Laboratory Testing for Abnormal Uterine Bleeding
All patients with abnormal uterine bleeding require a pregnancy test (beta-hCG), complete blood count with platelets, thyroid-stimulating hormone (TSH), and prolactin levels as initial bloodwork 1.
Essential First-Line Laboratory Tests
The ACOG guidelines explicitly recommend the following laboratory evaluation 1:
- Pregnancy test (beta-hCG) - Mandatory in all reproductive-age women to rule out pregnancy complications including ectopic pregnancy (life-threatening) and trophoblastic disease
- Complete blood count (CBC) with platelets - To assess for anemia from blood loss and evaluate for coagulopathy 2
- Thyroid-stimulating hormone (TSH) - Thyroid dysfunction is a common reversible cause of ovulatory dysfunction
- Prolactin level - Hyperprolactinemia causes anovulation and abnormal bleeding
Additional Testing Based on Clinical Presentation
Beyond the core tests above, additional bloodwork should be ordered based on specific clinical features 3:
For suspected hyperandrogenic conditions or PCOS:
- Testosterone
- Dehydroepiandrosterone sulfate (DHEAS)
For suspected coagulopathy (especially in adolescents or heavy bleeding since menarche):
- Coagulation profile - von Willebrand disease is the most common inherited bleeding disorder causing menorrhagia 4
- Consider von Willebrand factor testing if history suggests bleeding disorder
For suspected ovulatory dysfunction requiring further characterization:
- Estradiol
- Progesterone (mid-luteal phase)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
Critical Clinical Context
A common pitfall is failing to order a pregnancy test in all reproductive-age women - ectopic pregnancy can be fatal if missed, and delayed diagnosis of gestational trophoblastic disease worsens prognosis 3.
The need for hormone panels (estradiol, progesterone, FSH, LH, testosterone, DHEAS) should be individualized based on clinical presentation rather than ordered routinely 3. For example, these are most useful when evaluating causes of anovulation such as polycystic ovary syndrome, hypothalamic dysfunction, or premature ovarian failure.
Women 35 years or older with recurrent anovulation, those under 35 with endometrial cancer risk factors, or those unresponsive to medical therapy require endometrial biopsy 4 - though this is a tissue diagnosis rather than bloodwork.
The evidence consistently supports this tiered approach across multiple guidelines and research studies, with the four core tests (pregnancy, CBC, TSH, prolactin) forming the foundation of evaluation before pursuing additional hormone testing based on clinical suspicion 1, 3, 4, 2.