A new technique for simultaneous urethrocystometry including measurements of the urethral pressure profile

Novel insight into pressurization of the male and female urethra through application of a multi-channel fibre-optic pressure transducer: Proof of concept and validation

Purpose

To confirm feasibility of recording pressure along the length of the urethra using a multi-sensor fibre-optic pressure catheter; to identify the spatial and temporal features of changes in pressure along the urethra at sites related to specific striated pelvic floor muscles; and to investigate the relationship between urethral pressures and activation of individual pelvic floor muscles estimated from ultrasound imaging.

Materials and Methods

Proof-of-concept study including one male (47 years old) and one female (33 years old). A multi-sensor fibre optic pressure catheter (10 mm sensor separation) was inserted into the urethra. Pressure data were recorded simultaneously with trans-perineal ultrasound imaging measures of pelvic floor muscle activity during sub-maximal and maximal voluntary contractions and evoked coughs.

Results

Pressure changes along the urethra were recorded in all tasks in both participants. Face validity of interpretation of pressure measures with respect to individual muscles was supported by correlation with ultrasound-measured displacements induced by the relevant muscles. Onset of pressure increase occurred in a distal to proximal sequence in the urethra of the male but not the female during voluntary contraction. Peak urethral pressures varied in location, timing and amplitude between tasks. Evoked cough induced in the greatest urethral pressure increase across all tasks for both participants.

Conclusions

The high spatial resolution pressure catheter provide viable and valid recordings of urethral pressure in a male and female. Data provide preliminary evidence of sex differences in spatial and temporal distribution of urethral pressure changes.

Submaximal pelvic floor muscle contractions: similar bladder-neck elevation, longer duration, less intra-abdominal pressure

INTRODUCTION AND HYPOTHESIS

An adequate pelvic floor muscle contraction (PFMC) elevates the bladder neck (BN) and stabilizes it during increased intra-abdominal pressure (IAP). A maximal PFMC may increase the IAP and thereby prevent BN elevation. The aim of this study was to assess BN elevation during submaximal and maximal PFMC and their achievable duration.

METHODS

We recruited 68 women with stress urinary incontinence and 14 vaginally nulliparous continent controls who were able to perform a PFMC on vaginal palpation. Women were upright and performed a maximal PFMC as long as possible, followed by a submaximal PFMC, controlled by vaginal electromyogram (EMG). BN position was measured with perineal ultrasound, IAP and urethral pressure with a microtip catheter, and breathing with a circular thorax sensor.

RESULTS

A submaximal PFMC elevated the bladder neck 4 mm in continent and incontinent women (p = 0.655) and 4.5 vs. 5 mm during maximal PFMC (0.528). Submaximal PFMC was maintained significantly longer than a maximal PFMC (33 vs 12 s) with no difference between groups. A maximal PFMC resulted in BN descent in 29% of continent and 28% of incontinent women, which was not observed during submaximal PFMC. Breathing was normal in 70% of continent and 71% of incontinent women during submaximal PFMC but stopped completely in 21 and 50%, respectively, during maximal PFMC (p = 0.011). IAP increase was significantly greater with maximal PFMC in both groups (24 vs. 9.6 cmH₂O and 17 vs. 9 cmH₂O, respectively).

CONCLUSION

Submaximal PFMC are sufficient to elevate the bladder neck, can be maintained longer, and breathing was not influenced.

Aspects of present and future possibilities for intraluminal pressure recordings in the urogenital tract

In this brief survey some aspects of present and future possibilities for intraluminal pressure recordings in the urogenital tract are considered. It is emphasized that present water-filled catheter-manometer systems are afflicted with several biotechnical disadvantages. Although the micro-transducers and centre-hole catheters seem to be superior to conventional pressure recording systems, they ought to be further improved. Feed-back pressure transducers, electronic compensation, and micro-manometers could be realistic alternatives for pressure recordings in the urogential tract in the future. Some results from pressure recordings obtained with different measuring systems are presented and discussed.

Decreased innervation of the paraurethral epithelium in stress urinary incontinent women

OBJECTIVE

To determine whether there is a difference in the innervation of the paraurethral vaginal epithelium between stress urinary incontinent women of fertile age and comparable controls.

