Adenomyosis is an estrogen-dependent gynecologic disease characterized by the presence of endometrial tissue within the myometrium. Adenomyosis presents with abnormal uterine bleeding, pelvic pain and infertility. Recently, patients with adenomyosis with life-threatening disseminated intravascular coagulation (DIC) or thromboembolic events have been reported. The purpose of the present systematic review was to examine the possible associations between adenomyosis and severe complications, and to investigate the clinical characteristics, risk factors and potential mechanisms. A literature search was performed for case reports, reviews of the literature, and preclinical and clinical studies published between January, 2000 and November, 2021 in the PubMed and Google Scholar databases using a combination of specific terms. A total of 20 articles reported these complications. Adenomyosis is characterized by morphologically and functionally abnormal blood vessels, with increased intramural pressure, increased expression of pro-angiogenic markers, excessive angiogenesis and increased microvascular density. Changes in blood coagulation-fibrinolysis markers are encountered even in asymptomatic women during menstruation. Repeated bleeding in larger lesions causes coagulopathy that may result in localized thrombosis or DIC. In addition, elevated levels of mucinous tumor markers, CA125 and CA19-9, induce blood hyperviscosity and hypercoagulability that predispose patients to thromboembolism. On the whole, as demonstrated herein, adenomyosis may cause a wide range of symptoms from asymptomatic to life-threatening DIC and/or thromboembolism.