The nature of urethral injury in cases of pelvic fracture urethral trauma

PURPOSE: We examine the urethral injury associated with pelvic fracture that is said to be due to a shearing force through the membranous urethra which inevitably destroys the urethral sphincter mechanism. MATERIALS AND METHODS: A total of 20 asymptomatic cases were prospectively studied, including symptomatically, radiologically, endoscopically and urodynamically, 1 to 4 years after an apparently successful anastomotic repair of a pelvic fracture urethral distraction defect. RESULTS: There was evidence of urethral sphincter function, including urodynamically in 11 (55%), endoscopically in 13 (65%) and functionally in 17 (85%) patients. CONCLUSIONS: These findings, coupled with surgical observation, suggest that the urethral injury associated with pelvic fracture is avulsion of the membranous urethra from the bulbar urethra rather than a shearing through the membranous urethra, and that some degree of urethral sphincter function is preserved in a significant percentage of patients.     

Urodynamics in spinal shock patients

We investigated 17 spinal shock patients with traumatic complete cord lesions with cystometry, urethral pressure profile, anal and rectal pressure recordings, and electromyography of the pelvic floor sphincters. Bladder filling was accompanied by an elevation of resistance in the bladder neck area, with a concomitant increase of pressure in the external sphincter zone but without a simultaneous increase of the electromyographic activity. These results indicate an increased sympathetic activity in the smooth muscle component of the entire urethra. In the majority of patients the continuous withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile had higher values in the membranous urethra than the interrupted withdrawal pressure profile, revealing the importance of sensory afferents from the urethral mucosal receptors in producing artifactual reflex activity in the pelvic floor muscles. In the majority of interrupted withdrawal urethral pressure profiles higher pressures were recorded in the juxtabulbous region than in the mid part of the membranous urethra. A somewhat decreased electromyographic activity was found in the anal and urethral sphincters at rest. It did not often relate to the amount of resistance recorded in either sphincter. High urethral sphincter pressures and somatic activity of the conus medullaris reflexes show that external urethral and anal sphincters escape spinal shock, the primary characteristic of which is areflexia.     

Urethral injury secondary to pelvic fracture: anatomical and functional classification

OBJECTIVE: To develop a new functional and anatomical classification of urethral injury secondary to pelvic fracture. MATERIAL AND METHODS: Fifty-six male patients (20 children, 36 adults) with urethral injuries secondary to pelvis fracture were evaluated. Clinical examination, retrograde urethrogram immediately after the accident, operative findings in the emergency state, subsequent combined retrograde urethrography and suprapubic cystography, operative findings during urethral reconstruction and postoperative follow-up were critically reviewed retrospectively. RESULTS: A new classification of urethral injury secondary to pelvic fracture is proposed as a result of our findings: Type 1. Injury to the prostate; 1a. Proximal avulsion of the prostate; 1b. Incomplete or complete trans-prostatic rupture. Type 2. Stretching of the membranous urethra. Type 3. Incomplete or complete pure rupture of the prostatomembranous junction, supradiaphragmatic. Type 4. Incomplete or complete rupture of the bulbomembranous urethra, infradiaphragmatic. Type 5. Variable combined urethral injuries affecting more than one level of the urethra, prostatic and membranous or prostatomembranous and bulbomembranous, injury to proximal sphincteric mechanism combined with prostatic and/or membranous urethral injury. CONCLUSIONS: This anatomical and functional classification includes all types of urethral injuries secondary to pelvic fracture; moreover, it directs the attention towards evaluation of the urethral sphincteric mechanism, which is essential for the therapeutic and medicolegal aspects.     

Surgical anatomy of the male and female urethra.

The urethra is lined by transitional and stratified columnar epithelium. The urethra can be divided into both anatomic (prostatic, membranous, bulbar, and pendulous) and functional (anterior and posterior) segments. In the male, the anterior urethra is contained within the corpus spongiosum and penis. The urethra in the male and female is located within the urogenital triangle and pierces the superficial and deep perineal spaces of the pelvic floor. The urethra is surrounded by perineal and pelvic musculature that provide support and also form the urethral sphincter mechanism. Cancers of the anterior urethra preferentially drain into superficial inguinal lymph node channels. Those of the posterior urethra (prostatic, membranous, and bulbar segments in the male and the proximal two thirds of the urethra in the female) generally drain into pelvic lymphatic channels. A thorough knowledge of urethral and regional anatomy allows for complete tumor excision, optimal reconstruction, and in selected cases, restoration of urinary tract function.     

