocholithiasis and main pancreatic duct stone formation further worsening the patient's symptoms. Other common complications of chronic pancreatitis include; pancreatic inflammatory space occupying lesions, pancreatic pseudocysts, walled of pancreatic necrosis can occur in either acute, subacute and rarely chronic pancreatitis. In cases where there is no known identifiable cause of chronic pancreatitis, empiric therapy is initiated targeting to pain, exocrine and endocrine pancreatic insufficiencies. Failure of empiric therapy will most likely lead to identifiable causes or complications of chronic pancreatitis like main pancreatic duct stones, dominant pancreatic duct stricture, pancreatic pseudocysts, walled of pancreatic necrosis and sometimes benign or malignant pancreatic neoplasms [58].

Pancreatic ductal stones can be spontaneously expelled. But when they persist ERCP + ES with or without stenting is done, the stones are extracted during ERCP and incase of failure of stone extraction by dormie baskets or stone extraction balloon catheters, mechanical or ESWL can be attempted. If the endotherapy options fail then open or laparoscopic surgical intervention is done.

Dominant pancreatic ductal strictures are managed based on the location and etiology, short strictures at the ampullar can be treated with either ERCP + ES with stenting or ampullectomy in case of small ampullary lesions causing ampullary strictures. Distal pancreatic ductal strictures will warrant endoscopically placing the stents across the stricture either via trans-papillary approach or a rendezvous approach. Failure in endotherapy will necessitate surgical intervention [59].

Pancreatic pseudocyst if asymptomatic and small are managed conservatively for at least 4 to 6 weeks. Large symptomatic pancreatic pseudocysts can be drained endoscopically during ERCP via the trans-papillary approach with stent insertion. They can also be drained via the trans-mural approach with the aid of endoscopic ultrasound guidance into the stomach, duodenum or proximal jejunum. EUS identifies the pseudocyst, maturity of the cyst wall, vascularity of the surrounding structures and helps in guided and safe creation of the cysto-gastrostomy or cysto-enterostomy with stent insertion. Endoscopic placement of the stent across the endoscopically created cystoenterostomy ensures adequate pseudocysts drainage hence minimizing recurrence. Ultrasound guided percutaneous drainage can be done but increases the chances of a persistent pancreatico-cutaneous fistula formation. In case of failure of endoscopic drainage, open or laparoscopic surgical intervention can be done. Walled off pancreatic necrosis in the setting of chronic pancreatitis can be drained in the same way as pancreatic pseudocysts. The endoscope can be inserted into the cavity of the pancreatic necrosis cavity and the necrosectomy is done under direct vision after dilatation of the cysto-enterostomy. Stents are left across the cysto-enterostomy. Failure of endoscopic interventions may then warrant open or laparoscopic surgical intervention [60].

Endoscopic ultrasound in important in diagnosis of benign or malignant pancreatic neoplasms, sample can be taken for histological diagnosis and then a decision on the most appropriate management approach is chosen. Benign small asymptomatic pancreatic lesions less than 2 cm can be followed up with repeat EUS 3–6 months intervals. For symptomatic benign and malignant pancreatic lesions irrespective of the size will need endoscopic, laparoscopic or open resection with aim of obtaining clear resection margins post intervention. Small symptomatic lesions at the ampullar may undergo endoscopic ampullectomy but large lesions will necessitate surgical intervention [61].