METHODS

Transvaginal biopsies close to the external orifice of the urethra were obtained from 11 stress urinary incontinent women and from ten comparable controls. The specimens were processed for indirect immunohistochemistry using protein gene product 9.5 (PGP 9.5) as a general neuronal marker. From each biopsy, ten randomly selected fields of 1 mm2 projected area were investigated and nerve fibre profiles were quantificated in a microscope equipped with light- and dark-field optics.

RESULTS

Nerve fibre profiles/mm2 of projected epithelial area were significantly lower in the incontinent group than in the control group (P < 0.01).

CONCLUSION

Our study indicates that stress urinary incontinent women have a significantly lower total innervation of the paraurethral vaginal epithelium than continent controls.

Clinical outcome and changes in connective tissue metabolism after intravaginal slingplasty in stress incontinent women

The intravaginal slingplasty procedure (IVS) was carried out on 75 patients with genuine stress urinary incontinence. The main aims of the operation are to create an artificial pubourethral ligament and to tighten the suburethral vaginal wall. An important ingredient in the supportive structures of the genitourinary region is fibrous connective tissue, consisting mainly of collagen. To analyse this component biopsies were obtained transvaginally, close to the position of the sling, both preoperatively and 2 years after surgery, from 6 patients. Collagen was analysed for concentration and extractability. Extractability by pepsin digestion was increased by 60% 2 years following surgery. Postoperative follow-up studies from 12 months to 3 years showed complete restoration of continence in 63 patients (84%) and considerable improvement in 4 others (5%). The 8 failures (9%) were all related to early rejection of the sling. The IVS procedure is an attractive surgical procedure as it necessitates minimum invasion and can be performed under local anesthesia, with a short hospital stay and sick-leave period. The enhanced collagen extractability indicates a changed metabolism, most likely induced by the implanted sling, resulting in a restoration of the elastic properties of the connective tissue.

An ambulatory surgical procedure under local anesthesia for treatment of female urinary incontinence

The object was to study prospectively the results of a modified intravaginal slingplasty for the surgical treatment of female stress incontinence, carried out under local anesthesia as a day procedure. Seventy five patients with genuine stress incontinence were operated upon and followed for a 2-year period. All patients were diagnosed urodynamically to have genuine stress incontinence. Pad tests and quality of life assessments were carried out in all patients both pre- and postoperatively. There were no intra- or postoperative complications and 63 patients (84%) were completely cured throughout the 2-year follow-up period. Six patients (8%) were significantly improved, i.e. they did not loose urine apart from an occasional leakage during severe cold etc. In the remaining 6 patients (8%) no improvement was seen. These failures were obvious at the first postoperative check-up after 2 months. Thus, there were no relapses after 2 months. All but 5 patients were able to void properly directly after surgery. These 5 needed an indwelling catheter during the night directly after the operation. All 75 patients were released from the hospital the same day or the day after surgery without catheterization. Mean sick leave was 10 days and mean operation time 22 minutes. No defect healing or rejection of the sling occurred. It is concluded that the procedure described is a promising new technique for the surgical treatment of female stress incontinence. Prospective long-term studies including more patients are in progress to establish the definitive place of this technique in the clinical routine.

Cough transmission ratio: an indicator of suburethral vaginal wall tension rather than urethral closure?

The significance of cough transmission ratios (CTR) in 6 unoperated and 15 previously operated patients is discussed. It is concluded that CTR is an index of periurethral muscle contractile activity, and vaginal wall tension, rather than urethral closure.

Six-microtransducer catheter connected to computer in evaluation of urethral closure function of women

A new instrument consisting of a six-transducer catheter, one transducer for the bladder and five transducers for urethral pressure recordings, and a computer with specific software was developed for urodynamic investigation of women. Twenty-six patients with stress urinary incontinence (SUI) and 10 continent female patients were evaluated during the single cough, the first and the fourth ones of the forced coughings in supine and standing positions. The results were compared with those obtained with the conventional two-transducer method. Negative urethral closure pressure (UCP) at stress, indicative of SUI, was present in 88 percent of the cases with the six-transducer method, and in 77 percent with the two-transducer method. The fourth cough in the standing position with the six-transducer method was most diagnostic. In SUI, the six-transducer method indicated exactly, e.g., the minimum bladder pressure needed for negative UCP and the duration of negative UCP. Patients with SUI had significantly lower UCP at rest, UCP at stress, and pressure transmission ratio (PTR) than continent women. Findings, that UCP at stress decreased and duration of negative UCP at stress increased but PTR did not change when the fourth cough was compared with the first one in SUI, suggest that factors which are responsible for the altered urodynamics during prolonged stress are anatomic rather than functional.

