Sphincter Volume Research Articles

Racial differences in female urethral morphology and levator hiatal dimensions: An ultrasound study

To compare the urethral sphincter morphology and levator hiatal dimensions between white and black premenopausal nulliparous asymptomatic women using 3D/4D translabial ultrasonography. Nulliparous black and white women were recruited in a tertiary gynecological center. All women were completely asymptomatic for pelvic floor dysfunction. Women were assessed with 3D/4D translabial ultrasound scan of the pelvic floor, at rest. Measurements of the total urethral sphincter volume (TSV), rhabdosphincter volume, (RSV) and levator hiatal dimensions (LH) were taken at rest, after voiding. Twenty-three white and 14 black women (37 in total) were investigated. Subjects did not differ by age or body mass index (BMI). Black women were found to have significantly larger rhabdosphincters (RS) than their white counterparts (8.88 cm(3) ± 1.65 vs. 5.97 cm(3) ± 1.82, respectively, P = 0.000). With respect to levator hiatal dimensions at rest, black women had a significantly wider transverse diameter (LHt) than white women (mean difference of LHt = 0.43 cm, 95% CI 0.08-0.78, P < 0.05). Asymptomatic black nulliparous women have significantly larger rhabdosphincters than their white counterparts. Racial differences in the female urethral morphology could provide an insight on the pathophysiology of stress urinary incontinence.

The effect of solifenacin on urethral sphincter morphology

The aim of the study was to determine whether a 6-week course of 5 mg of solifenacin succinate used to treat mixed incontinence, produces measurable changes in the appearance of the urethral sphincter. Twenty-six women undergoing treatment for mixed incontinence were recruited from a urogynaecology unit after failing to improve with conservative treatments and bladder drill. All underwent dual channel subtracted cystometry, which showed mixed urodynamic stress incontinence and detrusor overactivity. All patients underwent a 3D transperineal ultrasound before solifenacin therapy was started and after 6 weeks of treatment. The urethral length, width and volume of the smooth muscle and total sphincter volume were compared before and after the treatment. Clinically, 13 reported no improvement in either stress or urge incontinence. Eight women reported improvement in their urgency symptoms but no benefit in their stress leakage. Four women reported resolution of both stress and urge incontinence. One woman reported worsening of her bladder symptoms. There was no significant change in the urethral length (p = 0.27), width (p = 0.50), volume of smooth muscle (p = 0.87) or total sphincter volume (p = 0.60) before and after treatment with solifenacin. A 6-week course of solifenacin resulted in no measurable changes in the appearance of the urethral sphincter.

Le désordre primaire de la relaxation sphinctérienne ou syndrome de Fowler

The primary disorder of sphincter relaxation or Fowler's syndrome constitutes the first cause of urinary retention in young women after ruling neurological, iatrogenic and local origins out. It includes painless urinary retention, polycystic ovaries in more than 50% of the cases, high maximum urethral closure pressure, increase in sphincter volume and striated urethral sphincter electromyography abnormalities. So far, the only treatment restoring micturation in this condition is sacral neuromodulation.

Three‐dimensional ultrasound of the urethral sphincter predicts continence surgery outcome

To assess the predictive value of three-dimensional (3D) ultrasound volumes of the urethral sphincter in women undergoing continence surgery. Women with urodynamic stress incontinence undergoing to Burch colposuspension were prospectively studied using videocystourethrography (VCU), urethral pressure profilometry (UPP) and a 3D transvaginal ultrasound scan of the urethra. The total urethral sphincter volume, urethral volume, maximum cross sectional area, and rhabdosphincter volume were calculated, preoperatively. Surgical outcome was assessed at 6 months using VCU. Urethral function parameters were correlated to surgical outcomes using the Mann-Whitney U-test. Ninety-one women were studied. Women who failed continence surgery had significantly smaller preoperative urethral sphincter volumes than those who had an objective cure (P < 0.001). UPP parameters were not found to be predictive of surgical outcome (P = 0.5). The assessment of the urethral sphincter using a 3D ultrasound scan predicts the outcome of continence surgery.

