What laboratory investigations are recommended for evaluating heavy menstrual bleeding?

Laboratory Investigations for Heavy Menstrual Bleeding

All women presenting with heavy menstrual bleeding require a pregnancy test, complete blood count with hemoglobin, serum ferritin, and thyroid-stimulating hormone (TSH) as essential first-line laboratory investigations. 1

Essential First-Line Laboratory Tests

Mandatory Initial Testing

• Pregnancy test (beta-hCG): Must be performed in all women of reproductive age to exclude pregnancy-related bleeding 1
• Complete blood count (CBC): Identifies anemia from blood loss, with 65% of hematologists routinely performing this as first-line testing 1
• Serum ferritin: Critical for detecting iron deficiency, which affects 42.8% of women with HMB when using a cutoff <15 μg/L, and 72.5% when using <30 μg/L 2
• Thyroid-stimulating hormone (TSH): Screens for thyroid disease as a cause of ovulatory dysfunction, performed by 45% of specialists as first-line testing 1
• Prolactin level: Evaluates for hyperprolactinemia causing anovulation 1

Coagulation Screening (High Priority)

Coagulation testing should be performed in all adolescents with HMB and in adults with specific bleeding indicators 3, including:

• Prothrombin time (PT) and activated partial thromboplastin time (aPTT): Performed universally (100%) as first-line tests 1
• Von Willebrand factor (VWF) testing: Performed by 84% of specialists as first-line testing, as bleeding disorders affect approximately 90% of women with underlying coagulopathy 1, 4
• Factor VIII, IX, and XI assays: Performed by 62% as first-line testing 1
• Fibrinogen levels (Clauss or derived): Performed by 90% in first-line testing 1

Recent data reveals that coagulation screening identifies potential congenital bleeding disorders in approximately 10% of women with HMB, including von Willebrand disease in 9.2% of previously undiagnosed cases 2.

Clinical Indicators Requiring Coagulation Testing

Specific menstrual patterns warrant hematologic evaluation 4, 3:

• Menses lasting >7 days
• Menstrual flow requiring >5 sanitary products per day or nighttime changes
• Blood clots ≥1 inch diameter
• "Flooding" (pad/tampon change more frequently than hourly)
• Failure to respond to conventional hormonal therapies
• Personal or family history of bleeding symptoms

Additional Testing Based on Clinical Context

Iron Studies Beyond Ferritin

• Serum iron: Performed by 69% of specialists as first-line testing 1
• Iron deficiency with or without anemia is commonly found and requires supplementation even in transfused patients 5

ABO Blood Group

• Performed by 70% of specialists, as blood type O is associated with lower VWF levels 1

Hemodynamic Assessment in Acute Bleeding

• Orthostatic blood pressure and pulse measurements: Essential for assessing hemodynamic stability in acute presentations 3

Second-Line Testing (When First-Line Normal)

If initial coagulation screening is normal but bleeding history remains convincing 1:

• Platelet function testing (light transmission aggregometry): Most frequently performed second-line test (60%)
• Additional coagulation factor assays (FII, FV, FVII, FX, FXIII): Performed by 52-60% of specialists
• Platelet flow cytometry: Performed by 42%
• Genetic testing: Performed by 48% as second-line

Critical Pitfalls to Avoid

• Do not skip ferritin testing: Overt anemia (hemoglobin ≤120 g/L) occurs in 34.7% and low ferritin in 42.8% of women with HMB, yet many remain undiagnosed 2
• Do not delay coagulation screening in adolescents: Bleeding disorders are now recognized as a common cause of menorrhagia in this population 6
• Do not use hemoglobin alone: Ferritin is superior for detecting iron deficiency before overt anemia develops 5
• Do not overlook the need for hematology referral: HMB with flooding, prolonged menses, or positive bleeding history warrants specialist evaluation 4

Laboratory Interpretation Context

The PALM-COEIN classification system guides the diagnostic approach by distinguishing structural causes (polyp, adenomyosis, leiomyoma, malignancy) from nonstructural causes (coagulopathy, ovulatory dysfunction, endometrial, iatrogenic) 1. Laboratory testing specifically addresses the nonstructural etiologies, particularly coagulopathy and ovulatory dysfunction, while imaging addresses structural causes.