When can intrauterine fetal death (IUFD) be diagnosed in a 17-year-old primigravida with a confirmed missed abortion?

When to Diagnose Intrauterine Fetal Death (IUFD)

In a 17-year-old primigravida with confirmed missed abortion, IUFD is diagnosed when ultrasound demonstrates absent cardiac activity in an embryo with crown-rump length ≥7 mm, or when no embryo is visible in a gestational sac with mean diameter ≥25 mm. 1, 2

Diagnostic Criteria by Gestational Age

First Trimester (Before 11 weeks)

• Embryonic demise is confirmed when crown-rump length measures ≥7 mm without cardiac activity on ultrasound 1, 3
• Anembryonic pregnancy is diagnosed when mean gestational sac diameter measures ≥25 mm without a visible embryo 1, 2
• Absence of embryo ≥14 days after initial visualization of gestational sac also confirms early pregnancy loss 1

At or After 11 Weeks Gestation

• The term "fetal demise" (rather than embryonic demise) should be used specifically at ≥11 weeks gestation 1, 3
• At 11 weeks from last menstrual period, an embryo with cardiac activity should be clearly visible on ultrasound if the pregnancy were viable 2
• The absence of cardiac activity at this gestational age, combined with dating from last menstrual period, eliminates the possibility of dating error 2

Critical Terminology Considerations

Avoid using outdated terms like "blighted ovum," "pregnancy failure," or "nonviable pregnancy" when communicating with patients 1, 2. The preferred modern terminology includes:

• "Early Pregnancy Loss (EPL)" for losses before viability 1
• "Embryonic demise" for losses before 11 weeks 1
• "Fetal demise" for losses at ≥11 weeks gestation 1, 3
• "Anembryonic pregnancy" when gestational sac ≥25 mm lacks an embryo 2

Ultrasound Evaluation Requirements

Essential Assessment Components

• Document crown-rump length measurement precisely if embryo is present 2
• Measure mean gestational sac diameter if no embryo is visible 1, 2
• Confirm absence of cardiac activity using appropriate ultrasound modalities 3
• Evaluate adnexa to rule out ectopic pregnancy, though presence of intrauterine gestational sac makes this extremely unlikely 2

At Advanced Gestational Ages (≥18 weeks)

• Ultrasound should document absent cardiac activity, assess fetal anatomy for structural abnormalities, evaluate placental appearance, and measure amniotic fluid volume 3
• Comprehensive examination should assess for signs of hydrops, growth restriction, or other pathology 3

Management Implications After Diagnosis

Contraindications to Expectant Management

• Active evacuation is required, not expectant management, once IUFD is confirmed due to increased risk of intrauterine infection, coagulopathy, and maternal sepsis with prolonged retention 1, 3
• Expectant management carries significantly higher maternal morbidity (60.2% vs 33.0% with abortion care) and should be avoided 1
• Intraamniotic infection occurs in 38.0% of cases with expectant management compared to 13.0% with abortion care 1

Signs Requiring Immediate Intervention

• Do not wait for fever to diagnose intrauterine infection, as symptoms may be less evident in early gestations 1
• Look for maternal tachycardia, purulent cervical discharge, fetal tachycardia (if applicable), and uterine tenderness 1
• If infection is suspected, initiate broad-spectrum antibiotics immediately and proceed with urgent evacuation 1

Common Pitfalls to Avoid

• Never delay treatment waiting for fever if there is clinical suspicion of infection—proceed with evacuation based on clinical assessment 1
• Do not perform amniocentesis or other invasive procedures before confirming fetal demise by ultrasound; these should only be considered after diagnosis if there is clinical indication to determine cause of death 3
• Ensure Rh prophylaxis: All Rh-negative women must receive anti-D immunoglobulin (50 mcg dose for incomplete or complete abortion) to prevent alloimmunization, as fetomaternal hemorrhage occurs in 32% of spontaneous abortions 1