Significance and clinical value of the transitional zone volume (TZV) or index (TZI) in assessing the degree of lower urinary tract obstruction: Revisited

Abstract

Introduction: A lot of diagnostic tools are present for assessing the degree of LUTs. Pressure-flow studies are invasive and cannot be justified in all patients suffering from LUTs. From here came the clinical importance of searching for another clinical tool, to help in assessing the degree of LUTS.

Objective: The aim of this work was to evaluate the significance and clinical value of the TZI, which has been a point of debate over the last decade.

Patients and methods: Between November 2011 and November 2012, sixty-two male patients above the age of 45 years were included in the study. They were divided into 3 groups (obstructed, retention and control groups). Assessment included IPSS, physical examination, DRE, labs, uroflowmetry, pressure flow studies, TRUS and a pelvic ultrasound for PVR. The transitional zone index (TZI) was calculated as being the transitional zone volume/whole gland volume ratio of the prostate. The whole gland volume, adenoma volume and TZI were compared in each group to each specific symptom, total IPSS, PSA, PdetQmax and Qmax.

Results: No statistically significant correlation was found between the IPSS and the volume measurements, whether between the IPSS and whole gland volume or the IPSS and the TZV or TZI in the obstructed group and the control group. However, when dividing patients according to their TZI into two groups utilizing a TZI of 0.5 as a cutoff value, a possibility existed that patients might be more accurately classified into obstructed and non-obstructed.

Conclusion: Estimating the transition zone volume during TRUS is a reasonable way to obtain the requiredinformation about the TZI. Calculating the TZI could not be directly correlated with any of the differentparameters, making the clinical value of such an index questionable. The observation that the obstructed and the retention groups both had a TZI above 0.5 deserves further research that can help in the classification of patients into obstructed and non-obstructed.

Keywords: Prostate; Benign prostatic hypertrophy; Transrectal ultrasonography; Transitional zone