Pregnancy and perinatal outcomes in women with different phenotypes of adenomyosis: A retrospective cohort study.

BACKGROUND

To evaluate maternal and perinatal outcomes in women with different adenomyosis phenotypes and to assess the impact of placental attachment site in patients with intrinsic adenomyosis.

METHODS

This retrospective cohort study analysed 255 patients with adenomyosis who delivered between January 2014 and December 2019. Patients were classified into diffuse (n = 119), intrinsic (n = 89) and extrinsic (n = 47) phenotypes. Within the intrinsic group, patients were further subdivided into lesion-attached (n = 49) and lesion-unattached (n = 40) subgroups according to placental location relative to the adenomyotic lesion. To identify independent risk factors for key outcomes while adjusting for potential confounders, multivariable logistic regression analysis was employed.

RESULTS

The rates and volume of postpartum haemorrhage (PPH) were significantly higher in the diffuse group compared to the focal phenotypes, with uterine atony identified as a key contributing factor. Among patients with intrinsic adenomyosis, the lesion-attached subgroup exhibited significantly greater blood loss, a lower mean gestational age at delivery (37.4 ± 2.9 vs. 38.8 ± 1.3 weeks, P = 0.006), and a higher preterm birth rate (26.5 % vs. 5.0 %, P = 0.009) compared to the lesion-unattached subgroup. Multivariate analysis confirmed placental attachment site as an independent predictor of preterm delivery, although the estimate was imprecise due to wide confidence intervals. A post hoc power analysis indicated 82 % power to detect the observed difference in preterm birth rates between these subgroups.

CONCLUSIONS

Diffuse adenomyosis and lesion-attached intrinsic adenomyosis are associated with an increased risk of postpartum hemorrhage. Furthermore, placental attachment to an adenomyosis lesion significantly elevates the risk of preterm delivery in patients with intrinsic disease. These findings underscore the importance of phenotype-specific and placental-site assessment for antenatal risk stratification.