Can the parameters of penile duplex assessment predict the success of urethroplasty?

Abstract

Background

This work aimed to study the role of penile duplex in predicting the outcome of anastomotic urethroplasty.

Methods

Between March 2022 and February 2023, all patients presented with posterior urethral distraction defect (PUDD) underwent anastomotic end to end urethroplasty. Preoperative evaluation of sexual function was performed using international index of erectile function (IIEF-5) and penile doppler parameters (the response E1 to E5, peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI)). Each patient was, routinely, evaluated through 12 month-follow up using IIEF-5, penile doppler parameters, uroflowmetry for Qmax and pelvic ultrasound for postvoid residual urine (PVR). The procedure was considered successful if Qmax > 15 ml/s and PVR < 50 cc at the end of follow up. The correlation between the success rate of anastomotic urethroplasty and pre-operative penile Doppler parameters was the primary outcome.

Results

Thirty patients with a mean age of 29.47 ± 9.79 years were evaluated. Twenty patients (66.7%) had previous orthopedic surgery. The stricture site was membranous in 6 patients (20.0%) and bubo-membranous in 24 (80.0%). The mean stricture length was 2.52 ± 0.98 cm. There was a statistically significant increase in mean end-diastolic velocity (P < 0.001) with a subsequent significant decrease in mean resistance index (P < 0.001). 14.3% of pre-operatively potent patients developed venous leakage (P < 0.001), while there was no change of arteriogenic or venogenic erectile dysfunction. In addition, of the patients who have arteriogenic erectile dysfunction, 37.5% did not require surgery, 25% had a urethrocystoscopy, and 37.5% required a repeat end to end urethroplasty. There is a significant association between pre-operative peak systolic velocity and the need for re-operation (P = 0.005).

Conclusion

Penile duplex may anticipate anastomotic urethroplasty efficacy in the case of PUDD.

1 Background

Four to fourteen percent of pelvic ring fractures result in posterior urethral distraction defect (PUDD). Pelvic hematoma and fibrosis, developed from pelvic fracture, completely obstruct the in-between urethral lumen in 65% of cases making the both end of urethral injuries in different directions [1, 2]. For PUDD, anastomotic urethroplasty is the gold standard technique that has demonstrated remarkable long-term efficacy [3]. Successful anastomotic urethroplasty requires tension free, fibrosis free, mucosa to mucosa suturing and adequate blood supply to the urethra. The vascularity of the penis is an essential factor for procedural success. The urethra receives dual blood supply from the bulbourethral arteries from common penile artery from internal pudendal artery and from the dorsal penile arteries which supply the glans penis then backflow through the corpus spongiosum suppling the urethra [4]. In PUDD, the bulbourethral arteries may be compromised leaving the urethra depends on single blood supply which comes retrograde from glans penis. Impaired urethral blood flow may cause failure of the urethroplasty owing to the anastomotic ischemia. The incidence of erectile dysfunction associated with pelvic fracture urethral injury (PFUI) is widely variable between 26–72% which is usually vasculogenic in nature [3]. Therefore, those patients with pelvic fracture urethral injury (PFUI) and vasculogenic ED may carry risk of urethral ischemia and failure of urethroplasty, as the penis and urethra have common blood supply. While the urethroplasty may cause ED in 2–5% postoperatively due to either iatrogenic injury to the neurovascular bundle surrounding the membranous urethra or venous leakage from corpus cavernous affection. The literature is deficient as regard the association between the outcome of urethroplasty and the state of penile vasculature which has no consensus, in addition to lacking of proper researches in this field. Therefore, this work was performed to assess the role of evaluating the penile arterial integrity using the penile duplex as a prediction tool for urethroplasty outcomes and the correlation between the success of urethroplasty and duplex parameters as a primary endpoint. The secondary endpoint was to evaluate the sexual function outcome of urethroplasty for PUDD.

2 Methods

This cross-sectional analytic investigation included the male patients with PUDD due to pelvic trauma between March 2022 and February 2023. After local ethical committee approval (MS-185-2022) and obtaining written consent from all patients, they underwent anastomotic end-end urethroplasty, followed for 12 months in Kasr Al-Ainy Hospital, Cairo University. Patients with genitourinary malignancies, neurogenic bladder, and those with ED for other reasons rather than vasculogenic ED were ruled out.

Pre-operatively, the patients were assessed through careful history taking, including trauma analysis and physical examination. Kidney-bladder ultrasound and retrograde urethrography combined with cystogram from the suprapubic catheter with micturition film were performed to identify of PUDD. For the erectile function, the patients were evaluated through the international index of erectile function (IIEF-5) questionnaire and penile duplex with measurement of cavernosal artery diameter changes and parameters of the cavernosal artery [peak systolic velocity (PSV), end diastolic velocity (EDV), resistivity index (RI)] post intra-cavernosal injection (ICI) of PGE2.

