OC11.04: Direct MUSA features of adenomyosis impact live birth rates after first <i>in vitro</i> fertilization / intracytoplasmic sperm injection treatment

To determine the cumulative live birth rate (CLBR) after the first in vitro fertilization (IVF) or Intracytoplasmic sperm injection (ICSI) treatment in women with or without direct features of adenomyosis, using the revised Morphological Uterus Sonographic Assessment (MUSA) group definitions. We included 1037 women aged 25-≤39 years undergoing their first IVF/ICSI treatment at a university hospital between January 2019 and October 2022. To confirm the presence of direct features of adenomyosis, all women underwent a systematic two – and three-dimensional transvaginal ultrasound examination prior to starting their first fertility treatment. All ultrasound examinations were performed using GE Voluson 10 Expert ultrasound equipment with a 5-9 MHz transvaginal transducer. Modified Poisson regression with robust error variances was used to estimate adjusted relative risk (RR). Adjustments were made for potentially confounding factors such as age and presence of endometriosis. The main outcome measure was CLBR in women with or without adenomyosis. Women with only indirect MUSA features were regarded as not having adenomyosis. The CLBR after the first IVF/ICSI treatment was lower in women with at least one direct feature of adenomyosis, [25/102 (24.5%; 95% CI, 17.5-31.5)] compared to women without any direct feature, [399/935 (42.7%; 95% CI, 39.5-45.8)], p < 0.001. The crude (RR) for live birth for women with direct features of adenomyosis compared to women without was 0.58; 95% CI, 0.41-0.82, p = 0.002 and the adjusted RR for 0.61; 95% CI, 0.47-0.78, p < 0.001. Women with direct features more often had miscarriage after frozen embryo transfer (n = 10/102, 9.8%) compared to women without direct features (n = 29/906, 3.1%), p = 0.003. The presence of direct MUSA features of adenomyosis indicates a reduced chance of live birth after the first IVF/ICSI treatment. For adequate counselling, detailed ultrasound examination should be considered for all women undergoing IVF/ICSI treatment.