Abstract
The pelvic floor (Figure 8.1) plays an important role in providing bladder and bowel control, and assists in parturition by promoting the rotation of the foetal head. It also supports the pelvic viscera including the enlarged gravid uterus. It is weakened during pregnancy, childbirth and menopause. This can lead to:
1 The Pelvic Floor
The pelvic floor (Figure 8.1) plays an important role in providing bladder and bowel control, and assists in parturition by promoting the rotation of the fetal head. It also supports the pelvic viscera including the enlarged gravid uterus. It is weakened during pregnancy, childbirth and menopause. This can lead to:
anterior vaginal wall prolapse: cystocele and urethrocele
central prolapse: uterine prolapse and vaginal vault prolapse
posterior vaginal wall prolapse: rectocele and enterocele
Figure 8.1 The pelvic floor.
The pelvic floor is formed by two important muscles:
levator ani
coccygeus/ischiococcygeus
1.1 Clinical Significance
Levator ani contracts to occlude levator hiatus or urogenital hiatus. This action occludes the vaginal canal and prevents the prolapse of pelvic organs.
Constant baseline contraction of the levator ani holds the load of pelvic viscera.
The puborectalis creates the anorectal angle; thus maintaining anal continence and reinforcing the external anal sphincter.
Relaxation of the levator ani permits micturition and defecation.
During parturition, when the head reaches the pelvic floor, the levator ani contracts to rotate the fetal head. As a result, the fetal head entering the pelvic brim in the transverse axis rotates to the anteroposterior axis of the pelvic cavity. Next, the anterior fibres of the levator ani relax to enlarge the size of the urogenital hiatus and birth canal. After parturition, the levator ani recoils to acquire normal position.
Laceration of the perineal body results in pelvic floor weakness.
Kegel’s exercises should be advocated postpregnancy and postmenopause to strengthen the levator ani muscles.
2 Ureter
The ureter is 25–30 cm long and 3 mm in diameter, and runs through the retroperitoneal space. It shows three sites of constriction where a calculous may obstruct the lumen:
pelviureteric junction
brim of lesser pelvis
ureterovesical junction
2.1 Course of the Pelvic Ureter
Initially, the direction is posterolateral along the anterior border of the greater sciatic notch. At the level of the ischial spine, it turns anteromedially to reach the base of the urinary bladder. At this point, it lies in proximity to the uterine artery and passes under the cervical (Mackenrodt) ligament. This is where it is most vulnerable to injury. See Figure 8.2.
