Introduction: If a woman suffers from congenital fibrinogen deficiency (CFD), she might undergo hypermenorrhea monthly and possibly to suffer from hemoperitoneum due to a ruptured follicle or corpus luteal cyst every month, which seriously threaten her health and quality of life. Here, we creatively used a combination of the levonorgestrel-releasing intrauterine system (LNG-IUS) and the combined oral contraceptives (COC) for a girl with CFD. Case presentation: A 14-year-old girl presented with no obvious cause of persistent and severe lower abdominal pain that began 8 h prior. After examination, she was diagnosed as hemoperitoneum. CFD was diagnosed when she was 2 years old and she had two hospitalizations due to hemorrhagic anemia caused by menorrhagia. Therefore, after successful conservative treatment of hemoperitoneum, a combination of LNG-IUS and COC was used for the long-term conservative management of hypermenorrhea and hemoperitoneum. During the half-year of follow-up, she had hypomenorrhea without hemoperitoneum. Conclusions: To the best of our knowledge, this was the first patient treated with such a procedure in the literature, and we recommend every woman with CFD at puberty or reproductive age receives this two-pronged treatment.