The erection rigidity was assessed during penile duplex at maximal erection point using the penile erection hardness scale and classified into 5 grades: E1; flaccid, E2; enlarges but not hard, E3; hard but not enough for penetration, E4; hard enough for penetration but not completely rigid, E5: fully rigid. Using the IIEF-5 score, the patients were classified as regard the erectile function into: normal erectile function (IIEF 22–25), mild ED [17,18,19,20,21], mild to moderate ED (IIEF 12–16), moderate ED (IIEF 8–11) and sever ED (IIEF 5–7). Normal cavernous artery peak systolic velocity (PSV) is > 30 cm/s. The sum of the right and left PSV should be > 50–60 cm/s to rule out significant arteriogenic ED while the End diastolic velocity of the cavernosal artery should not Exceed 3 cm/sec. RI < 0.8 suggestive veno-occlusive dysfunction and is Calculated = (PSV-EDV)/PSV [5].

The surgical procedure was performed under spinal anesthesia unless contraindicated. The patient was scrubbed in exaggerated lithotomy position. urethrocystoscopy was done to assess the site of urethral injury and through the cystotomy to evaluate the bladder neck and posterior urethra. Through perineal midline incision, the bulbospongiosus muscle and bulbar urethra were dissected till the site of perineal body which was transected. The site of urethral transection was determined using a 16 fr nelaton catheter passed through the anterior urethra. All fibrous tissue at the urethral end was sharply removed. The proximal urethral end was identified by passing metal urethral sound (bougie) through the cystostomy and bladder neck to be felt at the perineum. In difficult cases when the proximal urethral end was too deep to perform tension free end to end anastomosis, additional steps were used including: anterior urethral dissection, crural separation ± partial inferior pubectomy. The both urethral ends were anastomosed mucosa to mucosa using 6 sutures 4/0 vicryl without any tension on 18 fr silicon catheter to be removed after 3 weeks. Finally, the wound was closed in layers using 2/0 and 4/0 vicryl sutures.

Total operative time, hemoglobin drop, and intraoperative blood transfusion were monitored. Post-operatively, mean hospitalization and catheterization time were monitored. Directly after catheter removal, post voiding residual urine, Uroflowmetry (Qmax), and retrograde urethrography were done, and all patients were re-evaluated using the IIEF-5 questionnaire and penile duplex after post operatively after 3 months and up to 12 months follow up schedule.

Successful outcome for the urethroplasty after pelvic fracture urethral injury was identified as successful voiding without urinary catheter with a Qmax of 15 ml/sec and absent or less than 50 ml of postvoiding residual urine, also the follow-up cystourethrography should be devoid of any evident narrowing of the posterior urethra.

3 Statistical analysis

The data were encoded and entered in version 28 of the statistical application for the social sciences (SPSS) (IBM Corp., Armonk, NY, USA). For continuous data, the standard deviation, the mean, maximum, and minimum were utilized to summarize the information. Relative frequency (percentage) and frequency (count) were employed for categorical data. To compare continuous variables, the non-parametric Kruskal–Wallis and Mann–Whitney tests were applied. To compare serial measurements across all patients, the non-parametric Wilcoxon signed rank test was implemented. The chi-square (χ2) test was employed to compare categorical data. However, the exact test is utilized when the anticipated frequency is below five. For statistical significance, p-values below 0.05 were deemed valuable.

4 Results

Forty-four patients with PUDD and suprapubic catheter due to traumatic fracture pelvis were presented to our institute. 4 patients were excluded due to massive distraction defect for which end to end anastomotic urethroplasty was not feasible and staged procedure was performed in the form of perineal urethrotomy for later repair. In addition, another 10 patients were excluded: 3 of them with neurogenic ED and 7 cases due to missed follow up. 30 patients were included in our study with mean age 29.47 ± 9.79 years. None of the patients had history of medical illness. Regarding surgical history, twenty patients (66.7%) only had previous orthopedic surgery (Table 1). The site of urethral distraction was membranous in 6 patients (20.0%) and bubo-membranous in 24 (80.0%) (Fig. 1). The mean urethral distraction defect length was 2.52 ± 0.98 cm. The mean operative time was 3.62 ± 0.68 h. All patients had no significant Hb drop or need for blood transfusion. The mean hospital stay was 36 ± 13.5 h and the mean catheterization time was 21 ± 9.5 days.

Table 1 History of studied patients

Fig. 1

Pre-operative site of urethral injury

Post-operatively, 25 patients (83.4%) had mean PVR < 50 ml, mean Qmax 14.50 ± 8.25 ml/second and mean voided volume 299.27 ± 180.70 ml. Salvage VIU for short stenotic segment was required in two patients, who had PVR 50–150 ml and Qmax 6 ml/sec, two weeks after catheter removal. Their 6 month follow up revealed insignificant PVR and Qmax > 14 ml/sec. On other side, 3 patients required redo anastomotic urethroplasty at 6 months follow up as they had urine retention for which suprapubic was fixed.

