Laparoscopic myomectomy: predicting the risk of conversion to an open procedure

BACKGROUND: Laparoscopic myomectomy (LM) has some advantages over laparotom y; however, it is reputed to be technically difficult, and the risk of conv ersion to laparotomy might be an obstacle in using this procedure. The aim of this study was to identify the pre-operative factors affecting the risk of conversion to an open procedure (either laparoscopic assisted myomectomy or laparotomy), and to develop a simple prediction model based on availabl e pre-operative data with the use of multiple logistic regression. METHODS: A total of 426 women presenting with a subserous or intramural myoma measu ring 20 rum or more underwent LM between March 1989 and October 1999. Of th ese patients, 378 had successful LM. Forty eight patients [11.3%, 95% confi dence interval (CI) 8.3-14.3] had a conversion to an open procedure. A tota l of 265 women had adequate pre-operative ultrasonography (US) and were use d for the analysis. RESULTS: The best prediction model included four preope rative factors that were found to be independently related to the risk of c onversion: size greater than or equal to 50 mm at US (adjusted OR = 10.3; 9 5% CI = 2.8-37.9), intramural type (adjusted OR = 4.3; 95% CI = 1.3-14.5), anterior location (adjusted OR = 3.4; 95% CI = 1.3-9.0) and pre-operative u se of gonadotrophin-releasing hormone (GnRH) agonists (adjusted OR = 5.4; 9 5% CI = 2.0-14.2). The regression coefficients were then scaled and rounded to integers to provide an estimate of the risk for conversion. For a given patient with selected characteristics the predicted risk varied from 0-73% . CONCLUSIONS: This prediction model provides a useful tool that enables mu ltiple criteria to be taken into account simultaneously to help select case s for LM. GnRH agonists should been used only in selected cases. US evaluat ion is essential before performing LM.