Studies demonstrate predictive value of intravesical prostatic protrusion.
Intravesical prostatic protrusion (IPP) is a useful predictor of outcomes in patients with BPH, studies show.

In one study, researchers at the Western General Hospital in Edin-burgh, UK, demonstrated that IPP is superior to prostate volume in predicting the outcome of trial without catheter (TWOC) in men presenting with acute urinary retention (AUR). The investigators, led by Paramananthan Mariappan, MD, found that men with IPP greater than 10 mm are more likely to fail TWOC.

In addition, South Korean investigators showed that IPP predicts bladder outlet obstruction in BPH patients, and a team in Singapore found that men with good urinary flow can be urodynamically obstructed by IPP, but that a high IPP grade increases the likelihood of outlet obstruction.

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The Edinburgh study looked at 54 men with BPH-related AUR (mean age 70 years) receiving alpha blockers for AUR. The patients’ mean prostate volume and IPP were 69.7 mL and 12.8 mm, respectively. The investigators measured IPP with standard transrectal ultrasonography (TRUS).

Of the 54 men, 22 (40.7%) had a successful TWOC, Dr. Mariappan reported. His team observed no association between TWOC outcome and age, retention volume, or whether AUR had been spontaneous or precipitated. Mean IPP was sig-nificantly smaller in those who had a successful TWOC compared with those who did not (7.6 vs. 16.5 mm).

An unsuccessful TWOC was defined as inability to void or a voiding ef-ficiency [voided volume/(voided volume + post-void residual volume)] less than 50%. Mean prostate volume also was smaller in men with a successful TWOC, but ROC curve analysis showed that this was a weaker predictor of TWOC outcome. Men with an IPP greater than 10 mm had an 80% risk of unsuccessful TWOC (a sixfold higher risk compared with those with an IPP less than 10 mm).

Dr. Mariappan told listeners that in men with IPP greater than 10 mm,“It may be reasonable to avoid a trial without catheter and go straight for surgery.”
The South Korean study, by Seong Jin Jeong, MD, and his colleagues at Seoul National University Hospital, included 379 patients who had a mean of 64.2 years. Their mean International Prostate Symptom Score was 16.2. The men had a mean PSA level of 2.4 ng/mL, prostate volume of 40 mL, maximum flow rate of 13.4 mL/sec, and residual urine volume of 37.8 mL. The mean IPP, as measured by TRUS, was 4.7 mm.
Dr. Jeong’s group divided patients into three groups based on IPP (Group 1 = less than 5 mm; group 2 = 5 mm and higher but lower than 10 mm; group 3 = 10 mm and greater). For groups 1, 2, and 3, the mean Abrams-Griffiths numbers were 25.2, 37.2, and 79, respectively. Residual volumes also predicted bladder outlet obstruction; the volumes for the three groups were 21.5, 47.2, and 129.6 mL, respectively.
The third study, by Henry Ho, MD, and his group at Singapore General Hospital, included 57 men older than 50 years (mean 65.5 years) and who had good urinary flow, defined as a maximum greater than 12 mL/sec. The researchers graded IPP as follows: grade 1 = less than 5 mm; grade 2 = 5-10 mm; grade 3 = greater than 10 mm. Dr. Ho’s team observed grade 1 IPP in 20 men, grade 2 IPP in 20 men, and grade 3 in 17.
Of the men with grade 1 IPP, only three were obstructed. Among men with grade IPP 3, 11 were obstructed.