Three‐dimensional endoanal ultrasound assessment of the anal sphincters: Reproducibility

Volume measurement of the anal sphincter can be a future method for assessing volume loss, muscle atrophy or laceration. Three-dimensional (3D) endoanal ultrasound is a technique for assessing the volume of the anal sphincters, but the reproducibility of the method is scarcely known. Cross-sectional, repeated measurements. Twenty women were recruited for the study after written consent according to an ethically approved protocol, nine 0-gravida and 11 with traumatic vaginal deliveries. Endoanal 3D-ultrasound volume was obtained during rest and squeeze. The length of the anal canal and the volume of the external and internal sphincters were determined by two observers. Observer 1 repeated the measurements three times for all 20 women, and observer 2 for the nine 0-gravida, and intra- and inter-observer variation was assessed. During rest, the anal length measurement had intra-class correlation coefficients of 0.91 for observer 1 and 0.85 for observer 2. The limits of agreement for inter-observer measurement were (-0.81 to 1.61) measured in centimeters. For the external anal sphincter volume, the intra-class correlation coefficients and the limits of agreement were correspondingly: 0.89, 0.78 and (-7.29 to 6.03) measured in cm(3), and for the internal anal sphincter volume: 0.85, 0.69 and (-1.72 to 2.95). The variation in identifying the external anal sphincter could rise to a corresponding 30% error in volume measurement. Although intra-class correlation coefficients showed good reproducibility for endoanal ultrasound measurements, the limits of agreement were less reassuring with sizeable variation in the volume assessment, probably due to uncertainty in landmark identification.

Perineal Ultrasound Evaluation of Dysfunctional Voiding in Women With Recurrent Urinary Tract Infections

We used urodynamics and perineal ultrasound to assess the function and morphology of the urethral sphincter and detrusor muscle in the evaluation of dysfunctional voiding in female patients with recurrent urinary tract infections. Patients selected for study purposes completed the American Urological Association Symptom Index and underwent multichannel video urodynamics and perineal ultrasound to evaluate urethral sphincter volume and detrusor thickness. Of the 337 patients referred to our institution for recurrent urinary tract infections 166 were finally evaluated, including group 1-65 women with recurrent urinary tract infections and dysfunctional voiding, group 2-77 with recurrent urinary tract infections without dysfunctional voiding and group 3-24 healthy controls. Storage and emptying symptoms were recorded in 87.6% and 84.6% of group 1 patients, respectively. Opening and maximum flow detrusor pressure significantly correlated with urethral sphincter volume, and mean and maximum urethral closure pressure and detrusor thickness correlated with urethral sphincter volume. Dysfunctional voiding could be diagnosed by ultrasound when an increase in detrusor thickness and striated sphincter volume were observed. A threshold sphincter volume of 1.96 cm3 had 100% sensitivity and 63.2% specificity, and a threshold detrusor thickness of 4.95 mm had 100% sensitivity and 85.4% specificity for identifying patients with dysfunctional voiding. We think that perineal ultrasound is useful in the evaluation of dysfunctional voiding in women with recurrent urinary tract infections.

The effect of mode of delivery on pelvic floor functional anatomy

The objective of this study is to investigate and compare the effects of different modes of delivery on urethral sphincter volume, bladder neck mobility, and changes to levator hiatus distensibility using ultrasound imaging. This study is a prospective observational cohort study. The setting of this study is at a London teaching hospital. The population is composed of 156 women recruited in their first ongoing pregnancy. Primigravid women were recruited between 32 weeks and term. Antenatal ultrasound measurements of levator hiatus and bladder neck mobility were assessed at rest, maximum strain, and maximum valsalva using transvaginal ultrasound imaging. Urethral sphincter volume was calculated using a three-dimensional transvaginal probe. The investigations were repeated at 6 weeks and at 6 months postpartum. Total urethral sphincter volume, rhabdosphincter volume, bladder neck position at rest, and rotational mobility from maximum contraction to maximum valsalva were measured in this study. Levator hiatus area at rest and levator hiatus on valsalva and squeeze were also measured. The 156 women underwent antenatal ultrasound pelvic floor assessment. One hundred ten (71%) completed the 6-month follow-up. There were no differences in the urethral sphincter volume between the different modes of delivery. Overall, the urethral sphincter was smaller after delivery compared to the third trimester. Vaginal delivery was associated with a significantly larger levator hiatus area on valsalva antenatally and at rest, squeeze, and valsalva postnatally compared to caesarean section. Antenatal and postpartum bladder neck mobility was also significantly greater in the women who delivered vaginally. Urethral sphincter changes postpartum are independent of mode of delivery. Vaginal delivery is strongly associated with a larger, more distensible levator hiatus and a greater degree of bladder neck mobility both antenatally and postpartum.

