In an 18‑week pregnant woman presenting with decreased fetal movement and absent fetal heartbeat (previously normal), what is the next diagnostic step?

Next Diagnostic Step for Fetal Demise at 18 Weeks

The next step is D. USG Abdomen (ultrasound examination), which is the definitive diagnostic procedure to confirm fetal demise, assess fetal anatomy for structural abnormalities that may have caused the death, evaluate placental appearance, and measure amniotic fluid volume. 1

Why Ultrasound is the Correct Next Step

Ultrasound is the gold standard for confirming fetal demise at 18 weeks gestation. At this gestational age, ultrasound can reliably document absent cardiac activity and provide comprehensive evaluation of the fetus and intrauterine environment. 1 The American College of Radiology recommends ultrasound as the primary diagnostic modality for confirming fetal demise and evaluating associated findings. 1

Key Diagnostic Features on Ultrasound

The ultrasound examination should document:

• Absent fetal cardiac activity - This is the definitive criterion for fetal demise at 18 weeks. 1
• Fetal anatomical assessment - Evaluation for structural abnormalities that may have caused the demise. 1
• Placental appearance and location - Assessment for placental pathology. 1
• Amniotic fluid volume - Measurement to evaluate for oligohydramnios or polyhydramnios. 1
• Signs of hydrops, growth restriction, or other pathology - Comprehensive evaluation for additional findings. 1

Why Invasive Procedures Are NOT the Next Step

Amniocentesis (A), placental tissue sampling (B), and umbilical cord sampling (C) should only be considered AFTER fetal demise is confirmed by ultrasound, and only if there is a clinical indication to determine the cause of death. 1 The American College of Obstetricians and Gynecologists recommends that invasive diagnostic testing such as chromosomal microarray analysis be offered when fetal growth restriction or malformations are detected, but this follows initial ultrasound diagnosis. 1

Critical Pitfall to Avoid

Never proceed directly to invasive testing without first confirming fetal demise with ultrasound. Invasive procedures carry risks of maternal complications including bleeding, infection, and uterine injury. These risks are only justified after ultrasound confirms the diagnosis and identifies specific indications for determining the cause of death (such as structural abnormalities or growth restriction). 1

Clinical Management After Ultrasound Confirmation

Once fetal demise is confirmed at 18 weeks:

• Active evacuation is recommended, not expectant management - Due to increased risk of intrauterine infection, coagulopathy, and maternal sepsis with prolonged retention of fetal tissue. 1, 2
• Dilation and evacuation (D&E) is the preferred surgical method at this gestational age. 2
• All Rh-negative women must receive anti-D immunoglobulin to prevent alloimmunization. 2

Warning Signs Requiring Urgent Intervention

Do not delay treatment if any of the following are present:

• Maternal tachycardia - May indicate developing infection even without fever. 2
• Purulent cervical discharge - Sign of intrauterine infection. 2
• Uterine tenderness - Suggests chorioamnionitis. 2
• Profuse vaginal bleeding - Requires immediate surgical evacuation. 2

Clinical symptoms of infection may be less evident at earlier gestational ages, and treatment should not be delayed waiting for fever to develop. 2