In these patients, stent placement may be more difficult due to anatomic alteration resulting from surgery, and sometimes functional results are disappointing [17, 18].

An accurate endoscopic and radiologic evaluation is mandatory before stent placement in order to know the type of surgical procedure performed.

The lack of symptomatic improvement after stent insertion may be due to multiple bowel strictures or ileus as a result of peritoneal seeding [4, 17, 18].

Multiple strictures occur in 11 % of cases, and stent placement for two successive synchronous strictures is exceptional [13].

SEMS insertion may be performed both by endoscopically guided and by fluoroscopically guided methods. Similar high technical success (TS) and clinical success (CS) rates have been reported (92 and 90 % TS and CS, respectively, in endoscopic approach vs TS at 94–100 % and CS at 90–96 % in fluoroscopic approach) [4, 5, 22, 23].

However, the advantages of the endoscopic method in patients with distal gastrectomy are the ease of accessing the stricture site and the avoidance of looping the delivery system through the dilated gastric lumen due to the stiffness of the endoscope [20].

The friction between the working channel of the endoscope and the long delivery system may result in a difficult stent insertion when the endoscope is in an angulated position [22, 25]. Balloon dilatation can be exceptionally performed when the tightness of strictures does not allow the introduction of the delivery system; excessive dilatation should be avoided to prevent stent migration [24].

A stent at least 2–4 cm longer than the stricture should be chosen to allow for a 1–2 cm extension beyond the proximal as well as distal tumor margins [15].

Generally, in patients treated with SEMS, dysphagia is relieved in approximately 90 % of cases, and these patients undergo significantly fewer procedures, thus spending fewer days in the hospital [26, 27].

Stent placement has several advantages over surgery: it is a less-invasive procedure is preferred both by the patient and surgeon because of its lower morbidity, shorter procedural time and hospital stay, as well as faster recovery of gut function [17, 18, 28].

This is important for patients whose life expectancy is of 4–6 months, or less.

The overall survival rate for stent-treated patients has been reported to be similar to that for patients undergoing surgery, whose hospitalization is three times longer and costs are three times greater [29].

The recurrent rate of stenosis in patients with SEMS placed for anastomotic malignant obstruction ranges from 8 to 46 % after an interval of 2–21 weeks. It is generally due to tumor in-overgrowth [5, 30].

Some studies report that early occlusion of SEMS (within 4 weeks after their implantation) occurs more frequently in patients with the stent at the anastomotic level, than in those treated for unresectable cancer, but the causes are unknown [5, 6, 31].

Chemotherapy could decrease the tumor ingrowth and overgrowth; however, chemotherapy after stent placement is likely to shrink the tumor, increasing stent migration, if a covered SEMS has been used [5, 19, 32].

Stent migration rates range from 4.2 to 27.8 %; a pooled analysis of 21 studies reports that migration rate was 2.7 and 16 % for uncovered and covered stents, respectively [33].

An appropriate choice among the marketed SEMS according to the type of surgery performed may reduce the migration rate of stents placed in malignant recurrences [17].

A retrospective study reported that a double coaxial stent had a longer patency and lower migration rate than an uncovered stent in anastomotic recurrence [5].

At present, several types of SEMS are available, varying by type of alloy, configuration, degree of shortening after their release, lengths and diameters, presence, type, and extent of covering, delivery system, expandable force, presence or absence of anti-reflux valve, and removability.

Most SEMS are made of nitinol, an alloy of nickel and titanium, whose peculiarity is super-elasticity and shape memory.

The covering is either polyurethane, silicone, or polytetrafluoroethylene (PTFE). Their flexibility, the small diameter of the delivery system, and the large availability of models allow the treatment of any type of malignant obstruction [26, 34].

There are no data to date demonstrating significant differences in outcomes or complications among SEMS types. Therefore, the choice of specific SEMS is often based on the endoscopist’s experience, although the initial stent selection has a significant impact on the clinical outcome in patients with inoperable malignancy [35].

Use of a self-expandable plastic stent (Polyflex® stent, Boston Scientific, Natick, MA, USA) is not recommended in GI anastomotic malignant recurrence. The major disadvantage of the current version of plastic stents is the large diameter and stiffness of the stent delivery system when compared with metal stents. Therefore, plastic stents cannot be released in patients with angulated strictures as in anastomotic ones.

SEMS may be placed hardly in some cases, especially in the presence of narrow bowel loops. In such situations, SEMS cannot fully expand, and they may migrate or cause perforation due to excessive stretching of gut wall, determined by the device. New D-Weave Niti-S colonic stent (TaeWoong Medical Co., Seoul, South Korea) has characteristics that may reduce the risk of such complications. It is a self-expandable nitinol stent, whose particular configuration confers some interesting properties to the device, such as compliant flexibility, high expansible force, and negligible foreshortening, in order to reduce the risk of migration, perforation, and inadequate expansion [36].

SEMS for malignant anastomotic obstruction after: