The significance of urethral hyperechogenicity in female lower urinary tract symptoms

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1 Ultrasound Obstet Gynecol 2004; 24: Published online 8 June 2004 in Wiley InterScience ( DOI: /uog.1067 The significance of urethral hyperechogenicity in female lower urinary tract symptoms J.-M. YANG* and W.-C. HUANG *Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei Medical University and Department of Obstetrics and Gynecology, Cathay General Hospital, Taipei, Taiwan, Republic of China KEYWORDS: maximum urethral pressure; urethral function; urethral hyperechogenicity; urodynamic study; voiding function ABSTRACT Objective To explore the significance of hyperechogenic spots in the urethra on ultrasound cystourethrography. Methods One hundred and five women with lower urinary tract symptoms who had undergone urodynamic study and ultrasound cystourethrography were included. Ultrasound cystourethrography was used to evaluate the morphology of the lower urinary tract, including the bladder neck position, bladder wall thickness at the trigone and dome, and presence or absence of hyperechogenic spots (urethral hyperechogenicity) in the urethra and their location and number. Results Of the 105 women, 30 (29%) had hyperechogenic spots in the urethra, including 26 (87%) with only one spot; 17 (53%) of the echogenic spots were located in the proximal urethra, including four cases with multiple echogenic spots. No significant differences were found in the demographics, urinary symptoms, ultrasonographic, urodynamic and urethrocystoscopic findings between those women with and without urethral hyperechogenicity, except for parity (P = 0.030). There was no association between urethral hyperechogenicity and urinary symptoms. A weak but negative correlation between the number of echogenic spots in the urethra and maximum urethral pressure was found in the subgroup with urethral hyperechogenicity (r = 0.421; P = 0.023). Conclusion On ultrasound cystourethrography, a single echogenic spot in the urethra is not associated with specific urinary symptoms and does not affect urethral function. Copyright 2004 ISUOG. Published by John Wiley & Sons, Ltd. INTRODUCTION The urethra has the dual functions of a urinary conduit and controller of continence. Stress urinary incontinence occurs when the bladder neck and urethra fail to maintain a watertight seal at rest and under conditions of increased intra-abdominal pressure. Urethral resistance at rest is generated by the interaction of urethral smooth muscle, urethral wall elasticity and vascularity, and periurethral striated muscle 1. Normal voiding is accomplished by relaxation of the urethra, followed by a sustained contraction of the detrusor so that the bladder empties completely 2. Local pathology in the urethra, such as strictures and diverticula, may cause variations in the urethral pressure and result in voiding dysfunction or urinary incontinence 3,4. On ultrasonography, the urethra appears as a tubular structure with a central echolucent urethral mucosa and surrounding hyperechogenic urethral sphincters 5. Alteration of the anatomy of the lower urinary tract may result in functional disorders and vice versa. Hypermobility of the bladder neck and proximal urethra and decreased thickness of the urethral sphincter are the ultrasonographic features associated with stress urinary incontinence 6. On Valsalva maneuver, funneling of the bladder neck at submaximal bladder capacity signifies the potential coexistence of intrinsic sphincter deficiency with urethral hypermobility in primary stress urinary incontinence 7. Constriction in the echolucent part of the urethra (i.e. the urethral mucosa) has been reported to be associated with voiding dysfunction 8.Onoccasion, ultrasonographic evaluation of the lower urinary tract may detect echogenic spots in the echolucent urethral mucosa. The nature of these findings and their effect on the urethra have never been reported. This study was designed to explore the significance of echogenic spots in the urethra. METHODS From January 2002 to January 2003, 138 consecutive women with lower urinary tract symptoms (frequency, Correspondence to: Dr J.-M. Yang, Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, 92 Chung-Shan North Road, Section 2, Taipei 104, Taiwan, ROC ( yangjm0211@hotmail.com) Accepted: 9 March 2004 Copyright 2004 ISUOG. Published by John Wiley & Sons, Ltd. ORIGINAL PAPER

68 Yang and Huang nocturia, urgency, urge or stress incontinence, or voiding dysfunction) for at least 3 months who had undergone functional evaluation of the lower urinary tract by multichannel

