Diagnosis and surgical treatment of distal urethral stenosis caused by fibrous periurethritis in women. Our experience

OBJECTIVE: To report on our experience in the diagnosis and surgical treatment of distal urethral stenosis arising from fibrous periurethritis in women. METHODS: 9 patients who had undergone surgery for distal urethral stenosis caused by fibrous periurethritis are described. Patient history, clinical symptoms, the surgical technique employed, complications and post-operative course are presented. RESULTS: All 9 patients had a history of recurrent urinary infection and alteration of the urinary stream. The results obtained by surgery were satisfactory in all cases. CONCLUSIONS: Distal urethral stenosis arising from fibrous periurethritis is uncommon, but not rare. Diagnosis is principally based on the clinical symptoms, characterized by low urinary obstructive symptoms, and the finding at physical examination of a narrow meatus and periurethral enlargement caused by fibrous tissue surrounding the distal urethra. The Richardson urethrolysis technique achieved satisfactory results in these patients.     

Thoracic CT in the intensive care unit: assessment of clinical usefulness

PURPOSE: To enlarge the prostatic urethra with thermal coagulation with transrectal radio-frequency (RF) application in dogs. MATERIALS AND METHODS: Eight aged dogs underwent RF ablation of periurethral prostatic tissue for 6 minutes. Eighteen-gauge electrodes were placed into the periurethral tissues with a transrectal approach and ultrasound (US) guidance. Prostatic and rectal temperatures were measured during RF application. US, conventional and computed tomographic (CT) retrograde urethrography (RUG), and CT were performed immediately (n = 8) and at 3-96 days (n = 6) after ablation. Histopathologic analysis was performed at sacrifice immediately (n = 2), at 28 days (n = 2), or at 3 months (n = 4) after treatment. RESULTS: All procedures were successful with no complications and were performed in less than 30 minutes. Rectal mucosal temperature did not exceed 38 degrees C. Immediately after treatment, CT and US demonstrated 1.2-cm foci of altered periurethral tissue that corresponded to solid coagulated tissue at histopathologic analysis. By day 3, CT, RUG, and US demonstrated that these foci had begun to cavitate, resulting in enlargement of the urethra. Complete cavitation was demonstrated by day 28. Minimal reduction in the degree of urethral enlargement was noted by day 60, but narrowing, urethral strictures, or fistulas were not observed at 3 months. At histopathologic analysis, focal cavitary enlargement with at least doubling of the urethral diameter and with normal urothelium was noted in all dogs surviving at least 28 days. CONCLUSION: Transrectal RF urethral enlargement is feasible and safe in animals and merits investigation for alleviating urethral obstruction due to benign prostatic hyperplasia.     

The reliability of cysto-urethrographic signs in the diagnosis of detrusor instability in children

OBJECTIVE: To assess whether the signs associated with detrusor instability (DI), as assessed by video-urodynamic studies, can be evaluated by conventional voiding cysto-urethrography (VCUG). PATIENTS AND METHODS: Fifty-nine children who underwent cystometry and VCUG were reviewed and divided into two groups; group 1 comprised 51 neurologically normal children who had DI (47 girls and four boys, mean age 7.9 years, range 4-14), with no malformations or previous surgery. Most had mixed symptoms, including urinary tract infections (44) and nocturnal enuresis with daytime symptoms (20); group 2 (control) comprised eight children (seven girls, mean age 9.7 years, range 6-15) with a stable bladder and the same clinical presentation. The interval between VCUG and cystometry ranged from 1 day to 5 months (mean 47 days) and was similar in both groups. Signs considered suspicious of DI were sought in the findings of VCUG. RESULTS: In group 1, VCUG was normal or showed no specific signs (only vesico-ureteric reflux or vaginal voiding) in 25 (49%) of patients, whereas 26 (51%) had some signs suspicious of DI. Suspicious signs were urethral ballooning (in 11), bladder trabeculation or a constricting ring (eight), a 'spinning-top' urethra (three), urethral notching (two) and Mercier's bar (one). In group 2, five patients had no abnormal findings on VCUG and three had suspicious signs. The positive predictive value of VCUG was high (0.89) but the diagnostic yield of suspicious signs was low, because the sensitivity (0.5), specificity (0.62) and overall accuracy (0.52) were low. CONCLUSION: Radiological signs suspicious of DI cannot be regarded as such in conventional VCUG, as although they were detected in half the patients with DI, they also occurred in three of eight children with a stable bladder.     

