When using flexible cystoscopy for visualization, the bladder should be moderately filled owing to the necessity for sufficient space within which to bend the cystoscope. Therefore, we believe that IPP detection by cystoscopy is less influenced by the degree of bladder filling than is IPP evaluation via US [7
]. We demonstrated here that PVP was an effective therapy for BPH patients with or without IPP. Improvement of the IPSS obstructive subscore was much higher in the IPP group than in the no IPP group during early (<3 months) postoperative follow-up. However, the superiority of the improvement in the IPP group was not sustained at a relatively late period (postoperative month 6). This might be because the elimination of a protruding mass in the bladder neck may have a greater effect on early improvement of voiding symptoms than the release of luminal compression of the prostatic urethra. Therefore, patients with IPP experience early improvement because of the elimination of IPP. According to a long-term study [8
], significant improvement of obstructive symptoms after PVP was shown at months 1 and 6. Relatively more symptoms of discomfort were noted in patients with IPP than in those without IPP.
Despite the significantly lower preoperative Qmax in the IPP group, PVP resulted in marked improvement in both groups, with flow rates at the 6 months follow-up even greater in the IPP group than in the no IPP group. This finding might be due to delayed degradation of luminal compressed tissue. However, this possibility should be confirmed with further large-scale controlled studies.
Several studies have investigated the prevalence of IPP in BPH. Chia et al. [1
] showed a positive correlation between IPP and BOO. They graded IPP in enrolled patients by using US and correlated these findings with urine pressure flow studies. The results showed that a higher grade of IPP correlated with a higher BOO index. Keqin et al. [9
] also reported that IPP was a useful predictor of BOO and of detrusor muscle function. Lee et al. [3
] argued that a higher IPP grade is associated with a higher risk of clinical progression of BPH. In that retrospective analysis of 259 men, IPP was graded as 1 (up to 5 mm protrusion), 2 (5 to 10 mm), or 3 (greater than 10 mm). With the use of predefined definitions of disease progression, including a deterioration of four points on the IPSS or an increased PVR of greater than 100 mL, the odds ratio of disease progression of a grade 3 protrusion was significantly higher than that of a grade 2 protrusion. Mariappan et al. [10
] reported that a BPH trial without catheterization is more likely to fail in patients with an IPP larger than 10 mm.
Most prior studies, including those cited here, evaluated IPP by using abdominal US because of its noninvasive ability to identify intravesical anatomy. However, abdominal US has limited reliability in finding IPP and is highly operator-dependent. The degree of bladder filling also affects the accurate evaluation of IPP by use of US. Reliability is best when viewing a comfortably full bladder (-200 mL). When the bladder is overdistended (>400 mL), the prostate recedes below the pubic symphysis and is difficult to image correctly by US. In contrast, too little urine in the bladder (i.e., <100 mL) tends to result in overestimation of IPP [7
]. Therefore, US findings tend to be subjective rather than definitive because of the difficulty of standardizing US procedures and the variability in patient bladder status.
Flexible cystoscopy is a reliable procedure for evaluation of the whole urethra and bladder at the same time. Although flexible cystoscopy is more invasive than US, some researchers have reported various methods for minimizing patient pain during the procedure, such as viewing the monitor and increasing hydrostatic pressure (the "bag squeeze" technique) [11
]. Abdominal US is a noninvasive modality for the identification of vesical anatomy during optimal bladder filling. However, abdominal US cannot directly identify infravesical anatomical obstructions such as urethral obstruction or the degree of "kissing" of the prostate lateral lobes. Therefore, US can initially be useful in evaluating a patient with voiding difficulty, but this method is not ideal for following up patients who do not improve with optimal medical management for obstructive symptoms.
The PVP procedure is an effective treatment modality to manage a moderately enlarged prostate. Alexis et al reported that PVP was effective for long-term (12-month) improvement of obstruction secondary to BPH in 139 patients who had a mean prostate mass of 54.6 g [13
]. Lukacs et al. [14
] reported the superiority of PVP over transurethral resection of the prostate (TURP) in reducing the length of hospital stay and in improving uroflowmetry parameters. Complication rates were comparable between PVP and TURP in this multicenter prospective trial. On the basis of their meta-analysis results, Zhang et al. [15
] reported that PVP and TURP provide comparable functional improvements, including lowering the IPSS and increasing the Qmax, at the 6-, 12-, and 24 months follow-ups. Korean researchers have confirmed that PVP is an effective modality for removing obstructive prostate tissue, including a protruding median lobe [16
Long-term medical therapy for BPH has shown good efficacy and evidence of decreasing disease progression in several studies, including the MTOPS, ALTESS, CombAT, and ALF-ONE trials. However, in real clinical practice, some BPH patients are unresponsive after several months of medical treatment and require reevaluation and individually tailored disease management [17
]. Therefore, to identify patients who require surgical correction for BPH, early evaluation of the status of the urethra and bladder by use of accurate and reliable diagnostic methods, such as flexible cystoscopy, is needed. Additionally, flexible cystoscopy is less invasive and causes less patient discomfort than does conventional rigid cystoscopy. When appropriate medical therapy over a period of months does not result in symptom improvement in BPH patients, we recommend flexible cystoscopy to confirm whether lateral lobe "kissing" or median lobe protrusion exists, which would be indications for surgical correction.
A limitation of this study is that we did not investigate the effect of more than 3 months of sustained medical therapy on BPH patients with IPP. To confirm the superiority of early intervention with flexible cystoscopy and PVP, comparative studies with extended medical therapy should be performed.