Objective: To evaluate the correlation between assessment of postvoid residual urine by transabdominal ultrasound and catheterization in patients after radical or transvaginal hysterectomy.
Material and Method: A cross-sectional study was conducted and 46 patients were enrolled after they had radical and transvaginal hysterectomy. After surgery, urinary catheter was indwelled. After catheter removal and the 3rd private voiding, the patients were sent for transabdominal ultrasound assessment of PVR at the Division of Maternal-Fetal Medicine. Complete drainage of bladder with standard catheterization was then performed and catheterized urine volume was recorded. PVR was calculated from previously published equation and compared with actual PVR from catheterization.
Results: Mean age of the patients was 55.9 years. The most common diagnoses were procidentia uteri (23.9%), Carcinoma of cervix stage 1b1 (23.9%), and prolapsed uteri grade 2 (21.7%). Radical hysterectomy with pelvic node dissection and vaginal hysterectomy with anterior colporhaphy and posterior colpoperiniorhaphy was performed each in 50% of cases. Mean duration of urinary catheter indwelling was 7.17 days for those underwent radical hysterectomy and 5 days for vaginal hysterectomy. The calculated PVR was significantly correlated with catheterized urine volume with correlation coefficient 0.93 (p < 0.001). If the usual cutoff of PVR > 100 ml was used to determine the necessity of re-indwelling catheter, among those with calculated PVR from ultrasound measurement < 100 ml, still 30% actually had actual PVR of > 100 ml. Among those with calculated PVR from ultrasound measurement >100 ml, all actually had actual PVR of > 100 ml.
Conclusion: PVR estimation by ultrasound significantly correlated with actual PVR. This could reduce the process of repeat catheterization and give more comfort to the patients when the PVR is > 100 ml.

Keywords: Ultrasound, Postvoid residual urine volume