Background
Intraperitoneal drains are frequently placed at the end of complex abdominal operations [
1]. These drains were initially thought to enable the early identification of hemorrhage or anastomotic dehiscence, allowing timely re-operations. It has also been hypothesized that prophylactic intraperitoneal drainage can prevent additional interventions for intraabdominal fluid collections [
2]. However, many studies, including randomized controlled trials, systematic reviews and meta-analyses have shown that routine drainage after various general surgical procedures such as appendectomy, cholecystectomy, hepatectomy, colectomy and gastrectomy does not reduce the number of complications [
1]. Some of these studies even found an increased risk of complications with drains [
2,
3]. This is thought to be a result of an artificial access to the peritoneal cavity, of an inflammatory response to the drain as a foreign body, and of increased pain due to the drain itself. Despite a high level of evidence favoring the omission of drains, clinical practice has only slowly changed [
1].
The evidence for or against intraperitoneal drainage after pancreatic resection is much less clear. Here, drains are placed to detect hemorrhage in the immediate postoperative period, but are also frequently left in place for an extended period of time to allow for detection of leakage of the pancreatic anastomosis/pancreatic stump [
2]. Though this concept has not been substantiated by reliable evidence, it is the standard of care all over the world. Interestingly, it had already been challenged in 1992, when Jeekel and co-authors published a series of 22 patients without intraperitoneal drainage [
4]. Here, omission of drains was not associated with an increased rate of complications. In 1998, the first retrospective study from the Memorial Sloan Kettering Cancer Center (MSKCC) was published, comparing patients with intraperitoneal drainage to those without. There was “no statistical difference in the rate of fistula, abscess, CT drainage, or length of hospital stay” [
5]. Because of these findings, the MSKCC group at that time designed and conducted a randomized controlled trial to generate better evidence. The results were published in the Annals of Surgery in 2001 [
6]. 179 patients with pancreaticoduodenectomy or distal pancreatectomy had been randomized to the drain or no drain group. There was no significant difference in the number or type of complications between the groups. Thus, for the first time, level 1b evidence had shown that intraperitoneal drains may not be necessary after pancreatic resection. Several years later, the authors of this randomized study validated their promising initial results by another retrospective report on 1,122 patients of their institution. They again advocated the benefits of omitting drains [
7]. However, the latter retrospective non-randomized analysis also revealed that the participating surgeons still decided to place a drain in roughly half of all pancreatic resections.
Subsequently, with only very few exceptions, several retrospective reports did not identify significant differences between drain and no drain groups regarding morbidity, pancreatic fistula, abscess, interventional radiology procedures, re-operation, length of hospital stay, or mortality [
5,
7‐
11]. These studies demonstrated that drains could probably be safely omitted after pancreatic resections. However, the available level of evidence was still not convincingly enough to change clinical practice. A main reason for this was that the prospective, randomized trial from the Memorial Sloan Kettering Cancer Center [
6] had not reported complications (and particularly, leak rates) according to current standards – owing to the lack of such reporting standards at that time. This reasoning prompted the initiation of a multi-center, randomized trial whose results have recently been reported [
12]. In this study, 137 patients with pancreaticoduodenectomy for benign or malignant pancreatic pathologies were randomized to placement or no placement of an intraperitoneal drain. The study was conducted at nine academic high-volume pancreas surgery centers in the United States. Randomization by demographics and clinical characteristics was performed thoroughly, minimizing the risk for any systematic bias. Unexpectedly, the group of patients without a drain had a higher complication rate, a higher complication severity, and most importantly, a higher mortality rate (12% versus 3%). The trial was thus prematurely terminated by the Institutional Review Board. These results were surprising [
12,
13], given that the trial has been multi-centric and all institutions had a vast experience in pancreatic surgery. In addition, a recent retrospective study published by one of the authors of the trial had demonstrated less complications and comparable mortality with omission of drains after pancreaticoduodenectomy and distal pancreatectomy [
8].
Because of these recent publications, we sought to provide pooled estimates of the available literature to allow for a better interpretation of the current evidence.
Discussion
In this meta-analysis, prophylactic intraperitoneal drainage after pancreatic resection increased the risk of complications, but not the rate of mortality. Pooled estimates of outcomes in the subgroup ‘pancreaticoduodenectomy’ demonstrated different results. Here, the rate of complications was comparable with or without a drain; however, mortality was increased by omission of intraperitoneal drains.
