CT confirms fractures of the right superior and inferior pubic rami with associated haematoma within the right pelvic side wall / obturator internus muscle. There is also buckling of the anterior cortex of the right sacral ala lateral to the sacral foramina consistent with a sacral fracture in Dennis zone 1. Combination of the pubic rami and sacral ala fracture is consistent with a vertical shear mechanism also known as Malgaigne fracture. There is a small volume of pre-sacral haemorrhage seen in association with the sacral fracture. Presence of pre-sacral fluid on a trauma CT is a reliable sign that there will be a sacral fracture and should always prompt close investigation of the bones.