Uroflowmetry or Urethroscopy as a Surveillance Tool After End-to-End Anastomotic Urethroplasty Done for PFUI—A Blinded Study

Abstract

Background/Objectives: Uroflowmetry is done in the surveillance period after End-to-end Anastomotic Urethroplasty for pelvic fracture urethral injury. But is maximum flow rate a reliable surrogate for urethral calibre in these cases? The above question laid the foundation of the study. The aim of the study was: “Is uroflowmetry alone sufficient to predict a successful outcome following urethroplasty after pelvic fracture urethral injury (PFUI)?” Methods: We conducted a prospective masked study of all patients undergoing end-to-end anastomosis (EEA) urethroplasty for PFUI from January 2017 to September 2022. The first follow-up was 4 weeks after surgery, micturating cystourethrogram (MCU) was done after urethral catheter removal and at the same time, uroflowmetry was also done. The second follow-up was 6 months after surgery, when uroflowmetry was repeated, and urethroscopy was performed. The urologist performing urethroscopy was blinded to the uroflowmetry results. Results: In total, 26 patients were included in the study. After 6 months, 1 patient had poor flow (maximum flow rate [Q max] < 10 mL/s), 7 patients had flow with Q max 10–15 mL/s, and 18 patients had normal flow (Q max > 15 mL/s). On urethroscopy, all patients had a normal and easily passable urethra. The International Prostate Symptom Score (IPSS) and quality of life (QoL) scores showed a positive correlation. The urologist performing urethroscopy and the investigator recording uroflowmetry reached different conclusions. Conclusions: A reduced peak on uroflowmetry after EEA urethroplasty in PFUI does not always indicate surgical failure. Urethroscopy enables direct visualisation of the anastomotic site and provides more detailed information than uroflowmetry. The IPSS score and quality of life are more important than Q max alone.

1. Introduction

Five to 25% of pelvic fracture cases are associated with pelvic fracture urethral injuries (PFUI) [1]. The treatment modalities are endoscopic realignment, laser urethrotomy, and end-to-end anastomosis. The laser urethrotomy has a low success rate of about 9% [2]. Delayed end-to-end anastomotic urethroplasty yields better results, but the recurrence rates are also significant. It is about 3.8% immediately and about 9.1% even 24 months after surgery [3]. Practising urologists most commonly prefer uroflowmetry after urethroplasty to detect stricture recurrence [4]. But how accurate is uroflowmetry as a surveillance tool in predicting the calibre of the urethral lumen after end-to-end anastomosis (EEA) urethroplasty done for PFUI? Is the maximum flow rate (Qmax) in the surveillance period a reliable surrogate for urethral calibre?

2. Materials and Methods

A prospective, single-blinded study was conducted from January 2017 to September 2022. The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Kovai Medical Center and Hospital, Coimbatore, India (EC/AP/882/01/2022) on 31 January 2022.

Inclusion criteria were all male patients who underwent end-to-end anastomotic urethroplasty for PFUI. Revision surgeries were also included in this study. Exclusion criteria were female sex and patients with concomitant urethral pathology, such as Balanitis Xerotica Obliterans (BXO). The study pro forma included uroflowmetry, urethroscopy, International Prostate Symptom Score (IPSS) score, and the quality of life because of urinary symptoms score. The same urologist performed urethroscopy throughout the study, who was blinded to the rest of the data, in particular the uroflowmetry result.

As per institute protocol, EEA urethroplasty patients were discharged with a per-urethral catheter and suprapubic catheter (SPC). The first follow-up visit was at 4 weeks, when the per-urethral catheter was removed, a voiding study and uroflowmetry were done, and the SPC was removed after reviewing the uroflowmetry results. The second follow-up was done at 6 months.

Parameters recorded during uroflowmetry included Qmax (maximum flow rate), Q average (average flow rate), voided volume, and residual volume. The maximum flow rates were rounded to the nearest whole number, and the voided volume was rounded to the nearest 10.

Qmax was divided into three categories: Qmax less than 10 mL/s (poor flow), 10 to 15 mL/s (intermediate/borderline), and more than 15 mL/s (normal). A volume of more than 150 mL was required for all patients. Uroflowmetry was repeated if the voided volume was less than 150 mL. In paediatric cases, the required voided volume was the calculated bladder capacity.

