Page 155 - Clinical Anatomy

ECA2 7/18/06 6:43 PM Page 140

140 The abdomen and pelvis

internal os with the cervical canal which, in turn, opens into the vagina by
the external os.
The nulliparous external os is circular but after childbirth it becomes a
transverse slit with an anterior and a posterior lip.
The non-pregnant cervix has the firm consistency of the nose; the preg-
nant cervix has the soft consistency of the lips.
In fetal life the cervix is considerably larger than the body; in childhood
(the infantile uterus) the cervix is still twice the size of the body but, during
puberty, the uterus enlarges to its adult size and proportions by relative
overgrowth of the body. The adult uterus is bent forward on itself at about
the level of the internal os to form an angle of 170°; this is termed anteflexion
of the uterus. Moreover, the axis of the cervix forms an angle of 90° with the
axis of the vagina—anteversion of the uterus. The uterus thus lies in an almost
horizontal plane.
In retroversion of the uterus, the axis of the cervix is directed upwards and
backwards. Normally on vaginal examination the lowermost part of the
cervix to be felt is its anterior lip; in retroversion either the os or the poste-
rior lip becomes the presenting part.
In retroflexion the axis of the body of the uterus passes upwards and
backwards in relation to the axis of the cervix.
Frequently these two conditions co-exist. They may be mobile and
symptomless—as a result of distension of the bladder or purely as a devel-
opment anomaly. Indeed, mobile retroversion is found in a quarter of the
female population and may be regarded as a normal variant. Less com-
monly, they are fixed, the result of adhesions, previous pelvic infection,
endometriosis or the pressure of a tumour in front of the uterus (Fig. 103).

Relations
•◊◊Anteriorly—the body is related to the uterovesical pouch of peritoneum
and lies either on the superior surface of the bladder or on coils of intestine.
The supravaginal cervix is related directly to bladder, separated only by
connective tissue. The infravaginal cervix has the anterior fornix immedi-
ately in front of it.
•◊◊Posteriorly—lies the pouch of Douglas, with coils of intestine within it.
•◊◊Laterally—the broad ligament and its contents (see below); the ureter lies
12mm lateral to the supravaginal cervix.

Clinical features

The most important single practical relationship in this region is that of the
ureter to the supravaginal cervix. At this point, the ureter lies just above the
level of the lateral fornix, below the uterine vessels as these pass across
within the broad ligament (Fig. 104). In performing a hysterectomy, the
ureter may be accidentally divided in clamping the uterine vessels, espe-
cially when the pelvic anatomy has been distorted by a previous operation,
a mass of fibroids, infection or malignant infiltration.