Impaired anal sphincter function in professional cyclists

The purpose of our study was to assess anal function in professional mountain bikers, as an increasing number of cycling enthusiasts report functional and morphological problems in the anal region. We tried to find out if constant saddle vibration suffered by professional cyclists could lead to defecation disorders. 19 professional male mountain bikers took part in this study. The findings were compared with those of a control group (CG) of healthy volunteers who rode bikes less frequently. Both groups underwent rectal examination and anorectal manometry. Rectal sensation, rectal compliance and the anorectal inhibitory reflex were also assessed. Information on anal pain, blood on the toilet tissue, history of hemorrhoids, anal fissure, abscess formation and problems with defecation was collected by questionnaire and local examination was carried out. Sphincter resting pressures (89 +/- 27 mmHg vs CG: 69 +/- 16 mmHg), squeeze pressures (137 +/- 36 mmHg vs CG: 96 +/- 19 mmHg) and sphincter volumes (resting vector volume: 513 +/- 277 cc vs CG 273 +/- 170 cc, squeeze vector volume: 1389 +/- 867 cc vs CG: 490 +/- 219 cc) were significantly higher in the professional mountain bikers. Values reflecting rectal sensation (sensory threshold: 51 +/- 32 ml vs CG: 46 +/- 12 ml) were not significantly different between the groups. Proctological problems are very common in professional mountain bikers. Permanent microtrauma through constant saddle vibration may lead to chronic inflammation and anal fissure resulting in anal pain and therefore high sphincter pressure. Muscle hypertrophy as a consequence may lead to defecation disorders.

Results of Double-Blind Placebo-Controlled Crossover Study of Sildenafil Citrate (Viagra) in Women Suffering from Obstructed Voiding or Retention Associated with the Primary Disorder of Sphincter Relaxation (Fowler’s Syndrome)

ObjectivesWomen with the primary disorder of sphincter relaxation find voiding difficult. Studies have identified neuronal nitric oxide synthase in the female urethral sphincter, and nitric oxide donors have been shown to decrease sphincter pressures. The aim of our study was to determine if sildenafil could improve sphincter relaxation and thereby increase flow rates and improve bladder emptying. MethodsTwenty women with complete (5), partial retention or obstructed voiding (15) with a maximum flow rate (Qmax) of less than 15ml/min with an elevated maximal urethral closure pressure (92 – age cmH2O) and sphincter volume (>1.6cm3) were included in the study. The study was a double-blind, randomised, placebo-control, crossover design, with patients taking sildenafil or placebo, and with measurement of flow rate and residual volume at baseline and after each treatment phase. Voiding diary, quality of life, and International Prostate Symptom Score (IPSS) data were also collected. ResultsNo statistical significant difference was seen in any voiding parameters and diaries when sildenafil citrate was compared with placebo. There was a significant mean decrease in IPSS of 3.64 between baseline and the sildenafil phase (p=0.0083), but not when compared with placebo. In the subgroup of women with partial retention and obstructed voiding (15/20), there was a statistically significant increase in Qmax of 4.7ml/sec (p=0.025) between sildenafil and baseline; however this difference was not seen when compared with placebo. ConclusionsThis is the first study looking at sildenafil in voiding dysfunction in women. Clinical improvements with sildenafil were not significant when compared with placebo. Sildenafil was not effective as a therapeutic pharmacologic agent in this group of patients.

Urinary retention in women: its causes and management

To report the experience of the last 4 years from a centre to which women with voiding difficulties and urinary retention were referred nationally, describing what investigations were helpful in making a diagnosis and the management strategies used. Women with voiding difficulties and urinary retention remain a diagnostic and management challenge, and those with no anatomical or neurological basis for their symptoms may be dismissed, assuming that their retention has a psychogenic basis. The finding of an electromyographic (EMG) abnormality of the striated urethral sphincter explaining their disorder (Fowler's syndrome) has led to the referral of women for consideration of that diagnosis. Thus we audited the referrals to the centre over a 4-year period of such women. In all, 247 women (mean age 35 years) with complete (42%) or partial retention (58%) were referred; 175 (71%) had urethral pressure profilometry, 141 (57%) had a transvaginal ultrasonographic measurement of the sphincter volume, and 95 (39%) had sphincter EMG. The mean maximum urethral closure pressure difference between patients with an EMG abnormality (101.5 cmH(2)O) and the patients with known other causes of voiding dysfunction (66.2 cmH(2)O) was 35.3 cmH(2)O (P < 0.05). In patients with complete retention there was a significant difference in sphincter volume between those who were EMG-positive (2.14 mL) or EMG-negative (1.64 mL) (P < 0.05). These investigations helped to classify the cause of retention in two-thirds of cases. The commonest diagnosis was Fowler's syndrome, in which sacral nerve stimulation is the only intervention that restores voiding.

