Changes in urethral resistance after surgery for stress urinary incontinence

URODYNAMICS

CHANGES

IN URETHRAL

SURGERY

FOR STRESS URINARY

NARENDER ARIEH MICKEY

N. BHATIA,

BERGMAN, KARRAM,

RESISTANCE

AFTER

INCONTINENCE

M.D.

M.D. M.D.

From the Division of Gynecologic Urology, Department of Obstetrics and Gynecolog); Harbor-UCLA Medical Center and Cedars Sinai Medical Center, University of California School of Medicine, Los Angeles, California

ABSTRACT-SScwnty u>OlnCll with stress urinary incontinence underwent simultaneous voidinglrrc~throcystolnctry using microtip transducers and an a-channel recorder, before and three to twelve months after either the modified Burch (48/70) or the modified Pcreyra (22170) retropubic urethropexy. Increase in urethral resistance (p < 0.005) was more marked following the Pereyra procedure (0.042 f 0.039 to 0.07 f 0.061) and 30 percent experienced postoperative voiding difficulties, compared with the Burch procedure (0.035 f 0.029 to 0.055 f 0.03) where 20 percent experienced postoperative voiding difficulties. Of those patients who voided without a detrusor developed to contraction prior to surgery (35/70). in 50 percent a detrusor contraction component their voiding mechanism postoperatively (p < 0.05) and overcame the increased urethral resistance with no postoperative voiding difficulties. In the remaining 50 percent a detrusor contraction failed to develop during postoperative voiding and 90 percent of them demonstrated reduced flow rates and increased use of Valsalva maneuver, and needed prolonged postoperative bladder drainage prior to resumption of spontaneous voiding (p < 0.005). Inability to develop a detrusor contraction during voiding in face of increased urethral resistance promoted by the incontinence surgery provided a suitable explanation for post surgery voiding difficulties in 20 to 30 percent o_f patients.

Determination of outflow urethral resistance to voiding requires simultaneous measurement of detrusor pressure and the peak urinary flow rate. Inability to resume spontaneous voiding and/or a need for prolonged postoperative bladder drainage after surgery for stress urinary incontinence often results from alterations in urethral resistance. I.? Recently, it has been shown that 50 percent of patients with stress urinary, incontinence void effectively with good uroflow and minimal residual urine in the absence of a detrusor contraction.” Reduced uroflow observed in these patients after incontinence surgery represents either bladder hypotonicity or varying degrees of increased urethral resistances4 fi The present study vvas undertaken to evaluate clinically and urodynamically the mecha-

200

nism by which two different surgical procedures for urinary stress incontinence affect urethral resistance and voiding following surgery. Material

and Methods

In a group of 70 female patients with stress urinary incontinence, the mean age was fiftyseven (range 27-76 years), and the mean parity was 3 (range 1-9). Thirty-two were premenopausal (mean age 41), and 38 were postmenopausal (mean age 60). Thirteen patients had hda previous surgery for stress urinary incontinence (8 patients had anterior colporrhaphy and 5 had previous retropubic urethropexy). Diagnosis of stress urinary incontinence was established based on history and physical

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VOLUME

XXXIV,

NUMBER

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examination, negative urine cultures, urethrocystoscopy, provocative urethrocystometry, urethral pressure profiles at rest and under stress, and voiding simultaneous urethrocystometr!: Voiding patterns were determined by recording changes in urethral, bladder, and abdominal pressures during voiding. Only those patients w.ho were able to void, around the catheter, were included in this stud\: Patients \\.ith bladder instability or an\. other urologic pathologic condition except genuine stress urinarj. incontinence were not included in this studv. . Tilis stud!. group represented 70 of 105 successil’c patients evaluated and operated on for stress urinary incontinence. Thirty-five patients either were lost to follow-up or were unable to \roid around the catheter. UrodJrnamic evaluation was performed using t\vo small semiflexible Millar catheters (PC380. and PC-Xl). \\?th microtip sensitive pressure transducers. An 8F catheter kvhich contained a single transducer was used to record the abdominal pressure (approximated from an intrarectal recording). A second catheter with t\vo pressure microtransducers, 6 cm apart, was used for simllltaneous vesical and urethral pressllre recording. All pressures were recorded on an S-channel electrophysiologic recorder (Beckman Instruments. Inc., Model R-612). T\+,ent\.-t\nro of the i0 patients under\vent a modified Pereyra procedure” which was usuall!. chosen when an additional gynecologic indication existed for vaginal surgery (12 had vaginal hysterectomy). Fortv-eight patients underwent the Tanagho7 modif&ation of the Burch retroptlbic llrethropex\. kvhich was chosen \\rhen no significant pelvic relaxation was present or \\.hen a g!-necologic indication for laparotom!. w.as present (25 had abdominal hysterectomy). Following surgery, a Stameyx suprapubic catheter ~.as left in the bladder for continuous drainage.” On postoperative day 3, the catheter 11.a~ clamped. and the patient was allowed to \.oicl spontaneously with a full bladder and immediately thereafter residual urine volume was checked through the suprapubic catheter. The catheter \vas removed if postvoid residual volumes \\‘ere less than 50 mL on two consecutive occasions. Patients \frho were unable to \,oid or had large postvoid residuals (250 mL) were discharged to home with their suprapubic catheter on their seventh postoperative da> \vith instructions to measure and record post-

