Laboratory and Diagnostic Workup for Abnormal Uterine Bleeding in a 44-Year-Old Woman
In the emergency department, immediately obtain a pregnancy test (β-hCG), complete blood count, and transvaginal ultrasound, followed by thyroid-stimulating hormone and prolactin levels to evaluate for both structural and non-structural causes of bleeding 1.
Essential Laboratory Tests
First-Line (Obtain Immediately in ED)
- Pregnancy test (β-hCG): Mandatory regardless of contraceptive use or reported sexual history—ectopic pregnancy can be life-threatening and must be ruled out first 2
- Complete blood count: Assess for anemia and platelet abnormalities; critical for determining hemodynamic stability and need for transfusion 1, 2
- Coagulation profile: Particularly important if heavy bleeding is present, as coagulopathies (especially von Willebrand disease) are underdiagnosed causes 3
Second-Line Laboratory Tests
- Thyroid-stimulating hormone (TSH): Thyroid dysfunction is a common reversible cause of abnormal bleeding 1
- Prolactin level: Hyperprolactinemia causes ovulatory dysfunction leading to irregular bleeding 1
Imaging Studies
Primary Imaging Modality
Transvaginal ultrasound is the first-line imaging study and should be performed in the ED or arranged urgently 4. This evaluates for:
- Endometrial thickness and abnormalities
- Structural causes: polyps, leiomyomas (fibroids), adenomyosis
- Intracavitary lesions
Critical consideration: At age 44, this patient is at increased risk for endometrial pathology, making imaging essential rather than optional 1.
When Ultrasound Is Inadequate
If transvaginal ultrasound cannot adequately visualize the endometrium due to body habitus, uterine position, or presence of fibroids/adenomyosis 4:
- Saline infusion sonohysterography: 96-100% sensitivity for intracavitary lesions 1
- MRI with diffusion-weighted imaging: Superior tissue characterization when ultrasound is inconclusive 4
Endometrial Sampling Indications
At age 44, endometrial biopsy is indicated if any of the following apply 1:
- Age ≥35 years with recurrent anovulatory bleeding
- Risk factors for endometrial cancer (obesity, diabetes, PCOS, prolonged unopposed estrogen)
- Bleeding unresponsive to initial medical therapy
- Thickened endometrium on ultrasound
Endometrial biopsy is preferred over dilation and curettage because it is less invasive, safer, and lower cost 1.
Algorithmic Approach Using PALM-COEIN Classification
The workup systematically evaluates 1, 4:
Structural causes (PALM):
- Polyp
- Adenomyosis
- Leiomyoma
- Malignancy/hyperplasia
Non-structural causes (COEIN):
- Coagulopathy
- Ovulatory dysfunction
- Endometrial disorders
- Iatrogenic
- Not classified
Common Pitfalls to Avoid
- Failing to obtain pregnancy test: Never assume pregnancy is impossible—ectopic pregnancy can present with irregular bleeding 2
- Racial disparities in care: Recent data shows non-Hispanic Black patients are significantly less likely to receive ultrasound (OR 0.58) or follow-up referrals (OR 0.54) in ED settings 5—ensure equitable diagnostic evaluation
- Delaying imaging in perimenopausal women: Age 44 places this patient in a higher-risk category for endometrial pathology requiring structural evaluation 4, 5
- Incomplete ultrasound evaluation: If endometrium cannot be fully visualized, proceed to advanced imaging or endometrial sampling rather than empiric treatment 4
ED-Specific Considerations
- Hemodynamic stability assessment: Vital signs and orthostatics determine urgency of intervention
- Transfusion threshold: Clinical status drives transfusion decisions in active bleeding, not arbitrary hemoglobin cutoffs 6
- Consultation: Involvement of gynecology consultation increases likelihood of appropriate ultrasound ordering 5
The evidence strongly supports comprehensive evaluation in the ED rather than empiric treatment, particularly given this patient's age and associated endometrial cancer risk.