Reinforcing the Staple Line with Surgicel® Nu-knit® in Roux-en-Y Gastric Bypass: Comparison with Bovine Pericardial Strips
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- Moon, R., Teixeira, A., Varnadore, S. et al. OBES SURG (2013) 23: 788. doi:10.1007/s11695-013-0898-y
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In the literature, staple line leak rate is reported to be 1–6 %, and hemorrhage rate is 2–5 % in laparoscopic Roux-en-Y gastric bypass (LRYGB). Various buttress materials are available in an attempt to reduce perioperative complications. The aims of our study are to evaluate the effect of using absorbable hemostat (SNK) as buttress material and compare its usage with bovine pericardial strips (PSD).
Between January 2006 to May 2007 and from October 2007 to December 2009, a total of 1,074 patients underwent LRYGB at our institution. Of these 1,074 patients, PSD was used in 443 (41.2 %) patients, and SNK was used in 631 (58.8 %) patients. A retrospective review of a prospectively collected database was performed for all LRYGB patients, noting the outcomes and complications of the procedure.
Five (1.1 %) patients required transfusion of packed red blood cells (PRBC) during early postoperative period (postoperative 1–3 days) in the PSD group, while two (0.3 %) patients required transfusion in the SNK group. SNK patients received significantly lower mean units of PRBC (1.0 unit) when compared to that of PSD patients (5.0 units). One (0.2 %) anastomotic leak was found in the PSD group on postoperative day (POD) 10. One (0.2 %) patient in the SNK group also showed an anastomotic leak on POD 2. Additionally, the cost of SNK per procedure was significantly less than that of PSD.
The use of absorbable hemostat as buttress material may be effective in reducing acute postoperative bleeding in LRYGB at a significantly lower cost.
KeywordsGastric bypassButtressBovine pericardial stripsStaple line hemorrhageStaple line leakSurgicelNu-knit
The use of staplers became inseparable from laparoscopic bariatric procedures such as laparoscopic Roux-en-Y gastric bypass (LRYGB), biliopancreatic diversion with or without duodenal switch, and laparoscopic sleeve gastrectomy (LSG) . Two major complications of staple lines have been reported, sometimes leading to calamitous results. Staple line leaks occur at a rate of 0.5–5.6 % [2–5] and hemorrhage at 1.9–4.4 % [6–8] in LRYGB procedures.
In order to reduce incidences of staple line leak and hemorrhage, reinforcement of the staple line has gained popularity among bariatric surgeons. Of several reinforcement methods, incorporation of buttress material into staple lines has shown effectiveness in LRYGB according to numerous publications [9–11].
Buttressing the staple line has also demonstrated decreased leak and bleeding after LSG, which has the longest continuous staple line in bariatric procedures [12–14]. Currently, various buttress materials are available in three different categories of absorbability. Nonabsorbable materials include ePTFE® and Xylos®, semi-absorbable materials include bovine pericardium™ and bovine pericardium collagen™, and absorbable materials include Seamguard® and Duet® [15, 16]. Bovine pericardium strips (Peri-strips® or Peri-strips Dry®) offered improvement in preventing tissue tearing, but had drawbacks including handling problems and costs . Seamguard® had benefits of simple loading, safety, biocompatibility, and rapid absorption but also had drawbacks of increased cost [11, 15].
Surgicel® is an absorbable, oxidized regenerated cellulose commonly used for hemostasis , and Surgicel® Nu-knit® (SNK) is a variation with high tensile strength for heavier bleeding (Johnson and Johnson, Somerville, NJ, USA). Lee et al.  reported two successful cases of buttressing the staple line with Surgicel® in lung volume reduction surgery that prevented postoperative air leakage.
The aim of our study is to demonstrate the effectiveness of utilizing SNK as a buttress material. We compared leak and hemorrhage rates as well as costs, between SNK and Peri-strips Dry® (PSD) used as buttress materials in LRYGB.
