Surgical anatomy of the mid-vagina

Abstract

Aim: The 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).

Methods: Literature 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 Unpublished pre- and postoperative quantitative data on 300 women undergoing posterior vaginal compartment repairs are presented.

Results: The 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).

Conclusion: An 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.

Keywords: mid-vagina; surgical anatomy.

Figure 1

The mid‐vagina is Level II of the vagina ¹

Figure 2

Compressed rectangular shape of the mid‐vagina with trapezoid shape for the anterior and posterior vaginal walls: (i) supero‐inferior length a mean 5 cm; (ii) superior width (adjacent to Level I—VV) is around 4.5 cm; (iii) inferior width (adjacent to the hymen and Level III) is around 3.5cm. Hymen is not included in the figure

Figure 3

Inverse trapezoid

Figure 4

Axial view of the pelvis (Visible Human Project, National Library of Medicine, NLM. USA—with permission)

Figure 5

Sagittal view of the pelvis (Visible Human Project, National Library of Medicine, NLM. USA—with permission)

Figure 6

Coronal view of the pelvis (Visible Human Project, National Library of Medicine, NLM. USA—with permission)

Figure 7

Vaginal histology: “HistologyGuide. com. T. Clark Brelje and Robert L. Sorenson, University of Minnesota, Minneapolis, MN” (with permission from Dr Brelje)

Figure 8

POP‐Q staging of mid‐vaginal prolapse

Figure 9

(A) (Left) cystocele seemingly without major uterine or vaginal vault descent; (B) (Far right) cystocele largely related to vaginal vault descent (NB cuff scar),

Figure 10

POP‐Q Schema: (Anteriorly) Points Aa and Ba as well as Point C are relevant to anterior mid‐vaginal prolapse; (Posteriorly) Points Ap and Bp as well as Point C are relevant to posterior mid‐vaginal prolapse

Figure 11

(A) (Left ¹ ) Rectocele seemingly without major uterine or vaginal vault descent; (B) (Right middle ² ) Rectocele largely related to vaginal vault descent (NB: cuff scar)

Figure 12

(A) (Left), , : Mid‐vaginal laxity (vaginal vault undisplaced), (B) (right), , : Recto‐vaginal fascial laxity