Ultrasound (US)-guided caudal epidural injection is a method of drug administration into the epidural space through the sacral hiatus for both chronic pain management and perioperative analgesia. Here, we describe the usefulness of US sacral examination performed before a caudal epidural injection procedure, in which the results revealed a sacrococcygeal ligament ossification prompting us to avoid its puncture by placing the Thouy needle in the appropriate direction. This prevented an unwanted calcification rupture with a possible drag of material into the sacral canal. US has already been used as a diagnostic tool in caudal epidural injection, mainly to detect the agenesis of sacral hiatus or to measure its diameter. Our case underlines the possibility of finding ossification and calcification using US, which can make the injection difficult or impossible and be a side effect if not recognised.