BLOOD SUPPLY OF PERINEUM
The perineum and vulva are richly supplied with blood vessels, which become clinically significant during childbirth and surgical procedures. Blunt trauma to the area, such as straddle injuries in children, can result in significant bleeding or hematoma formation when vessels are ruptured and bleeding into the loose compartments of the perineum occurs.
The internal pudendal artery in the female is a far smaller vessel than
it is in the male, though its course is generally the same in both sexes. When
leaving the lesser pelvis through the lower part of the greater sciatic foramen,
it enters the ischiorectal fossa through the lesser sciatic foramen. Here,
accompanied by its venae comites and the pudendal nerve, it lies in a fibrous
canal (Alcock canal) formed by the fascia covering the obturator internus
muscle. The branches of the internal pudendal artery include small ones to the
gluteal region, the inferior hemorrhoidal artery, the perineal artery, and the
artery of the clitoris. The pudendal artery (and vein) is closely associated
with the pudendal nerve as it passes the ischial spine near the insertion of
the sacrospinous ligament (on the dorsal aspect of the coccygeal muscle),
placing it at risk when sacrospinous colpopexy is performed. (A rare
complication of this operation is massive hemorrhage from the inferior gluteal or
pudendal arteries.)
The inferior hemorrhoidal artery pierces the wall of Alcock canal and
passes medially through the ischiorectal fat to supply the anal canal, anus,
and perineal area. The perineal artery pierces the base of the urogenital
diaphragm to enter the superficial perineal compartment, where it supplies the
ischiocavernosus, bulbocavernosus, and transverse perineal muscles. A constant
transverse perineal branch runs along the superficial transverse perineal muscle
to the central point of the perineum. The terminal branches of the perineal
artery, the posterior labial arteries, pierce the deep layer of the superficial
perineal fascia (Colles fascia) to the labia.
The artery of the clitoris enters the deep compartment of the urogenital
diaphragm and runs along the inferior ramus of the pubis in the substance of
the deep transverse perineal muscle and the sphincter of the membranous
urethra, ending in four branches, which supply chiefly the erectile tissue of
the superficial perineal compartment. The artery of the bulb passes through the
inferior fascia of the urogenital diaphragm to supply the cavernous tissue of
the vestibular bulb and the Bartholin gland. The
urethral artery runs medial- ward toward the urethra and anastomoses with
branches from the artery of the bulb. The deep artery of the clitoris pierces
the fascial floor of the deep compartment just medial to the corpus cavernosum
of the clitoris, which it enters. The dorsal artery of the clitoris leaves the
deep perineal compartment just behind the transverse pelvic muscle and runs
over the dorsum of the clitoris to the glans.
The blood supply of the vulva and perineum is richly connected to the
vascular supply of the entire vaginal barrel, the cervix, and the uterus
through a number of ascending and descending anastomoses. This vascular net
surrounds the vaginal canal, with major trunks running in the lateral vaginal
wall at the 3- and 9-o’clock locations. Trauma to these areas, as with a
vaginal delivery, can result in significant blood loss that may be difficult to control.