Integrity of the Anal Sphincters After Pouch-Anal Anastomosis: Evaluation With Three-Dimensional Endoanal Ultrasonography

The aim of the present study was to assess the integrity of the anal sphincters after handsewn pouch-anal anastomosis performed with the help of a Scott retractor. For this purpose the anal sphincters were visualized with three-dimensional endoanal ultrasonography. Patients undergoing a colonic pouch-anal anastomosis or an ileal pouch-anal anastomosis were included. Before and six months after the procedure, the length and volume of both sphincters were assessed with three-dimensional endoanal ultrasonography, and anal manometry was performed. Continence scores were determined using the Fecal Incontinence Severity Index (FISI). Fifteen patients with a colonic pouch and 13 patients with an ileal pouch were examined. Six months after the procedure, three-dimensional endoanal ultrasonography showed significant alterations of the internal anal sphincter in eight patients with a colonic pouch-anal anastomosis (53 percent) and in eight patients with an ileal pouch-anal anastomosis (62 percent). These alterations were characterized by asymmetry or thinning. No defects were seen in the colonic pouch group, but, in two patients with an ileal pouch, a small defect in the internal anal sphincter was found. A decrease in internal anal sphincter volume was seen only in patients with a colonic pouch-anal anastomosis (P = 0.009). In both groups the length of the internal anal sphincter and the length, thickness, and volume of the external anal sphincter remained the same. After the procedure a reduction of maximum anal resting pressure was found in both groups (colonic pouch: P < 0.001, ileal pouch: P = 0.001). Maximum anal squeeze pressure was reduced in only patients with an ileal pouch-anal anastomosis (P = 0.006). The observed alterations of the internal anal sphincter and the manometric findings showed no correlation with the postoperative Fecal Incontinence Severity Index scores. Handsewn pouch-anal anastomosis, performed with the help of a Scott retractor, only rarely leads to internal anal sphincter defects, but three-dimensional endoanal ultrasonography shows alterations of the internal anal sphincter in 57 percent of the patients. No correlation was observed between these alterations and the functional outcome.

Volume Measurements of the Anal Sphincter Complex in Healthy Controls and Fecal-Incontinent Patients With a Three-Dimensional Reconstruction of Endoanal Ultrasonography Images

The aim of this study was to determine sphincter volume, length, and external anal sphincter thickness in healthy controls and fecal incontinent patients by use of a three-dimensional reconstruction of endoanal ultrasonography images. Forty-four controls (15 males, 15 females, and 14 parous females) and 28 incontinent parous females (with and without a sphincter defect) were studied. Internal anal sphincter, external anal sphincter and puborectalis volume, sphincter length, and external anal sphincter thickness were measured. Intraobserver and interobserver variability were assessed. Anal pressure profile was also determined. Internal anal sphincter and external anal sphincter volumes were larger in males than in females (P = 0.001 and P = 0.04), and external anal sphincter volume was smaller in parous females but this was not significant (P = 0.084). Anterior sphincter length was longer in males (P = 0.004) and shorter in parous females (P = 0.06). Males had a larger anterior external anal sphincter thickness (P = 0.018); parity made no difference. Sphincter volumes were not smaller in incontinent females. Incontinent females with a sphincter defect had a shorter anterior sphincter length than that of continent (P = 0.001) and incontinent females without a sphincter defect (P < 0.001). Anterior external anal sphincter thickness was smaller in incontinent females with a sphincter defect (P = 0.006), and posterior and right external anal sphincter thickness was smaller in incontinent females without a sphincter defect (P = 0.02 and P = 0.03). Intraobserver variability was seen for internal anal sphincter volume and sphincter length, but there was no interobserver variability. Correlation between anal pressures and endoanal ultrasonography measurements was poor. Differences in anal sphincter volumes are seen for gender but not for parity. Fecal incontinence is not associated with loss of sphincter volume. However, anterior sphincter length and external anal sphincter thickness are smaller.