Magnetic resonance imaging of the male pelvic floor: The anatomical configuration and dynamic movement in healthy men

The male pelvic organs and the rhabdosphincter were visualized using magnetic resonance imaging (MRI) in five young male volunteers (mean age, 25.6 years). The prostate was crescent-shaped in three subjects and doughnut-shaped in two subjects. The external urethral sphincter (EUS) was located anterior to and lateral to the urethra but was rare on the rectal side. The membranous urethral length measured 28–35 mm (average, 31.0 mm). The pubourethral portion of the levator ani embraced the urinary bladder, the prostate, and the membranous urethra, and the most distal portion of the levator was thickened. During anal contraction, the EUS became thinner on both coronal and sagittal images and the levator was approximated closer to the urethra. Consequently, the prostate and the bladder base were elevated and the membranous urethra was elongated by 0–12mm (average, 5.6 mm). On sagittal images, the prostate, the membranous urethra, and the rectum were pulled closer to the pubic bone by anal contraction and the retropubic area became narrower. This study clearly demonstrated that MRI was useful in examining the anatomical configuration of the male pelvic floor and its dynamic movement during anal contraction. Neurourol. Urodynam. 17:591–597, 1998. © 1998 Wiley-Liss, Inc.     

Staged pendulous-prostatic anastomotic urethroplasty followed by reconstruction of the anterior urethra: an effective treatment for long-segment bulbar and membranous urethral stricture

OBJECTIVES: To describe a novel surgical technique for male long-segment urethral stricture after pelvic trauma using the intact and pedicled pendulous urethra to replace the bulbar and membranous urethra, followed by reconstruction of the anterior urethra. METHODS: Two patients with long-segment post-traumatic bulbar and membranous urethral strictures with short left pendulous urethras who had undergone several failed previous surgeries were treated with staged pendulous-prostatic anastomotic urethroplasty followed by reconstruction of the anterior urethra. This procedure was divided into three stages. First-stage surgery was mobilization of the anterior urethra down to the coronary sulcus and then rerouted to the prostatic urethra followed by pendulous-prostatic anastomotic urethroplasty with transposition of the penis to the perineum. Second-stage surgery was transecting the anterior urethra at the revascularised coronary sulcus 6 mo later, followed by straightening of the penis and urethroperineostomy. Third-stage surgery was reconstruction of the anterior urethra 6 mo later. RESULTS: Postoperatively, the two patients reported satisfactory voiding. For patient 1, retrograde urethrography showed that the urethra was patent, and that the mean maximal flow rate (MFR) was 18.4 ml/s with no postvoiding residual urine after the third-stage surgery and at 3-yr follow-up. For patient 2, a 22F urethral catheter could pass smoothly through the urethra, and the MFR was 19.5 ml/s with no postvoiding residual urine at 2-yr follow-up. CONCLUSIONS: This procedure was an effective surgical option for men with complex long-segment post-traumatic bulbar and membranous urethral strictures, especially for those who had undergone failed previous surgical treatments.     

Partial tears of prostatomembranous urethra in children.

Five boys having sustained a pelvic fracture were found to have incomplete tears of the prostatomembranous urethra. Three patients were treated with suprapubic cystostomy drainage alone and fared better than 2 who were treated with urethral catheter stenting and drainage. A recommendation is made for the "hands-off" approach to the evaluation and management of membranous urethral injuries.     

