At what gestational age is the detailed fetal anatomy ultrasound typically performed?

• A. 10–12 weeks
• B. 34–38 weeks
• C. 18–22 weeks
• D. 28–32 weeks

Answer: (C)

The mid-trimester window, around 18–22 weeks, is when a detailed fetal anatomy ultrasound is best performed. At this gestational age most organ systems are sufficiently developed and positioned to be visualized clearly, allowing a systematic check of the brain, face, heart, spine, abdomen, limbs, and also the placenta and amniotic fluid. Earlier scans (10–12 weeks) focus on early measurements such as crown-rump length and nuchal translucency and aren’t ideal for a full anatomy assessment. Later scans (34–38 weeks) are less optimal for detailed anatomy because visualization can be limited by fetal position and ossification, though they’re useful for growth and well-being checks. A scan at 28–32 weeks may assess growth and anatomy to some extent, but the standard timing for a comprehensive anatomy survey remains 18–22 weeks.