Therapeutic endoscopic ultrasound for postoperative fluid collections: a surgeon’s best friendReferring to Yang J et al. p. 715–721
25 July 2019 (online)
Endoscopic ultrasound (EUS) has become an essential diagnostic modality because of its ability to identify targets for fine needle aspiration (FNA) that are not easily seen or accessible through other means. The next level of indispensability for EUS was achieved with the development of a means of accessing and draining intra-abdominal and retroperitoneal fluid collections, usually pseudocysts . No longer was an endoscopically visible bulge required to successfully achieve internal drainage . EUS-guided cystgastrostomy or cystduodenostomy has emerged as the preferred method for management of pancreatic walled-off necrosis (WON). Since the early reports, EUS-guided treatment of WON has been a rewarding area of growth in the field.
Initially, plastic double-pigtail stents were used to accomplish drainage after puncture. After the description of the first lumen-apposing metal stent (LAMS) in 2011 , increased use of LAMSs has been seen, likely owing to their easier placement compared with plastic stents. The introduction of a cautery-enhanced delivery catheter for the LAMS made deployment even more straightforward and eliminated several procedural steps. Besides improving the technical success of placement, LAMSs have generally been found to have a higher clinical success rate as well, which is usually ascribed to the larger stent diameter, which prevents stent clogging, and the ability to carry out endoscopic debridement of the WON more easily.
Following the success of endoscopic WON management, EUS-guided drainage of postoperative fluid collections (POFCs) was performed by enterprising interventional endoscopists . EUS-guided internal drainage with placement of plastic stents avoids the need for placement of percutaneous drains or a repeat surgical procedure, along with the discomfort and morbidity associated with these. As would be expected, LAMSs designed for WON management were applied to POFCs, with very successful results. Mudireddy et al.  published results of a multicenter retrospective study of 47 patients with POFCs managed with LAMSs. More than half (55 %) had fluid collections after pancreatic surgery, with a wide variety of other surgeries making up the remainder. There was an impressive 93.6 % technical success rate, 89.3 % clinical success rate, and a post-procedural adverse rate of 6.4 %. A prior unsuccessful attempt at drainage (usually percutaneous) had been made in many of the patients (27.6 %).
“...interventional EUS has a very bright future and will likely become a first-line treatment modality in the management of postoperative fluid collections”
In this issue of the journal, Yang et al.  present a similar retrospective multicenter experience of LAMSs for the management of POFCs in 62 patients. Echoing the results of the previously described study, most of the POFCs (35/62; 57 %) occurred after pancreatic resection, with tail resection accounting for almost half of the cases (46.8 %). A prior unsuccessful non-endoscopic intervention had been performed in 12.9 %. The technical and clinical success rates were impressive at 96.8 % and 91.9 %, respectively. Adverse events occurred in 11.3 % of patients. Percutaneous drainage was required because of non-resolution in 8.1 % of patients (a single case requiring percutaneous drainage was encountered in the Mudireddy study).
In the current multicenter study, 16 % of the collections were drained less than 30 days after the surgery. A rule of thumb often cited by interventional endoscopists is that 4 weeks should elapse before attempted internal drainage of a pancreatic WON. However, collections from another etiology, as in these cases, may be clinically and anatomically different, and may be ready for drainage earlier than 4 weeks. In addition, the presence of infection may “ripen” the collections sooner, allowing earlier intervention. Therefore, suitability for internal drainage can apparently be based on CT assessment of the wall of the collection, and not strictly on an arbitrary amount of time elapsed.
EUS-guided placement of LAMSs for intra-abdominal or retroperitoneal collections has high technical and clinical success rates and they are easier and quicker to place. But are there any downsides? An obvious one is the cost of the LAMS, which can be 100 times the price of a plastic stent. However, placement of plastic stents requires the use of many other single-use devices (EUS needle, biliary guidewire, dilation balloon, stent pusher, stents), as well as the overhead costs associated with the need for fluoroscopic guidance, perhaps making the gap not quite as wide. Cost-savings could be achieved by limiting the use of LAMSs to drainage of collections that contain a significant amount of debris, as visualized on EUS, and using plastic stents for collections without debris.
Another potential downside of the use of LAMSs is the possibility of delayed bleeding or tissue overgrowth induced by the metal stent (“buried LAMS syndrome”), which was described in a prospective randomized trial of LAMSs versus plastic stents for WON . In the present study, there were no instances of delayed bleeding, and only three cases occurred soon after placement (on days 0, 1, and 4). In the study Mudireddy et al., there were no instances of early or delayed bleeding. The reason for this difference compared with the prospective WON study is not entirely clear. It may be that the postoperative state of the retroperitoneum after partial pancreatectomy contains fewer blood vessels that are at risk compared with a WON, where branches of the splenic artery and vein may lurk unnoticed. It is also possible that drainage of areas outside the upper retroperitoneum, where some of these postoperative fluid collections were found, are also less likely to result in treacherous encounters with larger blood vessels.
The unique ability to access POFCs through EUS, saving the patient the discomfort and inconvenience of percutaneous drainage or repeat surgery, has been one of the most impressive developments in the entire realm of EUS to date. This study further demonstrates that interventional EUS has a very bright future and will likely become a first-line treatment modality in the management of POFCs. Surgeons should take note and refer patients for EUS drainage instead of applying the percutaneous route whenever possible. In the future, modifications to the LAMS (for example longer stent length or different stent materials) may increase the applications and safety of this technology.
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