Post-void residual urine was recorded for all patients. It ranged from 0 to 170 mL.

Urethroscopy was done for all patients 6 months after surgery under local anaesthesia only, except those who needed analgesics too. In adults, a 14 Fr rigid cystoscope was used. In paediatric patients, eight Fr Cystoscopes were used. No attempt was made to enter the bladder, as the intention was only to assess urethral patency and avoid discomfort or pain to the patient.

Those patients who had undergone EEA urethroplasty at the time of conducting this study were followed up at 4 weeks with uroflowmetry (when catheter and SPC were removed). The second follow-up was at 6 months, when uroflowmetry and urethroscopy (after uroflowmetry) were performed, and their IPSS and quality of life (QoL) scores were evaluated. Patients who had undergone surgery before the commencement of the study were followed up with uroflowmetry, urethroscopy, IPSS, and QoL scores, and this data was considered as the 6-month post-surgery data. In these patients, uroflowmetry data collected 4 weeks after surgery were retrospectively analysed.

A urine culture was performed, and an appropriate antibiotic was administered just before the procedure. Urethroscopy was delayed in the presence of an active urinary tract infection (UTI) and performed after the infection resolved. Parameters recorded at Urethroscopy were: (a) Scope easily passable or not. (b) Any area of pallor, necrosis, rigidity or distortion at the site of anastomosis.

Statistical analysis was carried out using SPSS software, version 29 and Social Science Statistics. p values less than 0.05 were considered significant. For statistical analysis, data were entered into a Microsoft Excel spreadsheet. The categorical variables were analysed using the Pearson chi-square test. Statistical analysis was carried out using social science statistics. A p-value of <0.05 was considered statistically significant.

3. Results

In total, 26 patients were included in this study, aged 13 to 56 years. The mean age was 32 and the mean body mass index (BMI) was 23. Two patients had diabetes, and ten patients were smokers. Five patients were referred for surgery and were considered failed cases. Three patients had earlier undergone internal fixation for pelvic fracture, and the remaining 23 were treated conservatively for the fracture. Most of the patients had a pubic rami fracture. Six patients had sacral fractures. Three patients had pubic diastasis, and one patient had a bladder neck injury.

Four weeks after surgery, when the per-urethral catheter was removed, uroflowmetry was done. All the patterns were either bell-shaped or delayed. The maximum flow rate (Maximum Flowrate at 1 month [Qmax1mo]) ranged from 4 to 32 mL/s, with a mean and median of 19 mL/s. At the second visit (at least 6 months after surgery), the maximum flow rate ranged from 9 to 32 mL/s, with a mean of 19 mL/s and a median of 19. The difference between Qmax1mo and Maximum flow rate at or after 6 months (Qmax6mo) was not significant (p-value = 0.345).

The IPSS score was evaluated for all 26 patients: 22 had scores <7 (Mild lower urinary tract symptoms [LUTS]), 3 had scores 8–19 (moderate LUTS), and 1 had a score >20 (severe LUTS). This has been shown in

Table 1. Number of Patients with mild, moderate and severe LUTS.

Mild LUTS	22
Moderate LUTS	3
Severe LUTS	1

LUTS: lower urinary tract symptoms.

.

The quality of life due to urinary symptoms was evaluated in all patients.

Table 2. Quality Of Life Due To Urinary Symptoms.

Patient’s Response	Number of Patients
Delighted	18
Pleased	1
Mostly Satisfied	4
Mixed—About Equally Satisfied and dissatisfied	1
Mostly dissatisfied	1
Unhappy	1
Terrible	0

shows the results. Eighteen patients said they were delighted, 1 patient said he was pleased, 4 patients said they were mostly satisfied, 1 had a mixed response, 1 was mostly dissatisfied, and 1 was unhappy.

Urethroscopy was done for all 26 patients by the same urologist throughout the study. He was blinded to the rest of the data. His urethroscopy report was that all 26 patients had easily passable, patent urethrae with healthy anastomotic sites after at least 6 months of surgery.