Methods and Materials
After Institutional Review Board approval and following Health Insurance Portability and Accountability Act guidelines, the authors performed a retrospective review of a prospectively maintained database and medical chart review of 1,074 patients who underwent primary LRYGB from January 2006 to December 2009. PSD was used in consecutive 443 cases from January 3rd, 2006 to May 7th, 2007, and SNK was used in consecutive 631 cases from October 31st, 2007 to December 30th, 2009. We have excluded patients from May 8th, 2007 to October 30th, 2007 because we experimented different materials including Seamguard® and did not want these cases to intervene with our results.
846 (78.8 %)
351 (79.2 %)
495 (78.4 %)
228 (21.2 %)
92 (20.8 %)
136 (21.6 %)
42.9 ± 11.3
42.3 ± 10.9
43.2 ± 11.5
48.1 ± 8.5
49.5 ± 8.7
47.2 ± 8.3
LRYGB was performed by one surgeon according to the National Institutes of Health criteria for the management of morbid obesity. All data for age, BMI, and packed red blood cells (PRBC) are demonstrated as mean ± standard deviation, unless otherwise noted. Statistical analysis was performed using descriptive analysis and two-tailed Student’s t test, with p < 0.05 regarded as statistically significant.
Preparation of Surgicel® Nu-knit®
The Roux limb was brought in as antecolic, antegastric fashion. Two stay sutures were placed between the pouch and jejunum, and enterotomy and gastrotomy were performed. Endo-GIA 45 stapler was inserted and fired at 2.5 cm mark, creating the gastrojejunal anastomosis. The opening for the GIA was closed transversely with Endo-GIA 45 and 60 in two applications after advancing the Edlich tube to the jejunum. No buttress material was used in the gastrojejunal anastomosis. Staple line was reinforced with running stitch of 2–0 Polysorb.
Patients in the PSD group required eight to ten pairs of PSD and the cost of PSD was approximately $150 per pair. Total cost of PSD in one procedure resulted in minimum of $1,200. Patients in the SNK group required one 6 in. × 9 in. SNK for one procedure, and the cost of one SNK was approximately $110. Two patients from the PSD group and six patients from the SNK group were converted to open gastric bypass due to extensive adhesions.
Preoperative BMI was slightly lower in SNK patients (47.2 ± 8.3 kg/m2) than PSD patients (49.5 ± 8.7 kg/m2). Patient characteristics were clinically comparable (Table 1).
Acute Postoperative Bleeding
PRBC were given when patients had stable vital signs, but had hemoglobin level less than 9.0 mg/dl or Jackson–Pratt drainage of more than 500 cc. Patients were taken back to the operating room when their vital signs became unstable.
Of 441 patient population in the PSD group, excluding two patients with open procedure, six (1.4 %) required transfusion of PRBC during early postoperative period (postoperative 1–3 days). Of 625 patients in the SNK group, excluding six patients with open procedure, three (0.5 %) patients required PRBC transfusion within the same time frame.
Characteristics of patients who received transfusion
Units of PRBC
DM, HTN, GERD, hyperlipidemia
DM, HTN, GERD, hyperlipidemia
6 + 4 FFP
DM, HTN, GERD, hyperlipidemia, on Lovenox
HTN, GERD, hyperlipidemia
One (0.2 %) patient in the PSD group received 10 units of PRBC and 4 units of fresh frozen plasma, and one (0.2 %) received 7 units of PRBC. One (0.2 %) patient in the PSD group was on chronic Lovenox® treatment. Three (60.0 %) out of five patients in the PSD group required immediate transfusion on postoperative day (POD) 0. On the contrary, no SNK patient required transfusion on POD 0 (Table 2).
Comparison of patients requiring postoperative PRBC transfusion
Number of patients
5 (1.1 %)
2 (0.3 %)
5.0 ± 3.5 (range 1–10)
1.0 ± 0.0 (range 1)
3.4 ± 1.7 (range 2–6)
2.0 ± 0.0 (range 2)
Postoperative Acute Anastomotic Leak (Within 30 Days)
One (0.2 %) patient in the SNK group showed a small leak in Gastrograffin upper gastrointestinal studies (UGI) 2 days postoperatively. He was put on nothing by mouth (NPO) and gastrostomy tube feeding, and UGI on postoperative day 9 did not show any leak. He was followed up for longer than 24 months, and the patient did well.