Exclusion criteria included: (1) hematuria, recurrent dysuria, abnormal urinalysis or positive urine culture; (2) a history of pelvic surgery, neuropathy (central or peripheral), diabetes mellitus or

2 68 Yang and Huang nocturia, urgency, urge or stress incontinence, or voiding dysfunction) for at least 3 months who had undergone functional evaluation of the lower urinary tract by multichannel urodynamic testing together with morphological assessment of the lower urinary tract by ultrasound cystourethrography 7,9 were enrolled in this study. Exclusion criteria included: (1) hematuria, recurrent dysuria, abnormal urinalysis or positive urine culture; (2) a history of pelvic surgery, neuropathy (central or peripheral), diabetes mellitus or radiation therapy or (3) estrogen replacement therapy for postmenopausal symptoms. Thirty-three women were excluded, leaving 105 study subjects. A full urodynamic study included a 1-h pad test, spontaneous uroflowmetry, filling and voiding phase cystometry, and a urethral pressure profile on both resting and straining. Cystometry was performed at a filling rate of 80 ml/min with the patient lying supine in a birthing chair. The intravesical pressure was measured with a fluid-filled catheter (4.5 Fr) and the intra-abdominal pressure was measured transrectally with a latex rectal catheter. During filling, provocative maneuvers, such as coughing, standing, heel bouncing and hearing running water, were performed. At the maximal cystometric capacity, the patient stood up, and a stress test followed with the legs apart to the width of the shoulders. If the stress test was positive, the Valsalva leak point pressure (VLPP) was measured by asking the patient to strain, and the intravesical pressure was recorded at the point of visible urine loss. The lowest pressure obtained on two attempts was used. A voiding study was then carried out with the patient seated and the catheters still in place. After voiding, residual urine volume was measured and the bladder was refilled with 200 ml of 0.9% saline solution. A microtransducer catheter with two sensors positioned 5 cm apart (Gaeltec, Dunvegan, UK) was introduced through the urethra with both sensors within the bladder oriented at the 9 o clock position. The rate of transducer withdrawal and chart recording was 2 mm/s. The resting and stress urethral pressure profiles were then measured with the patients sitting at 45. Data were recorded continuously on a MMS UD-2000 (Medical Measurement System, Enschede, The Netherlands) multichannel recorder. The curves for resting and stress urethral pressure profiles were divided into four quartiles along the functional profile length (Q1, 0 25%; Q2, 26 50%; Q3, 51 75%; Q4, %). We measured the highest pressure, the resting urethral closure pressure, and the pressure transmission ratios (the increment in urethral pressure on stress as a percentage of the simultaneously recorded increment in intravesical pressure) in each quartile. The VLPP values were divided into three categories: low VLPP, < 60 cmh 2 O; mid- VLPP, between 60 and 90 cmh 2 O; and high VLPP, > 90 cmh 2 O. Ultrasound cystourethrography was performed with patients in a supine position with a comfortably full bladder. We performed introital and transvaginal ultrasonography with a Toshiba SSA-260A (Toshiba, Tokyo, Japan) or Voluson 730 (Medison-Kretztechnik, Zipf, Austria) scanner and an endovaginal probe with a frequency range of MHz. The morphology of the lower urinary tract was evaluated at rest and during a maximum Valsalva maneuver as described in a previous study 9. Color Doppler imaging was performed with pulse repetition frequency of 4.0 khz and wall filters of 50 Hz. Data recorded included the bladder neck position, bladder wall thickness at the trigone and dome, and the presence or absence of echogenic spots in the urethra (urethral hyperechogenicity) and their number and location (Figure 1). Three-dimensional ultrasonographic examinations were performed in 10 cases, including six with a single echogenic spot and four with multiple spots. The study subjects were analyzed in two groups according to the presence or absence of urethral hyperechogenicity. Of the 105 study subjects, 39 (37%) had additionally undergone diagnostic urethrocystoscopy for evaluation of voiding dysfunction and/or restricted bladder volume. The procedure was performed under Figure 1 Transvaginal ultrasonography displaying a hyperechogenic spot (arrow) in the (a) distal and (b) proximal urethra. BL, bladder; SP, pubic symphysis; U, urethra.

