Sonographic Findings of Acute Urinary Retention Secondary to an Impacted Pelvic Mass

Transcription

1 Case Series Sonographic Findings of Acute Urinary Retention Secondary to an Impacted Pelvic Mass Jenn-Ming Yang, MD, Wen-Chen Huang, MD Objective. To describe the sonographic findings in a series of cases of acute urinary retention due to an impacted pelvic mass. Methods. The anatomic changes of the lower urinary tract in 6 patients with impacted pelvic masses and acute urinary retention (3 cases of an impacted uterine leiomyoma and 3 cases of a retroverted gravid uterus) were evaluated with transabdominal and transvaginal sonography. Results. When patients were in the supine position, the impacted pelvic masses displaced the cervix superiorly and anteriorly, compressing the lower bladder, leading to obstruction of the internal urethral orifice. During straining, there was no limitation of urethral mobility, but the increased abdominal pressure further compressed the lower bladder. When the subjects stood, the lower bladder filled with urine. There was descent of the bladder neck, and obstruction was relieved. Conclusions. Acute urinary retention in cases of an impacted pelvic mass is caused by a displaced cervix compressing the lower bladder, obstructing the internal urethral orifice. The urethra itself is not compressed or distorted. Key words: impacted pelvic mass; sonography; urinary retention. Abbreviations TAS, transabdominal sonography; TVS, transvaginal sonography Received May 14, 2002, from the Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei Medical University, Taipei, Taiwan, Republic of China (J.-M.Y.); and Department of Obstetrics and Gynecology, Cathay General Hospital, Taipei, Taiwan, Republic of China (W.-C.H.). Revision requested June 3, Revised manuscript accepted for publication June 26, We thank Mary Jeanne Buttrey, MD, for counsel and constructive criticism of the manuscript. Address correspondence and reprint requests to Jenn-Ming Yang, MD, Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, 92 Chung-Shan N Rd, Section 2, Taipei 104, Taiwan, Republic of China. When a mass such as the retroverted gravid uterus, an ovarian cyst, or a fibroid in the posterior uterine wall crowds the pelvic space, occasionally the mass fails to clear the promontory of the sacrum and becomes impacted in the pelvis. The mass then fills the pelvis, displacing and compressing the lower urinary tract and inciting acute urinary retention. 1 3 Acute urinary retention is treated initially by catheterization, but the cause must be determined to allow definitive treatment. Currently, videocystourethrography is the modality used for evaluating voiding dysfunction, simultaneously offering both functional and anatomic assessment of the lower urinary tract. However, the procedure is not widely available, and there are concerns about radiation exposure, especially to the fetus. Sonography is reproducible and noninvasive and provides an excellent assessment of anatomic changes of the lower urinary tract. The goal of this study was to assess the sonographic findings in patients with acute urinary retention secondary to an impacted pelvic mass by the American Institute of Ultrasound in Medicine J Ultrasound Med 21: , /02/$3.50