Transrectal sonographic investigation of urethral and paraurethral structures in women with stress urinary incontinence

Transrectal sonography of the urethra was used in 14 asymptomatic volunteers, 37 women with frequency-urgency syndrome, 42 patients with mild stress urinary incontinence, and 18 with severe stress urinary incontinence. Transverse scanning over the midurethra was performed and cross-sectional images of the urethral and paraurethral structures were compared among the four groups, with P < 0.05 being considered statistically significant. The total cross-sectional area of the midurethra was significantly smaller in patients with stress urinary incontinence than in those without this disorder (86.7+/-29.9 versus 104+/-35.6 mm2, P = 0.005); this difference resulted from a significantly smaller peripheral striated muscle component in patients with stress urinary incontinence (42.8+/-20.7 versus 58.3+/-27.3 mm2, P = 0.001). The thickness of the urethropelvic ligaments was significantly thinner in patients with stress urinary incontinence than in those without (5.9+/-1.7 versus 8.9+/-2.1 mm, P < 0.001). The distribution of the peripheral striated muscle around the urethra was variable: complete surrounding the urethra was noted in 35.7% of the control women and in 48.6% of frequency-urgency patients, but only in 16.7% of patients with mild stress urinary incontinence and 5.3% of patients with severe disease. Bladder neck incompetence was seen in 42 patients with stress urinary incontinence but in none of the control women. The length of the pubourethral ligaments was similar in the four groups. Our finding showed that stress urinary patients had a smaller striated muscle component in the midurethra and thinner urethropelvic ligaments. These defects in the continence mechanisms might have great implications in the pathophysiology of stress urinary incontinence. Transrectal sonography of the urethra is a valuable investigative tool in assessing urethral and paraurethral conditions in patients with stress urinary incontinence before deciding treatment modality.     

The natural history of condyloma in children

OBJECTIVES: To prospectively evaluate our previously established pathologic risk factors in women undergoing cystectomy for bladder cancer and to determine if these criteria identify appropriate female candidates for orthotopic diversion. METHODS: Prospective pathologic evaluation was performed on 71 consecutive female cystectomy specimens removed for primary transitional cell carcinoma of the bladder. The histologic grade, pathologic stage, presence of carcinoma in situ, number, and location of tumors were determined. In addition, final pathologic analysis of the bladder neck and proximal urethra was performed and compared with the intraoperative frozen-section analysis of the distal margin (proximal urethra). RESULTS: Tumor at the bladder neck and proximal urethra was seen in 14 (19%) and 5 (7%) cystectomy specimens, respectively. Bladder neck tumor involvement was found to be the most significant risk factor for tumor involving the urethra (P <0.001). All patients with urethral tumors demonstrated concomitant bladder neck tumors. However, more than 60% of patients with bladder neck tumors had a normal (tumor-free) proximal urethra. Furthermore, no patient with a normal bladder neck demonstrated tumor involvement of the urethra. Intraoperative frozen-section analysis of the distal surgical margin was performed on 47 patients: 45 without evidence of tumor and 2 patients with urethral tumor involvement. In all cases, the intraoperative frozen-section analysis was correctly confirmed by final permanent section. CONCLUSIONS: We prospectively demonstrate that bladder neck tumor involvement is a significant risk factor for urethral tumor involvement in women. However, despite bladder neck tumor involvement, a number of women undergoing cystectomy for bladder cancer have a normal urethra and may be candidates for orthotopic diversion. Furthermore, our data demonstrate that intraoperative frozen-section analysis of the distal surgical margin accurately and reliably evaluates the proximal urethra and currently determines which patients undergo orthotopic diversion at our institution.     

