Oral anticoagulant therapy is essential for managing conditions like deep venous thrombosis, pulmonary embolism, and atrial fibrillation. However, a recent analysis from a large national claims database reveals a significantly increased risk of oral anticoagulant AUB (Abnormal Uterine Bleeding) among users compared to nonusers. This real-world evidence highlights a critical patient safety issue. Consequently, clinicians must proactively screen for and manage this common complication.
Key Findings: Incidence and Clinical Impact
The study, a nested matched case-control analysis, included nearly 277,000 anticoagulant users and 1.38 million matched controls. Overall, the incidence of AUB within one year was more than double in users (6.1%) versus nonusers (3.0%). Furthermore, this translates to an adjusted odds ratio (AOR) of 1.81. This finding clearly demonstrates that anticoagulation is a major independent risk factor for AUB. Importantly, the clinical impact extends beyond simple bleeding. Anticoagulant users experienced significantly higher odds of AUB-related hospitalization (AOR 62.32), emergency department visits (AOR 5.78), and outpatient encounters (AOR 1.42). Therefore, AUB frequently leads to complex medical interventions and patient morbidity.
Risk Stratification: Younger Women and Oral Anticoagulant AUB
Age plays a substantial role in the relative increase in bleeding risk. Women younger than 50 years of age showed a greater relative increase in AUB (19.7% vs 9.2%, AOR 1.96) compared with women aged 50 years or older (3.8% vs 2.0%, AOR 1.63). This is especially pertinent to premenopausal women receiving treatment for VTE, where up to two-thirds may experience AUB. Consequently, a careful menstrual history is mandatory both before and after initiating therapy. Physicians must recognize this elevated risk in younger women to ensure appropriate counseling and early intervention.
Comparative Safety: Rivaroxaban vs. Other Agents
The study examined users of warfarin, apixaban, rivaroxaban, dabigatran, and edoxaban. Among all these agents, rivaroxaban was associated with the highest overall risk of AUB. Previous systematic reviews have also suggested a higher AUB risk with rivaroxaban compared to warfarin. In contrast, other data indicate that the risk of heavy menstrual bleeding (HMB) may be lower with agents like apixaban or dabigatran. Consequently, individual risk assessment should factor in the specific oral anticoagulant agent chosen.
Management of Anticoagulant-Associated AUB
Managing abnormal uterine bleeding in anticoagulated patients requires a multidisciplinary approach. The mainstay of treatment involves hormonal therapies. Specifically, the levonorgestrel intrauterine system (LNG-IUS) is often the preferred option. It is highly effective for reducing blood loss and provides the added benefit of contraception, which is crucial for women taking teratogenic agents like warfarin. Clinicians should generally avoid modifying the anticoagulation dose or temporarily stopping the medication, particularly during the acute phase of VTE treatment (first three to six months), as this drastically increases the risk of VTE recurrence. Additionally, antifibrinolytics like tranexamic acid can be used during menstrual flow for HMB, but clinicians must consider the perceived—though often not proven in large trials—risk of thrombosis when co-administering with anticoagulants.
Frequently Asked Questions
Q1: Which patient group has the greatest relative increase in AUB risk on oral anticoagulants?
Women younger than 50 years of age experienced the greatest relative increase in the odds of abnormal uterine bleeding, with an adjusted odds ratio (AOR) of 1.96 compared to nonusers.
Q2: Is one oral anticoagulant agent associated with a higher AUB risk than others?
Yes. The study concluded that among warfarin, apixaban, rivaroxaban, dabigatran, and edoxaban, rivaroxaban conferred the highest overall risk of abnormal uterine bleeding.
Q3: Should anticoagulation be stopped to manage severe AUB?
No. Modification, reduction, or temporary cessation of anticoagulation is generally not recommended in the acute phase of treatment due to a significant increase in the risk of recurrent venous thromboembolism (VTE). Instead, hormonal therapies like the LNG-IUS are the mainstays of AUB management.
References
- Yellin LR et al. Abnormal Uterine Bleeding Among Oral Anticoagulant Users. Obstet Gynecol. 2026 Jan 08. doi: 10.1097/AOG.0000000000006165. PMID: 41505758.
- Management of heavy menstrual bleeding on anticoagulation. J Thromb Haemost. 2020 Dec;18(12):3283-3294.
- Clinical Guides – Management of Heavy Menstrual Bleeding for Patients on Anticoagulation. Thrombosis Canada.