Purpose: To prospectively compare the diagnostic accuracy of intravesical prostatic
protrusion (IPP), detrusor wall thickness (DWT), prostate volume (PV) and serum prostate specific
antigen (PSA) levels for detecting bladder outlet obstruction (BOO) and predicting acute urinary
retention (AUR) secondary to benign prostatic obstruction.
Patients and methods: In all, 135 men who presented with lower urinary tract symptoms due to
benign prostatic enlargement were enrolled in the study; among them, 50 presented with AUR. Thirty
normal men in the same age group were included and represented a control group for normative data.
Their evaluation included a digital rectal examination, International Prostate Symptom Score and
quality-of-life question, uroflowmetry and serum total PSA assay. Transabdominal ultrasonography
was used to measure the PV, IPP DWT and post-void residual urine volume. Pressure-flow urodynamic
studies were used as the reference standard test for BOO, differentiating obstructed from unobstructed
bladders. DWT, IPP, PV and total PSA level served as index tests. To compare the usefulnessof the various indices, the area under the curve (AUC) of receiver-operator characteristic curves was
calculated for each index.
Results: According to presentation and urodynamic studies, patients were classified into three
groups: Group 1 (no BOO), 50 patients with a BOO index (BOOI) of 40; and group 3 (AUR), 50 who presented with AUR. The IPP, DWT, PV and PSA
levels differed significantly between obstructed and unobstructed patients, with a significant
correlation with the BOOI. The AUC for IPP, DWT, PSA and PV were 0.885, 0.783, 0.745 and
0.678, respectively. The IPP threshold at 8 mm provided the best diagnostic accuracy (80%) for
detecting BOO, followed by combined DWT and IPP (77.6%). Between patients with and without
AUR, there was a highly significant difference in IPP, DWT and PSA; a combined IPP threshold
of >8 mm and DWT >2 mm detected AUR in 45 of 50 patients (90%).
Conclusion: All four noninvasive indices were correlated significantly with BOOI. The IPP as a single
variable and combined with DWT predicted BOO and AUR better than PSA or PV. |