Membrano-bulbo-urethral junction stenosis. Posterior urethra obstruction due to extreme caliber disproportion in the male urethra

OBJECTIVE: Based on 4 cases of infravesical obstruction due to extreme caliber disproportion between the posterior urethra and the penile urethra, a pathophysiological mechanism for this dynamic obstruction is given and endoscopic treatment is described. SUBJECTS: Four cases of membrano-bulbo-urethral junction (MBUJ) stenosis, seen between September 1995 and April 1996, are described. Two boys had previous successful valve resection but still showed extreme ballooning of the posterior urethra. The other 2 boys showed bladder instability on urodynamics and the male variant of the spinning top urethra on voiding cystourethrography (VCUG). RESULTS: All cases were successfully treated by endoscopic incision at the 12 o'clock position of the kink between the posterior and the penile urethra which is seen when the full bladder is expressed. Disproportion in the posterior urethra, seen on VCUG, together with bad urinary flow measured on uroflowmetry raise the suspicion of MBUJ stenosis. CONCLUSION: Although rarely seen, extreme caliber disproportion in the male urethra can cause obstruction. Ballooning of the posterior urethra, caused by urethral valves, bladder instability resisted by voluntary sphincter contraction or congenital posterior urethral dilatation, creates an obstructive kink in the urethra comparable to some obstructions in ureteropelvic junction stenosis. If suspicion of such a form of obstruction arises, cystoscopy during pressure on the full bladder is mandatory in order to see the obstruction, descending as a membrane from the vault of the urethra.     

Intranasal steroids and septum perforation--an overlooked complication? A description of the course of events and a discussion of the causes

One of urodynamic diagnostic methods is visualisation of the bladder neck opening which enables seeing the difference between internal and external urethral sphincter disfunction. Micturition video cysto-urethrography with X-rays makes possible to carry on such examinations, but it requires catheterisation which makes the method invasive. My purpose is to replace this examination by dynamic functional evaluation of the internal urethral sphincter during transrectal ultrasonography. During 10 routine transrectal ultrasound examinations of the prostate, patients were asked to urinate. During examination changes in configuration of the bladder neck and prostatic urethra were observed. Two patients could not urinate in horizontal position. In the rest of the patients very clear pictures showing changes in the shape and dimensions of the urethra during urination, were achieved. They were much more clear in comparison with X-ray video cystourethrography. Transrectal sonography is a perfect technique of the visualisation of the bladder neck and prostatic urethra during urination. The suggested method should be included into the urodynamic examinations.     

Urethral diverticula in women. Apropos of 15 cases

Urethral diverticulum is a rare disease, arising in the urethrovaginal septum and communicating with the urethra through an orifice. Characterised by clinical polymorphism, it is diagnosed by urethrocystography and transvaginal ultrasound. We report a series of 15 cases of urethral diverticulum over a 10-year period. The mean age of the patients was post-voiding was 36 years (range 24-50). The symptoms were recurrent urinary tract infections (66%), post-voiding urethral leakage (22%), vaginal pain (22%). Clinical examination found a vaginal mass in all patients. Retrograde urethrocystography showed the diverticulum in every cases, while IVP confirmed the diagnosis in only 62% of cases. Treatment is surgical and consists of removing the diverticulum via a vaginal approach. Short and long-term course is favourable. All patients were asymptomatic and the follow-up urethrocystography showed no diverticular recurrence.     

Long-term outcome of caliceal diverticula following percutaneous endosurgical management

PURPOSE: We review the morbidity and long-term outcome of percutaneous caliceal diverticulectomy and associated stone extraction. MATERIALS AND METHODS: Percutaneous caliceal diverticulectomy was performed in 19 women and 11 men (age range 20 to 58 years), of whom 26 had stones (all 15 mm. or less). The diverticula were located throughout the kidney, including the upper (11 patients), middle (15) and lower (4) calices. Percutaneous caliceal diverticulectomy included 28 direct and 2 indirect accesses (1 via a previously placed nephrostomy tract and 1 due to stones in other areas of the kidney). In all cases the stone was removed and the diverticular neck was incised or dilated. Fulguration of the diverticular walls was performed in 22 cases. Transdiverticular percutaneous renal and ureteral drainage was maintained from 2 to 7 days until a nephrostogram demonstrated no extravasation. RESULTS: The average operating room time and hospital stay were 171 minutes (range 75 to 330) and 4.1 days (range 2 to 7), respectively. Major complications occurred in 6.6% of the cases, requiring 1 blood transfusion and 1 chest tube placement, and minor complications occurred in 13.4%. There was no mortality. Followup for more than 1 year was available in 27 patients. Stone-free rate was 93% with obliteration of the diverticulum in 76% of patients. Overall, 85% of patients are asymptomatic at average followup of 3.5 years (range 1 to 7.3). CONCLUSIONS: Direct percutaneous endosurgical management provides a safe, efficacious and durable means of treating stone bearing caliceal diverticula, regardless of stone size or location of the diverticulum.     

