A prospective controlled study of the effect of intramural uterine fibroids on the outcome of assisted conception

BACKGROUND: Although uterine fibroids occur in 30% of women and are associated with a degree of subfertility, the effect of intramural fibroids on the outcome of IVF or ICSI treatment has not been prospectively studied. METHODS: Data were prospectively collected on 434 women undergoing IVF/ICSI in the assisted conception unit of an inner London teaching hospital. Patients were assessed for the presence of fibroids by transvaginal ultrasound and hysterosonography or hysteroscopy where appropriate. RESULTS: During the study period, 112 women with (study), and 322 women without (controls), intramural fibroids were treated. Patients were similar regarding the cause and duration of their infertility, number of previous treatments, and basal serum FSH concentration. Women in the study group were on average 2 years older (36.4 versus 34.6 years; P <0.01). There was no significant difference in the duration of ovarian stimulation or gonadotrophin requirement, number of follicles developed, oocytes collected, embryos available for transfer or replaced. When analysing only women with intramural fibroids of less than or equal to 55 cm in size (n = 106) pregnancy, implantation and ongoing pregnancy rates were significantly reduced: 23.3, 11.9 and 15.1 respectively compared with 34.1, 20.2 and 28.3% in the control group (P = 0.016, P = 0.018 and P = 0.003). The mean size of the largest fibroids was 2.3 cm (90% range 2.1-2.5 cm). Logistic regression analysis demonstrated that the presence of intramural fibroids was one of the significant variables affecting the chance of an ongoing pregnancy, even after controlling for the number of embryos available for replacement and increasing age, particularly age greater than or equal to 40 years, odds ratio 0.46 (CI 0.24-0.88; P = 0.019). CONCLUSION: This study demonstrated that an intramural fibroid halves the chances of an ongoing pregnancy following assisted conception.