Urethral complications following ischiectomy in spinal cord injury patients: a urethral pressure study

Ischial ulcers are the most common pressure sores in spinal cord injury patients and ischiectomy often is used in the over-all management. Because a high percentage of spinal cord injury patients with total ischiectomy had complications of the membranous and proximal bulbous urethra, we evaluated urodynamically 15 ischiectomy patients in the supine and sitting positions to determine if pressure usually borne by the ischial tuberosities was transmitted to the membranous and proximal bulbous urethra. Of the 8 patients with a complete ischiectomy at least on 1 side 5 had problems of the membranous and proximal bulbous urethra, and the average urethral pressure increase from the reclining to the sitting position was 111 cm. water. The increase in urethral pressure was not related to any change in bladder or abdominal pressure. The average urethral pressure increase in the nonischiectomy patients was only 16 cm. water and none had any problems of the membranous and proximal bulbous urethra. Some retrospective clinical studies have implicated ischiectomy in the development of these urethral complications. Our urodynamic data lend some direct evidence that a more complete ischiectomy results in excessive urethral pressure with the patient in the sitting position, thereby predisposing the membranous and proximal bulbous urethra to problems related to ischemia. Five of the 8 patients with more complete ischiectomy and 1 with bilateral partial ischiectomy had high urethral pressures and complications, such as pseudodiverticulum, diverticulum and dilatation. More incomplete ischiectomy should be used to obviate this urethral damage.     

Reconstruction of Membranous Urethral Strictures

Purpose of Review

Due to the proximity of the rhabdosphincter and cavernous nerves to the membranous urethra, reconstruction of membranous urethral stricture implies a risk of urinary incontinence and erectile dysfunction. To avoid these complications, endoscopic management of membranous urethral strictures is traditionally favored, and bulboprostatic anastomosis is reserved as the main classical approach for open reconstruction of recalcitrant membranous urethral stricture. The preference for the anastomotic urethroplasty among reconstructive urologists is likely influenced by the familiarity and experience with trauma-related injuries. We review the literature focusing on the anatomy of membranous urethra and on the evolution of treatments for membranous urethral strictures.

Recent Findings

Non-traumatic strictures affecting bulbomembranous urethra are typically sequelae of instrumentation, transurethral resection of the prostate, prostate cancer treatment, and pelvic irradiation. Being a different entity from trauma-related injuries where urethra is not in continuity, a new understanding of membranous urethral anatomy is necessary for the development of novel reconstruction techniques. Although efficacious and durable to achieve urethral patency, classical bulboprostatic anastomosis carries a risk of de-novo incontinence and impotence. Newer and relatively less invasive reconstructive alternatives include bulbar vessel-sparing intra-sphincteric bulboprostatic anastomosis and buccal mucosa graft augmented membranous urethroplasty techniques. The accumulated experience with these techniques is relatively scarce, but several published series present promising results. These approaches are especially indicated in patients with previous transurethral resection of the prostate in which sparing of rhabdosphincter and the cavernous nerves is important in attempt to preserve continence and potency. Additionally, introduction of buccal mucosa onlay grafts could be especially beneficial in radiation-induced strictures to avoid transection of the sphincter in continent patients, and to preserve the blood supply to the urethra for incontinent patients who will require artificial urinary sphincter placement. The evidence regarding erectile functional outcomes is less solid and this item should be furtherly investigated.

     

Role of the transversus perinei profundus muscle on voiding: The meaning of UPmax in patients with paralyzed urethral sphincter

Urodynamic study of 66 patients with caudal injury and of 7 patients who underwent saddle block was evaluated by putting emphasis on the maximal pressure of the urethra (UPmax). The static pressure of 49.7 ± 10.8 cm H₂O in the membranous urethra of the patients with completely paralyzed sphincter raised the question that some active muscle that functions to open the membranous urethra must have been working during physiological urination. Urodynamic findings of detrusor sphincter relationship, monitored by pressure and electromyogram (EMG) measurement, suggested that the combined reflections of the pelvic floor muscle and urethral sphincter are present. We concluded that this would be induced by the transversus perinei profundus muscle contraction and the urodynamic interpretation would be re-integrated on the role of this muscle on active urethral opening mechanism. © 1996 Wiley-Liss, Inc.     

