When performing ultrasound you may see findings that you were not expecting or are unsure of. In these cases, it is appropriate to seek more experienced advice or further imaging, always remembering and using your clinical judgement. In this case an urgent CT confirmed sigmoid perforation. The aorta is retroperitoneal, so most ruptures do not cause free fluid (if they then rupture into the peritoneal cavity, the tamponade effect is lost and the patient usually rapidly exsanguinates). Although free fluid with particulate matter could represent an aortic rupture with fibrin and clot, if this were the case the patient would be expected to be moribund.