Correlating structure and function: three-dimensional ultrasound of the urethral sphincter.

Three-dimensional (3D) ultrasound facilitates assessment of the anatomy of the urethral sphincter, a decrease in sphincter volume being associated with stress incontinence. Urethral pressure profilometry (UPP) is used to assess urethral sphincter function although it is not diagnostic of stress incontinence. The aim of this pilot study was to determine whether 3D sphincter volume can be correlated with the area under the UPP curve. Primigravid women were recruited antenatally between 32 and 42 weeks' gestation. 3D transvaginal ultrasound scans of the urethra were performed in modified lithotomy position with a comfortably full bladder. Length and cross-sectional area were measured allowing the sphincter volume to be calculated. UPP measurements were performed with a Gaeltec solid-state pressure transducer and the area under the curve mapped out and calculated. All scans and measurements were repeated between 3 and 6 months postpartum. Nineteen women participated in the study. Antenatal and postnatal data were available in all cases. There was a statistically significant correlation between antenatal sphincter volumes and area under the UPP curve although this relationship was lost following delivery. There appears to be a correlation between structural anatomy and functional anatomy in the antenatal period although following delivery this is lost.

Three-dimensional reconstruction of magnetic resonance images of the anal sphincter and correlation between sphincter volume and pressure

Objective: The purpose of this study was to assess the correlation between internal and external anal sphincter volumes and manometric anal pressures. Study Design: Ten healthy nulliparous women underwent anal sphincter magnetic resonance imaging and anal manometry measurement. A 3-dimensional reconstruction of magnetic resonance images was accomplished with the use of 3-dimensional slicer. Sphincter volumes were measured 3 times by the same observer for each of 10 patients. The intrarater reliability was measured with the use of the intraclass correlation coefficient (ICC = σ2patients/(σ2patients + σ2error)) from a 2-way analysis of variance model with terms for patient and measurement trial. Measurements that were recorded on anal manometry included squeeze length, length of the high-pressure zone, and maximal resting and squeeze pressures. Results: The mean volumes (± SD) were 18.77 ± 4.64 cm3, 13.82 ± 3.8 cm3, and 32.36 ± 8.37 cm3 for internal, external, and combined sphincters, respectively. Intrarater reliability was 98% for external sphincter volume (95% CI, 94%-99%), 98% for internal sphincter volume (95% CI, 94%-99%), and 99% for total volume (95% CI, 97%-100%). On the 3-dimensional images, the internal sphincter was found to be cylindric in shape, with an ellipse as a base. It is elongated in the anterior and posterior direction and flattened on the sides. The external sphincter was found to be funnel-shaped, being narrower caudad and widening in the cephalad direction. Similar to the internal sphincter, the external sphincter is elongated in the anteroposterior diameter. Volumes of the internal, external, and combined sphincters did not correlate with the maximum pressures at rest and squeeze. Correlations higher than r = 0.5 were observed for all 3 sphincter volume measurements versus high pressure zone at squeeze. The highest correlation, r = 0.66, was for internal sphincter volume versus high pressure zone at squeeze Conclusion: Three-dimensional reconstruction of the rectal sphincter musculature can be performed easily with 3-dimensional software. Measurements of the sphincter volumes have excellent intrarater reliability. Sphincter volumes do not correlate with pressures at rest or squeeze, but the internal sphincter volume correlates with the length of the high pressure zone at squeeze. Contrary to current generalized concepts, it is possible that the internal sphincter may play some role in generating the squeeze pressure. More research is necessary in applying 3-dimensional magnetic resonance image reconstruction in patients with different parity and continence status. Reconstruction of magnetic resonance images of the rectal sphincter musculature may prove to be beneficial in planning the treatment of patients with fecal incontinence. (Am J Obstet Gynecol 2003;189:130-5.)

