prolapse
[pro´laps]1. the falling down or downward displacement of a part or viscus; called also procidentia and ptosis.
2. to undergo such displacement.
prolapse of cord protrusion of the umbilical cord ahead of the presenting part of the fetus in labor. 
Variations of prolapsed umbilical cord. From McKinney et al., 2000.
prolapse of the iris protrusion of the iris through a wound in the cornea.
mitral valve prolapse see mitral valve prolapse.
rectal prolapse (prolapse of rectum) protrusion of the rectal mucous membrane through the anus.
prolapse of uterus downward displacement of the uterus so that the cervix is within the vaginal orifice (first-degree prolapse), the cervix is outside the orifice (second-degree prolapse), or the entire uterus is outside the orifice (third-degree prolapse).
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
iris, prolapse of the
Protrusion of a portion of the iris into a corneal wound. It results from either trauma, a severe corneal ulcer or an operation. In some cases an anterior synechia may develop as the iris remains fixed in the wound by scar tissue.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann