ObjectivesTo investigate whether there is any difference in coagulability between patients with adenomyosis-associated heavy menstrual bleeding (ADM-HMB) and women without adenomyosis. Methods and materialsSeventy-two premenopausal patients with histologically diagnosed adenomyosis, but free of metabolic or hematological diseases, who experienced either moderate/heavy menses (MHB) or excessive (EXB) menstrual blood loss (MBL) based on their amount of MBL (>60mL but ≤100mL vs. >100mL) were recruited. Additionally, 50 patients without adenomyosis were also recruited. Their demographic, clinical and coagulation information were collected. All recruited subjects had platelet count, prothrombin time (PT), thrombin time (TT), activated partial thromboplastin time (aPTT), and plasma fibrinogen and D-dimer levels. AMD-HMB patients also had data on anti-thrombin activity and fibrin degradation products (FDPs). ResultsADM-HMB patients had significantly higher platelet count, fibrinogen and D-dimer levels but shorter PT and aPTT as compared with women without adenomyosis. Within the ADM-HMB patients, patients who complained of EXB had significantly higher plasma D-dimer and FDP levels but shorter aPTT and lower fibrinogen levels than those who complained of MHB. ConclusionThese data strongly suggest that ADM-HMB women are in a hypercoagulable state as compared with women without adenomyosis, especially in those complained of excessive MBL. Our findings suggest that precautionary or even prophylactic measures may be advised to reduce the risk of thrombotic events in ADM-HMB patients, especially those with excessive MBL. In addition, our data suggest that anti-thrombotic/anti-coagulation therapies may hold therapeutic potentials.