Clinical Review

2022 Update on abnormal uterine bleeding

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Insights into the COVID-19 vaccine’s effects on menstrual cycle irregularities; results of an RCT that examined the use of drospirenone 4 mg in a 24/4 regimen as an AUB treatment; a systematic review on placing a levonorgestrel-releasing intrauterine system after endometrial ablation; and a cost-effectiveness analysis of 2 treatments for HMB



In this Update, we focus on therapies for abnormal uterine bleeding (AUB) that include a new formulation of a progesterone-only pill (POP), drospirenone 4 mg in a 24/4 regimen (24 days of drospirenone/4 days of inert tablets), which recently showed benefit over the use of desogestrel in a European randomized clinical trial (RCT). Two other commonly used treatments for AUB— the levonorgestrel-releasing intrauterine system (LNG IUS) and endometrial ablation—were studied in terms of cost-effectiveness as well as whether they should be used in combination for added efficacy. In addition, although at times either COVID-19 disease or the COVID-19 vaccine has been blamed for societal and medical problems, one study showed that it is unlikely that significant changes in the menstrual cycle are a result of the COVID-19 vaccine.

COVID-19 vaccination had minimal effects on menstrual cycle length

Edelman A, Boniface ER, Benhar W, et al. Association between menstrual cycle length and coronavirus disease 2019 (COVID-19) vaccination: a US cohort. Obstet Gynecol. 2022;139:481-489.

Does receiving the COVID-19 vaccination result in abnormal menstrual cycles? Patients often ask this question, and it has been a topic of social media discussion (including NPR) and concerns about the possibility of vaccine hesitancy,1,2 as the menstrual cycle is often considered a sign of health and fertility.

To better understand this possible association, Edelman and colleagues conducted a study that prospectively tracked menstrual cycle data using the digital app Natural Cycles in US residents aged 18 to 45 years for 3 consecutive cycles in both a vaccinated and an unvaccinated cohort.3 Almost 4,000 individuals were studied; 2,403 were vaccinated and 1,556 were unvaccinated. The study vaccine types included the BioNTech (Pfizer), Moderna, Johnson & Johnson/Janssen, and unspecified vaccines.

The primary outcome was the within-individual change in cycle length in days, comparing a 3-cycle postvaccine average to a 3-cycle prevaccination average in the 2 groups. (For the unvaccinated group, cycles 1, 2, and 3 were considered the equivalent of prevaccination cycles; cycle 4 was designated as the artificial first vaccine dose-cycle and cycle 5 as the artificial second-dose cycle.)

Increase in cycle length clinically negligible

The investigators found that the vaccinated cohort had less than a 1-day unadjusted increase in the length of their menstrual cycle, which was essentially a 0.71-day increase (98.75% confidence interval [CI], 0.47–0.94). Although this is considered statistically significant, it is likely clinically insignificant in that the overlaid histograms comparing the distribution of change showed a cycle length distribution in vaccinated individuals that is essentially equivalent to that in unvaccinated individuals. After adjusting for confounders, the difference in cycle length was reduced to a 0.64 day (98.75% CI, 0.27–1.01).

An interesting finding was that a subset of individuals who received both vaccine doses in a single cycle had, on average, an adjusted 2-day increase in their menstrual cycle compared with unvaccinated individuals. To explain this slightly longer cycle length, the authors postulated that mRNA vaccines create an immune response, or stressor, which could temporarily affect the hypothalamic-pituitary-ovarian axis if timed correctly. It is certainly possible for an individual to receive 2 doses in a single cycle, which could have both been administered in the early follicular phase. Such cycle length variability can be caused by events, including stressors, that affect the recruitment and maturation of the dominant follicle.

Counseling takeaway

This study provides reassurance to most individuals who receive a COVID-19 vaccine that it likely will not affect their menstrual cycle in a clinically significant manner.

This robust study by Edelman and colleagues on COVID-19 vaccination effects on menstrual cycle length had more than 99% power to detect an unadjusted 1-day difference in cycle length. However, given that most of the study participants were White and had access to the Natural Cycles app, the results may not be generalizable to all individuals who receive the vaccine.

Continue to: Drospirenone improved bleeding profiles, lowered discontinuation rates compared with desogestrel...


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