Surgical anatomy of the mid-vagina.

aimThe mid-vagina (MV) represents Level II of the vagina. The surgical anatomy of the MV has not been recently subject to a comprehensive examination and description. MV surgery involving anterior and posterior colporrhaphy represents a key part of surgery for a majority of pelvic organ prolapse (POP).

methodsLiterature review and surgical observations of many aspects of the MV were performed including MV length and width; MV shape; immediate relationships; histological analysis; anterior and posterior MV prolapse assessment and anterior MV surgical aspects. Unpublished pre- and postoperative quantitative data on 300 women undergoing posterior vaginal compartment repairs are presented.

resultsThe MV runs from the lower limit of the vaginal vault (VV) to the hymen. Its length is a mean of 5 cm. Its shape in section overall is a compressed rectangle. Its longitudinal shape is created by its anterior and posterior walls being inverse trapezoid in shape. Histology comprises three layers: (i) mucosa; (ii) muscularis; (iii) adventitia. MV prolapse staging uses pelvic organ prolapse quantification (POP-Q). Anterior MV prolapse can be quantitatively assessed using POP-Q while posterior MV prolapse can be assessed with POP-Q or PR-Q. Around 50% of both cystocele and rectocele are due to VV defects. POP will increase anterior MV width and length. Native tissue anterior colporrhaphy is the current conventional repair with mesh disadvantages outweighing advantages. Posteriorly, Level II (MV) defects are far smaller (mean 1.3 cm) than Level I (mean 6.0 cm) and Level III (mean 2.9 cm).

conclusionAn understanding of the surgical anatomy of the MV can assist anterior and posterior colporrhaphy. In particular, if VV support is employed, the Level II component of a posterior repair should be relatively small.