Role of striated and smooth muscle components in the urethral pressure profile in traumatic neurogenic bladders: a neuropharmacological and urodynamic study. Preliminary report

Urodynamic investigations with urethral pressure profile, and vesical, intrarectal and anal pressure recordings were performed in 37 patients with spinal cord lesions. The recordings were done before and after phentolamine injections and/or pudendal nerve blocks to evaluate the respective contribution of sympathetic and somatic innervation to the maximum urethral closure pressure in the mid and distal portions of the membranous urethra. A pressure gradient was demonstrated in the membranous urethra with higher values in the distal than in the mid portion. These results emphasize that the interrupted withdrawal technique is superior to the continuous technique in patients with upper motor neuron bladders. Mid urethral striated and smooth muscle components were shown to represent approximately 60 and 30 per cent of the maximum urethral closure pressure, respectively. In the distal urethra striated and smooth components are more abundant than in the mid portion and contribute in equal proportion to the maximum urethral closure pressure. No substantial role was found for the vascular bed in the maximum urethral closure pressure. The greatest pressure decrease in the mid and distal urethra of patients with lower motor neuron bladders was believed to be an effect of denervation supersensitivity. The results of pudendal blocks showed sphincter dyssynergia to be mediated through pudendal nerves via spinal reflex arcs. Phentolamine effects on bladder activity suggest that blockade of alpha-adrenergic receptors inhibits primarily the transmission in vesical and/or pelvic parasympathetic ganglia and acts secondarily through direct depression of the vesical smooth muscle. Our neuropharmacological results raise strong doubts as to the existence of a sympathetic innervation of the striated urethral muscle in humans.     

Normal anatomy of urethral sphincter complex in young Chinese males on MRI

Purpose

In this research, the normal anatomy of urethral sphincter complex in young Chinese males has been studied.

Methods

The sagittal, coronal, and axial T2-weighted non-fat suppressed fast spin-echo images of pelvic cavities of 86 Chinese young males were studied.

Result

Urethral sphincter complex is a cylindrical structure surrounding the urethra and extending vertically from bladder neck to perineal membrane. Urethral striated sphincter covers the anteriolateral urethra like a hat from bladder neck to verumontanum, while it surrounds the urethra in a ring shape from verumontanum to perineal membrane and backwards ends in central tendon of the perineum. From bladder neck to perineal membrane, the thickness of urethral smooth sphincter decreases gradually, and it extends forward to surround urethra with urethral striated sphincter as a ring. The length of urethral striated sphincter is 12.26–20.94 mm (mean 16.59 mm) at membranous urethra: 27.88–30.69 mm (mean 28.99 mm) from verumontanum to perineal membrane. The thickness of striated sphincter at membranous urethra is 4.29–6.86 mm (mean 5.56 mm) for the muscle of the anterior wall and 2.18–2.34 mm (mean 2.26 mm) for the muscle of the posterior wall.

Conclusions

In this paper, we summarized the normal anatomy of urethral sphincter complex in young Chinese males with no urinary control problems.     

Management of male pelvic fracture urethral injuries: Review and current topics

Pelvic fractures from high‐energy blunt force trauma can cause injury to the posterior urethra, known as pelvic fracture urethral injury, which is most commonly associated with unstable pelvic fractures. Pelvic fracture urethral injury should be suspected if a patient with pelvic trauma has blood at the meatus and/or difficulty voiding, and retrograde urethrography should be carried out if the patient is stable. Once urethral injury is confirmed, urinary drainage should be established promptly by placement of a suprapubic tube or primary realignment of the urethra over a urethral catheter. Although pelvic fracture urethral injury is accompanied by subsequent urethral stenosis in a high rate and it has been believed that primary realignment can reduce the risk of developing urethra stenosis, it also has a risk of complicating stenosis and its clinical significance remains controversial. Once inflammation and fibrosis have stabilized (generally at least 3 months after the trauma), the optimal management for the resulting urethral stenosis is delayed urethroplasty. Delayed urethroplasty can be carried out via a perineal approach using four ancillary techniques in steps (bulbar urethral mobilization, corporal separation, inferior pubectomy and urethral rerouting). Although pelvic trauma can impair continence mechanisms, the continence after repair of pelvic fracture urethral injury is reportedly adequate. Because erectile dysfunction is frequently encountered after pelvic fracture urethral injury and most patients are young with a significant life expectancy, its appropriate management can greatly improve quality of life. In the present article, the key factors in the management of pelvic fracture urethral injury are reviewed and current topics are summarized.     