Intravesical prostaglandin F2 for promoting bladder emptying after surgery for female stress incontinence

Prostaglandin F2 alpha 10 mg was administered intravesically in a double-blind placebo-controlled study to promote micturition in cases of urinary retention after operative treatment of urinary stress incontinence in women. Fifteen of 18 patients (83%) succeeded in voiding after treatment with prostaglandin F2 alpha, but the placebo was ineffective in all 18 patients (P less than 0.001). Although the effect of prostaglandin F2 alpha on bladder muscle contraction was short-lived, it seemed to enhance the restoration of bladder motor function with no serious side effects, and thus to be clinically useful in the treatment of post-operative urinary retention.

Urodynamic analysis of successful and failed incontinence surgery

Seventy-nine patients were investigated by simultaneous urethrocystometry before and, on average, 15 months after vaginal and/or suprapubic operations for stress urinary incontinence. Subjective and objective success rates were 78% and 60%, respectively, with no significant differences between operation types. Patients with a low (less than 0.6) index of urethral relaxation at stress preoperatively indicating excessive loss of basal urethral pressure at stress, had objective success rates of 39% whereas a higher index was associated with a success rate of 70%. Maximal urethral closure pressure and functional urethral length did not correlate with the operative result and were virtually unchanged postoperatively. Successful operations increased the index of urethral relaxation at stress and urethral pressure peaks at stress especially in the distal functional urethra. No significant quantitative differences except for sling operations producing higher urethral closure pressure at stress in the proximal and lower in the distal functional urethra compared to the other operations were found. The results indicate, that successful operations eliminate the failure to maintain adequate basal urethral pressure at stress and emphasizes the importance of reflex activity of pelvic floor musculature at stress for continence.

Results of various operations for urinary stress incontinence

Four hundred and eleven women with urinary incontinence were studied and treated over a 12-year period. The surgical procedures undertaken included 45 colporrahies with Kelly stitches, 12 interposition operations, 49 fascial slings, 49 Zoedler slings using Mersilene, 66 slings using dura, 136 retropubic colpourethrocystopexies, and 54 other operations. Retropubic operations, such as colpourethrocystopexy, should be considered the primary operation for stress incontinence, for if correctly executed, they give the best long-term cure rate (97%).

Comparative urodynamic studies of women with prolapse and stress incontinence before and after abdomino-vaginal sling urethro-plasty

The effect of abdomino-vaginal sling urethro-plasty according to lyodura slings on the intravesical and intraurethral pressure was evaluated in 25 women with prolapse and stress incontinence. The investigations including a gynecological examination, urine and simultaneous urethro-cystometry. Prior to the operation, all incontinent women had a negative urethral closure pressure at stress. After surgery all 25 patients reported continence, which was confirmed by positive urethral closure pressures. The urethral pressure at rest was significantly decreased in all patients 2 weeks after operation but returned to the same value 1 year after surgery as before surgery. The functional and the absolute urethral lengths increased minimally after the operation.

The unstable female urethra

Four hundred forty-seven patients with urinary incontinence were examined at the outpatient clinic and then referred to urodynamic investigation by urethral pressure profile measurement and simultaneous urethrocystometry. On urodynamic investigation, 55 patients showed signs of an unstable urethra (momentary variations in urethral pressure exceeding an amplitude of 15 cm of water by or without registration of bladder instability). Urethral instability was found in 15 patients with stress incontinence, in 23 patients with urge incontinence, and in 13 patients with combined stress and urge incontinence (i.e., signs and symptoms of both stress and urge incontinence). In four patients, urethral instability was the only pathologic finding when the recordings were made. From the pressure recordings, three types of urethral instability could be recognized: type 1, relatively small fluctuations in the urethral pressure at large bladder volumes; type 2, relatively large variations in urethral pressure with frequent decreases in the pressure, often combined with signs of unstable bladder; type 3, marked variations in the urethral pressure which appeared already at the start of urethrocystometry, i.e., at low bladder volumes. The variations in urethral pressure prevailed during the whole recording procedure, whereas bladder pressure was completely stable at all times.

