Intussusception has an analogue in prolapsus ani.

Prolapsus ani is a volvulus without a sheath, and it is characterized by an inversion of the internal portion of the intestinal tubing. It represents a sausage-shaped or pyriform tumor, which is contracted at the anus, so as to form a pedicle, and at the free extremity there is, in trifling cases, a round central opening, which in larger prolapsus assumes an eccentric position, and, following the traction exerted upon it by the mesorectum, recedes so as to present a mere fissure. The external mucous layer is the seat of inflammation and swelling, which partly proceeds from mechanical hyperaemia, partly from irritation produced by the atmosphere. It is the result of violent and lasting diarrhoea in children, or of blenhorrhoea of the rectum in adults and old people.