The reliability and reproducibility of ultrasonography for measuring the residual urine volume in men with lower urinary tract symptoms

Objective:
To assess the reliability and reproducibility of abdominal ultrasonography (US) for measuring the postvoid residual urine volume (PVR), and to compare measurements by a radiologist and urologist, in men with lower urinary tract symptoms (LUTS), as a significant PVR is common in patients with LUTS and an assessment of the PVR could protect patients from unnecessary catheterisation.

Patients and methods:
This was a prospective comparative study of 45 men aged ⩾45 years with LUTS attending a urological outpatient clinic from July 2011 to May 2012. A detailed history was taken, with an assessment of LUTS using the Arabic Validated International Prostate Symptom Score (IPSS) and complete general and local examination. The PVR was measured by US twice by a radiologist and urologist, and then repeated after 1 week. Within ⩽2 min after US a urethral catheter was used to measure the PVR.

Results:
The mean (range) age of the patients was 63.8 (45–88) years and the mean IPSS was 16.18. Reliability testing between the PVR measured by US and the catheterised measure of PVR showed that US was not reliable (Cronbach’s α < 0.7). The US measurement was reproducible for both single examiner over two sessions, and with two examiners in one session. The PVR obtained by the urethral catheter was significantly higher than the US measurement (P < 0.05).

Conclusions:
The measurement of PVR by US is reproducible by either a urologist or radiologist, but it is not reliable, as the urethral catheter estimate gives a significantly higher PVR.