Prediction of operation time for laparoscopic myomectomy by ultrasound measurements.

BACKGROUND

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

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.