Multicoil MR imaging of symptomatic female urethral and periurethral disease

High-resolution magnetic resonance (MR) imaging with phased-array pelvic and endorectal coils has dramatically enhanced the ability to visualize abnormalities of the female urethra and periurethral tissues. These include developmental abnormalities (eg, urethral duplication, ectopic ureterocele), benign processes (eg, urethral diverticulum, caruncle, leiomyoma, trauma, and fistula; stress incontinence; paravaginal cyst), and malignant processes (eg, primary urethral carcinoma, secondary urethral malignancies). High-resolution MR imaging can be used to assess complications such as fistula formation and periurethral abscess, localize various entities, exclude pathologic processes whose presence could lead to an incorrect diagnosis, differentiate processes that might be confused at physical examination, and contribute to surgical planning and facilitate surgical correction.     

Role of MR imaging with transrectal coil in the evaluation of complex urethral abnormalities

OBJECTIVE: The purpose of this study was to show the usefulness of MR imaging with a transrectal coil (TRC) in the management of various urethral abnormalities. This report also reveals the appearance of various postsurgical changes relating to the therapy of urethral abnormality. CONCLUSION: The high-resolution images obtained with TRC MR imaging were useful in evaluating urethral abnormalities. The imaging guided therapy in most cases. In two patients, TRC MR imaging more accurately depicted abnormality than did voiding cystourethrography and transvaginal sonography. In one case, TRC MR imaging was the only imaging technique that revealed the abnormality of periurethral scarring.     

Experience with the hemi-Kock ileocystoplasty with a continent abdominal stoma

We describe our experience with the hemi-Kock ileocystoplasty with a continent abdominal stoma as an alternative to an indwelling catheter or supravesical diversion in 14 women and 4 men with various problems who could not perform intermittent urethral self-catheterization. The aim of management was also to provide, if possible, a competent urethra for additional access. Mean patient age was 37 years (range 22 to 75) and mean followup was 26 months (range 5 to 58). Preoperative management in the 11 wheelchair dependent women with neurological disease was an indwelling catheter in 7, urethral intermittent catheterization with the patient in the supine position in 3 and diapers in 1. Two women with a nonneurogenic bladder and a grossly incompetent urethra (1 after multiple incontinence and fistula repairs, and 1 after severe obstetrical trauma) wore diapers, while 1 with urinary retention and inability to perform self-catheterization had an indwelling catheter. The 4 men included 2 wheelchair dependent incontinent spinal cord injury patients who could not be managed with condom drainage, 1 with multiple anomalies who had trouble with self-catheterization, and 1 with an impassable postoperative stricture and a suprapubic tube. Surgery included anti-incontinence procedures in 10 patients and bladder neck closure in 3. A total of 15 patients required bladder augmentation in addition to the stoma and 3 had a stoma alone. Postoperative intervention was necessary in 4 women for stomal incontinence and in 2 of these bladder stones were removed simultaneously. One of these women was later treated for recurrent stones cystoscopically through the stoma. Overall, 17 of 18 patients are dry on intermittent stomal catheterization, with 1 lost to followup. We conclude that this procedure is a good alternative in patients with an end stage urethra or who cannot perform urethral catheterization because of physical disability. Establishing urethral continence and maintaining patency leaves a safety valve should the stoma fail. Since the bladder remains as a reservoir no ureteral surgery is necessary.     

Anomalous venous drainage of the hypoplastic right lung and other malformations (scimitar syndrome)

Patients with lower abdominal symptoms, indicating colonic disorder, were classified into predefined clinical syndromes. Two important syndromes were colicky sigmoid syndrome and chronic diverticular disease. The first one, characterized by presence of colicky lower abdominal pains but absence of colonic diverticula, probably covers what is generally referred to as 'irritable bowel syndrome'. The second one was characterized by presence of lower abdominal colics and of colonic diverticula. The results showed a significant correlation between the presence of lower abdominal colics and a high pressure activity in the sigmoid colon after intravenous neostigmine. There was, however, no correlation between the presence of diverticula and a high pressure activity. The generally accepted theory of a high pressure activity as the dominant factor in the pathogenesis of colonic diverticula, therefore, was questioned, as was the equally accepted theory of a gradual development of chronic diverticular disease from the adiverticular colicky sigmoid syndrome.     