There was a statistically significant increase in mean end-diastolic velocity (P < 0.001), with a subsequent significant decrease in mean resistance index (P < 0.001). A notable alteration occurred in response to intra-cavernosal injection; 6.25% of E3 changed to E2, and 33.3% of E5 became E4. However, no change in E2 and E4 occurred (P < 0.001).

A notable disparity existed between pre- and post-operative degrees of erectile dysfunction; 14.3% of pre-operatively potent patients developed venous leakage, while there was no change in arteriogenic or venogenic erectile dysfunction (P < 0.001). A notable disparity existed between pre- and post-operative IIEF-5 urethroplasty; postoperatively, 33.3% of potent patients at E5 downgraded to E4 after ICI with no clinical significance because these patients did not complain of any alteration in their sexual function.

There was significant correlation between the type of preoperative erectile dysfunction and the need for re-operation as those patients with arteriogenic ED preoperatively showed higher need for reoperation than those with normal erectile function or venogenic ED (Table 2, Fig. 2).

Table 2 Pre-operative type of erectile dysfunction regarding the need for operation

Fig. 2

Pre-operative degree of erectile dysfunction regarding the need for re-operation

A notable correlation existed between the pre-operative PSV and the need for re-operation (P = 0.001). Among patients with arteriogenic erectile dysfunction (PSV < 25 ml/s), 37.5% did not need re-operation, 25% of them underwent urethrocystoscopy, and 37.5% of them were required to re-do ETE urethroplasty. The results revealed a significant association between pre-operative peak systolic velocity and the need for re-operation (P = 0.005) (Table 3).

Table 3 Relation between pre-operative peak systolic velocity and the need for re-operation

5 Post hoc pairwise comparisons

Pre-operative peak systolic velocity was significantly higher in patients who did not need re-operation than those who needed to re-do ETE (P = 0.012) (Fig. 3).

Fig. 3

Post-hoc pairwise comparison between groups regarding pre-operative peak systolic velocity

6 Discussion

Major trauma-associated pelvic fractures may be complicated by posterior urethral injury, the incidence of which is estimated by investigations to range from 1.5% to 25%. The predominant cause of urinary tract damage associated with pelvic fractures is road traffic accidents [6].

The urethra is subsequently stretched and damaged in cases of pelvic fractures, which result in the prostate organ being forced into the perineal membrane. Significant morbidity can result from posterior urethral injury, such as erectile dysfunction (ED), urethral stricture, and urinary incontinence. ED is a considerable concern identified in studies examining individuals who have undergone reconstruction operations and have urethral strictures [6].

The penile duplex is a precise and minimally invasive approach regarded as the benchmark for assessing penile hemodynamics. The severity and nature of the injury determine the extent to which penile ultrasound findings alter in patients with urethral stricture, ranging from normal to severe arterial impairment. Reduced cavernosal artery blood flow could result from mixed vascular damage following trauma to penis, perineum or pelvic crush injuries [6]. the determination of PSV has become the generally accepted first-line tool in the assessment of arterial integrity [7]. Moreover, it was reported that the urethral stricture length was inversely correlated with RI and that RI measurement after ICI was a reliable predictor of erectile function in patients with urethral stricture, especially posterior stricture [6].

Haines & Rourke [8] and Urkmez et al. [9] observed no disparity between penile and bulbar reconstruction in the incidence of ED after urethroplasty. The mean pre-operative urethral distraction defect length in our study was 2.52 ± 0.98 cm, ranging between 1 and 4 cm. Similarly, 93.3% of the patients had a median length of 2.5 cm (1.5–5) in the Ballesteros Ruiz et al. [10] study.

Moreover, there was a significant decrease in the mean resistivity index in the present study (P < 0.001). In disagreement with the current study, thirty-five individuals who received urethroplasty and were evaluated pre-operatively and post-operatively for 6 months using the Pharmacological Color Doppler Ultrasonography (PCDU) and the IIEF-5 were enrolled in the research conducted by Mondal et al. [11]. They reported no significant change in the resistivity index of the cavernosal artery over time.

Post-urethroplasty, a significant change was observed in response to intra-cavernosal injection in the current study; 6.25% of E3 changed to E2, and 33.3% of E5 became E4. No change in E2 and E4 was observed (P < 0.001). In disagreement with the current study, a study conducted by Erickson et al. [12] demonstrated that urethroplasty does not have a substantial impact on erections among individuals as determined by penile color Doppler ultrasonography (peak systolic velocity at cavernosal arteries before and after the procedure: right 26.87 ± 6.93 vs. 26.16 ± 6.53 and left 27.23 ± 5.21 vs. 26.52 ± 4.38 respectively).