The urethra during pelvic floor contraction: observations on three-dimensional ultrasound

OBJECTIVE:To investigate with three-dimensional ultrasound how voluntary pelvic floor contractions influence the morphology of the female urethra’s components.METHODS:Twenty female patients with benign gynecologic disorders (mean age: 29 years; range: 19–40) had transrectal sonography using a 7.5-MHz mechanical sector endoprobe with three-dimensional features during both pelvic floor muscle relaxation and pelvic floor muscle contraction. The multiplanar display of the scanned volumes allowed detailed morphologic assessment of the urethra and the measurement of distances and volumes of the urethral components. Statistical end points were maximum sagittal and transverse urethral diameter, maximum sphincter length and thickness, maximum smooth muscle thickness, and the volumes of the sphincter, the smooth muscle, and the entire urethra.RESULTS:All 20 rectal scans were feasible. Two patients had to be excluded from analysis because of poor image quality, leaving 18 patients for evaluation. When compared with pelvic floor relaxation, the following measures were smaller during pelvic floor contraction: sagittal urethral diameter (10.4 versus 11.5 mm; P = .004), transverse urethral diameter (14.1 versus 15.0 mm; P = .009), urethral sphincter thickness (2.4 versus 2.7 mm; P = .012), urethral sphincter volume (0.5 versus 0.6 mL; P = .003), and total urethral volumes (1.4 versus 1.5 mL; P = .007). Sphincter length and smooth muscle thickness, as well as smooth muscle volume, did not change significantly during pelvic floor contraction.CONCLUSION:On three-dimensional ultrasound, the morphologic changes of the female urethra during pelvic floor contraction suggest external compression of the urethra rather than contraction of the sphincter muscle.

The Urethra During Pelvic Floor Contraction

In Brief OBJECTIVE To investigate with three-dimensional ultrasound how voluntary pelvic floor contractions influence the morphology of the female urethra's components. METHODS Twenty female patients with benign gynecologic disorders (mean age: 29 years; range: 19–40) had transrectal sonography using a 7.5-MHz mechanical sector endoprobe with three-dimensional features during both pelvic floor muscle relaxation and pelvic floor muscle contraction. The multiplanar display of the scanned volumes allowed detailed morphologic assessment of the urethra and the measurement of distances and volumes of the urethral components. Statistical end points were maximum sagittal and transverse urethral diameter, maximum sphincter length and thickness, maximum smooth muscle thickness, and the volumes of the sphincter, the smooth muscle, and the entire urethra. RESULTS All 20 rectal scans were feasible. Two patients had to be excluded from analysis because of poor image quality, leaving 18 patients for evaluation. When compared with pelvic floor relaxation, the following measures were smaller during pelvic floor contraction: sagittal urethral diameter (10.4 versus 11.5 mm; P = .004), transverse urethral diameter (14.1 versus 15.0 mm; P = .009), urethral sphincter thickness (2.4 versus 2.7 mm; P = .012), urethral sphincter volume (0.5 versus 0.6 mL; P = .003), and total urethral volumes (1.4 versus 1.5 mL; P = .007). Sphincter length and smooth muscle thickness, as well as smooth muscle volume, did not change significantly during pelvic floor contraction. CONCLUSION On three-dimensional ultrasound, the morphologic changes of the female urethra during pelvic floor contraction suggest external compression of the urethra rather than contraction of the sphincter muscle. On three-dimensional ultrasound the female urethra shows signs of external compression rather than active contraction during voluntary pelvic floor activity.

MAXIMUM URETHRAL CLOSURE PRESSURE AND SPHINCTER VOLUME IN WOMEN WITH URINARY RETENTION

In 1988 a syndrome of isolated urinary retention in young women that is associated with electromyographic abnormality of the striated urethral sphincter was described. It was hypothesised that urinary retention resulted from a failure of sphincter relaxation. The electromyographic abnormality causes overactivity of the muscle and may induce changes of work hypertrophy. If the hypothesis that the electromyographic abnormality is the cause of urinary retention is correct, we would expect the urethral sphincter to be enlarged and the urethral pressure profile to be increased in these women. We evaluated the role of static urethral pressure profilometry and transvaginal ultrasound in women in urinary retention. A total of 66 women in complete or partial urinary retention underwent electromyography of the striated urethral sphincter using a concentric needle electrode, followed by urethral pressure profile and/or urethral sphincter volume measurement by transvaginal ultrasound. Maximum urethral closure pressure plus or minus standard deviation was significantly increased in patients with versus without the electromyographic abnormality (103 +/- 26.4 versus 76.7 +/- 18.4 cm. water, p <0.001). Maximum urethral sphincter volume was also increased in women with versus without the abnormality (2.29 +/- 0.64 versus 1.62 +/- 0.32 cm.3, p <0.001). The results of this study are consistent with the hypothesis that a local sphincter abnormality is the cause of urinary retention in a subgroup of women. Urethral pressure profilometry and sphincter volume measurement are useful for assessing these cases, especially when sphincter electromyography is not readily available.

