Hypothesis / aims of study
Lower urinary tract symptom (LUTS) is one of the most common problems in aging men, which is usually suggestive of benign prostatic hyperplasia (BPH). The total prostate volume (TPV) has no remarkable association with the severity of LUTS. Prostatic urethral angle (PUA) has been suggested to significantly associate with male LUTS. However, the correlation between LUTS severity and other anatomical prostatic factors in men with small prostate volume have not yet been investigated. Hence we used VUDS to investigate the relationship between the PUA and Bladder outlet obstruction (BOO) in men with LUTS and small prostate volume.
Study design, materials and methods
This is a single center study and we retrospectively obtained the medical records of first-visit male patients with LUTS from January 2019 to October 2022. A total of 158 male patients were enrolled. To access prostatic anatomical factors, all of them received transrectal ultrasound scan by a single urologist (Fig. 1). The TPV and transitional zone volume (TZV) were measured using the ellipse formula. Patients with a TPV=40 mL or less was included. TZI was calculated according to the formula of TZV divided by TPV. Intravesical prostate protrusion (IPP) was measured from the tip of the protruding prostate into the bladder to the circumference at the prostate base in the sagittal plane. PUA was defined as the angle formed by the proximal and distal prostatic urethra on the mid-sagittal plane image. The International Prostate Symptom Score (IPSS) of the patients were also recorded during the medical history taking. Uroflowmetry and bladder sonography were also performed to record the maximum flow rate (Qmax), void volume (VV) and post-void residual volume (PVR). Patients were excluded if they had any neurological disease, uncontrolled diabetes mellitus, history of prostate surgery or urethral stricture, malignant disease such as prostate cancer, and cognitive disorder or impaired verbal communication. Patients who had already taken alpha blockers or active urinary tract inflammation were also not included.
Results
The mean age was 68.4 ± 9.6 years. There are 30.6% of patients have benign prostate obstruction (BPO) and 36.9% had bladder neck dysfunction (BND). The mean PUA was 26.2±19.1 and IPP was 0.33±0.60 cm. Qmax was significantly lower in patients with BPO (p=0.026). The TPV, TZI, PUA, IPP, Pdet and BOOI are higher in patients with BPO. The cQmax is significantly higher in patients without BND (p=0.020). In patients with PUA ≥ 20, they have significant higher TPV, TZI, IPP, Pdet, BOOI and lower Qmax and cQmax. In ROC analysis, the patients with TPV ≤ 30 mL, the area under the curve using the PUA was 0.622 [95% CI, 0.485-0.659]. Using 20.0 degree as the cut-off value, the sensitivity and specificity for predicting the presence of BND reached 50.0% and 63.1%, respectively. The area under the curve (AUC) using the PUA was 0.783 [95% CI, 0.469-0.762]. Using 15.0 degree as the cut-off value, the sensitivity and specificity for predicting the presence of BPO reached 75.0% and 53.5%. In patients with TPV≤40 mL, the area under the curve using the PUA was 0.560 [95% CI, 0.489-0.632]. Using 20.0 degree as the cut-off value, the sensitivity and specificity for predicting the presence of BND reached 58.7% and 55.7%, respectively. The area under the curve using the PUA was 0.638 [95% CI, 0.552-0.724]. Using 15.0 degree as the cut-off value, the sensitivity and specificity for predicting the presence of BPO reached 83.3% and 47.0%.
Interpretation of results
The PUA may have a role in diagnosis of bladder outlet obstruction, including bladder neck dysfunction and benign prostate obstruction in men with LUTS and small prostate volume, as well as providing a cut-off value, sensitivity and specificity. It may be an important clinical factor in male LUTS management.