Urethral echogenic spots 69 local anesthesia. This subset was also analyzed according to the presence or absence of urethral hyperechogenicity.

For categorical data, proportions were calculated and the Chi-square or Fisher s exact test was used to compare the results of subjects with and without urethral hyperechogenicity.

Associations between urethral hyperechogenicity and urinary symptoms, in addition to the numbers of echogenic areas and urodynamic variables, were evaluated using Spearman s rank correlation (rho)

3 Urethral echogenic spots 69 local anesthesia. This subset was also analyzed according to the presence or absence of urethral hyperechogenicity. Statistical Package for Social Sciences (SPSS) 10 software (SPSS Inc., Chicago, IL, USA) was used for data analysis. For categorical data, proportions were calculated and the Chi-square or Fisher s exact test was used to compare the results of subjects with and without urethral hyperechogenicity. For continuous data, the mean and standard deviation were used to summarize the results. For parametric comparisons, a Student s t-test was used. Associations between urethral hyperechogenicity and urinary symptoms, in addition to the numbers of echogenic areas and urodynamic variables, were evaluated using Spearman s rank correlation (rho) test. Values of P < 0.05 were considered statistically significant. Approval to carry out the study was obtained from the local ethics committee. RESULTS The mean patient age, mean gravidity and mean parity were 50.6 (range, 27 84) years, 4.6 (range, 0 12), and 3.1 (range, 0 7), respectively. Of the 105 study subjects, 33 (31%) were postmenopausal, 59 (56%) had a diagnosis of urodynamic stress incontinence, nine (9%) had detrusor overactivity (having a detrusor contraction in association with urgency and/or urinary leakage during the filling phase of cystometry), nine (9%) had mixed incontinence (having criteria for both urodynamic stress incontinence and detrusor overactivity) and 28 (27%) had normal urodynamic findings. The prevalence of urethral hyperechogenicity was 29% (30/105). Only one echogenic spot was present in 87% (26/30) of the subjects; 57% (17/30) of the echogenic spots were located in the proximal urethra, including four cases with multiple echogenic spots (Table 1). Three-dimensional ultrasonography clearly demonstrated that the echogenic spots were confined within the echolucent urethral mucosa and had no anatomic connection with surrounding urethral sphincters (Figure 2a). Color Doppler sonography did not demonstrate any hypervascularity in association with urethral hyperechogenicity (Figure 2b). Except for parity, no significant differences were found in the demographics, frequency of urinary symptoms (Table 2), the occurrence of urodynamic diagnoses and urodynamic findings (Table 3) between the two groups. Table 1 Characteristics of urethral hyperechogenicity (n = 30) Characteristic n (%) Echogenic spots (n) 1 26 (87) 2 1 (3) 3 2 (7) 4 1 (3) Location of echogenic spots Proximal urethra 17 (57) Distal urethra 13 (43) Figure 2 Transvaginal ultrasonographic and urethrocystoscopic findings in a case with more than four echogenic spots (white arrows) in the proximal urethra. (a) Three-dimensional scanning clearly displaying the relationship between echogenic spots and neighboring tissues. (b) Color Doppler scanning showing normal blood flow inside the urethra. (c) Urethrocystoscopic examination revealing two brighter spots (black arrows) on the urethral crests. BL, bladder; U, urethra.