The effect of inorganic pyrophosphate on the transport of oleanolic acid monoglycosides into vacuoles isolated from Calendula officinalis leaves

OBJECTIVE: The objective of our study was to determine the value of using color and power Doppler sonography to reveal extrathyroidal feeding arteries in the detection of abnormal parathyroid glands. SUBJECTS AND METHODS: Forty-four patients with primary hyperparathyroidism were imaged prospectively with high-resolution gray-scale, color flow, and power Doppler sonography. The presence of extrathyroidal arteries supplying the adenomas was noted. All patients underwent subsequent neck exploration. The locations of the abnormal glands were recorded. RESULTS: At surgery, 51 abnormal parathyroid glands were removed in the 44 patients. Sonography correctly revealed an adenoma in 40 of the 44 patients. Likewise, sonography revealed 42 of the 51 adenomas. Nine false-negative and two false-positive interpretations of the sonograms were made. Thus, overall sensitivity was 83%, specificity was 98%, and accuracy was 94%. Three of the false-negative interpretations were ectopic glands within the superior mediastinum. Excluding these three glands from analysis, the sensitivity for detection of adenomas within the neck was 88%, specificity was 98%, and accuracy was 95%. An extrathyroidal artery leading to a parathyroid adenoma was seen in 35 of the 42 adenomas revealed by sonography. The presence of an extrathyroidal artery leading to an adenoma was found to aid in the detection of an otherwise inconspicuous parathyroid gland in five patients, which improved sensitivity from 73% to 83%. CONCLUSION: Prominent vessels supplying parathyroid adenomas are frequently revealed by color flow and power Doppler sonography. These vessels can serve as "road maps" to abnormal parathyroid glands.     

Anatomical anterior exenteration with urethral and vaginal preservation: illustrated surgical method

PURPOSE: We describe in detail a method for urethral and vaginal preservation in women considering orthotopic urinary tract reconstruction after bladder removal. MATERIALS AND METHODS: We retrospectively reviewed the pathological reports of patients treated with anterior exenteration at our hospital between 1984 and 1997 for specific evidence of urethral, vaginal, cervical or uterine involvement by the primary bladder tumor. Based on our findings we describe our approach to anterior exenteration in 6 patients. RESULTS: A total of 46 patients were treated at our center with en bloc anterior exenteration and pelvic lymphadenectomy for primary bladder cancer between 1984 and 1997. In 7 patients (15%) pathological review of the surgical specimen documented urethral involvement by the primary tumor. In 1 patient (2%) microscopic evidence of tumor was identified in the cervix and 1 (2%) had tumor extension to the vagina documented in the final pathology report. CONCLUSIONS: The observed rates of vaginal and urethral involvement agree with those reported by others, and suggest that in the majority of women treated with anterior exenteration sacrifice of the urethra and vagina is usually not necessary from an oncological perspective. This procedure is particularly appropriate in women concerned with postoperative sexual function and those considering orthotopic reconstruction of the lower urinary tract after exenterative bladder cancer surgery.     

Some sexological characteristics of stress incontinent women

The goal of stress incontinence surgery is to prevent opening of the urethra during increases in intra-abdominal pressure. Greater refinements in the understanding of the pathophysiology of incontinence and experience with newer treatments have extended surgical thinking beyond the familiar paradigm "to place the urethra in a high retropubic position." When incontinence is associated with vaginal hypermobility, vaginal support may be sufficient to restore continence if the suburethral vaginal wall is sufficiently strong, an evaluation which must often be made by physical examination alone. However, when the vaginal wall is weak, the urethra will require an alternative form of support, usually a sling. If the urethra is intrinsically deficient, vaginal support may not be sufficient to prevent opening during increased intra-abdominal pressure, and coaptation by sling obstruction or periurethral bulking injection may be required. Most laparoscopic approaches to stress incontinence use Burch's method, which offers excellent urethral stability provided the suburethral vaginal wall is strong. Newer insights into the relation between vaginal mobility and urethral closure are discussed, as well as anatomic aspects of the Burch suspension relevant to laparoscopic repair.     