Excellent long-term success rates have been observed with posterior urethroplasty for urethral repair; however, the evaluation of long-term erectile and sexual performance in these individuals has been constrained by the predominant use of binary variables (yes vs. no) in the studies that report ED [13, 14]. The present study reported a notable disparity between pre- and post-operative degrees of erectile dysfunction; 14.3% of normal patients developed venous leakage, while no change in arteriogenic or venogenic erectile dysfunction was observed (P < 0.001). In agreement with our study, Mazzone et al. [15] reported that ED worsened in 16% of patients after urethroplasty. In addition, Joshi & Kulkarni [16] described a 56% rate of ED pre- vs. 63% post-operatively. Moreover, Tang et al. [17] used an IIEF questionnaire, where individuals who had neurogenic ED (IIEF 15 pre-operatively versus 10 post-operatively) reported a worsening of ED.

Consistent with our research, Xie et al. [18] examined the IIEF-5 scores at baseline and after posterior urethroplasty. They found a substantial reduction in IIEF-5 scores three months following posterior urethroplasty (17.05 vs. 9.37, P < 0.05).

Nevertheless, erectile function improved six months after posterior urethroplasty, particularly in subjects younger than forty. On the contrary, Koraitim et al. [19] discovered that there was no statistically significant distinction in the mean IIEF-5 score between the initial urethroplasty and the subsequent procedure (12.58 ± 9.01 and 10.88 ± 9.28, P = 0.220). Furthermore, according to the IIEF-5 erectile function questionnaire, urethroplasty by itself did not substantially affect patients' erectile function (13.12 ± 5.38 vs. 13.54 ± 5.44; P = 0.26), as demonstrated by Erickson et al. [12]. In addition, Mondal et al. [11] showed that 10 (28.50%) cases—seven of which had ED before surgery—showed deterioration. Three patients had a new-onset ED. Eleven participants (31.50%) demonstrated improvement, while 14 subjects (40.00%) showed no change in their IIEF score. The IIEF score decreased overall, although the difference was insignificant (P = 0.692).

According to Rajadoss [20], who supported our study, 28% of individuals with severe erectile dysfunction did not get the desired result. After the trauma, the individuals who were unable to urinate after urethral repair experienced severe erectile dysfunction. Each person with mild to moderate erectile dysfunction and normal erections had a satisfactory or good result. The pre-operative evaluation's finding of severe erectile dysfunction seems to be significant. A failed repair occurred in 9% of patients with a normal peak systolic velocity and 25% with an abnormal peak systolic velocity. Normal penile vascularity is essential to better wound healing and good operative outcomes. It was reported that severe erectile dysfunction was associated with abnormal peak systolic velocity and a poor surgical outcome.

Brandes and Borrelli [21] additionally discovered that a large number of PUDD patients exhibited evidence of unilateral or bilateral pudendal artery lesions. It was discovered that those patients would benefit significantly from penile artery revascularization to increase potency. Duplex ultrasound was used to evaluate patients after observing this link to potency. The results of duplex inspection revealed that patients with normal unilateral or bilateral pudendal arteries showed normal vascular parameters. Patients with just reconstituted bilateral or unilateral arteries never showed normal arterial parameters on duplex ultrasonography. Therefore, we could proceed with pudendal angiography selectively for patients exhibiting abnormal vascular characteristics on duplex ultrasonography results. Subsequently, they perform satisfactorily during reconstruction. After doing penile artery revascularization to increase vascularity in these patients, many authors could move on to urethral repair [22,23,24]. A multicenter study conducted by Johnsen et al. [25] reported that TAE, along with more extended distraction defects, were significantly associated with urethroplasty failure and that the success rate of excision and primary anastomosis for pelvic fracture urethral injury was 93.3% (99/106) without TAE, but only 75.0% (12/16) after TAE. Therefore, pelvic TAE appears to be detrimental to urethroplasty outcomes.

Generally erectile Dysfunction following the pelvic injury raises the concern that penile arterial blood flow should be assessed before doing a urethroplasty for PFUI. One of the proposed methods to overcome the bulbar ischemia, is to perform penile revascularization, in a study Zuckerman et al. (24) 17 patients with arteriogenic ED after PFUI were treated by penile revascularization; four of them had the treatment done before urethroplasty to avoid complications from bulbar ischemia.

7 Conclusion

Penile duplex could predict the success of anastomotic urethroplasty for PUDD. Moreover, posterior urethroplasty can be complicated by erectile dysfunction.

8 Recommendations

The function of a penile duplex in predicting the result of reconstructive posterior urethroplasty needs to be investigated in further large-scale prospective research. It is advised to assess the severity of erectile dysfunction before and after urethroplasty for extended periods.