It could be argued that drains following pancreatic resection (as in other abdominal operations) are associated with an, albeit small 1.4-fold (OR 1.43, 95% CI 1.02 – 1.96), increased risk of morbidity without significantly influencing mortality. In the case of pancreaticoduodenectomy, leakage/dehiscence of the pancreatic-intestinal anastomosis is a potentially dreadful complication significantly contributing to the overall mortality following this procedure. From the clinical experience as well as from the data of the included studies, it is possible to conceive that a drain could help to detect a leak earlier and to drain this potentially hazardous fluid (leading to haemorrhage etc.) earlier and more efficiently than an interventional placed drain. Thus, omission of a routine drain following pancreaticoduodenectomy results in a 2.5-fold (OR 2.47, 95% CI 1.03 – 5.94) increased risk of mortality.
These conclusions are supported by the eight included studies, making this meta-analysis the most comprehensive so far. Despite the proper methodological quality of all includes trials, this study has limitations. Because of the different surgical approaches, we performed a subgroup analysis for pancreaticoduodenectomy. In general, there are few studies available investigating the use of drains for pancreatic resections, and only two prospective randomized trials exist. Especially in consideration of the results of the most recent prospective multicenter trial [
12], future randomized studies may be ethically difficult to conduct.
The latter trial by Van Buren et al. [
12] was stopped preliminary due to the unexpectedly high rate of mortality after pancreaticoduodenectomy in the no drain group. Unfortunately, the reasons for this outcome remain unclear, especially since it was highly contradictory to prior studies. A thorough analysis of the potential factors contributing to these results is beyond the scope of this review. However, it has to be acknowledged that this was the first multicenter study with a well-planned study protocol and the participation of only highly experienced centers. Certainly, the results cannot be explained by the multicentric character, flaws in the study protocol or the lack of experience in the participating centers. As such, the data of the trial by Van Buren et al. have to be taken as high quality evidence.
Recently, a meta-analysis by Rondelli et al. was published, which also meta-analyzed the results of intraperitoneal drainage after pancreatic resection [
21]. In contrast to our meta-analysis, the results of the study by Paulus et al. [
10] were not included. Comparable to our results, intraperitoneal drainage was identified to be associated with an increase in the total post-operative complication rate (OR 1.52, 95% CI 1.30 – 1.78), and mortality did not differ significantly between the drain/no drain group. Rondelli et al. also performed a subgroup analysis for pancreaticoduodenectomy. As for our analysis, four studies were eligible and the authors found no difference in mortality when analyzing the available randomized study, or the remaining retrospective studies separately. However, when analyzing all studies on pancreaticoduodenectomy together, there was still no significant difference identified in the mentioned meta-analysis, which is in contrast to our results.
Conclusion
Taking together the data for all pancreatic resections and the subgroup analysis, intraperitoneal drains seem not to be harmful, but may not be beneficial in general either. This would argue for a concept of selective abdominal drain application with placement of a prophylactic drain according to patient factors (e.g. comorbidity, perioperative risk, anticoagulation), pancreatic texture (e.g., small pancreatic duct, soft tissue), surgeon (level of experience, type of operation), and setting (e.g., missing 24/7 availability of interventional radiology procedures) [
13]. However, mortality is increased if drains are omitted after pancreaticoduodenectomy. Though this result is driven by the inclusion of the most recent randomized trial into this meta-analysis, it should certainly be taken seriously. Thus, it is very difficult to argue for an omission of drains after a pancreaticoduodenectomy – even under circumstances where anastomotic complications are unlikely. With a reduction of morbidity after any kind of pancreatic resection however, omission of drains after distal pancreatectomy may truly be an option. The results of a currently ongoing randomized trial on distal pancreatectomy are eagerly awaited.
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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
UN carried out the review of the literature, participated in performing the meta-analysis and drafted the first version of the manuscript. TCM carried out the independent review of the literature. CS collected data and drafted the manuscript. LC performed and validated the statistical analyses. DW participated in the design of the study and drafted the manuscript. HF interpreted and reviewed the data. CWM made the study concept and drafted the manuscript. JK planned the study, coordinated the drafting of the manuscript, and edited the manuscript. All authors read and approved the final manuscript.