Reverse coitus: mechanism of urethral injury in male partner. Reverse coitus, a rarely used sexual position, makes the male urethra more vulnerable to injury from the pubic arch and symphysis pubis of the female partner. Severe pain, bleeding and immediate detumescence were observed in 3 patients. The lesion usually occurred at the fossa navicularis, responded well to conservative management and did not hinder micturition. Potency has been well preserved in all 3 patients. 