void residual volumes. Patients kvere followed up in the outpatient clinic, and their catheter was removed when residual urine volumes were 150 mL on two consecutive occasions. All patients underwent clinical and urod!rnamic evaluation preoperatively and three-to-twelve months postoperatively. A group of 11 patients with genuine stress urinary incontinence who were oonlparable for age, parit): and menopausal status, but tither refused to have the operation or \vCrt’ poor surgical risks, were used as a control group. The!. had clinical and urodynamic evaluations on initial presentation and one year later. In that period of time except for “timed voiding instructions,““’ the\, did not have an\’ other treatment. Urethrai resistance w,& calculated as described by Susset, Brissot, and Regnier” as UR = P/F2 where P = vesical pressure on voiding (cm/water), and F = maximal flow rate during uroflowmetry (mL/sec) .I:! If the patient voided without any demonstrable increase in detrusor pressure, she was considered to have a vesical pressure of one on voiding. Postoperative catheterization was considered prolonged if by postoperative day 7 the patient could not resume spontaneous voiding or had residual urine volumes of 250 mL. These are the patients who were discharged from the hospital with suprapubic catheters in place. Postvoid residual urine volumes of 250 mL were considered abnormal based on mean postvoid residuals determined on preoperative evaluation.” Normal peak flow rate Leas defined as 220 and uroflowmetry \vas repeated if mL/sec, < 200 m1, of urine Lvere 1.oided.l” ” All other terminolo&q. conforms to that proposed b!r the International Continence Society except \I-here specifically mentioned. The Student t test for paired data was used for statistilral analysis of the results. Results Success rate as defined b!v clinical and urodJ.namic means was achieved in 95.8 percent (46148) of patients following modified Burch retropubic urethropexy, and in 86.3 percent (19122) of patients following the modified Pere\.ra procedure. Cure was defined as absence of any \Jisible loss of urine during testing, with no pressure equalization between the bladder and the urethra during cough pressure profiles. Roth surgical procedures for stress urinary incontinence increased significantl;,, (p < 0.005)

Before Surger)

Procedure hlodified I’creyra (n = 22) (Mean t S.D.) hlodified Burch (N = 48) (Mean t S.D.) Control group (N = 11) (Mean f 50) h;b:\‘: h = IIUIIIIXYof

ptic~nh.

S.1).

0.042

+ 0.039

0.073

f

0.(x35

k 0.029

0.055

* 0.03

0.039

k 0.023

=

\tantlarcl

deviation.

Before Surgeqr

Procedure (cm H,O) Modified Pere!m (n = 22) (Mean 2 S.D.) Modified Rurch (N = 48) (hlean + S.D.) Control group (N = 11) (Mean + S.D.)

24 f

‘S.S.

202

= IIOhtati\tical

\ignlficancc.

p

9.S

1’ < 0.005

* 0.03 =

\ig:nificancc

N.S. I>!

~)urcd

t tr\t.

Statistical

After

:33 k !I. 1

Significance* p < 0.01

21.7

k

11.9

29.4

t

12.:3

p < 0.01

“3.6

f

10.2

23.7

+

11.1

N.S.

All 39 patients who voided preoperati\relJ, with good bladder contraction (2 15 cm/H20) maintained a good bladder contraction postoperatively; none required prolonged postoperati\re catheterization. Five of the 11 patients in the control group voided without a bladder contraction and continued to do so at the time of repeat urodynamic evaluation one year later. The other 6 patients in the control group voided with good bladder contraction at both urodynamic evaluations. Maximum flow rates and other values obtained at the time of uroflowmetry preoperatively, did not change significantly \\,hen these tests were repeated postoperati\rel>: Also,

Before Surger!.

Xlodified Pereyra (N = 22) (hlean + S.D.) ;2lodifiecl Burch (N = 48) (Mean f S.D.) Control group (n = 11) (hlean k S.D.)

0.041 and

1’ < o.ooFj

0.061

Surger!.

the urethral resistance (Table I). There \vas no change in urethral resistance in the control group (Table II). Thirt),-one Lvomen in this series voided preoperativel!. kvithout a bladder contraction. Fifteen of them (48% ) regained a good bladder contraction (2 15 cm/H20) on voiding follo\ving surgery, and none required prolonged postoperati\re catheterization. Sixteen patients voided preoperatively without a good bladder contraction (< 15 cmiivater) and did not regain one after surgery. Of these 16, 11 (87.3%) required prolonged ( > 7 days) post0peratiL.e catheterization. Of these 14 patients, 8 had a Burch procedure and 6 had a modified PereJrra procedure.

