PELVIC VISCERA
The interrelationships between the uterus and the surrounding muscles, nerves, vessels, and organs determine both the pathophysiology of uterine function and dysfunction in addition to the therapeutic modalities available when pathologies exist. The viscera contained within the female pelvis minor include the pelvic colon, urinary bladder and urethra, uterus, uterine tubes, ovaries, and vagina. As with the pictures illustrating the structures of the male pelvis, the topography of the female pelvis is demonstrated in two sections.
The pelvic colon is surrounded by peritoneum and attached by its
mesocolon to the medial border of the left psoas muscle and the sacrum, down to
the third sacral vertebra. Its greater part lies in a horizontal plane, though
it may occupy many positions, including the superior surface and posterior
aspect of the uterus. The rectum extends from the third sacral vertebra to just
beyond the tip of the coccyx. It is covered by peritoneum in front and at the
sides in its upper third and in front only in its middle third; its lower third
is devoid of peritoneum. During pregnancy, this close apposition between the
uterus and rectosigmoid often contributes to or worsens the impact of
constipation.
The ureter enters the true pelvis by crossing in front of the bifurcation
of the common iliac artery and descends to the pelvic floor on the lateral
pelvic wall. At the level of the ischial spine, it runs forward and medially,
beneath the broad ligament, between the uterine and vaginal arteries to the lateral
vaginal fornix. At this point it is approximately 2 cm lateral to the cervix, a
point of potential injury during hysterectomy. The ureter then ascends in front
of the vagina for a short distance to reach the base of the bladder, where it
opens into the lateral angle of the trigone by piercing the bladder wall
obliquely.
The urinary bladder lies behind the symphysis, in front of the uterus and
the vagina. Its base is in direct contact with the anterior vaginal wall. The
neck of the bladder lies on the superior surface of the urogenital diaphragm
and is continuous with the urethra. The superior surface is covered by
peritoneum and is in contact with the body and fundus of the anteflexed uterus.
It is this reflection that must be mobilized during the course of cesarean
delivery. The space of Retzius lies between the pubis and the bladder and is
filled with extraperitoneal adipose tissue.
The topographic relationships of the uterus are observed in the cross
sections as depicted on this page. The superior surface of the uterus is convex
and generally directed forward. The anterior surface is
flat and looks downward and forward, resting on the bladder. Its peritoneal
covering is reflected at the level of the isthmus to the upper aspect of the
bladder, creating the vesicouterine pouch. The posterior surface of the uterus
is convex and lies in relation to the pelvic colon and rectum. The peritoneum
of the posterior wall covers the body and upper cervix and then extends over
the posterior fornix of the vagina to the rectum, to form the rectouterine pouch or cul-de-sac of Douglas. Later- ally, the
visceral peritoneum becomes the anterior and posterior leaves of the broad
ligament.
The cervix is directed downward and backward to rest against the posterior vaginal wall. Only the upper half of its posterior surface is covered by peritoneum. The external os of the cervix lies at about the level of the upper border of the symphysis pubis in the plane of the ischial spine.
