perineum
Meaning of perineum: Three systems empty through one small patch of the body, which is why it turns up in obstetric, urinary and bowel examinations alike.
Definition of perineum
The perineum is the region at the base of the trunk between the thighs, bounded by the pubic bone in front, the tailbone behind and the sitting bones at either side. In everyday clinical use the word means the narrower strip of skin and muscle between the anus and the vulva in females, or between the anus and the scrotum in males.
What lies within it?
A line drawn between the two sitting bones splits the region in two. The front half carries the outlet of the urinary tract and, in females, the vaginal opening; the back half carries the anal canal and the ring of muscle closing it. Where the halves meet sits a dense knot of connective tissue into which several muscles anchor, and that knot is what gives the area its strength. The whole region lies below the broad muscular sheet that forms the floor of the pelvis, so the sheet is its roof rather than its contents, although the muscles of the perineum are usually counted alongside it when the pelvic floor is discussed as a working unit. Structures of the urinary, reproductive and digestive systems all pass through or beside it.
Why does it matter in childbirth?
It is the last soft tissue a baby passes on the way out of the birth canal, and it has to stretch far beyond its resting size to allow that. Tearing is common, and tears are graded by depth, from a superficial split of the skin to one extending into the muscle that controls the bowel. That deepest grade is the one with lasting consequences, since damage to the anal sphincter can affect control afterward. A deliberate cut, an episiotomy, is sometimes made to enlarge the opening. Repair and healing of the area are therefore assessed specifically after a vaginal delivery rather than being folded into a general check.
When else does it come up?
| Setting | Why the region is involved |
|---|---|
| Routine examination | Inspected during a pelvic examination and when the rectum or prostate is assessed |
| Injury | Straddle injuries and tears from falls onto a hard edge |
| Infection | Abscesses beside the anus and infections spreading through the tissue planes |
| Nerve signs | Loss of feeling across the area is a recognized warning of pressure on the nerve roots at the base of the spine |
Persistent pain in the region is a complaint in its own right, and because it sits at the junction of three systems, working out the source often means considering all of them rather than assuming the nearest one.
Used in a sentence
Physical examination included inspection of the perineum for signs of injury.
Good to know
The perineum can stretch and, in some cases, tear during vaginal delivery, which is why it is specifically assessed after childbirth in addition to during routine pelvic examination.
Word origin
Where “perineum” comes from
Formed from Greek peri-, meaning around, and inan, meaning to carry off waste, describing the region's location near the body's excretory openings.