Anatomy and pathogenesis
At 10cm dilation of the cervix, both CL and USL may be stretched or torn
because of pressure of the head as it enters the birth canal. In the
menopause, further ligament weakness may occur because of collagen break
down. CL prolapses down onto the lateral part of the cervix, fig3, and
the bladder rotates down like a trapdoor as a cystocele (transverse
defect), fig3.
The same 10cm cervical dilatation may overstretch the attachments of USL
to weaken and elongate them, fig 2, and separate them laterally to form
an enterocele.
It is evident from fig2, that the cardinal ligaments MUST elongate in
parallel with uterosacral ligament elongation. Therefore both CL and USL
must be repaired, and the fascial layer of vagina re-attached, fig3.