Year : 2012 | Volume
: 28 | Issue : 3 | Page : 368--369
Can urethral ultrasonography replace retrograde urethrogram to detect failure after buccal mucosal graft urethroplasty?
|How to cite this article:|
Mandal S. Can urethral ultrasonography replace retrograde urethrogram to detect failure after buccal mucosal graft urethroplasty?.Indian J Urol 2012;28:368-369
|How to cite this URL:|
Mandal S. Can urethral ultrasonography replace retrograde urethrogram to detect failure after buccal mucosal graft urethroplasty?. Indian J Urol [serial online] 2012 [cited 2019 Jul 19 ];28:368-369
Available from: http://www.indianjurol.com/text.asp?2012/28/3/368/102734
Retrograde urethrogram (RGU) is considered as the gold standard to diagnose urethral stricture and therefore is also used in follow up to document failure after urethroplasty. However, RGU is invasive, costly, and difficult to perform, exposes men to radiation and has complications like urinary infection.
The authors in this retrospective study used a novel algorithm consisting of urethral ultrasonography (USG), uroflowmetry and international prostate symptom score (IPSS) assessment to accurately define postoperative success and compared it with RGU. Strictures were bulbar in 39, penile in 4, and combined in 6 patients. Mean stricture length was 3.8 cm. All patients underwent buccal mucosal graft urethroplasty (BMGU). At a mean follow-up of 35 months, 4 out of 45 developed recurrence. Follow-up included three-monthly uroflowmetry (maximum flow rate, voiding curve shape and voided volume), post-void residual urine volume (PVRU) estimation and IPSS and six-monthly USG (using 7.5-MHz transducer) and RGU. A maximum diameter of 3 mm or less was considered as stricture recurrence on USG. Results of patients without recurrent stricture were compared with those with recurrent disease.
Uroflowmetry, PVRU, IPSS were significantly different among recurrent and normal patients. USG showed a mean diameter of 7.6 mm (range 5-13) in bulbar grafts and a mean diameter of 4.6 mm (range 4-6) in penile grafts in men without recurrence. In patients with recurrence (n=4), USG yielded significantly smaller mean urethral diameter of 2.3 (range 2-3) mm (penile strictures 2 mm each, bulbar strictures 2.2 mm and 3 mm). RGU confirmed recurrence in all these cases. Thus, USG alone was able to detect stricture recurrence in 100% of cases. USG yielded a greater stricture length compared with RGU (1.1 cm vs 0.5 cm, P<0.024). In three patients with recurrent strictures, a short flimsy stricture was found at the anastomotic area and was treated by a single direct vision internal urethrotomy. They had a mean stricture length of 0.8 cm (range 0.5-1) in USG. One patient with a 2-cm recurrent stricture (USG) underwent BMGU again. Therefore, respective success rates were 92% after BMGU alone and 98% after single urethrotomy. None of the functional analysis or questionnaire items alone were able to reliably define patients with postoperative success or failure. However, the addition of USG allowed for the correct determination of the postoperative status in all patients. In this cohort, the proposed algorithm yielded a positive and negative predictive value of 100% compared with RGU.
With increasing success in urethral reconstructive surgery with BMGU, there is ongoing debate about the ideal follow-up regimen in this set of patients. In the era of cost conscious, minimally invasive medicine, the role of routine RGU has been questioned. Variations in patient positioning and penile traction during injection of contrast medium can greatly alter the radiographic appearance of stenotic areas in RGU.  During standard retrograde urethrography, the pelvis is aligned obliquely with respect to the anteroposterior X-ray beam and the bulbar portion of the urethra is fixed in the same axis as the pelvis. As a result, the radiographic image is an "end on" view, which reduces apparent stricture length. Uroflowmetry alone was not a suf=icient tool to screen for recurrence, especially when only the maximum flow rate was used. Voiding curve data were more helpful, with 93% sensitivity and 84% specificity.  Monitoring voiding symptoms should be an integral part of any follow-up protocol because 85% of patients are symptomatic at the time of recurrence. Widespread availability of new generation, high-resolution scanners makes urethral ultrasound accessible and practical for imaging. Because the ultrasound unit is portable, repeat real-time assessments of questionable areas can be easily performed. Nevertheless, ultrasound has been criticized for its inherent interobserver and intraobserver variability. However, recent studies using modern ultrasound machines have shown that the reproducibility of urethral ultrasound findings is as high as 90%.  The widespread availability of high frequency transducers being used for scrotal ultrasound contributes to a significant cost reduction of USG compared with standard RGU. Moreover, USG is easy to learn and can be done by the urologist.  In the follow-up of BMGU, USG was able to detect all cases of stricture recurrence as confirmed by standard RGU and was helpful to plan the procedure of choice for redo surgery. Although it remains to be seen whether sonographic assessment of urethral vascular anatomy is clinically important, further investigation with color Doppler may be useful to assess vascularity before grafting procedures. 
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