What Is An Anomaly Scan?

6 min read

Written by Editorial Team

Editorial Team

anomaly scan

Scans in the course of pregnancy are significant. Scans help to detect possible fetal complications. Here we are discussing a scan that is scheduled during the second trimester of pregnancy and holds a lot of significance– the anomaly scan.

An anomaly scan is important for both mother and baby during the 20th week of pregnancy. This scan helps to check for any abnormalities in the growing baby. Finding out about problems before birth can help in providing post-birth care. This is particularly helpful for situations in which immediate surgery after birth might improve the chances of the baby recovering.

In This Article

What Is An Anomaly Scan?

The scan inspects every part of the fetus to check whether the child is growing normally. Sonographers pay special attention to the brain, face, arms, spine, heart, tummy, bowels, legs, and kidneys. Doctors perform this scan around the 20th week of pregnancy.

Why Do I Need An Anomaly Scan?

Though most babies are born normal, all women, whatever their age, have a little risk of delivering an infant with some physical and mental abnormalities. Many of such abnormalities can be ruled out or found with a fetal anomaly scan.

Why Am I Asked To Repeat My Anomaly Scan After Two Weeks?

15% of anomaly scans repeat. Most events that called for a repeat of anomaly scan are not consequential. The most common reason is that the person performing an anomaly scan has not seen all that he or she needs to see. This might be on the grounds that your kid is not lying in the right position.

In addition, the sonographer repeats this scan if the mother is moderately overweight since the sonographer will not be able to see all the details he needs to in that case. So, he will wait two more weeks before getting another scan. He will tell you straight up if there is anything to worry about.

What Does The Anomaly Scan Show?

What Does The Anomaly Scan Show_

During the anomaly scan, the doctor will look closely at the following factors.

  1.  Brain to detect abnormalities.
  2.  The doctor will check for any abnormalities in the appearance of the face of the fetus, which is clearly visible during an anomaly scan
  3. Examining the  spine of the fetus, both lengthwise and in cross-section
  4.  Examines the heart, the four chambers (two auricles and two ventricles), major blood vessels, and valves are clearly visible in the scan.
  5. The doctor will look into the abdominal wall of the fetus closely  for any abdominal wall defects
  6. There will be some black bubbles in the anomaly scan inside the stomach.
  7. The doctor confirms that the baby has two kidneys. He will also confirm that the urine is passing well to the bladder. Observing filling and emptying the bladder is easy to watch, as the little one passes urine every 30 minutes during this period
  8.  Thoroughly examines hands, arms, legs, and feet.
  9.  Position of the placenta
  10. The blood vessels in the umbilical cord are visible on this scan. Thus, the doctor can make certain that enough blood is flowing uninterruptedly through it
  11. For the baby to move in the womb, the doctor will check whether there is enough amniotic fluid

Measurements That Are Taken During An Anomaly Scan

During an anomaly scan doctor will evaluate the baby’s biometric parameters to assess the fetal size, like:

  • Abdominal circumference
  • Head circumference
  • Length of the femur or thigh bone
  • Length of the humerus or arm bone

What Abnormalities Can Be Detected In An Anomaly Scan?

What Abnormalities Can Be Detected In An Anomaly Scan_

The sonographer will examine all your baby’s organs and take measurements. Some abnormalities that  anomaly scan picks are:


Anomaly scan detects the following head abnormalities:

1. Anencephaly

Anencephaly is a condition in which the top of the head of the fetus is absent. Sonographers can detect 99% of such issues via this scan.

2. Hydrocephalus

It is a condition in which the brain of the fetus bears excess fluid. This screening detects 60% of hydrocephalus during this time of gestation. However,  hydrocephalus can happen in later in the course of pregnancy or even after delivery.


A facial abnormality that can be detected by the scan is:

Cleft lip

75% of the cleft lip can be picked up in an anomaly scan. However,  anomaly scans rarely select these abnormalities because the palate is present inside the baby’s mouth and very hard to pick up.


analysing scan

A spinal abnormality that can be detected by means of an the scan is,

Spina bifida

Also called a neural tube defect, spina bifida happens when the bones of the spine (vertebrae) don’t cover a part of the baby’s spinal cord. This will result in the opened spinal cord. If the skin does not cover the spine at the back. Sonographers can find 90% of spina bifida during the scan.


Your baby’s heart comprises 4 chambers, two in the top and two in the bottom. During an anomaly scan,

  • All the 4 chambers should be equal in size
  • The valves should be opening and closing with every heartbeat

Any deviation from these conditions indicates the chances of major congenital heart issues. This scan detects 60% of issues related to the heart during this phase of gestation.

Abdominal Wall

If the abdominal wall does not properly cover all the internal organs in the abdomen, the sonographer can detect it in an anomaly scan. There are 90% chances of detecting if the baby has any of the following abdominal wall defects:

1. Exomphalos

Though intestine and internal organs begin to develop inside the umbilical cord during the initial stage of pregnancy, they ought to move inside the abdomen a few weeks later (obviously before the 2nd trimester). Exomphalos is a condition in which some of the internal organs remain inside the umbilical cord outside the abdomen

2. Gastroschisis

A condition in which, the intestine and some of the internal organs protrude through a hole (depending on the size) near the point where the umbilical cord meets the baby’s tummy (belly button)



Renal abnormalities are one of the most common congenital anomalies this scan detects. Anomaly scans can pick up 85% of such abnormalities.

1. Unilateral Renal Agenesis

The complete absence of one kidney.

2. Bilateral Renal Agenesis

The complete absence of both kidneys.

3. Kidney Dysplasia

Kidney dysplasia is a condition in which either one or both of the fetal kidneys do not develop normally, though the condition occurs with only one kidney. While your baby may be able to grow normally if only one of its kidneys is functioning, we cannot rule out future health problems.

In most cases, a pregnancy may not complete its time if a baby has kidney dysplasia that affects both kidneys. And if the pregnancy completes the term, the baby will require dialysis and kidney transplant very early in their life

4. Duplex Kidney System

Two ureter tubes are present rather than the normal single ureter tube for each kidney in this condition.


Missing or abnormal limbs can be detected in this screening test.


The scan can detect any complications due to the position of the placenta.

Amniotic Fluid

Excess or deficiency of amniotic fluid can be detected.

Diaphragmatic Hernia

A condition occurs when the diaphragm does not form properly. The diaphragm is a thin sheet of muscle separating the chest from the abdomen. In a diaphragmatic hernia, due to malformation of the diaphragm, a hole appears in the diaphragm. The sonographer will be able to detect it in the scan.

What If Some Issues Are Found In My Anomaly Scan?

On the off chance that the sonographer recognizes some issues during the screening. In that case, he will direct you to consult a medical specialist in a couple of days. The specialist will examine you again. You will find out whether your infant needs treatment, while inside the womb or if treatment will be necessary soon after birth. Sometimes, you can choose to end your pregnancy. You will receive guidance and support when making this massively difficult decision.

Is Anomaly Scan 100% Accurate?

Regardless of the fact that your result is normal, there is a little risk that your child will even now have an issue. A few conditions, including certain heart issues and bowel blocks, may not be able to detect until later in your pregnancy. Therefore, despite the fact that this scan will help you rule out any defects, it still cannot guarantee 100 % accuracy.

How Much Does An Anomaly Scan Cost?

The costs of this scan vary across different places in India. Anyhow, mostly the charge comes some were between 1500 to 3000 INR.

Editorial Team,

With a rich experience in pregnancy and parenting, our team of experts create insightful, well-curated, and easy-to-read content for our to-be-parents and parents at all stages of parenting.Read more.

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