THE CAUSE AND NATURAL HISTORY OF ISOLATED URINARY RETENTION IN YOUNG WOMEN

Using a questionnaire mailed to patients we evaluated the course and natural history of urinary retention in women, of which the cause is attributed to electromyography abnormality of the striated urethral sphincter. Previously urinary retention in young women has often been considered to be due to multiple sclerosis or a manifestation of a psychogenic disorder. A questionnaire was mailed to 216 women with abnormal sphincter electromyography and urinary retention. Of the 112 responses we analyzed the 91 from those who had been in complete urinary retention. Mean patient age at the onset of complete retention was 27.7 years (range 10 to 50). No patients had neurological features indicating a cauda equina lesion or central demyelination and none had progressed to features of a general neurological disorder. Mean maximum bladder capacity at the initial episode of complete retention was 1,208 ml. Of the women 65% reported an event that had apparently precipitated urinary retention, most commonly a gynecologic surgical procedure using general anesthesia. Sacral neuromodulation was the only therapeutic intervention that restored voiding. The concept of an organic cause of urinary retention in otherwise healthy young women has considerable importance in terms of correct management. Neurological investigation in these women does not reveal underlying neurological disease. It is thought that this disorder is due to a primary failure of relaxation of the striated urethral sphincter.

Three-dimensional ultrasound: a novel technique for investigating the urethral sphincter in the third trimester of pregnancy.

To measure urethral sphincter volume by three-dimensional (3D) ultrasound. To assess the reproducibility of this measurement technique and to compare volumes obtained using 3D ultrasound with volumes calculated from a formula based on 2D ultrasound measurements. Women were recruited as part of an ongoing study of changes to the pelvis resulting from pregnancy and childbirth. One hundred and eleven women in the third trimester of pregnancy (between 32 and 41 completed weeks' gestation) underwent a 3D transvaginal ultrasound scan of the urethra. In 10 cases the scan was analyzed twice by different observers to assess the reproducibility of the measurements from the scans and the results were analyzed using limits of agreement. The interobserver error was consistent between all the linear, 2D and 3D measurements obtained from the area scanned. There was a significant difference between volumes calculated directly by 3D ultrasound and the approximated volumes from conventional 2D measurements. Three-dimensional ultrasound appears to be a useful tool in measuring urethral sphincter volume. The error is consistent with that of linear and 2D imaging. However, the increase in normal range generated by biological variation in all three planes makes 3D ultrasound a more sensitive method of evaluating change to the urethral sphincter.

Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter

Background: Anal endosonography has become an important imaging method in the diagnosis of anorectal disorders. However, little information exists as to whether anal endosonography reliably defines pelvic floor structures. The aim of this study was to correlate endoanal sonography with cross-sectional anatomy and histology. Methods: Endosonographic tomograms were obtained from 9 human cadavers before fixation and cross-sectioning at identical levels. Muscular layers were defined by visual inspection, histology, immunohistology, and morphometry using three-dimensional sphincter reconstructions. Results: Endosonography visualized only two muscular layers, whereas anatomic sections always revealed three. Comparisons revealed identical findings with regard to internal sphincter volumes and asymmetries. However, due to its failure to identify the longitudinal muscle, endosonography largely overestimated external sphincter volumes. In contrast to current beliefs, anatomic studies failed to detect striated muscle fibers within the longitudinal muscle and did not show an intersphincteric space. However, anatomic cross sections demonstrated “anterior bands” as newly described anchoring mechanisms for the anal sphincters. Conclusions: Anal endosonography supplies accurate information with regard to internal anal sphincter dimensions, but does not reliably outline deeper muscular layers. However, despite these drawbacks, comparisons of modern imaging techniques with cross-sectional anatomy may enhance our understanding of pelvic floor anatomy. (Gastrointest Endosc 1999;50:804-10.)