Artwork representing the condition known as phimosis. It is caused by a tight foreskin which may not be drawn back over the head (glans) of the penis. It obstructs the passage of urine and also prevents a proper cleaning of the glans. This may lead to balanitis, the infection of the glans, and may increase the risk of cancer. Phimosis makes erection painful and may cause paraphimosis in which the glans is constricted by the tight foreskin. Phimosis is treated by circumcision.