A Fetal Anomaly Scan, also called a Level II ultrasound, level 2 scan, or fetal anatomy ultrasound, is a detailed pregnancy ultrasound usually performed in the second trimester to closely examine your baby’s developing body. Many people also know it as the 20-week pregnancy scan (even though it’s typically done anytime from about 18 to 22 weeks).

This scan uses sound waves (not radiation) to create real-time images of the baby and the uterus. A specially trained sonographer and/or doctor checks your baby’s growth and carefully reviews major organs and structures, commonly including:

• Brain and skull
• Face (including lips) and neck
• Spine
• Heart (four chambers and outflow tracts) and heartbeat
• Lungs and diaphragm
• Stomach, kidneys, bladder, and abdominal wall
• Arms, legs, hands, and feet
• Placenta location and appearance
• Umbilical cord (including number of vessels)
• Amniotic fluid amount
• Cervix (in some cases, to assess risk of preterm birth)

What the results mean: A “normal” anomaly scan means no structural problems were seen at the time of the exam and your baby’s growth and anatomy look appropriate for gestational age. If something is described as “suboptimal views” or “incomplete,” it often means the sonographer couldn’t get clear images of one or more areas (commonly due to baby’s position, maternal body habitus, uterine fibroids, or low/high amniotic fluid) and a repeat scan may be recommended. If a potential abnormality or “soft marker” is identified, it does not always mean a serious problem—your clinician may suggest follow-up imaging, a fetal echocardiogram, or genetic screening/diagnostic testing to better understand the finding.

The fetal anomaly scan is a standard part of routine prenatal care for most pregnancies because it is the best time to do a detailed structural review: the baby is large enough for organs to be seen clearly, and there is typically enough amniotic fluid to help imaging.

It may be recommended routinely between 18–22 weeks, and may be especially emphasized or repeated if there are additional reasons to look more closely, such as:

• Screening for birth defects in the brain, spine, heart, kidneys, abdominal wall, limbs, and other organs.
• Dating and growth assessment if the due date is uncertain or if fundal height measurements don’t match expected growth.
• Placenta concerns, such as evaluating placenta previa (placenta low in the uterus) or checking for placental abnormalities.
• Amniotic fluid concerns (too much or too little fluid).
• Multiple pregnancy (twins or more), to assess anatomy and growth patterns.
• Risk factors for fetal anomalies, including maternal diabetes, certain infections, exposure to teratogenic medications/substances, or a prior pregnancy affected by a congenital anomaly.
• Family history of congenital heart disease or genetic conditions.
• Abnormal earlier tests, such as unusual first-trimester ultrasound findings, abnormal NIPT/combined screening, or elevated maternal serum AFP (which can be associated with open neural tube defects or abdominal wall defects).
• Symptoms that need evaluation, such as bleeding, suspected leaking of fluid, significant abdominal pain, or concerns about fetal wellbeing—your clinician may combine an anatomy review with other ultrasound assessments depending on the situation.

Because ultrasound is an imaging test, you won’t usually “feel” symptoms that directly indicate a structural anomaly. The main purpose is early detection so you and your care team can plan next steps, which may include additional imaging, specialist referral (maternal-fetal medicine), delivery planning, or newborn care planning.

• Congenital heart defects (e.g., ventricular septal defect, outflow tract abnormalities)
• Neural tube defects (e.g., spina bifida, anencephaly)
• Cleft lip and/or palate
• Abdominal wall defects (e.g., gastroschisis, omphalocele)
• Congenital diaphragmatic hernia
• Renal/urinary tract abnormalities (e.g., hydronephrosis, renal agenesis)
• Brain/ventricular abnormalities (e.g., ventriculomegaly)
• Chromosomal condition risk indicators/“soft markers” (e.g., findings that may be associated with Down syndrome, trisomy 18, trisomy 13)
• Placenta previa and other placental location abnormalities
• Amniotic fluid disorders (polyhydramnios, oligohydramnios)

• Routine second-trimester pregnancy screening and reassurance about fetal development
• Early identification of structural anomalies to enable timely specialist referral and care planning
• Monitoring fetal growth and confirming gestational age when needed
• Assessing placenta position (e.g., ruling out or tracking placenta previa) to support safe delivery planning
• Evaluating amniotic fluid levels to guide monitoring and treatment decisions
• Planning additional testing (e.g., repeat ultrasound, fetal echocardiography, genetic counseling/testing) when indicated
• Optimizing birth setting and newborn care by anticipating potential medical or surgical needs after delivery