What is the next step in managing a 27-year-old patient with abdominal cramping, vaginal bleeding, a closed cervix, and an empty gestational sac on ultrasound 9 weeks after last menstrual period (LMP) with a positive home pregnancy test?

Management of Suspected Anembryonic Pregnancy (Blighted Ovum)

The next step is to obtain serial quantitative β-hCG levels and perform a follow-up transvaginal ultrasound in 7-10 days to confirm the diagnosis before proceeding with any intervention. 1

Diagnostic Considerations at 9 Weeks LMP

At 9 weeks from LMP with an empty gestational sac on ultrasound, you are dealing with either:

• Anembryonic pregnancy (blighted ovum) - most likely given the timeline
• Early pregnancy loss/embryonic demise
• Pregnancy of unknown location (PUL) - less likely but must be excluded
• Ectopic pregnancy - critical to rule out given the closed cervix and bleeding 1

Why Confirmatory Testing is Essential

Do not proceed directly to evacuation based on a single ultrasound. 1 The ACR guidelines emphasize that:

• An empty gestational sac alone is insufficient for definitive diagnosis of pregnancy failure 1
• Continued absence of embryonic cardiac activity on transvaginal ultrasound at least 7 days later confirms embryonic demise 1
• The diagnosis of ectopic pregnancy should be based on positive findings, not solely on absence of an intrauterine pregnancy 1

Immediate Diagnostic Workup

Obtain the following immediately:

• Quantitative serum β-hCG level - critical for interpretation 2, 3
• Complete blood count - assess for anemia from bleeding 4
• Blood type and Rh status - for potential RhoGAM administration

Key β-hCG thresholds to know:

• At β-hCG levels of 1,500-3,000 mIU/mL (discriminatory zone), a normal intrauterine pregnancy should show a gestational sac on transvaginal ultrasound 2, 3
• In normal pregnancy, β-hCG increases by 80% every 48 hours 2
• Failure to visualize an intrauterine pregnancy with β-hCG above the discriminatory level raises concern for ectopic pregnancy or early pregnancy loss 3

Critical Ectopic Pregnancy Exclusion

Before any uterine intervention, you must definitively exclude ectopic pregnancy. 1, 5 The ACR guidelines are explicit:

• Absence of intrauterine pregnancy with positive pregnancy test requires careful evaluation of extrauterine locations 1
• Examine both adnexa for extraovarian masses, particularly ipsilateral to the corpus luteum (70-80% of ectopic pregnancies) 1, 5
• Assess for free fluid in the pelvis - even without an identifiable adnexal mass, free fluid with internal echoes is concerning for ectopic pregnancy 1, 5
• A nonspecific heterogeneous adnexal mass is the most common sonographic finding of tubal pregnancy 1, 5

Follow-Up Protocol

Repeat transvaginal ultrasound in 7-10 days with specific criteria: 1

• Mean gestational sac diameter ≥25 mm with no embryo confirms anembryonic pregnancy 3
• Crown-rump length ≥7 mm without cardiac activity confirms embryonic demise 3
• Serial β-hCG should show appropriate rise (80% every 48 hours) for viable pregnancy or plateau/decline for failed pregnancy 2

If β-hCG is declining and repeat ultrasound confirms empty uterus:

• This suggests completed spontaneous abortion
• Continue monitoring β-hCG to zero

If β-hCG is rising or plateauing with persistent empty uterus:

• High suspicion for ectopic pregnancy 3, 6
• Consider methotrexate or surgical management based on clinical stability and β-hCG levels

Management Options After Confirmed Diagnosis

Once anembryonic pregnancy is confirmed on repeat imaging:

Three evidence-based options: 2, 3

1. Expectant management - effective for many patients with incomplete abortion 2
2. Medical management - misoprostol is highly effective for early intrauterine pregnancy failure 2
3. Surgical management - uterine aspiration/evacuation 3

Critical Pitfalls to Avoid

• Never perform uterine evacuation based on single ultrasound at 9 weeks - dating errors and early viable pregnancies can be mistaken for anembryonic pregnancy 1
• Never assume empty uterus equals intrauterine pregnancy failure - ectopic pregnancy must be excluded first 1
• Do not rely on β-hCG value alone - use in conjunction with ultrasound findings and clinical presentation 5, 3
• Ensure hemodynamic stability - if patient becomes unstable with increasing pain or bleeding, suspect ruptured ectopic and proceed emergently 4, 6

Patient Counseling During Workup

While awaiting confirmatory testing:

• Advise patient to return immediately for severe pain, heavy bleeding, dizziness, or syncope (signs of ruptured ectopic) 4, 6
• Explain that 7-10 day wait is standard of care to prevent inappropriate intervention 1
• Discuss all three management options for confirmed pregnancy loss 2, 3