Procedure (mL/sw)

Statistical Si,qnificance

After Surger!.

“3.4

+ 5

23.2

* 3.7

2ij.6

+ 6.1

II)- ~)aircd

t tmt.

After Surger!22.6

Statistical Significance*

+ 3.7

N.S.

22 + 3.3

N.S.

23.2

+ 3.2

N.S.

there \vas no change in any of these \.alues in the control group (Table III). Comment The effect of incontinence surgery on urethro\,esical dynamics is debatable. Numer011s in\.estigators ha1.e demonstrated minimal”’ or no change” Ih in urethral functional length and closure pressure, and/or the achievement of increased abdominal pressure transmission to the proximal urethra’” following surgerjx. The basic l)athopli~siolog~. of stress urinar!. incontinence is reduced urethral resistance to bladder pressure. \\,hen intra-abdominal pressure increases. ’‘I 2’‘I Slqerv that cures stress incontinence is sllpposeh tA alter this patholog\.. The rcslllts ot this series clearl!. demonstrate a significant inc*rclasct in urethral resistance achie\.ed I)!surger!.. This x4es. as \\.ell as others.:’ 22“” demonstrates tlrat stlrger\- in the \rast majorit!. of cases docls not rcasult in lkg-term lroiding difficulties. IJroflo\\.metr\. stlldies performed a fex\. months aftc’r surqer!. ho not seem to be significantl!. different from preopc’rati,re tests:’ ‘4 as \\‘ab tllcb case in this stxric> (Table III). f lilt011 and Stanton” 2:’made thus obsc,r\,atiorl that fortunatel>. in w.omt’n w.itli stress urinar! inc*ontincancc nornlal \Toiding mechanisms de\,cstop l)ostol’erati\,el~. \frith normal dctrusor contract1on.s. but no e\-idence or ex_planatioIl K;~S gix,en to support this clinical obser\.ation. Ollr results I)ro\.c this obser\ration to txh true. Cignificant incrcasc in bladder contraction prc’ss”rc drlring voiding \\.as noted after surger!’ in almost FjO percent (Table, II ). F’rlrthermorc. of \Z~OIII~II n.hc) preoperati\rel\. \roided xvithout a hladdcr cbontraction. an effecti\.e bladder contraction (, 2 13 cm. \\.ater) delreloped following .

‘~I~of.o(;~

(K:‘I’oI1E:l~

IWJ

\‘OI.IJ\lE;

SXSl\:

NUSlHE:.R

1

203

Slate GE (Ed): Disorders of the Female Urethra and Urinary Incontinence. Baltimore. \Villiams and Wilkins, 1982, pp 25-40. 16. Bhatia NN, and Ostergard DR: Urodvnamic effect of retropubic urethropexy in genuine stress incnnt&nce, Am J Obstet G~necol 140: 936 (1981). 17. Bergman A, and McCarthy TA: Urodvnamic changes after successful operation for stress urinary inc&inence, Am J Obstet Cywxol 147: 325 (1983). 18. Henriksson I,. and Ulmsten U: A urodynamic evaluation of the effect of abdominal llrethroc).stopex~ and vaginal sling urethroplasty in women with stress incontinenw. Am J Ohstet (:ynccol 131: 77 (1978). 19. Hilton P. and Stanton SL: A clinical and urndynamic aswssment of the Burch colposuspcnsion for genuine stress incontinence. Br J Ohstet Cynecol 90: 934 (1983). 20. Tanagho EA: Urndynamics of female urinary incontinence

204

with emphasis on stress incontinence, J Urol 122: 200 (1979). 21. Sussct J, and Plantc I’: Studies of female urethral pressure profile. Part II. Urethral prcssurc profile in female incontinence. J Urol 123: 70 (1980). 22. Stanton SL. and Cardozo LD: Results of the colposuspcnsion operation for incontinence and prolapse, Br J Ohstct Cyn~ol 86: 693 (1979). 23. Mundy AR: A trial comparing the Stanley bladder neck suspension procedure with colposqxnsion for the treatment of stress incontinence, Br J Urn1 55: 687 (198.3). 24. Stanton SI,, Cardozo L. and Choudhury S: Spntaneou voiding after surgery for urinary incontinence. Br J Obstrt C!.necol 85: 149 (1978). 25. Stanton SL. Ozsoy D, and Hilton P: Voiding difficlllties in the female: prevalence, clinical and urodynamic revie\v, Ohstct Cynecol 61: 144 (1983).

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1989

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