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A NOVEL PANCREATOGASTROSTOMY METHOD USING ONLY ONE PURSE STRING SUTURE AND FOUR CORNER MUCOSAL SUTURES: EARLY POSTOPERATIVE SURGICAL RESULTS

Objective: Pancreatic ﬁstula remains the single most important cause of morbidity following Pancreatoduodenectomy (PD) and perhaps contributes most to increased mortality. Pancreatogastrostomy (PG) has been used by many surgeons in recent years because of its theoretical advantages over Pancreatojejunostomy (PJ). In this study, we analysed the outcome of modiﬁed binding PG technique following PD. Methods and Material: 20 consecutive patients were studied from April 2013 to March 2015 all of whom underwent binding PG after PD, where a single purse-string suture was taken on the posterior wall of the stomach with additional four mucosal corner sutures thereby creating a Pancreato-gastric anastomosis. Results: We prospectively analysed patient characteristics, perioperative outcomes and surgical results. In this average study age was 50.9 years with body mass index 21.5 ± 2.6 kg/ m 2 . All patients underwent standard PD and meant operative time was 377.5 ± 44.14 minutes.The mean operative time taken to complete pancreatogastrostomy after complete mobilisation of the pancreatic stump was 9.2 minutes(range 7-11minutes). Mean hospital stay was 16.55 ± 3.83 days (range, 8 to 21 days). Postoperative mortality was 5% (n=1) due to pneumonitis. Only two patients developed Grade A pancreatic ﬁstula, which were managed conservatively. One patient had postoperative haemorrhage, and four patients developed delayed gastric emptying (DGE). Conclusion: Results of our study are auspicious, proving that modiﬁed binding PG is a simple, fast and safe reconstruction procedure after PD. However, to determine its superiority over conventional PG, this procedure needs to be more comprehensively evaluated in a larger group of patients. Pancreatoduodenectomy, pancreatic pancreatogastrostomy


Introduction:
Pancreatoduodenectomy ranks as one of the most complicated and technically demanding surgical procedures in surgical armamentarium. In most of the recent series, mortality has decreased substantially, but morbidity rate remains high (30-50%), even at high volume centres [1][2]. The critical step in pancreatic surgery is no more extended resection itself but reconstruction of the pancreatoenteric anastomosis. Postoperative pancreatic fistula (POPF) is one of the most feared complication after PD with an incidence ranging 5-30% [3]. Various reconstruction techniques have been evaluated with the aim to reduce the incidence of POPF, but none has been demonstrated to be superior compared to others. Based on results of recent randomised clinical trials PG has been advocated as procedure associated with lower postoperative complications, mortality and pancreatic fistula rates than PJ [4][5][6][7][8][9]. Several PG anastomotic technique has been published: duct to mucosa anastomosis, binding PG using two purse-string sutures, or one binding purse-string with two transfixing mattress sutures, one continuous seromuscular suture and various other techniques with minor variations [9-13,p]. In this present study, we describe our reconstruction method with minor modification to previously described techniques of binding pancreatogastrostomy (BPG), consisting of full-thickness purse string suture in the posterior gastric wall and addition of 4 corner sutures placed between mucosa of posterior gastric wall and pancreas, which we now use as standard method for reconstruction after PD. Our preliminary results in twenty patients are presented.

Patients and methods:
This retrospective descriptive survey of anastomotic technique included 20 patients who underwent PD with binding PG between December 2013 to December 2015. The institutional ethical board approved the study. Patients demographics, the texture of pancreas, complications, hospital mortality, hospital stay, postoperative interventional procedures and re-explorations were prospectively documented.

