What is the next step for diagnosis in a pregnant female in her second trimester, at 18 weeks gestation, with decreased fetal movement and no fetal heartbeat, who had a normal fetal heartbeat on a previous visit?

Ultrasound Abdomen is the Next Step for Diagnosis

In a patient at 18 weeks gestation with decreased fetal movement and no detectable fetal heartbeat on clinical examination, an ultrasound is the immediate next diagnostic step to confirm fetal demise before considering any invasive procedures. 1

Diagnostic Rationale

• Ultrasound can reliably document absent cardiac activity at 18 weeks gestation, assess fetal anatomy for structural abnormalities that may have caused the demise, evaluate placental appearance, and measure amniotic fluid volume. 1

• The Society of Radiologists in Ultrasound recommends using the term "fetal demise" (specifically at ≥11 weeks gestation) when cardiac activity is absent on ultrasound examination. 1

• At 18 weeks with an HCG level well above the discriminatory threshold, a viable intrauterine pregnancy should be clearly visible on ultrasound with cardiac activity if the fetus were alive. 2

Why Invasive Procedures Are NOT the Next Step

• Invasive procedures like amniocentesis, placental tissue sampling, or umbilical cord sampling 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

• These invasive procedures carry procedural risks and are not diagnostic tools for confirming fetal viability—they are reserved for determining etiology after demise is documented. 1

• The Society for Maternal-Fetal Medicine recommends diagnostic testing including chromosomal microarray analysis when fetal growth restriction or malformations are detected, but this follows initial ultrasound diagnosis, not precedes it. 1

Clinical Management After Ultrasound Confirmation

• Once fetal demise is confirmed at 18 weeks, active evacuation (not expectant management) is recommended due to increased risk of intrauterine infection, coagulopathy, and maternal sepsis with prolonged retention. 1

• A comprehensive ultrasound examination should assess any signs of hydrops, growth restriction, or other pathology, in addition to confirming absent cardiac activity. 1

Common Pitfalls to Avoid

• Never proceed directly to invasive testing without first confirming fetal viability status with ultrasound—this exposes the patient to unnecessary procedural risks. 1

• Do not delay ultrasound imaging based on hope or rely solely on clinical examination (Doppler) for definitive assessment, as this can lead to maternal psychological distress and potential complications from retained nonviable tissue. 2

• Handheld Doppler devices are unreliable before 12 weeks gestation and can fail to detect cardiac activity even in viable pregnancies at 18 weeks, making formal ultrasound imaging necessary for diagnostic certainty. 2

Answer: D. USG Abdomen