Prediction of operation time for laparoscopic myomectomy by ultrasound measurements

This study aimed to develop a regression-based prediction equation for operation time for laparoscopic myomectomy (LM) using ultrasound measurement.

Patients who were to undergo laparoscopic myomectomy from March 2003 to December 2005 were enrolled prospectively in a tertiary institution. Ultrasound was performed before operation. The myoma weights were calculated and converted into mass units (g) by an assumed smooth muscle density of 1.04 g/cm3. Myomas were weighed immediately after operation, and the correlation between these two weights was assessed by linear regression and limits of agreement. A multivariate linear regression model was fitted to the ultrasound parameters and clinical variables to predict operation time.

Of 109 patients, 203 myomas were removed laparoscopically with a mean ultrasound-measured myoma weight of 137.9 (100.7) g, a diameter of the dominant myoma of 6.30 (1.92) cm, and an operation time of 125 (41) min. Strong correlations were observed between the ultrasound-measured and operated myoma weights. A predictive model, in which operation time = 0.14 x ultrasound-measured myoma weight + 1.68 x BMI + 5.21 x operated myoma number + 0.06 x (ultrasound-measured myoma weight x operated myoma number) + 43.97, was developed.

Operation time was significantly related to the myoma weight measured by ultrasound. The ultrasound-derived prediction equation is valid and reliable in predicting operation time for LM.