Supplementary Material for: An unusual complication of self-expandable metal stent(SEMS) placement in malignant sigmoid obstruction

SEMS for malignant colorectal obstruction is widely used as a bridge to elective surgery or palliative treatment. However, with the increasing use of SEMS for treatment, complication rates associated with stents have been raised as a concern. We experienced a rare migration-related complication that a stent partially migrated out of the anus with an incarceration. A 62-year-old man was admitted with sigmoid malignant obstruction. Due to multiple metastases, he refused to undergo colostomy, and an uncovered SEMS was placed. Subsequently, he started chemotherapy. Seven months after placement, the stent migrated into the rectum. After unsuccessful attempts to extract the stent, he sought our assistance. We observed that half of the stent was outside the anus, and a 15mm lump of mucosa was embedded in the proximal end of the stent. After several attempts, we successfully removed the SEMS. Stent incarceration following migration is not a common occurrence, but it serves as a reminder that clinicians need to be more vigilant about complications that may arise after stent implantation. We describe this unusual complication and share our experience about the removal of the stent.