2 Acute Urinary Retention Secondary to Impacted Pelvic Mass Materials and Methods From March 2001 to February 2002, 6 women with impacted pelvic masses and acute urinary retention were referred to our clinic for assessment and treatment. These included 3 women with uterine leiomyomas (fibroids; Table 1, patients 1 3) and 3 in the late first trimester of pregnancy (Table 1, patients 4 6). Sonography was performed to evaluate the anatomic changes of the lower urinary tract by using an Aloka SSD scanner (Aloka Co, Ltd, Tokyo, Japan) with a 3.5-MHz convex probe and a 5.0-MHz vaginal probe. The bladder neck position was quantitatively measured by using the angle between the bladder neck symphyseal line and the midline of the pubic symphysis 4 in the supine position, during a Valsalva maneuver, and in the standing position (Fig. 1). Urodynamic studies were performed in patients with uterine leiomyomas. Results Table 1 shows the clinical symptoms and sonographic findings in our study patients with impacted pelvic masses and acute urinary retention. In the cases of impacted uterine leiomyomas, transabdominal sonography (TAS) revealed a retroverted uterus with a prominent leiomyoma in the posterior uterine wall, occupying the pelvis and lifting the cervix superiorly. In the supine position, transvaginal sonography (TVS) showed the impacted fibroids displacing the cervix superiorly and anteriorly, compressing the lower bladder until it obstructed the internal urethral orifice (Fig. 2A). Pushing the cervix inward with a vaginal probe relieved the compression so that the lower bladder refilled with urine (Fig. 2B). At that point, the distinction between the urethra and bladder became clear. In the women with a retroverted gravid uterus, TAS showed an enlarged uterine corpus with a fetus. The demarcation between the urethra, cervix, and uterine corpus was obscure. Transvaginal sonography allowed clear discrimination of these structures (Fig. 3). During a Valsalva maneuver, there was no limitation of urethral mobility. The descent of the bladder neck was either vertical or rotational, with the motion ranging from 23 to 46. As abdominal straining increased, the lower bladder was compressed even more. The cervix, rather than lying adjacent to the proximal urethra, compressed the lower bladder to the point that it totally covered the internal urethral orifice. When the patients stood, the lower bladder gradually refilled with urine, together with a further descent of the bladder neck. Urodynamic studies in the cases with impacted uterine leiomyomas revealed high maximum urethral closure pressure and pressure transmission ratios (the increment in urethral pressure on stress as a percentage of the simultaneously recorded increment in intravesical pressure) at the proximal urethra. On the basis of the sonographic findings, we suggested the following measures to avoid urinary retention: limit fluid intake before sleep; change from the supine to the prone position for a while before getting up to go to the toilet; lean forward when initiating voiding; avoid any Valsalva maneuver; and use a Credé maneuver to Table 1. Demographic and Sonographic Data Timing of Acute Urinary Retention Necessitating Pelvic Mass Occupying Bladder Neck Position, Patient Diagnosis Age, y G/P Catheterization the Cul-de-sac At Rest During Straining Standing 1 Impacted 45 4/3 Early morning Leiomyoma cm leiomyoma 2 Impacted 51 2/2 Midnight and early morning Leiomyoma cm leiomyoma 3 Impacted 41 0/0 Midnight Leiomyoma cm leiomyoma* 4 RGU, 12 wk GA 35 1/0 Midnight CRL 5.7 cm RGU, 12 wk GA 28 2/1 Early morning CRL 6.0 cm RGU, 14 wk GA 25 1/0 Midnight CRL 6.9 cm CRL indicates crown-rump length; GA, gestational age; G/P, gravidity/parity; and RGU, retroverted gravid uterus. *Recurrent J Ultrasound Med 21: , 2002

