Pressure transmission theory-The Rasputin of incontinence

Abstract

Background: Enhorning's pressure transmission theory (PTT), though mortally wounded by multiple invalidations from the 1990 Integral Theory of female urinary incontinence (IT), like Rasputin, continues to survive as a theory for continence and incontinence.

Aim: To examine the questions: How has the PTT survived? What is its contribution to knowledge?

Methods: Eleven different invalidations are presented based on images, pressure readings, clinical examples, experiments by the author, and others, for example, flow mechanics, finite element models, and surgical operations.

Results: Each of the 11 invalidations prima facie invalidate the PTTs of enhorning and others.

Conclusions: "How has the PTT survived?" Having provided a plausible explanation for all abdominal stress urinary incontinence operations since 100 years, PTT, unsurprisingly, like climate change today, had become an entrenched convention which abdicated the need for midurethral sling (MUS) surgeons to learn the very different functional surgical anatomy underlying the MUS. "Has the PTT progressed knowledge, or retarded it?" This lack of knowledge by the surgeons of how and why the MUS works could be held responsible for the large number of major complications reported by the TVT: including, transected urethras, obturator nerve damage, perforation of external iliac vessels, more than 20 deaths. The role of the sling is to strengthen the pubourethral neoligament to prevent the urethra opening out under stress, not to elevate it. Elevating the sling remains the major cause of the most frequent complication of the MUS today, postoperative urinary retention.

Keywords: Integral Theory; Pressure Transmission Theory; SUI pathogenesis; midurethral sling; pubourethral ligament.

Figure 1

Xrays from the prototype midurethral sling (1990). Left side all xrays at rest. Right side, all rays straining. Upper level = preop; middle level = sling in place (dotted lines); Bottom level = after sling removed, patient continent after the surgery.

Figure 2

Abdominal ultrasound in a continent woman. Left: at rest. E, insertion of external urethral meatus, (external urethral ligament); H, hammock; PS, pubic symphysis; U, urethra. Right: straining. the arrows demonstrate how the urethral cavity (U) is closed by muscle forces acting on the attached vaginal wall from behind (arrows). “E” denotes the attachment of the external urethral meatus to pubic symphysis (PS). From Petros and Ulmsten

Figure 3

The bladder neck is not actually elevated by the tape. The tape (right side black dots) anchors the posterior urethral wall to prevent it being pulled open by stress (see Figure 5)

Figure 4

Still photo of Video 2 at rest. A, anterior vaginal wall; P, posterior vaginal wall; PUL, pubourethral ligament inserting into midurethra; R, rectum

Figure 5

Schematic view and ultrasound of defective urethral closure mechanisms, woman with SUI. SUI, stress urinary incontinence. (Upper figure) Bladder smooth muscle continues as the longitudinal smooth muscle layer of urethra. Pubourethral ligament (PUL) attaches to midurethra and also, vagina [12].  “L” signifies elongation of PUL because of structural weakness (collagen deficiency). A weak PUL cannot hold the vagina (broken lines) and allows the posterior muscle vectors (arrows), LP (levator plate) and LMA (conjoint longitudinal muscle of the anus)  to pull down vagina,  so the urethra goes from “C” closed, to “O” “open.” Pubovesical ligament (PVL) inserts into Arc of Gilvernet (arc) on anterior wall of bladder which holds the anterior urethra and “arc” firm  during action by LP/LMA. The hemostat supports PUL, prevents extension to “L,” prevents urethral opening by LP/LMA and therefore, SUI. (Lower figure) A woman with SUI Transperineal ultrasound corresponds to the upper figure. REST: a&p, anterior and posterior vaginal walls; B, bladder; S, symphysis; U, urethra; white lines directly below “S” outline the distal urethra; red spots outline  PUL; blue ovoid “G” shows arc of Gilvernet. STRAIN: “a” and “p” are tensioned backwards and downwards, opening out bladder neck and distal urethra; PUL lengthens to four dots. There is no indentation of the superior wall of bladder. MID/UR ANCHOR A hemostat (white arrow) applied immediately behind the symphysis at the origin of PUL as in Video 1, prevents urine loss on effort and restores closure at bladder neck and distally