Validity of three calliper-based transrectal ultrasound methods and digital rectal examination in the estimation of prostate volume and its changes with age: the Krimpen study.

BACKGROUND: Prostate volume and its changes are important parameters in studies of the natural history of benign prostatic hyperplasia (BPH), for prediction of treatment effect and the risk of adverse outcomes. The validity of three calliper-based transrectal ultrasound (TRUS) methods and digital rectal examination (DRE) is compared to transrectal planimetric prostate ultrasonometry.

METHODS: Data were collected from 1,688 population-based men aged 50-78 years. Measurements included DRE, TRUS using the planimetric method, and three different calliper-based TRUS methods for the estimation of prostate volume. After 2.1 and 4.2 years these measurements were repeated. The agreement between these methods and the ability to discriminate between prostates with volumes above or below a certain cut-off was analyzed. The performance of the different methods to measure changes in prostate volume with age was also studied.

RESULTS: All three ultrasound-based methods showed good discrimination compared to the planimetric method. However, the agreement between planimetric volumetry and the other ultrasound methods and DRE is poor. In this study, 22.6% of the men had a real increase in prostate volume after 4.2 years, using the planimetric technique of transrectal ultrasonometry. Only a small percentage of the men (<1.5%) has a real decrease in prostate volume. The alternative measurement methods had a low predictive value for changes in prostate volume with age as measured with the planimetric method.

CONCLUSIONS: Calliper-based ultrasonometry and DRE show poor agreement with planimetric volume measurement of the prostate. Changes in prostate volume as determined by the planimetric method are poorly detected by the alternative methods. (c) 2004 Wiley-Liss, Inc.