Pulmonary embolism following spacer hydrogel intravasation: A case report of a rare rectal spacer complication in prostate cancer radiotherapy.

Localised prostate cancer is increasingly being treated with radiotherapy. As a result, rectal spacers such as the SpaceOAR™ System, Boston Scientific, Marlborough, MA, USA (SpaceOAR) are increasingly used to reduce radiation-related rectal toxicity. We report a rare case of hydrogel intravasation following rectal spacer insertion, with subsequent pulmonary embolisation detected on follow-up imaging. This case highlights the anatomical considerations underlying this complication, the limitations of intra-procedural safeguards, and the importance of routine post-procedural imaging to detect potentially asymptomatic but clinically significant adverse events.