4 70 Yang and Huang Table 2 Demographics and urinary symptoms in the study groups with or without urethral hyperechogenicity Urethral hyperechogenicity* Demographics/ urinary symptoms Present Absent P n Age (years) 49.2 ± ± 11.5 NS Gravidity 4.5 ± ± 2.9 NS Parity 5.5 ± ± Menopause 7 (23%) 26 (35%) NS Body mass index (kg/m 2 ) 24.2 ± ± 3.7 NS Urinary symptoms Frequency 12 (40%) 29 (39%) NS Nocturia 12 (40%) 31 (41%) NS Urgency 13 (43%) 21 (28%) NS Urge incontinence 8 (27%) 17 (23%) NS Stress incontinence 23 (77%) 46 (61%) NS Voiding dysfunction 14 (47%) 23 (31%) NS *Data are presented as mean ± SD or n (%). NS, not significant. There were also no differences between the two groups in the ultrasonographic parameters including resting and stress bladder neck angles, rotation angle of the bladder neck and bladder wall thickness at the trigone and dome. Of the 39 cases that had undergone diagnostic urethrocystoscopy, 15 had urethral hyperechogenicity and 24 did not. Urethrocystoscopy revealed a benignappearing papillary lesion in 14/15 (93%) cases with urethral hyperechogenicity and 15/24 (63%) cases without urethral hyperechogenicity. Urethrocystoscopy demonstrated two tiny brighter spots on the urethral mucosa in one subject who had more than four echogenic spots (Figure 2c). We found no significant differences between the two groups with regard to urethrocystoscopic findings of urethral polyps and brighter spots. Simultaneous ultrasonographic scanning during urethrocystoscopy revealed the site of the brighter spots on urethrocystoscopy as being equivalent to the location of urethral hyperechogenicity on ultrasonography. The spots resembled white caps on the urethral crests, which were of normal appearance and color. The bladder was mildly trabeculated in only one subject who did not exhibit urethral hyperechogenicity. There was no association between urethral hyperechogenicity and specific urinary symptoms. In the subgroup with urethral hyperechogenicity there was a weak but negative correlation between the number of echogenic spots and maximum urethral pressure (r = 0.421; P = 0.023). DISCUSSION The urethra is a pliable structure whose lumen must be completely sealed to maintain continence but must be fully relaxed during voiding. Constriction in the echolucent part of the urethra may cause voiding difficulty 8. In the present study no significant differences were found in the urinary symptoms and the ultrasonographic and Table 3 Urodynamic studies in the study groups with or without urethral hyperechogenicity Urethral hyperechogenicity* Parameters Present Absent P Urodynamic diagnosis Urodynamic stress 17 (57%) 40 (53%) NS incontinence Detrusor overactivity 3 (10%) 5 (7%) Mixed incontinence 2 (7%) 7 (9%) Negative findings 8 (27%) 23 (31%) Urethral pressure profile MUP (cmh 2 O) 90 ± ± 25 NS MUCP (cmh 2 O) 71 ± ± 26 NS FPL (cm) 2.7 ± ± 0.6 NS AUC total (cmh 2 O.cm) 152 ± ± 63 NS AUC proximal (cmh 2 O.cm) 88 ± ± 40 NS Pressure transmission ratio (%) Q1 101 ± ± 39 NS Q2 92 ± ± 29 NS Q3 83 ± ± 36 NS Q4 57 ± ± 46 NS VLPP < 60 cmh 2 O 1 4 NS cmh 2 O 7 9 > 90 cmh 2 O 9 27 Pressure flow study Q max (ml/s) 21.7 ± ± 10.5 NS Time to Q max (s) 13.3 ± ± 38.5 NS P ves Q max (cmh 2 O) 52 ± ± 24 NS P det Q max (cmh 2 O) 27 ± 8 36± 45 NS Miction resistance 0.15 ± ± 1.77 NS (cmh 2 O/(mL/s) 2 ) P ves.op (cmh 2 O) 47 ± ± 22 NS P det.op (cmh 2 O) 22 ± 8 26± 20 NS *Data are presented as mean ± SD or n (%). AUC proximal, proximal area under the urethral pressure profile curve; AUC total, total area under the urethral pressure profile curve; FPL, functional profile length; MUCP, maximum urethral closure pressure; MUP, maximum urethral pressure; NS, not significant; P det Q max, detrusor pressure at Q max ; P det.op, detrusor opening pressure; P ves Q max, intravesical pressure at Q max ; P ves.op, intravesical opening pressure; Q 1, pressure transmission ratio (PTR) in the first quartile of the urethra; Q 2, PTR in the second quartile of the urethra; Q 3,PTRin the third quartile of the urethra; Q 4, PTR in the fourth quartile of the urethra; Q max, peak flow rate; VLPP, Valsalva leak point pressure. urodynamic variables between those individuals with and without urethral hyperechogenicity, whereas the number of echogenic spots was negatively correlated with maximum urethral pressure. Conventional urethral pressure measurement yields a single pressure at a given site in the urethra. The effect of a single echogenic spot on the urethra may, therefore, not be manifested on traditional urodynamic studies. The fact that 89% of our subjects had only one echogenic spot may explain why their pressures were normal. The presence of two or more spots, however, might be expected to generate a difference on urodynamic studies. In this study, multiple echogenic spots were associated with reduced closure

