Which laboratory studies are indicated for a patient presenting with menorrhagia?

Laboratory Evaluation for Heavy Menstrual Bleeding

Every patient presenting with heavy menstrual bleeding requires a complete blood count with platelet count, serum ferritin, thyroid-stimulating hormone, and coagulation screening including PT/aPTT and von Willebrand factor studies. 1

Essential First-Line Laboratory Tests

Hematologic Assessment

• Complete blood count with platelet count is mandatory to identify anemia from chronic blood loss and detect thrombocytopenia that may signal an underlying coagulopathy. 1
• Serum ferritin must be measured even when hemoglobin is normal, because depleted iron stores precede anemia and indicate ongoing occult blood loss; iron deficiency is highly prevalent among women with bleeding disorders. 1

Endocrine Evaluation

• Thyroid-stimulating hormone (TSH) testing is required to detect hypothyroidism, an easily correctable contributor to abnormal uterine bleeding. 2, 1
• Prolactin level should be checked as part of the diagnostic workup for ovulatory dysfunction. 2

Pregnancy Testing

• Serum β-hCG must be performed in all reproductive-age women with abnormal uterine bleeding before initiating any treatment, regardless of sexual history or contraceptive use. 2, 3

Coagulation Screening (Critical and Often Missed)

Initial Hemostatic Work-Up

• Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are essential to screen for common clotting factor abnormalities. 1
• Von Willebrand factor antigen and activity assays (ristocetin cofactor or GP1b binding) are mandatory because von Willebrand disease affects 10–20% of women with menorrhagia and is systematically under-diagnosed. 1, 4
• Factor VIII level should be included in the initial coagulation panel. 1

Critical pitfall: Do not rely solely on normal PT/aPTT to exclude von Willebrand disease or platelet function disorders; specific von Willebrand factor assays are required. 1 Normal PT/aPTT miss a substantial proportion of bleeding disorders in women with menorrhagia. 5

When to Add Second-Line Hemostatic Tests

• Factor VIII, IX, and XI activity assays should be added if PT/aPTT are abnormal or clinical suspicion remains high despite normal initial screening. 1
• Platelet function testing (light-transmission aggregometry) is indicated when PT/aPTT and von Willebrand studies are normal but suspicion for platelet dysfunction persists. 1
• Fibrinogen level (Clauss method) should be measured as part of comprehensive hemostatic evaluation. 1

Special Considerations for Adolescents

• In adolescents with heavy menstrual bleeding, the prevalence of bleeding disorders is approximately 20%, making coagulation screening particularly important. 3, 6
• When possible, investigation should be undertaken before oral contraceptive therapy is instituted, because hormonally induced increases in factor VIII and von Willebrand factor may mask the diagnosis. 4
• If bleeding history other than menorrhagia, family history of bleeding, or parental consanguinity is absent in adolescents, detailed coagulation assays can be postponed since nearly 50% of adolescent menorrhagia is dysfunctional and transient. 7

Tests NOT Routinely Recommended

• ABO blood-group typing adds little diagnostic value for von Willebrand factor interpretation and is not recommended despite frequent use (performed in 80% of surveyed cases). 1
• Follicle-stimulating hormone (FSH) measurement is not part of standard guidelines for evaluating abnormal uterine bleeding and does not help exclude malignancy. 1

Additional Clinical Assessment

• Review medication history thoroughly, particularly aspirin and NSAIDs, as these agents impair platelet function and can mask inherited platelet disorders. 1
• Assess for joint hypermobility using the Beighton score, given its association with bleeding symptoms. 1

Common Pitfalls to Avoid

• Never omit ferritin even when hemoglobin is normal—this is one of the most common errors identified in quality improvement surveys (ferritin was only checked in 69% of cases). 1
• Always perform von Willebrand factor testing in women with menorrhagia and normal gynecological evaluation, as 11–16% will meet laboratory diagnosis of von Willebrand disease. 5
• Do not start hormonal contraception before completing the laboratory evaluation, as it can mask underlying bleeding disorders. 2, 4