Surgical technique:
After PD, any bleeding from the cut surface of the pancreatic stump was stopped by bipolar electrical coagulation or fine suture ligation and then the pancreatic remnant was mobilised to provide minimum 3 to 5 cm stump for burying into the stomach without undue tension. The distal pancreatic stump was transfixed at its cranial and caudal end with two 3/0 polypropylene suture. A polyethene 5 cm feeding tube, 5.0 or 7.5 French was introduced into main pancreatic duct depending on its diameter to ensure its patency. A 5-cm longitudinal incision was created in the anterior gastric wall proximal to the antrum. Transverse full thickness incision was made on the posterior wall of the stomach with a length of at the most 2/3 r d the diameter of the pancreatic stump, to ensure tight adherence of the gastric wall to the pancreatic remnant after completion of binding. The appropriate position of the incision was selected so that the stomach can be pushed over the pancreatic stump without tension. A full thickness purse-string suture was taken with polypropylene 2-0 on the posterior wall around the incision. The posterior stomach wall was then pushed over the pancreatic remnant. This manoeuvre was performed very gently to ensure tight wrapping of the posterior gastric wall around the pancreatic remnant and to avoid laceration of the pancreas. Ideally, the pancreatic remnant should protrude above the posterior gastric wall by 2-3 cm. The purse-string suture was then tightened. The feeding tube in the pancreatic duct was removed after ensuring patency of duct. Afterwards 4 point sutures of 4-0 polypropylene were placed between the mucosa of the posterior gastric wall and the pancreas. Finally the pancreatic remnant was checked for any minor bleeding. A nasogastric tube was positioned just above the PG. Bilioenteric reconstruction was done with the jejunal limb as an end to side hepaticojejunostomy followed by the side to side gastrojejunostomy with anterior gastrotomy site and then feeding jejunostomy.
All patients were treated by a standardised protocol including inj. Octreotide 100µg before the pancreatic transaction, 100µg s/c 8 hourly for next five days and proton pump inhibitors as prophylaxis against stress and marginal ulceration. The output from operatively placed drain was recorded daily and amylase level estimated on day three to five. The volume and the amylase activity of the drainage fluid was measured on postoperative day 3,4 and 5. The drain was removed when amylase level 3 times below normal serum amylase level was achieved without any suspicious contents irrespective of volume. As we were assessing particular technique of pancreatic-enteric anastomosis, the primary endpoint was pancreatic fistula rate. Other issues evaluated were an intraabdominal complication, i.e. biliary digestive tract fistula, intraabdominal collection, intraabdominal or digestive tract haemorrhage. Pancreatic, biliary fistula and post pancreatectomy haemorrhage was defined as per definition by ISGPS. Delayed gastric emptying was defined as being present when the postoperative nasogastric tube was required for more than ten days, or patiently is unable to tolerate standard oral feed on or after ten days.

Results:
The study consisted of 20 consecutive patients undergoing PD with this new technique. The technique was developed and performed in all patients by the senior author(RG). Data of patients operated on were collected in a prospectively maintained database and were retrospectively reviewed for this study. There were 11 male and nine female patients, with an average age of 50.9 years (range, 32 to 74 years) and their average body mass index was 21.5±2.6 kg/m 2 (range, 18.8 -23.6 kg/m 2 ). Nineteen patients were operated for carcinoma pancreas and one patient for a traumatic pancreatoduodenal laceration. All PDs were  Whipple procedure. Of the 20 patients, nine patients had a soft pancreatic texture, and 11 patients had a firm pancreatic texture. Sixteen patients had main pancreatic duct diameter >3 mm and four patients had diameter <3 mm. The mean operative time for the complete procedure was 377.5±44.14 minutes (range, 240 to 435 minutes).The mean operative time taken to complete pancreatogastrostomy after complete mobilisation of the pancreatic stump(from incision of gastric wall to completion of mucosal corner suture) was 9.2 minutes(range 7-11minutes). Mean hospital stay was 16.55±3.83 days (range, 8 to 21 days). The mean time of drain removal was 8.26±2.1 days. The mean time to start orally was 8.73±2.13 days. Two patients underwent re-exploration in the postoperative period. One patient operated for delayed intraluminal haemorrhage on POD 7. Operative findings revealed arterial bleeding present in the pancreatic stump and were managed with gastrotomy with ligation of bleeding artery and patient made an uneventful recovery. Another patient who was known case of ischaemic heart disease was re-explored on POD2 for persistent hypotension and tachycardia. On exploration was found to have multiple gangrenous patches in the caecum and ascending colon, probably secondary to the thromboembolic phenomenon and required right hemicolectomy. However patient expired on POD 9 due to pneumonitis and respiratory failure. The most frequent complication in our According to ISGP fistula definition, both patients had Grade A pancreatic fistula and were managed conservatively. All drains were eventually removed by POD7. All patients were followed up in an outpatient clinic with periodic physical examination, endoscopy and CT/MRI if indicated. What Median follow up was 18 months(range 12-30 months). Fourteen of 20 patients who underwent an endoscopic evaluation at 6 and 12 months showed healthy pancreatic stump.

