Laboratory Evaluation for Heavy Menstrual Bleeding
All reproductive-age women with heavy menstrual bleeding should undergo pregnancy testing, complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (PTT), and von Willebrand disease (VWD) screening with VWF antigen, VWF ristocetin cofactor activity, and factor VIII levels. 1
Essential Initial Laboratory Tests
Mandatory First-Line Tests
Pregnancy test (beta-hCG): Must be performed in all reproductive-age women presenting with abnormal uterine bleeding to exclude pregnancy-related bleeding 1
Complete blood count (CBC): Identifies anemia from blood loss and evaluates for thrombocytopenia or thrombocytosis as potential bleeding causes 1
Serum ferritin: Essential for assessing iron deficiency, which is highly prevalent in women with heavy menstrual bleeding 2, 3
Prothrombin time (PT) and activated partial thromboplastin time (PTT): These coagulation screening tests can identify coagulation factor deficiencies, though they do not evaluate for VWD 1
Von Willebrand Disease Screening Panel
The three VWD tests should be ordered together as initial evaluation 1:
- VWF antigen (VWF:Ag): Measures the quantity of von Willebrand factor protein
- VWF ristocetin cofactor activity (VWF:RCo): Assesses functional activity of VWF
- Factor VIII coagulant activity (FVIII): VWF carries and stabilizes factor VIII in circulation
These three tests establish the diagnosis and suggest the type and severity of VWD if present 1. VWD is the most common inherited bleeding disorder, affecting up to 1% of the population and causing heavy menstrual bleeding in approximately 90% of affected women 1, 4.
Important Testing Considerations
Timing of VWD Testing
A critical caveat: VWF and factor VIII levels increase during acute bleeding episodes due to stress response, potentially masking VWD diagnosis 5. While guidelines recommend testing at presentation 1, research shows that 69% of individuals with VWD had low VWF levels during acute heavy menstrual bleeding, but median levels were significantly higher during acute bleeding compared to follow-up 5. Consider repeat testing after bleeding resolution and anemia correction for more accurate diagnostic evaluation 5.
Additional Endocrine Evaluation
Thyroid-stimulating hormone (TSH): Thyroid dysfunction causes both anovulatory bleeding and can affect coagulation 1, 2, 6
Prolactin level: Hyperprolactinemia leads to anovulation and abnormal bleeding 1, 2
These endocrine tests identify ovulatory dysfunction as a cause of heavy menstrual bleeding 1, 2.
When to Expand Laboratory Evaluation
Bleeding Assessment Tool Utilization
Use a validated bleeding assessment tool (BAT) to systematically evaluate bleeding history, as 80% of providers managing bleeding disorders utilize these tools 1. Specific red flags warranting hematology referral include 2, 3, 4:
- Menses lasting >7 days
- Menstrual flow soaking >5 sanitary products per day
- Requiring product changes during the night
- Passage of blood clots ≥1 inch diameter
- Failure to respond to conventional hormonal therapies
- Personal or family history of bleeding symptoms
Specialized Testing
If initial VWD testing shows abnormally low results or abnormal VWF:RCo to VWF:Ag ratio (below 0.5-0.7), specialized VWD assays including multimer analysis should be performed to determine VWD subtype 1. This testing is technically complex and should be coordinated with a hematologist 1, 2.
Physical Examination Findings to Document
Beyond laboratory testing, the physical examination should specifically assess for 1:
- Hemodynamic stability: Orthostatic blood pressure and pulse measurements in acute bleeding 2
- Signs of anemia: Pallor, tachycardia
- Bleeding stigmata: Ecchymoses, hematomas, petechiae
- Liver disease signs: Jaundice, splenomegaly (affects coagulation)
- Connective tissue disorders: Joint and skin laxity (Ehlers-Danlos syndrome), telangiectasia (hereditary hemorrhagic telangiectasia)
- Gynecologic examination: Anatomic lesions, cervical pathology (only after excluding placenta previa in pregnancy) 1
Common Pitfalls to Avoid
Do not rely on bleeding time or platelet function analyzer (PFA-100) for routine VWD screening, as conflicting data exist regarding sensitivity and specificity, and current evidence does not support their routine use 1.
Universal support exists only for PT and PTT testing among hemostatic tests in the evaluation of bleeding disorders of unknown cause, highlighting the importance of VWD-specific testing when clinical suspicion exists 1.