BPH with lower urinary tract symptoms is a common problem in older males. TURP is still considered the gold standard surgical treatment, and ThuP and Holmium laser enucleation of prostate (Holep) have recently been incorporated into national and international guidelines due to their noninferior efficacy and safety.8 BNC is a common postoperative complication that typically occurs early within the first 2 years post-operation.9 A meta-analysis reported that the incidence of BNC was 2%.10 Another study showed that TURP resulted in BNC rates between 1% and 12.3%.2 The incidence of BNC reported after ThuP ranges from 0 to 2.4%.11-13 The incidence of BNC after Holep is between 1.3 and 2.1%. 14-16 Our study results were comparable with these previous studies as the incidence of BNC was 1.5% after TURP and 1.6% after ThuP. No significant difference was observed in the incidence of BNC between TURP and ThuP.
BNC after prostate surgery is a well-known complication but its underlying cause is not well understood. Many risk factors, including small prostate volume, higher International Prostate Symptom Score storage scores, preoperative uncontrolled infection, unsuitable resectoscope, large resection loop, extensive resection of the bladder neck, long operative time and postoperative Foley insertion have been shown to be associated with the risk of BNC. 7,9 The most reported risk factor is small prostate volume with over-resection of the bladder neck. Over-resection of the bladder neck can lead to fibrosis or scarring of the bladder neck, which in turn leads to BNC. Chiu et al reported that the incidence of BNC increased to 16% in patients with a prostate volume <20 g. 17 Our study showed that a prostate volume <42.9cm3 had a higher rate of BNC. Qian et al. reported thulium laser enucleation significantly reduce the risk of BNC in small prostate less than 30g due to no thermal injury to the bladder neck.18 The present study showed that small prostate volume, low weight of prostate resected, short operative time and low resection speed are risk factors for BNC. Low volume of prostate resected and short operative time were positively correlated with small prostate volume. Resection speed is a better parameter as it adjusts for resected prostate weight and operative time. Slow resection speed was correlated with unfavorable surgical processes, such as hemorrhage, poor endoscopic vision, prolonged operative time and perforation of the prostatic fossa or bladder neck. In these cases, more meticulate and extensive hemostasis using a bipolar resection loop or thulium laser fiber will likely be performed and this can lead to a higher chance of thermal injury of the bladder neck, which increases the risk of bladder neck scarring.
We hypothesized that preoperative comorbidities are potential risk factors for BNC. Microvascular disease may be associated with BNC due to poor healing and local ischemia.19 Development of microvascular disease, such as diabetes mellitus, coronary artery disease, cerebrovascular disease, hypertension and chronic kidney disease could theoretically alter the microvascular blood supply in the bladder neck, and accompanied by local ischemia and the wounds caused by TURP or ThuP, could lead to scar formation. In the current study, chronic kidney disease (p<0.05), coronary artery disease (p<0.05) and cerebrovascular accidents (p<0.05) were associated with increasead BNC risk. In addition, the presence of ≥2 comorbidities was a significant risk factor (p<0.05) and 3.2 for BNC, which could indicate that there is a correlation between microvascular disease and BNC.
A prophylactic incision of the bladder neck using a bipolar loop or laser at the end of surgery, may reduce the incidence of BNC.7 Incision of the bladder neck by laser is preferred. 20 Dysuria is the primary symptom of BNC, and a positive diagnosis is confirmed by cystoscopy. Urethral dilation is a potential management tool for BNC but repeat urethral dilation due to recurrent BNC was observed in 90% of patients in the first two years.21 BNC is managed by bladder neck incision, which has a 72% success rate. 22 In our study, 62 patients with BNC received bladder neck incision via bipolar instruments and there was no recurrence of BNC. Refractory BNC presents as recurrent dysuria in a short time and may require repeat bladder neck incision. Another technique combines bladder neck incision with a transurethral irrigation agent or transurethral injection of a cytotoxic agent. Eltahawy et al. reported an 83% success rate for the combination of bladder neck incision via Holmium laser and irrigation with triamcinolone, while Redshaw et al. showed a 75% success rate for bladder neck incision using a cold-knife and transurethral injection of mitomycin C. 23,24
This study had several limitations. First, we did not use the International Prostate Symptom Score as a parameter in the study due to incomplete medical records. Preoperative Foley status and maximal flow rates were not significant different between the BNC and NBNC patients (p>0.05). Second, it was a single center, retrospective study, the number of patients was small and selection bias would be existent. Third, some patients were lost to follow-up years after TURP or ThuP, which could lead to an underestimation of the BNC incidence rates. There were the same size of resectoscope, resection loop and energy settings, no previous endourological interventions and all patients were age-and operation-matched, all of which minimized bias in the present study.
Our study demonstrated that the incidence was the same in TUPR and ThuP and low prostate volume, low resection speed and the presence of ≥2 comorbidities were positively correlated with the development of BNC after TURP or ThuP. A small prostate volume less than <42.9cm3 had a higher rate of BNC. However, larger studies are needed to verify these results. Our study may serve as reference for clinical urologists and our results can be used during the explanation of BNC risks before surgery.