The effect of urinary tract reconstruction on neurologically impaired women previously treated with an indwelling urethral catheter

PURPOSE: We investigated the changes in sexuality and quality of life that evolve after lower urinary tract reconstruction in neurologically impaired women previously treated with an indwelling urethral catheter. MATERIALS AND METHODS: A total of 18 neurologically impaired women treated with an indwelling urethral catheter underwent bladder reconstruction. Pubovaginal sling urethral compression was required to restore perineal dryness in 13 patients and was the only operation required in conjunction with intermittent catheterization in 3. Eight patients underwent ileocystostomy, that is creation of a "bladder chimney," and 4 underwent augmentation cystoplasty with creation of a continent catheterizable stoma. In 3 patients ileocystoplasty alone with intermittent urethral catheterization was performed. All patients were followed 6 to 40 months (mean 18) after reconstructive surgery using a 9-part questionnaire to score numerically the effect of surgical reconstruction on sexuality and quality of life issues. RESULTS: On a scale of 0 (worst) to 5 (best) mean score for self-esteem improved from 1 preoperatively to 4 postoperatively, self-image from 1 to 4, sexual desire from 2 to 4 and ability to cope with disability from 1 to 4, respectively. In 4 of the 15 women who were sexually active preoperatively the frequency of sexual intercourse doubled from a mean of 3 to 6 times per month, respectively, and all 4 women reported improved sexual satisfaction. All 13 patients with pelvic pain and 5 with symptoms of autonomic dysreflexia noticed significant improvement if not complete resolution of the symptoms. CONCLUSIONS: Neurogenic lower urinary tract dysfunction treated with an indwelling urethral catheter is detrimental to sexuality and quality of life in neurologically impaired women. Urinary tract reconstruction restores not only quality of life but also sexuality by improving self-image, self-esteem and the ability to cope. Indwelling catheterization as a method of long-term urinary treatment should be avoided in women.     

The Bonney test: a reassessment

OBJECTIVE: The purpose of this study was to reassess the effects of the Bonney test versus direct urethral compression and to introduce the Miyazaki-Bonney test. STUDY DESIGN: Thirty-seven patients with a diagnosis of genuine stress incontinence were studied. Each patient underwent a classic Bonney test, direct urethral compression, and a Miyazaki-Bonney test, while the following observations and measurements were made: (1) urethroscopic observation of the bladder neck and proximal urethra, (2) cotton swab resistance to withdrawal, and (3) proximal urethral pressure changes with use of a microtip catheter. In 16 of the patients cough pressure transmission (pressure transmission ratio) to the proximal urethra was measured before and during a Bonney test. Apart from the study group, four patients with clinical type III urethras were evaluated with the Bonney and Miyazaki-Bonney tests. RESULTS: The effects of the Bonney test and direct urethral compression were grossly different on urethroscopy, cotton swab resistance to withdrawal, and proximal urethral pressure changes. With the Bonney test, the average increase in urethral pressure was 52 cm H2O, whereas with direct urethral compression the urethral pressure was >250 cm H2O. With the Miyazaki-Bonney test there was little or no change in urethral pressure. Cough pressure transmission ratios before the Bonney test averaged 64%, whereas during the Bonney test they averaged 152%. The Miyazaki-Bonney tests did not prevent leakage in three patients with type III urethras. CONCLUSION: The Bonney test does not work by direct urethral compression but instead appears to produce continence by restoring the anterior vaginal wall hammock. The Miyazaki-Bonney test duplicates the effects of the Burch bladder neck suspension and may still be a valid prognosticator of surgical success. A modified Bonney test that can be standardized is presented as the Miyazaki-Bonney test.     

Echographic diagnosis of female urethral diverticulum

OBJECTIVE: To describe the utility of transrectal ultrasound as an alternative imaging technique in the diagnosis of diverticulum of the female urethra. METHODS/RESULTS: A 35-year-old female that had been initially diagnosed as having a benign tumor of the vagina is described. The voiding cystogram, positive pressure urethrography with a double balloon catheter and urethroscopy were falsely negative for urethral diverticulum of the female urethra. Subsequent evaluation by transrectal ultrasound disclosed on oval-shaped, anechoic lesion located posteriorly to base of the bladder. CONCLUSIONS: Transrectal ultrasound could be the diagnostic imaging technique of choice in patients suspected as having diverticulum of the female urethra.