My quantitative hCG level is zero; why am I still experiencing vaginal bleeding?

Why Am I Still Bleeding with hCG of Zero?

Vaginal bleeding with an hCG of zero is not pregnancy-related and requires evaluation for non-pregnancy causes of abnormal uterine bleeding, including structural lesions, hormonal imbalances, infection, or coagulopathy. 1

Understanding Your Situation

When your quantitative hCG level is truly zero (< 5 mIU/mL), you are definitively not pregnant—neither with an intrauterine nor an ectopic pregnancy. 1 A negative serum hCG essentially excludes both possibilities because the hormone becomes detectable approximately 9 days after conception. 1

Post-Miscarriage Context

If you recently experienced a miscarriage or pregnancy loss, hCG can remain detectable for several weeks afterward. 1 However, once your hCG has declined to zero, any ongoing bleeding is no longer related to retained products of conception or persistent trophoblastic tissue. 2

• Serial hCG monitoring after miscarriage should continue until levels fall below 5 mIU/mL, confirming complete resolution. 2
• If hCG has reached zero but bleeding persists beyond 4–6 weeks post-loss, this warrants investigation for other causes. 2

Differential Diagnosis for Bleeding with Zero hCG

Structural Causes

• Cervical pathology: Cervicitis, cervical polyps, or cervical ectropion can cause vaginal bleeding independent of pregnancy status. 3
• Vaginal lacerations or trauma: These can be identified through careful pelvic examination. 3
• Endometrial pathology: Polyps, fibroids, or hyperplasia may cause irregular bleeding. 3

Hormonal Causes

• Anovulatory bleeding: Irregular shedding of the endometrium due to hormonal imbalance (thyroid dysfunction, hyperprolactinemia, polycystic ovary syndrome). 1
• Breakthrough bleeding: Related to contraceptive use or hormonal fluctuations. 1

Other Considerations

• Coagulation disorders: Particularly if bleeding is heavy or prolonged. 3
• Infection: Endometritis or pelvic inflammatory disease. 3
• Premature ovarian insufficiency: Leading to irregular bleeding patterns. 1

Recommended Diagnostic Workup

Obtain a thorough menstrual history, including timing of last normal menses, pattern of current bleeding (duration, volume, associated pain), recent pregnancy loss, contraceptive use, and risk factors for structural or hormonal pathology. 1

Physical Examination

• Perform a speculum examination to visualize the cervix and vagina, looking for polyps, lacerations, cervicitis, or other visible sources of bleeding. 3
• Conduct a bimanual examination to assess uterine size, tenderness, and adnexal masses. 3

Imaging

• Transvaginal ultrasound is the primary imaging modality to evaluate endometrial thickness, identify structural lesions (polyps, fibroids), and assess for retained tissue if recent pregnancy loss occurred. 3, 2
• An endometrial stripe of 8 mm or less after confirmed pregnancy resolution is typically physiologic regeneration rather than pathology. 2
• Ultrasound should specifically document any echogenic masses, endometrial irregularities, or free fluid. 2

Laboratory Testing

• Complete blood count to assess for anemia from blood loss. 3
• Thyroid function tests (TSH) to exclude thyroid dysfunction causing anovulatory bleeding. 1
• Prolactin level if menstrual irregularity or galactorrhea is present. 1
• Coagulation studies if bleeding is heavy or patient has personal/family history of bleeding disorders. 3

When to Seek Emergency Care

Return immediately for evaluation if you experience: 2, 4

• Heavy bleeding soaking through one pad per hour for two consecutive hours
• Severe or worsening abdominal pain, particularly if unilateral
• Shoulder pain (may indicate intraperitoneal bleeding)
• Dizziness, syncope, or signs of hemodynamic instability

Critical Pitfalls to Avoid

• Do not assume bleeding is "leftover" from a prior pregnancy once hCG is zero—investigate alternative causes. 2
• Do not delay evaluation if bleeding is heavy, prolonged (> 7 days), or associated with severe pain. 3, 2
• Ensure the hCG test was performed correctly and consider repeat testing if clinical suspicion remains high, as rare cases of ectopic pregnancy with negative hCG have been documented (though exceedingly rare). 5
• If you had a recent pregnancy loss without documented intrauterine pregnancy, ensure ectopic pregnancy was definitively excluded, as chronic ectopic pregnancies can present atypically. 5

Management Algorithm

1. Confirm hCG is truly < 5 mIU/mL with quantitative serum testing (not just qualitative urine test). 1, 2
2. Obtain transvaginal ultrasound to evaluate for structural causes and assess endometrial thickness. 3, 2
3. Perform pelvic examination to identify cervical or vaginal sources of bleeding. 3
4. Order laboratory workup including CBC, TSH, and prolactin as clinically indicated. 1
5. Treat underlying cause once identified (hormonal therapy for anovulation, polypectomy for polyps, antibiotics for infection, etc.). 3, 1
6. If no cause is identified and bleeding persists, consider endometrial sampling or hysteroscopy to exclude endometrial pathology. 3

The key principle is that zero hCG definitively excludes pregnancy-related bleeding, shifting your diagnostic focus entirely to non-pregnancy causes that require systematic evaluation and targeted treatment. 1, 2