Analysis

After obtaining the results, the data were analysed and interpreted. The maximum flow rates at 1 month were divided into three categories: less than 10 mL/s, 10 to 15 mL/s, and more than 15 mL/s. After 1 month, uroflowmetry showed that 4 patients had poor flow, 2 had borderline flow, and 20 had normal flow (

Table 3. Number Of Patients With Poor, Borderline and Normal Flowrate at 1 Month.

Qmax1mo	Number of Patients
<10 mL/s (poor flow rate)	4
10 to 15 mL/s (borderline flow rate)	2
>15 mL/s (normal flow rate)	20

Qmax1mo: Maximum Flowrate at 1 month.

).

Uroflowmetry performed after 6 months (Qmax6mo) showed that 1 patient had poor flow, 7 patients had borderline flow, and 18 patients had normal flow. Here, we see that despite normal urethroscopy findings, the number of patients with borderline flow rates increased (

Table 4. Number of Patients With poor, Borderline and Normal Flowrate at 6 Months.

Qmax6mo	Number of Patients
Less than 10 mL/s (poor flow rate)	1
10 to 15 mL/s (borderline flow rate)	7
More than 15 mL/s (normal flow rate)	18

Qmax6mo: Maximum flow rate at or after 6 months.

).

In Table 4, four patients with Qmax1mo <10 mL/s and two patients with Qmax1mo between 10 and 15 mL/s showed an increase in peak flow rates 6 months after surgery.

Table 5. Comparison Of Maximum Flowrates At 1 Month And 6 Months of Patients Who Showed Subsequent Increase In Flowrate At 6 Months.

Qmax1mo (mL/s)	Qmax6mo (mL/s)
7	13
7	13
4	32
9	15
13	28
11	22

Qmax1mo: Maximum Flowrate at 1 month; Qmax6mo: Maximum flow rate at or after 6 months.

compares peak flow rates at 1 month and 6 months.

There was a weak negative correlation between age and maximum flow rate after 6 months of surgery (Qmax6mo), with a Pearson’s correlation coefficient of −0.085. Figure 1 shown below is a line fit plot with age on the X axis and Qmax6mo on the Y axis.

Among 26 patients, 11 showed a subsequent decrease in maximum flow rates (i.e., their maximum flow rates at the second follow-up were lower than at the time of first follow-up). On applying the Student t-test, the difference was statistically significant (p-value = 0.011; p-value < 0.05 is significant). Although the fall in the maximum flow rate was statistically significant, urethroscopy showed that all 11 had normal, easily passable urethrae with a healthy anastomotic site. The table below lists the maximum flow rates for these patients at 4 weeks and 6 months, along with their urethroscopy findings.

As mentioned earlier, it was observed that out of 26 patients, one patient had poor and seven had borderline maximum flow rates 6 months after surgery. Even though the flow rates were lower, these patients had normal, easily passable urethrae, and the QoLs of five patients were satisfactory; one had mixed reactions, and two patients were unsatisfied.

In total, 22 patients out of 26 (84.6%) had mild LUTS, including 14 (53.8%) who were asymptomatic and had an IPSS score of 0. Patients were mostly satisfied with their urine flow. A total of 23 patients (88.4%) had a satisfactory response to the quality of life question regarding urinary symptoms.

We compared the IPSS and quality of life scores. We applied Pearson’s correlation test. The R value was 0.3442, which meant a positive correlation. The p-value was 0.085, which was not significant (p < 0.05 is significant), suggesting that the IPSS score and quality of life due to urinary symptoms were not independent and showed a positive correlation. Figure 2 shows the line-fit plot for Pearson’s correlation mentioned above. Here, the X axis is the IPSS score, and the Y axis is the QoL score.

The Pearson correlation coefficient between QoL and maximum flow rate was calculated. The R value was −0.5383, suggesting a strong negative correlation. Figure 3 shows the line fit plot with QoL on the X axis and Qmax6mo on the Y axis.

Among 26 patients, 18 were delighted with their urine flow, 1 was pleased, 4 were mostly satisfied, 1 had mixed reactions, 1 was mostly dissatisfied, and one was unhappy. This is shown in Figure 4.

