Adequate Urethral Diameter Post-TURP for Normal Urinary Flow
The adequate urethral diameter post-Transurethral Resection of the Prostate (TURP) should be sufficient to allow for a maximum flow rate (Qmax) of at least 15 ml/sec, which typically corresponds to a well-resected prostatic urethra without stricture formation.
Urethral Patency Post-TURP
- TURP remains the gold standard surgical treatment for lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) for prostates between 30-80 ml in size 1
- A successful TURP should result in a significant improvement in maximum flow rate (Qmax), with post-operative values typically exceeding 10 ml/sec and ideally reaching 15 ml/sec or higher 1
- Urethral stricture is a well-known complication after TURP, with incidence rates varying between 2.2% and 9.8%, which can significantly impact urethral diameter and flow 2
Factors Affecting Post-TURP Urethral Diameter
- The size of the resectoscope used during TURP can influence the risk of urethral stricture formation, with larger instruments potentially causing more urethral trauma 1
- Most post-TURP strictures develop within 6 months of the procedure and present with poor flow, urinary tract infections, or acute retention 2
- Bladder neck contracture (BNC) is a specific complication that can reduce effective urethral diameter post-TURP, particularly at the bladder neck region 1
Assessment of Adequate Urethral Diameter
- Cystoscopy is superior to urethrography for evaluating post-TURP strictures, allowing direct visualization of the urethral lumen and immediate intervention if needed 3
- Uroflowmetry is an essential tool for assessing the functional outcome of TURP, with maximum flow rate (Qmax) serving as a proxy for adequate urethral diameter 1
- A post-TURP Qmax greater than 15 ml/sec generally indicates adequate urethral diameter and successful relief of obstruction 1, 4
Complications Affecting Urethral Diameter
- Urethral strictures post-TURP are often short (up to 10 mm) and can be treated during diagnostic cystoscopy 3
- Bladder neck contracture/stricture is another potential complication that can reduce effective urethral diameter and requires specific management 1
- Patients with detrusor underactivity may show less improvement in Qmax despite adequate urethral diameter post-TURP, highlighting the importance of considering bladder function when evaluating outcomes 4
Special Considerations
- For patients with a history of TURP who require repeat endoscopic procedures, special attention should be paid to the prostatic urethra to avoid further trauma 1
- In patients undergoing TURP for advanced prostate cancer (palliative TURP), the risk of postoperative urinary retention and need for reoperation is higher than in patients with BPH, which may affect long-term urethral patency 5
- The trend toward performing TURP in older patients with higher ASA grades may influence outcomes, including urethral patency and flow rates 6
Management of Inadequate Urethral Diameter
- For post-TURP urethral strictures, buccal mucosa graft urethroplasty offers a high success rate (82.4%) and should be considered over repeated dilations or internal urethrotomy 2
- Ventral approach urethroplasty is best suited for proximal bulbar strictures close to the membranous urethra 2
- Early identification and management of strictures is crucial to prevent long-term complications and maintain adequate urethral diameter 3