What could be causing heavy bleeding three weeks after a miscarriage despite a trans‑vaginal ultrasound showing an empty uterus?

Heavy Bleeding Three Weeks Post-Miscarriage with Clear Ultrasound

You are most likely expelling residual endometrial tissue as part of normal uterine healing, not retained products of conception, since your ultrasound shows an empty uterus. 1

What You're Actually Expelling

• The shedding of residual endometrial lining (approximately 8 mm thick) is a normal component of uterine healing after miscarriage and does not indicate retained products of conception. 1

• Intermittent bleeding arises from the placental implantation site as it remodels and heals after tissue expulsion, which can produce episodes of heavier flow even weeks later. 1

• Ongoing uterine involution involves gradual breakdown and expulsion of the endometrial lining, which can produce spotting or bleeding for several weeks post-miscarriage. 1

Why Your Ultrasound Being "Clear" Is Reassuring

• Endometrial thickness up to 20–25 mm in the early post-miscarriage period is considered nonspecific; measurements well below this range (such as 8 mm) are not diagnostic for retained products of conception. 1

• Ultrasound findings that would raise suspicion for true retained products include:

  • An echogenic endometrial mass with Doppler-detected vascularity 1
  • Focal endometrial thickening accompanied by blood flow on Doppler imaging 1
  • A discrete, identifiable mass rather than diffuse, uniform thickening 1

• If your scan showed none of these features—just an empty or thin endometrial stripe—then you do not have retained products requiring intervention. 1

When Heavy Bleeding Becomes an Emergency

You need immediate evaluation if you experience: 1

• Heavy vaginal bleeding (soaking more than one pad per hour for ≥ 2 consecutive hours) 1
• Fever ≥ 38°C (100.4°F) or foul-smelling vaginal discharge suggesting infection 1
• Hemodynamic instability such as dizziness, syncope, or orthostatic symptoms 1

Serial β-hCG Monitoring to Confirm Resolution

• Serial quantitative β-hCG measurements should demonstrate a progressive decline to undetectable levels following a complete miscarriage; this confirms resolution of trophoblastic tissue. 1

• Persistent or plateauing β-hCG levels may indicate residual trophoblastic tissue requiring further evaluation or, rarely, gestational trophoblastic disease. 1

• If your β-hCG plateaus over 3–4 consecutive weekly measurements, rises >10% across three values within 2 weeks, or remains detectable for ≥6 months, you should be evaluated for gestational trophoblastic disease. 1

When Intervention Is Actually Needed

Dilation and curettage should be reserved for: 1

• Heavy bleeding requiring transfusion 1
• Confirmed vascular retained products on Doppler ultrasound 1
• Persistent or rising β-hCG levels 1

Do not diagnose retained products of conception solely on endometrial thickness <20 mm; an approximately 8 mm stripe is normal after miscarriage. 1

Rare but Important Differential: Gestational Trophoblastic Disease

• Although uncommon, gestational trophoblastic disease should be considered when β-hCG fails to decline appropriately despite an empty uterine cavity on ultrasound. 1

• Markedly elevated initial β-hCG (>100,000 mIU/mL) is characteristic of gestational trophoblastic disease. 1

Bottom Line

Your heavy bleeding at three weeks post-miscarriage with a clear ultrasound is most consistent with normal endometrial shedding and placental-site healing. 1 Monitor for warning signs (soaking >1 pad/hour for ≥2 hours, fever, dizziness), and obtain serial β-hCG measurements to confirm appropriate decline to zero. 1 Intervention is only needed if you develop hemodynamic instability, confirmed vascular tissue on Doppler, or abnormal β-hCG patterns. 1