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Figures in Case Report by Peter Petros(*) - Michael Swash(**)

(*) Royal Perth Hospital, University of Western Australia
(**) Dept of Neurology, The Royal London Hospital, London, UK

The Musculo-Elastic Theory of anorectal function and dysfunction


(Fig. 1)

Perineal incision

Figure 1. The Pictorial Diagnostic Algorithm summarizes the relationships between structural damage in the three zones and urinary and fecal symptoms. The size of the bar gives an approximate indication of the prevalence (probability) of the symptom. The same connective tissue structures in each zone (red lettering) may cause prolapse and abnormal symptoms. Anterior zone: External urethral meatus to bladder neck; Middle zone: bladder neck to cervix; Posterior zone: vaginal apex, posterior vaginal wall and perineal body. R = rectum; RVF = rectovaginal fascia; PB = perineal body; PRM = m. puborectalis; LP = m.levator plate; LMA = m. longitudinal muscle of the anus; PCM = m.pubococcygeus; PUL = pubourethral ligament; USL = uterosacral ligament.

 

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(Fig. 2)

 

repair of the rectovaginal fistula
Fig. 2. – Muscles and ligaments of the pelvic floor 3D schematic sagittal view, ano-rectum closed. Organs: B = bladder; R = rectum; V = vagina; U = uterus; Ligaments and fascia: pubourethral ligament (PUL); uterosacral ligament (USL); PB = perineal body; RVF = rectovaginal fascia; Cardinal ligament (not shown) attached to anterior part of cervical ring (CX). Muscles upper layer: PCM = anterior portion of m.puboccygeus; LP = levator plate; middle layer: LMA = longitudinal muscle of the anus; PRM = m. puborectalis; lower (anchoring) layer: EAS = external anal sphincter; PM = muscles of the perineal membrane.

 

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(Fig. 3)

 

repair of the rectovaginal fistula
Fig. 3. – The related dynamics of anorectal and bladder closure and opening, pathogenesis and surgery. Arrows denote directional muscle forces. ATFP = arcus tendineus fascia pelvis; CL = cardinal ligament; circular broken lines = pelvic brim; Anorectal closure. The rectovaginal fascia (RVF) inserts into perineal body (PB), levator plate (LP) and the uterosacral ligaments (USL). Contraction of LP stiffens RVF and both walls of rectum. Contraction of LMA (longitudinal muscle of the anus) against USL stretches the rectum around puborectalis muscle (PRM), to create the anorectal angle and closure. Defaecation. PRM relaxes. LMA/LP vectors open out the anorectal angle (broken lines); pubococcygeus (PCM) vector stiffens PB and anterior wall of anus; rectum (R) empties. Urethral/ bladder neck closure. The forward vector (PCM) closes urethra from behind; LP/LMA vectors rotate bladder around pubourethral ligaments (PUL) to close off bladder neck. Micturition. Forward vector (PCM) relaxes. Posterior vectors (LP/LMA) stretch open posterior urethral wall (broken lines). Bladder contracts. Pathogenesis. Damaged ligaments decrease the force of opening and closure vectors for urethra and anus. Surgery according to this theory. Reinforcement of damaged ligaments with implanted polypropylene tapes, Fig. 5.

 

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(Fig. 4)

 

repair of the rectovaginal fistula
Fig. 4. – Pathogenesis-role of vaginal connective tissue in bladder and anorectal dysfunction. The circles indicate the intimate relationship between the fascia and ligaments ensheathing bladder, vagina and anorectum; also, overdistension of ligaments and fascia by the fetal head. Red circles: attachment points of ligaments and fascia to vagina and bladder; blue circles, to vagina and rectum. The circles pictorially explain the relationship between birth, urinary and feces dysfunction. CL = cardinal ligament; PB = perineal body.

 

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(Fig. 5)

 

repair of the rectovaginal fistula
Fig. 5. – Surgical repair of damaged ligaments Polypropylene tapes ‘T’ (in this case with attached soft tissue anchors) may be used to reinforce the main suspensory ligaments, pubourethral (PUL), uterosacral (USL) cardinal (CL) and arcus tendineus fascia pelvis (ATFP).

 

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