Self-expandable metallic stent placement for palliation in gastric outlet obstruction.

Malignant gastric outlet obstruction (GOO) often has a markedly adverse impact on the quality of life (QOL) of patients. Procedures in affected patients should aim to reduce obstructive symptoms and enable oral ingestion. Surgical gastrojejunostomy (GJJ) has been performed as a conventional palliative procedure. Enteral stenting has been increasingly used as an alternative to surgical palliation because of its lower invasiveness. Enteral stents used for GOO are made of a metal alloy mesh in a cylindrical shape, and are termed self-expandable metallic stent (SEMS). Of the two placement techniques, over-the-wire (OTW) and through-the-scope (TTS) deployment, TTS is easier and is now more frequently used. In general, the technical success rate is extremely high, at nearly 100%, and the clinical success rate is about 90%, but complications after placement can occur, most frequently late-developing stent dysfunction due to stent obstruction and migration. Biliary obstruction can occur concurrently with GOO, or before or after GOO, particularly in patients with pancreaticobiliary malignancies. Considering accessibility to the bile duct, biliary stenting should generally be conducted prior to enteral stenting. Transhepatic or transmural biliary stenting may be required if transpapillary stenting is not possible. Because enteral stenting is more commonly associated with late-developing stent dysfunction, it is better suited than GJJ for patients with a short life expectancy and poorer performance score. Chemotherapy may be beneficial in reducing the risk of stent obstruction, despite the possible risk of migration, particularly in patients with GOO due to gastric cancer. Many enteral stents with different structures are now commercially available, but the association between the design and mechanical properties of a stent and clinical outcomes is still poorly understood. Further, no consensus on the benefits of covered SEMS has yet been obtained. Further study to verify which types of SEMS are most suited for GOO is warranted.