Factors related to successful medication management with mifepristone and misoprostol in missed miscarriage: a retrospective case-control study.

BACKGROUND

Treatment with mifepristone in combination with misoprostol may be a safe and less expensive option compared with surgical management in missed miscarriage, but the efficacy of medication management varies in clinical practice. This study aims to identify the risk factors related to successful medical management using mifepristone and misoprostol for missed miscarriage.

METHODS

We carried out a retrospective case-control study in the First Affiliated Hospital with Nanjing Medical University from January 1, 2023 to December 31, 2023. Patients were recruited into this study if they were aged 16 years and older, diagnosed with a missed miscarriage by pelvic ultrasound scan in the first 13 weeks of pregnancy (by last menstrual period), and chose to have medication management. Women who failed to spontaneously pass the gestational sac within 24 h of the oral misoprostol dose were included in the case group, while women who had complete gestational sac expulsion within 24 h of the oral misoprostol dose were defined as controls. The baseline characteristics of the patients were collected in the electronic medical record system and the meteorological data were obtained from the Nanjing Meteorological Observation Centre. Logistic regression analysis was used to identify the risk factors which affected medication management efficacy.

RESULTS

A total of 163 patients met inclusion criteria, including 60 patients in the case group and 103 patients in the control group. Our results showed that the history of gravidity, history of parity, history of miscarriage, history of caesarean section, prior uterine surgery, and the use of supplemental vaginal misoprostol could be potential risk factors, while the remaining variables showed no significant differences between the two groups. The univariable logistic regression model demonstrated that the risk of unsuccessful medication management was increased 3.67-fold in patients who had been pregnant more than 3 times (95% CI: 1.66, 8.08; p = 0.001); increased 2.29-fold in parous women (95% CI: 1.13, 4.62; p = 0.021); and increased 2.09-fold in patients who had previous miscarriages (95% CI: 1.10, 4.00; p = 0.026). Additionally, prior uterine surgery was related to the outcomes of medication management (OR: 2.94; 95% CI: 1.46, 5.93; p = 0.003), especially caesarean section (OR: 2.09; 95% CI: 1.13, 4.62; p = 0.021). Interestingly, the repeated vaginal administration of misoprostol was not associated with an increased success rate (OR: 3.65; 95% CI: 1.76, 7.56; p = 0.001). Moreover, we evaluated the effect of meteorological factors on which the exposure of 4 days average visibility emerged as a statistically significant risk factor (OR: 1.13, 95% CI: 1.01, 1.27; p = 0.036). Multivariable logistic regression model showed that the history of parity, prior uterine surgery, use of supplemental vaginal misoprostol and 4 days average visibility were still independently associated with the outcomes of medication management, while the gestational age by ultrasound was no longer related.

CONCLUSIONS

The missed miscarriage patients who are parous or have uterine surgery history may suffer from a higher risk of unsuccessful medication management. The exposure to reduced visibility had a significant influence on the efficacy of mifepristone and misoprostol, while the supplementary administration of vaginal misoprostol could not increase the chance of successful miscarriage management.