Placement of Enteral Self-Expandable Metal Stents

Aaron J. Small, MD

Shayan Irani, MD

Enteral self-expandable stents (SEMSs) have become an effective treatment option for malignant strictures of the esophagus, stomach, proximal small bowel, gastroenteric anastomoses, and the distal small bowel (terminal ileum) or the jejunum in select patients.¹,² The goal is to achieve luminal patency, allowing food intake per os, and thereby obviating the need for more invasive operative alternatives. SEMSs although historically made of stainless steel now are almost exclusively made of nitinol (a shape-retaining alloy) and come in a variety of sizes and designs depending on the location of the stenosis. For the purposes of this chapter, we will focus on the application of metallic stenting within the lumen of the stomach and proximal small intestine, most commonly the duodenum. Endoscopic transmural stenting within the stomach and small intestine akin to the creation of an endoscopic anastomotic bypass is covered elsewhere in this handbook.

PATIENT SELECTION

Indications

Although enteral SEMSs have been used in both benign and malignant conditions, they have a limited role in benign diseases. Endoscopic stenting for palliation of a malignant gastroduodenal stricture from an intrinsic or extrinsic lesion has been shown to be safe and effective as therapy for restoring oral intake and improving patient quality of life.³,⁴,⁵,⁶,⁷ Preoperative enteral stenting as a “bridge to surgery” is a less common scenario. Insertion of enteral stents for benign diseases is principally for temporary placement for postoperative complications such as strictures, leaks, and fistula, although there have been other indications listed below.³

Malignant

1. Gastric obstruction
- a. Primary or recurrent gastric cancer
- b. Gastrojejunal anastomosis—afferent and efferent limb obstruction
2. Duodenal obstruction
- a. Primary pancreatic cancer or metastatic disease to the pancreas
- b. Cholangiocarcinoma or gallbladder cancer
- c. Periampullary cancer
- d. Locally invasive tumors (e.g., colon)
3. Small bowel
- a. Metastatic disease involving the ligament of Treitz or jejunum
- b. Pelvic cancers affecting the distal terminal ileum

Benign

1. Gastric
- a. Postoperative fistula/leaks: sleeve gastrectomy, gastrojejunal anastomosis
- b. Gastric sleeve stricture
2. Duodenum
- a. Peptic ulcer disease stricture (short stricture more amenable)
- b. Fistula, e.g., pancreaticoduodenal or enterocutaneous fistula (low success rates)
- c. Perforation⁸
3. Small bowel
- a. Anastomotic-jejunal limb stenosis, leak, perforation

CONTRAINDICATIONS

There are very few absolute contraindications to enteral stent placement which are the same as those that preclude an upper endoscopy.⁹ These include cardiopulmonary instability, recent myocardial infarction, or pulmonary embolus. Enteral stenting can be performed safely without cessation of antiplatelets or in anticoagulated patients. The presence of a transmural perforation which can sometimes be tumor-related, with or without associated peritonitis, may be too large of a defect for safe closure with a covered metal stent, and thus should be considered a relative contraindication.

Peritoneal carcinomatosis, while not an absolute contraindication, can portend a higher risk of primary stent failure since these patients will often have multifocal stenosis in more distal areas of the small intestine or have gastric or small bowel dysmotility from neural tumor invasion that is not alleviated by stent monotherapy.¹⁰

PATIENT PREPARATION

Preprocedural Planning and Equipment

Prerequisites

1. A basic prerequisite for placing enteral stents requires an endoscopy unit equipped with various endoscopes, stent types (discussed further below), high-quality fluoroscopy, and staff including endoscopic technicians/assistants, fluoroscopic operators, and anesthesia all of whom are comfortable with complex GI procedures.
2. In addition, knowledge of the patient’s anatomy and any history of prior surgeries should be understood to determine the feasibility of endoluminal stenting.

Imaging

1. CT scan with oral contrast can elucidate the location, length, severity of the stricture, and the presence of a possible leak.
2. Upper GI series and/or small bowel follow through studies while more detailed than CT scans in defining gastroduodenal strictures may also aid in determining whether there are multiple other focal areas of stenosis in the more distal small bowel.

Procedural considerations

Precautions to minimize the higher risk of intraprocedural aspiration in these patients who may have complete gastric outlet obstruction should be undertaken. Some of the interventions that may reduce this aspiration risk are the following: