Reservoir for inflatable penile prosthesis was incidentally noted on scanning the pelvis of this patient. Inflatable penile prosthesis consists of 3 parts which are pump, penile cylinders and reservoir. Following squeezing of the small pump implanted in the scrotum, fluid flows from a reservoir in the pelvis to the two cylinders in the penis causing erection.

It is important to recognize the appearance of the penile reservoir in the pelvis as it may be mistaken for pelvic collection in certain situations like trauma patients.