Comparative urodynamic studies of continent and stress incontinent women in pregnancy and in the puerperium

Twelve pregnant women were examined by urethral pressure profile measurement and simultaneous urethrocystometry early in pregnancy (weeks 12 to 16), in the thirty-eighth week, and 5 to 7 days after delivery. All patients reported symptoms of stress incontinence starting at an early 5 to 7 days after delivery. All patients reported symptoms of stress incontinence starting at an early gestational age, it was found that that the stress incontinent women, compared to 14 continent, healthy women from whom measurements were obtained earlier, had shorter urethral lengths. Furthermore, no increase in urethral length during pregnancy was registered among the stress incontinent women, whereas such an increase did occur in the continent women. In contrast to the continent women, the incontinent patients had a low urethral closure pressure at rest and this pressure did not appear to increase sufficiently to compensate for the progressive increase in bladder pressure during pregnancy. As a result the urethral closure pressure in the stress incontinent women, therefore, decreased more and more during stress situations as pregnancy progressed, resulting in an increased leakage of urine.

New technical possibilities for simultaneous cystometry

With the introduction of integrated semiconductor pressure pick-ups into the urodynamic methodology of analysis, the bladder and urethral manometry has been optimized, since the measuring transducer is positioned directly inside the lumen of the bladder. In this way, it is possible to eliminate the errors of conventional measuring methods with the liquid-filled or gas-filled catheter system, for example movements, vibrations, hydrostatic influences on the coupling medium by different vertical positions of the catheter or connecting tube, as well as cloggings due to haematuria or secretion of mucus. Owing to its dimensions and radiopaque properties, the IBW 78 tip manometer is suitable also for the pressure measurement in the upper urinary passages including the pyelon. The pressure signals obtained are further processed in a special plug-in unit for the biomonitor system, and thus they can be recorded on any multiple recorder.

Urodynamic studies in normal pregnancy and in puerperium

Fourteen primiparas (11 pregnant for the first time, and three with a history of one abortion) were examined during pregnancy to elucidate changes in parameters of importance of maintenance of urinary continence. Urethral pressure profile measurements and simultaneous urethrocystometry were carried out in the beginning of pregnancy (weeks 12 to 16), in the thirty-eighth week, and 5 to 7 days after delivery. Both the absolute and functional lengths of the urethra were found to increase throughout pregnancy by median values of 6.7 and 4.8 mm, respectively. Also, the maximum urethral pressure increased gradually during pregnancy, returning within 1 week after delivery to almost the same value as at the beginning of pregnancy. The urethral closure pressure also increased throughout pregnancy. Thus, the results of the investigation revealed that the physiologic changes which took place within the urethra during pregnancy were to advantage from standpoint of maintaining continence.

Laboratory comparison of urethral profilometry techniques

A comparison of urethral pressure profiles performed with the air infusion, water infusion, membrane catheter, and transducer tip catheter techniques was made in a canine model. The gas and water infusion methods gave statistically identical results if the gas studies were performed at flow rates of 100 ml./min. and pull rates of 5 cm./min. The transducer tip catheter and the gas and water infusion techniques gave accurate recordings of peak urethral pressure but were incapable of detecting multiple areas of urethral compression. The transducer tip catheter measurements often were difficult to interpret because of rotation and flexion artifact. The membrane catheter was capable of recording multiple areas of urethral compression but gave spuriously high recordings of peak urethral pressure. We conclude that none of the methods tested will give accurate recordings of urethral pressure in all clinical situations.

Comparative study of air and water measurements of peak and stabilized static urethral pressures

Air and water were forced through female dogs' urethras to determine static urethral pressures. The cauda equina was sectioned to eliminate reflex responses to urethral manipulation, and the urethras were compressed circumferentially with inflatable Silastic cuffs. The peak and stabilized urethral pressures were recorded at flow rates between 20 and 150 ml./min. while cuff pressures were varied between 0 and 100 cm. of water. When the fluid recordings of static urethral pressure were compared with Millar transducer tip catheter measurements of urethral pressure, there were no statistically significant differences between the air cystometer, aneroid sphygmomanometer, and Millar catheter recordings of urethral pressure. At these high flow rates, the water recordings of urethral pressure were significantly higher than the Millar catheter determinations of static uretheral pressure.