What initial laboratory studies are recommended for a woman with ongoing menstrual bleeding?

Initial Laboratory Studies for Ongoing Menstrual Bleeding

In women presenting with ongoing menstrual bleeding, obtain a complete blood count with platelet count, serum ferritin, thyroid-stimulating hormone, prothrombin time, activated partial thromboplastin time, and von Willebrand factor studies as first-line laboratory evaluation. 1

Essential Hematologic Assessment

• Complete blood count with platelet count identifies anemia from chronic blood loss and detects 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

• A critical pitfall: do not omit ferritin testing based on normal hemoglobin alone, as this misses early iron depletion. 1

Endocrine Screening

• Thyroid-stimulating hormone (TSH) detects hypothyroidism, an easily correctable contributor to abnormal uterine bleeding. 1

• Prolactin levels should be checked to assess for hyperprolactinemia causing ovulatory dysfunction. 2

Coagulation Studies

• Prothrombin time and activated partial thromboplastin time screen for common clotting factor abnormalities. 1

• Von Willebrand factor antigen and activity assays (ristocetin cofactor or GP1b binding) are essential because von Willebrand disease is under-diagnosed in women with menorrhagia—up to 20% of women with heavy menstrual bleeding have an underlying inherited bleeding disorder. 1, 3

• Do not rely solely on normal PT/aPTT to exclude von Willebrand disease or platelet function disorders; specific assays are required. 1

• If PT/aPTT are abnormal or clinical suspicion remains high, factor VIII, IX, and XI activity assays identify specific factor deficiencies. 1

Clinical Predictors Warranting Hematology Referral

• Heavy menstrual bleeding with "flooding" (changing pad/tampon more than hourly), clots ≥1 inch diameter, prolonged menses, or a personal/family history of bleeding strongly suggests a bleeding disorder and warrants hematology consultation. 4

• Menorrhagia in adolescents should be attributed to coagulopathy until proven otherwise. 5

Second-Line Hemostatic Tests

When first-line coagulation studies are unrevealing but bleeding persists:

• Platelet function testing (light-transmission aggregometry) for suspected platelet dysfunction despite normal PT/aPTT and von Willebrand studies. 1

• Fibrinogen level (Clauss method) as part of comprehensive hemostatic evaluation. 1

• Testing for rare factor deficiencies (II, V, VII, X, XIII) in selected cases with unexplained bleeding and normal routine screens. 1

Additional Assessments

• Pregnancy test must be performed in all reproductive-age women, as complications of pregnancy are the most common cause of abnormal bleeding in this population. 2, 5

• Review medication history for aspirin, NSAIDs, anticoagulants, antipsychotics, or antiepileptics that impair hemostasis or cause anovulation. 1, 6

• Assess for joint hypermobility using the Beighton score, given its association with bleeding symptoms. 1

Tests Not Routinely Recommended

• ABO blood-group typing adds little diagnostic value for von Willebrand factor interpretation despite frequent use. 1

• Follicle-stimulating hormone is not part of standard guidelines for evaluating abnormal uterine bleeding. 1

Evidence Quality

The 2024 International Society on Thrombosis and Haemostasis guidelines provide high-quality evidence for this laboratory approach, though survey data reveal that essential tests (CBC 65%, ferritin 69%, TSH 45%) are not universally ordered—representing a critical quality-improvement target. 1