Predicting uterine weight before hysterectomy: ultrasound measurements versus clinical assessment

The purpose of this study was to determine the most accurate method in estimating the preoperative uterine weight of enlarged nongravid uteri.

We performed a retrospective review of 1238 patients who were premenopausal and underwent hysterectomy for benign indications between January 1993 and July 1999. Eight hundred and sixty-four patients were selected to include only those that had both a reported bimanual assessment of preoperative uterine size and an ultrasonography report with all 3 estimated uterine dimensions. Reported uterine sizes on bimanual examination were converted to clinical weight (CWT). Two different calculations were used to estimate uterine weight from ultrasound measurements (UWT 1 and 2). Actual uterine weights (AWT) in pathology reports were then compared with the findings of bimanual assessment and the calculated weights to determine which method is the best predictor of AWT. Simple linear regression analysis was used to measure and compare how closely the estimated weights predicted the actual weight. Predictive residuals sum of squares (PRESS) was then used to determine the best predictor of actual weight.

After exploring the data using linear modeling, all 3 estimated weights were significantly correlated to the actual weight when compared, but PRESS scores showed that the clinical weight estimate was superior by far compared with the other 2.

In this study, bimanual assessment was shown to be the most accurate method of preoperative uterine weight estimation. Ultrasound examination may not be routinely needed when deciding the route of hysterectomy based on estimated weight.