骨盆骨折致后尿道损伤的手术方式选择与疗效评价

目的:探讨骨盆骨折致后尿道损伤的外科术式选择及手术治疗的临床效果。方法:自2000年6月至2010年8月,回顾性分析72例骨盆骨折合并后尿道损伤患者的临床资料,其中男46例,女26例;年龄26～62岁,平均35.2岁;受伤至入院时间1～3h。按Tile骨盆骨折分类:A型8例,B型45例,C型19例。35例尿道部分断裂患者中,30例行导尿术,5例行Ⅰ期尿道断端吻合术联合膀胱造瘘术;37例尿道完全断裂患者中,25例行早期尿道会师术,12例行单纯膀胱造瘘术。对所有患者进行尿失禁、阳痿及尿道狭窄的评估和比较。结果:72例患者均获得随访,时间5～10年,平均7.7年。膀胱造瘘术患者尿道狭窄、阳痿和尿失禁的发生率显著高于Ⅰ期尿道断端吻合术者和早期行尿道会师术者(P<0.05);导尿术患者尿道狭窄、阳痿、尿失禁的发生率均远低于其余3组(P<0.05)。结论:对于后尿道部分断裂患者,导尿术或Ⅰ期尿道断端吻合术应首先考虑;而对于后尿道完全断裂患者,早期尿道会师术操作简单、并发症少,可作为首选治疗方法。     

Mechanical properties and innervation of the smooth muscle layers of the urethra of greyhounds

OBJECTIVE: To investigate the properties of the smooth muscle layers in the urethral wall of male and female greyhounds, and to consider their roles in continence and micturition. MATERIALS AND METHODS: The distribution and innervation of the smooth muscle layers of the prostate capsule and membranous urethra of male greyhounds were assessed. Strips of smooth muscle from these regions were used to determine the neuropharmacological properties by assessing the excitatory and inhibitory responses to nerve stimulation, and the effects of blocking agents. These were compared with strips from the proximal urethra and from the female urethra. RESULTS: The smooth muscle of the membranous urethra comprised 9% of the wall and received its innervation exclusively in branches from the pelvic plexus. The cholinergic innervation in the male produced 80% of the total contractile response in the longitudinal membranous urethra, 50% in the prostate capsule and 13% in the circular muscle of the proximal urethra. In the female all areas had poor contractile responses. Inhibitory fibres produced relaxation in all parts of male and female urethrae with the major effect caused by nitric oxide. Adrenergic nerves contributed to both residual excitation (alpha receptors) and inhibition (beta receptors). CONCLUSIONS: The longitudinal smooth muscle of the male membranous urethra probably shortens the urethra during micturition, through the activity of cholinergic nerves, whereas the circular smooth muscle of the proximal urethra, under adrenergic control, may be contracted during continence and ejaculation. In the female, the smooth muscle plays a minor role.     

同步膀胱膜部尿道测压的临床意义

目的 探讨同步膀胱膜部尿道压力测定的临床意义。方法 采用ANTEC Duet尿动力学仪同步测定412例泌尿系病人和6例健康者充盈和排尿时的膀胱和膜部尿道压力,肌电图用直肠电极测定。结果 （1）健康人充盈期膜部尿道压,男性为40－50cmH2O,女性为20－30cmH2O,充盈期膜部尿道压高于膀胱压,且全充盈期没有明显变化,排尿时膜部尿道压力明显下降低于膀胱压。（2）逼尿肌尿道协同失调的病人,排尿时膜部尿道压升高,其中逼尿肌外括约肌协同失调（EDES）时合并有肌电活动明显增加,逼尿肌膀胱颈协同失调（DBDS）肌电活动正常,排尿期尿道测压膀胱颈处压力呈斜坡样下降。（3）尿道关闭机制下降或不全时充盈期膜部尿道压明显低,且充盈期膜部尿道膀胱压力差为负值。（4）尿道不稳定充盈期膜部尿道压突然下降且幅度≥15cmH2O。（5）正常尿道腹压传递率为20％－35％,而压力性尿失禁（GUI）病人尿道腹压传递率＜20％。结论 同步膀胱膜部尿道压力测定操作简单,在判断尿道关闭机制的正常与否、逼尿肌尿道的协同与否、尿道稳定性及腹压向尿道的传递效率方面有重要价值。     

Anatomical approach for surgery of the male posterior urethra

OBJECTIVE

To investigate, in a morphological study, the anatomy of the male rhabdosphincter and the relation between the membranous urethra, the rhabdosphincter and the neurovascular bundles (NVBs) to provide the anatomical basis for surgical approach of the posterior urethra as successful outcomes in urethral reconstructive surgery still remain a challenging issue.