Characteristics of patients with gastrojejunal anastomosis leak
Hypertension, sleep apnea
Postoperative day 10
Postoperative day 2
With the rapid development of laparoscopic procedures, came along substantially increased use of endoscopic staplers . With the use of staplers, acute leaks are reported at a rate of approximately 2.5 % and bleeding at about 3.5 % in LRYGB . Staple line leak after LRYGB can become a catastrophic complication leading to peritonitis, septic shock, multiple organ failure, and death [5, 9, 20, 21]. Less severe complications occur with staple line hemorrhage and formation of fistula .
The materials for reinforcement of the staple line have been introduced, with the anticipation of improving leakage, bleeding, and dehiscence . It has been suggested that buttressing materials distribute the pressure on the tissues at the staple line and reduce the blood flow to the cut edge by allowing more uniform force and therefore reducing the incidence of bleeding at the staple line .
Currently, various materials are available as buttress material, routinely categorized as nonabsorbable, semi-absorbable, and absorbable [15, 16]. Angrisani et al.  and Shikora  have demonstrated decreased staple line bleeding and the likelihood of decreased failure and leak by buttressing the staple line with semi-absorbable material bovine pericardial strips. Shikora et al.  also reported dramatically reduced incidences of linear gastric staple line complications with PSD and PSD with Veritas®, while questioning the effectiveness of absorbable material Seamguard®. Nguyen et al.  described that the use of Seamguard® significantly reduced the number of staple line bleeding sites and the time to obtain staple line hemostasis.
However, although without serious complications, Consten et al.  reported a case of a patient vomiting up PSD 4 weeks after laparoscopic duodenal switch procedure. Yu et al.  noted that 4 % of LRYGB patients with gastrointestinal symptoms requiring endoscopy had intraluminal PSD in the gastric pouch.
We used semi-absorbable material PSD until May 2007 and started utilizing SNK as buttress material since October 2007 due to its low cost, absorbability, and hemostatic ability. We have looked at significant hemorrhage rate requiring transfusion at early postoperative period. The difference was statistically significant between the PSD and SNK groups. While 0.3 % of SNK patients required a mean of 1 unit of PRBC transfusion, 1.1 % of PSD patients were transfused with a mean of 5 units of PRBC.
As Shikora et al.  have mentioned, it is difficult to discern the actual incidence of complications from the staple line, because many of the bleeding can occur at sites other than the linear stapled partitions. Nonetheless, we believe that the change of buttress material has contributed to the lower rate of transfusion. Leak rate at the gastrojejunal anastomosis did not differ between the two groups within 30 days of the procedure.
We would like to emphasize that this is from a single surgeon’s experience and this surgeon performed high-volume LRYGB since 2000. PSD and SNK were used at a different time period, but we do not think PSD patients received more transfusion due to the surgeon’s learning curve because the surgeon had operated on more than 1,000 LRYGB cases by 2005.
We would also like to remark that using SNK instead PSD lowered the cost of the procedure tremendously. Currently, the approximate cost of PSD is $150 a pair, resulting in at least $1,200 per procedure. The total cost of SNK was $110 per procedure.
The weakness of our study is that it is a retrospective review in nature. A randomized prospective study may be needed to strengthen our result. Also, it was difficult to discern the actual incidences of staple line bleeding from bleeding from a different site. Thus, our results can only represent an approximation to the data regarding the actual causes of bleeding. However, we believe that a large enough number of patients were included in this study to validate our results. We reviewed consecutive cases in both groups to minimize biased sampling. Most importantly, this is the first report of the effectiveness of utilizing SNK as buttress material in LRYGB.
The use of Surgicel® Nu-knit® as buttress material may be effective in reducing acute postoperative bleeding in LRYGB at a significantly lower cost.
Conflict of Interest
The authors Rena Moon, Andre Teixeira, Kelly Potenza, Sheila Varnadore, and Muhammad Jawad have no conflict of interest to report.