Discussion:
The pancreatoenteric anastomosis is entirely different from commonly done enteroenteric anastomosis between two hollow viscera such as gastrojejunostomy(GJ), jejunojejunostomy or colo- Other systemic complications 0 0% colic. First of all, the pancreas is a solid organ, so there is no landmark for the adequate thickness of suture bites. Secondly, this organ has numerous accessory pancreatic ducts, which if remain undrained or occluded can lead to pancreatitis and anastomotic failure. Third, soft and fragile pancreas lead to laceration during suturing with a needle or during tightening of suture thread. Fourth, among these two organs, one is fixed, and other is relatively mobile. As a result of these factors mentioned above, the pancreatoenteric anastomosis is more vulnerable to disruption than other anastomosis between hollow viscera. For these reasons, more than 80 technical variations of pancreatoenteric anastomosis have been described, and no firm conclusion can be drawn about the safest technique. First reported in 1946, PG has been established as a secure method of anastomosis as an alternative to the standard PJ. There are various theoretical, physiological and technical advantages of performing PG over PJ [14,15]. A physiologic advantage is that gastric acid inactivates pancreatic enzymes. Further, lack of enzyme enterokinase in the stomach which is required for conversion of trypsinogen to trypsin and the subsequent activation of other proteolytic enzymes seems to prevent autodigestion of the anastomosis and further consequences in case of minor leaks. Also, alkaline pancreatic secretions may aid in preventing marginal ulceration. The proximity of pancreas to the posterior wall of stomach hence less tension on the anastomosis, excellent blood supply and thickness of stomach wall holding sutures well are favourable to anastomotic healing. Nasogastric decompression provides for continuous emptying of the stomach thus less tension on the PG anastomosis, a benefit not possible with a pancreaticojejunal anastomosis. PG anastomosis is easily accessible endoscopically and so can be evaluated later for long-term outcome of the pancreatic stump. The findings of PG have been compared to PJ in more than a dozen retrospective studies which almost invariably have demonstrated the superiority of PG. A recent meta-analysis has reported that average pancreatic fistula rate was significantly lower (3.7%) after PG than PJ (16.5%) with a significant difference in mortality of 3% after PG compared with 9% after PJ and lower intra-abdominal complications than PJ [16][17].
Ohigashi and Peng have described new modified techniques describing the theoretical advantages of binding and transfixing modifications [18,19]. Bartsch reported another new technique for PG, which combines one binding purse-string and two transfixing mattress sutures between the pancreatic stump and the posterior gastric wall. These transfixing sutures techniques still require transpancreas sutures. Every suture carries the risk for pancreatic laceration resulting in pancreatic leakage, especially in a fragile and soft pancreatic remnant [20]. Peng et al. introduced four types of binding PG using binding purse-string without transpancreatic sutures. In Types, I and II the sutures were placed in the mucosal layer through an opening in the anterior gastric wall or the sealed distal gastric stump. However, this technique was not comfortable for surgeons and prolonged the operation time. Types III and IV were designed to avoid opening the anterior gastric wall or the sealed distal gastric stump, and, instead, the binding anastomosis was performed behind the posterior stomach wall directly. However, this was neither an easy nor was a safe procedure to place the inner suture.
The ideal pancreatic reconstruction should be easy to perform, reproducible and characterised by the lowest possible leak rate. Kostov et al. described a new technique for pancreatogastrostomy using one continuous seromuscular circular suture without transpancreatic sutures for PG [21]. In our view, this seromuscular approach in the stomach does not guarantee adequate hemostasis from the highly vascular gastric mucosa.We started doing binding PG with a full thickness purse-string suture on the posterior gastric wall that ensures the proper haemostasis from the posterior gastric wall. To minimise the pancreatic laceration during suturing with a needle or tightening of the suture thread, we introduced 4 points fine suture with the pancreatic capsule and gastric mucosa only. The approach of binding PG in our technique via the gastrotomy in the anterior gastric wall provides an excellent field of vision, enabled us to inspect bleeding points in the pancreatic stump after completion of the anastomosis and consequently much easier GJ anastomosis with anterior gastrostomy site. The pancreatic stump is sufficiently invaginated into the gastric lumen, and this guarantees adequate drainage of the pancreatic juice secreted from the accessory pancreatic ducts on the cross-section planes. The main pancreatic duct was cannulated using a short internal stent during the anastomosis to ensure that purse string is not too tight enough to obliterate the duct. Additional mucosal sutures are taken at the corners between the capsule of pancreatic stump and gastric wall secure the stump firmly within the stomach. Binding PG can be safely done in all pancreatic stumps irrespective of the diameter of duct or texture of pancreatic parenchyma. The percentage of pancreatic leak varies from 0-16%, and mortality varies from 0-12.3% in various RCTs and observational studies. Although small in numbers, the pancreatic leak of 10%(grade A only) and mortality of 5% in the present study is comparable to world literature. Postoperative haemorrhage developed in one patient only(5%), similar incidence has been described by others in literature.

Conclusion:
We believe that this technique is simple, secure, and reproducible and should be part of the pancreatic surgeon armamentarium. The main advantage of our technique is the easy placement of single full-thickness perfect hemostatic purse string suture through anterior gastrostomy incision under vision, no need for gastric wall resection, no deep pancreatic parenchymal sutures and mucosal approximation with corner sutures. It has several advantages over the conventional PG. The results of this novel technique are comparable to other studies concerning mortality and morbidity. To determine its superiority over the traditional procedures, this operative technique needs to be more comprehensively evaluated in a larger group of patients for statistical significance in future.