5 Urethral echogenic spots 71 pressure, which may correlate with urethral damage and explain the weak link with parity. However, the multitude of tests did not reveal any significant difference between subjects with and without urethral hyperechogenicity. It was possible that the weak correlation between echogenic spots and maximum urethral pressure was an unexpected result of the statistical analysis. Thus the existence of urethral hyperechogenicity did not result in any storage or voiding problems. Lack of pathological proof of the echogenic spots is a major drawback of this study. Of 15 cases with urethral hyperechogenicity, urethrocystoscopy demonstrated two tiny brighter spots on the surface of the urethral mucosa in only one case, suggesting that most of the echogenic spots were beneath the surface of the urethral mucosa and inaccessible to biopsy. The lesions were clinically insignificant and thus biopsy was not justified, especially in view of the risk of injury to the mucosa that might result in urethral stricture. But what could be the cause of this urethral hyperechogenicity? Ultrasonic artifact, air, calcium deposit or something else? Multiple scans of the urethra in different directions were performed to ensure that urethral hyperechogenicity was not an artifact. The echogenic spots remained at the same site and could not be displaced by to-andfro motion of the vaginal probe. This excluded the possibility of air entrapped inside the urethral mucosa. Urethral hyperechogenicity did not produce any acoustic shadows, as does calcified deposit or lithiasis. Although urethrocystoscopy revealed a high incidence (14/15, 93%) of inflammatory polyps at the vesical neck in subjects with urethral hyperechogenicity, ultrasonographic assessment did not demonstrate hypervascularity, which is common in inflammation and infection. Besides, there was also a significant incidence of polyps in women without echogenic spots (15/24, 63%). In summary, our data suggest that a single echogenic spot on ultrasonography does not occur in association with particular urinary problems or abnormalities of urethral function. In addition, the echogenic spots had no obvious correlation with findings on urethroscopy. Consequently, we suggest that these spots can safely be ignored. REFERENCES 1. Karram KK. Urodynamics: urethral pressure profilometry. In Clinical Urogynecology, Walters MD, Karram MM (eds). C. V. Mosby: St Louis, MO, 1993; Karram MM, Partoll L, Bilotta V, Angel O. Factors affecting detrusor contraction strength during voiding in women. Obstet Gynecol 1997; 90: Hojsgaard A. The urethral pressure profile in female patients with meatal stenosis. Scand J Urol Nephrol 1976; 10: Summitt RH, Stovall TG. Urethral diverticula: evaluation by urethral pressure profilometry, cystourethroscopy and voiding cystourethrogram. Obstet Gynecol 1992; 80: Huang WC, Yang JM. Transvaginal sonography in the treatment of a rare case of total urethral stenosis with a vesicovaginal fistula. J Ultrasound Med 2002; 21: Petri E, Koelbl H, Schaer G. What is the place of ultrasound in urogynecology? A written panel. Int Urogynecol J Pelvic Floor Dysfunct 1999; 10: Huang WC, Yang JM. Bladder neck funneling on ultrasound cystourethrography in primary stress urinary incontinence: a sign associated with urethral hypermobility and intrinsic sphincter deficiency. Urology 2003; 61: Huang WC, Yang JM. Transvaginal sonographic findings in diagnosis and treatment of urethral stricture. J Ultrasound Med 2003; 22: Yang JM, Huang WC. Discrimination of bladder disorders in female lower urinary tract symptoms on ultrasonographic cystourethrography. J Ultrasound Med 2002; 21:

KEYWORDS: cystocele; laparoscopic Burch colposuspension; ultrasound cystourethrography; urodynamic stress incontinence; voiding function

KEYWORDS: cystocele; laparoscopic Burch colposuspension; ultrasound cystourethrography; urodynamic stress incontinence; voiding function Ultrasound Obstet Gynecol 2005; 25: 289 295 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/uog.1838 Dynamic morphological changes in the anterior vaginal wall before