Chronic pancreatitis (CP) is progressive inflammatory disease that leads to irreversible destruction of the pancreatic parenchyma. Patients experience chronic pain and dyspepsia or diabetes mellitus (DM) owing to the permanent loss of exocrine and endocrine pancreatic functions [123]. They also experience acute pain, which necessitates the use of medications, such as opioid painkillers, and hospitalization for intravenous injection. The abdominal pain is caused by increased pressure in the main pancreatic duct (MPD) owing to pancreatic inflammation, which is similar to what is observed in compartment syndrome, and direct contact with the sensory nerve [456].

The main indications for surgical intervention in cases involving CP are intractable pain, suspicion of malignancy, and failure of other methods, such as medical and endoscopic management [78]. The basic goals of surgical procedures include ductal decompression and drainage. Among the surgical methods, Frey's procedure, which is known for its short operation time and fewer complications, is the preferred surgical treatment modality for CP in many areas around the world. However, there are still very few reports related to Frey's procedure in Korea; hence, we aimed to investigate and analyze our institution's experience and determine the benefits of surgical treatment for CP.

This was a retrospective study of 24 patients with CP who underwent Frey's procedure at Gangnam Severance Yonsei University between January 2007 and December 2017. The diagnosis of CP was based on clinical history, physical examination, and endoscopic ultrasound, CT, and endoscopic retrograde cholangiopancreatography (ERCP) findings (Fig. 1A, B). Exocrine pancreatic dysfunction was based on the presence of steatorrhea. The fecal elastase level was evaluated as well. Endocrine pancreatic dysfunction was based on DM diagnosis, which was defined as blood glucose level >200 mg/dL 2 hours after a 75-g oral glucose load or glycated hemoglobin (HbA1c) >6.5. Major complication was defined as Clavien-Dindo classification grade III and IV of surgical complications [9]. Postoperative pancreatic fistulas were scored using the International Study Group on Pancreatic Fistula definition [10]. The study protocol was approved by the institutional review board at Gangnam Severance Hospital, Yonsei University of Korea (3-2019-0011). Informed consent was obtained from all participants.

The most common etiology of CP is alcohol consumption. The incidence of CP due to alcohol consumption has been increasing in Korea [1213].

There are many reasons for surgery, and pain is one of the most important symptoms for choosing the procedure. In this study, 15 patients (62.5%) complained of abdominal pain before surgery, but only 5 patients (21%) complained of intermittent abdominal pain after surgery. In these 5 patients, abdominal pain recurred when they consumed alcohol or overate. Two patients had a pain attack within 2 years. Therefore, abdominal pain was major surgical indications in Frey procedure for CP patients.

There are many surgical procedures for CP such as pancreatic resection, Whipple's procedure, pylorus-preserving pancreatoduodenectomy, distal pancreatectomy, total pancreatectomy, duodenum-preserving pancreatic head resection (Beger's procedure), and local pancreatic head resection with longitudinal pancreatojejunostomy (Frey's procedure) [14]. We have summarized Beger's and Frey's procedures, which are widely used as surgical treatment of CP [1115161718]. Beger's procedure is organ sparing procedure, however, this procedure is technically more demanding, because of 2 anastomoses. This procedure is used for patients with a combination of CP and inflammatory mass in the head of pancreas. Frey's procedure has the advantage of a short operation time and single anastomosis, but has the disadvantage of removing the pancreatic parenchyma. The patients with obstruction in the left-sided pancreatic duct and with less severe inflammation in head of pancreas are indications for Frey's procedure.

Operation time was also shorter than other major surgeries (pancreaticoduodenectomy, distal pancreatectomy, Beger's procedure) and the estimated blood loss was less than other major surgery in our study. Frey's procedure had shorter operation time and lower complication rate than these procedures [14].

Many studies comparing Frey's and Beger's procedures have reported lower morbidity (9% vs. 20%), increased quality of life, and better pancreatic function in patients who underwent Frey's procedure. Furthermore, the average operation time in our institution was shorter than that of another study [19]. Four patients were readmitted due to recurrent abdominal pain.

Development of interventions such as ERCP, ESWL, and other techniques for pancreatic duct stone is improving [2021]. In Korea, many cases of ESWL case have been reported [22]. However, some of them have been reported to have undergone surgery due to large pancreatic stone.

Several studies have compared endoscopic and surgical approaches for CP. The results of these studies indicate that the surgical approach is associated with higher pain relief (86% vs. 61%) and more increase in weight (47% vs. 29%) [23]. In another study, a comparison of endoscopic with ESWL and surgical approach showed better physical quality of life after surgery [24].

Despite the difficulty of endoscopic intervention in large pancreatic stones, surgical intervention for pancreatic duct stone in CP patients were not considered as first-line treatment in many institutions. The reasons for this are postoperative complications and postoperative endocrine and exocrine dysfunctions. Comparison of preoperative and postoperative status has not shown poor results in CP patients. Furthermore, results showed that active surgical treatment had a good effect of pain management on patients with CP.

Other studies reported several complications such as pancreatic fistula and postoperative bleeding with abdominal abscess after Frey's procedure [2526]. However, there were no major complications in our institution. Another study concluded that patients with pancreatic stenting before operation had higher rates of postoperative pancreatic fistula than patients with nonpancreatic stenting [27]. In our case, previous pancreatic stenting did not increase the risk of pancreatic fistula.

The BMI and body weight of the patients decreased in comparison with those before the operation. The BMI and body weight were measured at the first outpatient checkup only 7 to 10 days after discharge, which could be the reason why no nutritional improvement was noted after surgery. Other studies have shown an increase in postoperative nutritional index after Frey's procedure [1].

In conclusion, Frey's procedure appears to be a less burdensome surgical procedure. Thus, it could be the optimal option for management of patients with CP with pancreatic stone.