A 3D anomaly scan is a mid‑pregnancy ultrasound that uses sound waves to create three‑dimensional images of the fetus to assess anatomy and detect structural abnormalities. Usually done around 18–22 weeks, it complements standard 2D scans by offering clearer views of the face, limbs, spine and organs. It’s non‑invasive but not all conditions are detected; further testing may be recommended if concerns arise.

The best time for a 3D (or 4D) fetal scan is typically between 26 and 32 weeks—often 28–30 weeks is ideal. By then the baby has more facial fat for clear features but still has enough amniotic fluid and room to move. Before 24 weeks features are immature; after 34 weeks the baby may be crowded, reducing image quality. Always discuss timing with your clinician.

Do you mean the "three‑vessel view" (3‑vessel and trachea view) of the fetal heart checked during the 20‑week anomaly scan, or a different "rule of 3"? If you mean the 3‑vessel view I can give a 50–75 word explanation now.

An anomaly scan, usually performed around 18–20 weeks, checks the baby’s anatomy for major structural abnormalities (brain, heart, spine, limbs, kidneys), confirms gestational age and fetal size, assesses placenta position and amniotic fluid, and can detect multiple pregnancies. Findings guide further testing or specialist referral if needed and provide reassurance about fetal development.

Yes and no. A prenatal 3D ultrasound can often determine fetal sex by visualizing external genitalia from about 16–20 weeks, with high but not perfect accuracy (affected by fetal position, gestational age, equipment and operator). In adults, 3D body scans show external anatomy and secondary sexual characteristics but cannot determine gender identity, which is a personal, social and psychological attribute.

An anomaly (mid-pregnancy) scan is generally not painful. It’s a non-invasive ultrasound using gel and a probe on the abdomen; you may feel mild pressure or brief discomfort, especially if your bladder is full or the sonographer presses for a better view. Transvaginal scanning is rarely needed. Severe or ongoing pain is uncommon—report any significant pain or concerns to your healthcare provider.