We analysed the quality of life of patients with Qmax6mo <10 mL/s and 10–15 mL/s. Six months after surgery, 8 patients had a peak flow rate of less than 15 mL/s, 5 were satisfied with their urine flow (QoL 0–2), 1 had mixed reactions (QoL 3), and 2 patients were dissatisfied (QoL 4 and 5). This has been shown graphically in Figure 5.

The urologist, performing urethroscopy, was blinded. His conclusion at the end of the study was that all 26 patients (100%) had normal urethrae with easily passable anastomotic sites. The investigators analysing the flow rates and other data were also blinded to the urethroscopy findings. They concluded that, out of 26 patients, 1 had poor, 7 had borderline, and 18 had normal maximum flow rates 6 months after surgery. Figure 6 shows the number of patients considered “Normal” by the urologist performing urethroscopy and by the investigators assessing uroflowmetry and maximum flow rate.

4. Discussion

Uroflowmetry is a common test performed during follow-up after EEA urethroplasty for PFUI. The advantage is that it is a non-invasive test. While most urologists use uroflowmetry, it alone does not appear to be a reliable test for recurrence of strictures [5]. This could be attributed to concomitant bladder pathologies or post-surgical periurethral adhesions, which may result in abnormal uroflowmetry patterns or flow rates. One or two tests may not accurately reflect the maximum flow rate. Multiple uroflowmetry measurements are most reliable for accurate assessment [6]. Quality control is another pertinent requirement that affects the outcome of uroflowmetry results. Environmental factors can significantly affect voiding outcomes.

In a seminal paper, Smith demonstrated that the urethral calibre must be less than 11 Fr with a normally functioning bladder before the urine flow rate is diminished. It is only when the urethral calibre is reduced to 11 Fr that the patient begins to experience LUTS during voiding [7]. This suggests that uroflowmetry may be normal at a given point in time, but the patient may develop symptoms later and should therefore be kept on prolonged follow-up. Each follow-up visit is an economic burden.

In this study, we set the follow-up period at 6 months, based on the work of Andrich and Mundy, in which patients with normal flow and urethrogram 6 months after surgery (end-to-end anastomotic urethroplasty for PFUI) rarely deteriorated. The literature suggests that if the initial post-catheter removal flow is good, it usually does not deteriorate over time, and evaluation at 3 months is needed to identify at-risk patients [8].

In our study, we observed that the maximum flow rates were inconsistent across the two visits. Some patients had decreased, and some had increased maximum flow rates during the second visit. Regardless of the maximum flow rate, urethroscopy in all patients was normal. Patients with poor flow rates and borderline flow rates had easily passable urethrae. As expected, there was a positive correlation between the IPSS and QoL scores, and a strong negative correlation between QoLs and maximum flow rates. There was a notable disparity between the conclusions drawn by the urologist performing urethroscopy and those of the investigators analysing flow rates and other data: the former concluded normal results in all 26 patients, whereas the latter found normal results in 18 of 26 patients, with the remaining eight patients having poor/borderline flow rates.

The images below show urethroscopy findings from two patients. Though peak flow rates were 9 mL/s and 16 mL/s, respectively, the anastomotic sites were easily passable with a 14 Fr integrated cystoscope. Figure 7 shows the urethroscopy image showing the anastomotic site of the patient with maximum flowrate of 9 mL/s at 6 months. Figure 8 is the urethroscopy image showing the anastomotic site of the patient with maximum flowrate of 16 mL/s.

A limitation of this study is the small sample size, as it was conducted during the pandemic.

5. Conclusions

Based on our study, we conclude that any patient with a borderline or poor urinary flow rate should undergo urethroscopy. Urethroscopy enables direct visualisation of the anastomotic site in PFUI cases who have undergone EEA urethroplasty and provides more detailed information than uroflowmetry. The maximum flow rate alone cannot serve as a surrogate for anatomical success. While a Qmax >15 mL/s is a sign of a patent urethra, importantly, a flow rate <15 mL/s does not always indicate re-stricture. Quality of life is an important tool for evaluation. We advocate for routine urethroscopy at 6 months after surgery to look for urethral patency and reduce the number of follow-up visits.