MATERIALS AND METHODS

In all, 11 complete pelves and four tissue blocks of prostate, rectum, membranous urethra and the rhabdosphincter were studied. Besides anatomical preparations, the posterior urethra and their relationship were studied by means of serial histological sections.

RESULTS

In the histological cross‐sections, the rhabdosphincter forms an omega‐shaped loop around the anterior and lateral aspects of the membranous urethra. Ventrally and laterally, it is separated from the membranous urethra by a delicate sheath of connective tissue. Through a midline approach displacing the nerves and vessels laterally, injuries to the NVBs can be avoided. With meticulous dissection of the delicate ventral connective tissue sheath between the ventral wall of the membranous urethra and the rhabdosphincter, the two structures can be separated without damage to either of them. This anatomical approach can be used for dissection of the anterior urethral wall in urethral surgery.

CONCLUSIONS

Based on precise anatomical knowledge, the ventral wall of the posterior urethra can be dissected and exposed without injuring the rhabdosphincter and the NVBs. This approach provides the basis for sparing of the rhabdosphincter and for successful outcomes in urethral surgery for the treatment of bulbo‐membranous urethral strictures.     

The role of urethrography in urethral disease. Part II. Indications for transphincter urethroplasty in patients with primary bulbous strictures.

We herein outline the radiological and clinical criteria that will aid the surgeon in deciding whether transphincter urethroplasty is required in patients whose primary stricture is in the proximal bulbous urethra. Sinc proximal bulbous urethral strictures are common the urologist frequently is called upon to make this important decision. The criteria described herein will help him to do so and, thus, avoid urethroplasty failure because of proximal stenosis in the membranous urethra. The concept of paradoxical dilatation of the membranous urethra on voiding urethrography also is described. Paradoxical dilatation means that in the presence of a primary obstructive bulbous urethral stricture the membranous urethra, although containing significant scar tissue, is dilated on the voiding study because of the distal obstruction. Relief of the bulbous urethral stricture alone may result in rapid contraction and stenosis of the previously dilated membranous urethra.     

前尿道代后尿道成形术治疗男性复杂性后尿道狭窄

目的探讨长段复杂性后尿道狭窄治疗新方法。方法采用分期前尿道代后尿道成形术治疗3例复杂性后尿道长段狭窄（6．5—10．0cm）患者。第一期行阴茎转位尿道端端吻合术，术后3—6个月行二期阴茎伸直、尿道会阴造口术，6个月后行第三期前尿道成形术（Johanson Ⅱ期尿道成形术）。结果例1术后排尿通畅，膀胱尿道造影检查示尿道通畅，双侧输尿管返流近消失，最大尿流率18．8ml／s，随访2年，最大尿流率18ml／s，无剩余尿。例2术后排尿通畅，最大尿流率19．5ml／s，无剩余尿，尿道扩张可顺利通过22F尿道探子。例3经会阴一耻骨联合径路行第一期阴茎转位尿道端端吻合术、尿道直肠瘘、尿道会阴瘘切除、修补术，术后尿道直肠瘘及尿道会阴瘘治愈，但因耻骨联合切口感染致吻合口狭窄，有待进一步治疗。结论分期前尿道代后尿道加前尿道重建方法是治疗男性长段复杂性尿道狭窄的有效方法。     

Combined electromyography and gas urethral pressure profilometry before and after transurethral resection of the prostate.

Combined electromyographic and gas urethral pressure profilometry was done on 10 consecutive patients before and 3 months after transurethral resection of the prostate. A significant reduction was found postoperatively in the functional urethral length, whereas the maximum urethral closure pressure remained unchanged. Increase in urethral resistance in prostatic obstruction of the posterior urethra was related to the increase in the functional length of the posterior urethra rather than to mechanical occlusion of the urethral lumen. Periurethral striated muscle activity was recorded from the membranous urethra to the urethrovesical junction with the maximal activity located in the membranous urethra. Marked striated muscle activity also was found consistently at the bladder neck.