The anatomy scan: a partner's guide to week 20

The 20-week anatomy scan is the most clinically detailed scan of the pregnancy. It takes longer than anything that's come before, checks far more than most people realise, and occasionally surfaces findings that require follow-up. Walk in knowing what to expect — for both of you.

What the anomaly scan is checking

The sonographer is working through a structured checklist of over 60 measurements and structural markers. This isn't a quick look — it's a systematic assessment of the baby's developing anatomy. Key areas include:

• Brain structure: ventricles, cerebellum, skull shape
• Face: lip and palate formation, nasal bone
• Heart: four chambers, major vessels, position
• Spine: full length, skin coverage
• Abdominal wall: organs are inside the body, not protruding
• Kidneys: present, appropriate size, no obstruction
• Limbs: length, bone structure
• Placenta position and amniotic fluid level

The scan typically takes 30–45 minutes, sometimes longer. If the baby is in an awkward position, you may be asked to walk around and come back. This is routine, not a concern.

Why it sometimes takes longer — and what that doesn't mean

Partners often become anxious when the sonographer spends extended time on one area, goes quiet, or leaves the room. These are common parts of the process. Sonographers are trained not to comment during the scan because they are not the person to deliver clinical findings — a midwife or doctor does that. Silence is not a signal.

Write down your questions before you go. You will get the opportunity to ask them after the scan is complete.

If something is flagged

The majority of 20-week scans come back with no concerns. But a proportion will identify findings that need further assessment — a "soft marker," an unexpected measurement, or something that requires specialist review. If this happens:

• You will not be sent home without information — a midwife or doctor will speak with you
• A finding at the anomaly scan is not a diagnosis; it is a reason for further investigation
• Write down exactly what you're told, including the name of the finding and the next step
• Ask: "What does this mean for the pregnancy from here?" — one question at a time
• Do not google the finding in the car park — wait until you're home and can process together

Her reaction may be shock, silence, or tears. Your job is not to fix or reframe it immediately. Sit with it. The conversation about what it means can happen once you're both ready.

Finding out the sex — or not

In Ireland and the UK, many hospitals will tell you the sex at the 20-week scan if you ask — though not all trusts or hospitals offer this routinely, and accuracy is not 100%. Agree in advance whether you want to know. If one of you does and one doesn't, that conversation needs to happen before the appointment, not in the room.

If you're not finding out, tell the sonographer clearly at the start so they can position the screen accordingly.

The 20-week scan is often described as exciting, and often it is. It's also the scan where the most complex findings surface. Being emotionally prepared for both outcomes isn't pessimism — it's good partnership.

Questions worth writing down before you go

• Is everything measuring within the expected range?
• Where is the placenta positioned — will that affect delivery planning?
• When is the next scheduled appointment after this?
• Is there anything we should be monitoring at home?

Keep up with everything week by week using the week-by-week guide, or join the Plus waitlist for scan-specific prep notes delivered to both of you in the week before each appointment.