3 initiate or maintain voiding. All women followed the instructions, and their voiding problems were alleviated except in patients 1 and 4. Patient 1 underwent hysterectomy, and TVS showed a marked difference in the lower part of bladder preoperatively and postoperatively (Fig. 4). Patient 4 required a Foley catheter for 1 month because of recurrent urinary retention. Discussion Although the results of urodynamic studies are similar in both prolapse and an impacted pelvic mass, we found that TVS revealed a different mechanism of voiding dysfunction in the latter disorder. Unlike with prolapse, with an impacted pelvic mass the urethrovesical junction was at a normal level behind the symphysis pubis, and urethral mobility was not restricted. 5 In our patients, it was the anteriorly and superiorly displaced cervix that compressed the lower bladder and interfered with drainage into the urethra. The urethra itself was not compressed or attenuated. During the day, irritability from the compressed bladder probably causes urinary frequency, so that frequent micturition prevents bladder overdistension. When the patient stands, urine accumulates in the lower part of the bladder, serving as a cushion to prevent lower bladder collapse and thus keeping the pathway to the internal urethral orifice patent. However, in the supine position, the upper portion of the bladder is dependent; therefore, urine collects there by gravity, and the cushioning effect is lost. The upper bladder may even exert pressure on the uterus, indirectly aggravating lower bladder compression. A vicious cycle ensues, particularly if there has been excessive fluid intake. Eventually the lower bladder collapses, and the internal urethral orifice is blocked. The collapsed part of the bladder may be mistaken for part of the proximal urethra on sonography, leading to a misunderstanding of the mechanism of obstruction. In the erect position, trying to void may be similar to trying to unplug a sink full of water. The more water in the sink, the more pressure it exerts on the plug, and the more difficult it is to pull the plug. The Valsalva maneuver merely adds further pressure on the impacted mass, leading to further lower bladder compression. Retroversion of the uterus is present in 15% of pregnancies during the first trimester, but the fundus will usually enter the abdominal cavity Figure 1. Transvaginal sonogram and schematic drawing showing measurement of the bladder neck position at the sagittal section by placing the vaginal probe at the introitus. The angle between the bladder neck symphyseal line and the midline of the pubic symphysis at rest was 105 in patient 2. BL indicates bladder; BNrest, bladder neck position at rest; BNstress, bladder neck position during stress; CX, cervix; M, leiomyoma; RA, angle of bladder neck at rest; SA, angle of bladder neck during stress; SP, pubic symphysis; U, urethra; and UM, internal urethral orifice. with no resulting complications by the end of the first trimester. Impaction of the retroverted gravid uterus occurs in approximately 1 per 3000 pregnancies. 2,3 Predisposing factors include congenital uterine anomalies, pelvic adhesions, posterior wall leiomyomas, endometriosis, and a deep sacral concavity with an overhanging sacral promontory. 1 3 Previous reports of such cases 1,2 document the inability of TAS to identify the anteriorly displaced cervix. The bladder is shown to be anteriorly and superiorly displaced in the abdomen. Such a finding on TAS should suggest the possibility of an impacted pelvic mass with urinary retention. Transvaginal sonography can then be used to clearly delineate the abnormality. The specific findings in TVS include the following: (1) the cervix is displaced superiorly and anteriorly by the impacted mass, compressing the lower bladder and causing it to override the internal urethral orifice; (2) pushing the cervix inward with a vaginal probe relieves the compression and makes clear the distinction between the urethra and bladder; and (3) there is no limitation of urethral mobility during a Valsalva maneuver. In conclusion, TVS is better than TAS in assessing changes in the lower urinary tract caused by an impacted pelvic mass. J Ultrasound Med 21: ,

4 Figure 3. Transvaginal sonograms from patients 4 (A) and 5 (B) showing a retroverted gravid uterus. BL indicates bladder; CX, cervix; FH, fetal head; FT, fetal trunk; SP, pubic symphysis; U, urethra; and UM, internal urethral orifice. Figure 2. A, Transvaginal sonogram from patient 1 showing compression of the lower bladder (open arrow) posteriorly by the cervix. B, Pushing the cervix inward relieves the compression and allows refilling of the lower bladder. C, Schematic drawing of TVS findings. A indicates anus; BL, bladder; CX, cervix; R, rectum; SP, pubic symphysis; and U, urethra. Figure 4. Transvaginal sonograms showing a marked difference in the lower part of bladder preoperatively (A) and postoperatively (B). Although the bladder neck position remained constant, the configuration of the lower bladder markedly changed from a concave, inward shape preoperatively to a convex, outward shape postoperatively. CX indicates cervix; M, leiomyoma; SP, pubic symphysis; and U, urethra J Ultrasound Med 21: , 2002

5 References 1. Hankins GDV, Cedars MI. Uterine incarceration associated with uterine leiomyomata: clinical and sonographic presentation. J Clin Ultrasound 1989; 17: Keating PJ, Walton SM, Maouris P. Incarceration of a bicornuate retroverted gravid uterus presenting with bilateral ureteric obstruction. Br J Obstet Gynaecol 1992; 99: Monga AK, Woodhouse C, Stanton SL. Pregnancy and fibroids causing simultaneous urinary retention and ureteric obstruction. Br J Urol 1996; 77: Mouritsen L, Rasmussen A. Bladder neck mobility evaluated by vaginal ultrasonography. Br J Urol 1993; 71: Yang JM. Factors affecting urethrocystographic parameters in urinary continent women. J Clin Ultrasound 1996; 24: J Ultrasound Med 21: ,