Which Week of Pregnancy Is Best For An Anomaly Scan?

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Which Week of Pregnancy Is Best For An Anomaly Scan?

Which Week of Pregnancy Is Best For An Anomaly Scan? 

An anomaly scan lay performed on the 18th week of pregnancy, sometimes on the 20th, and sometimes, during the 21st or 22nd week! It means your doctor is the one to decide which week of pregnancy is best for an anomaly scan to diagnose the life growing inside you!

It is the second scan your doctor up-takes during your pregnancy tenure and is therefore called the mid-pregnancy scan. It also gets called an anatomy scan, as it looks for the baby’s anatomical structures.


If you are pregnant, take periodic consultations from your doctor, and pursue body scans as a part of parental care, an anomaly scan is something your doctor is likely to recommend after your first trimester, typically in your second trimester, to see the anatomical growth of your baby. It is a scan that can tell you if there are any anomalies or abnormalities with the pregnancy and therefore earns such a name!

Your doctor is most plausible to order an ultrasound for it. No X-ray, CT scan, No MRI, or others! An ultrasound is the safest anomaly scan, non-invasive, quick, and does not involve radiation use! Thus, your fetus can be safe while you and your doctor see it; that too in detail!

But, yet again, it is not mandatory. You do not have to up-take an anomaly scan if you do not want it. Not that this scan can pick every condition of your pregnancy development so accurately!

When Do Doctors Recommend an Anomaly Scan?

While some medical experts argue that the 18th to 21st week of pregnancy is the best for an anomaly scan, many say the 20th to 24th week is the ideal time! Some healthcare professionals also say the 21st to 24th is when your child’s anatomy gets clearly seen.

Researchers even mention sticking to the 19th week as the best time for an ultrasound, the anomaly ultrasound! Hence, it’s evident that the answer to which week of pregnancy is best for an anomaly scan is subject to heated debates in medical science.

No matter which week of pregnancy your doctor opts for 18th to the 24th, there isn’t much change to expect in the scan results.

What Can An Anomaly Scan Diagnose?

An anomaly scan examines the growing baby’s bones, heart, brain, spinal cord, and kidneys.  This scan also looks for the baby’s facial features and abdomen in detail. Such an in-depth diagnosis allows your doctor to detect if there are any rare anomalies, as follows.

  • An anomaly scan can detect Anencephaly, the congenital condition in which the baby in your womb misses a part of the skull and the cerebral hemisphere of the brain.
  • Cleft Lip, a birth defect where your baby has an opening in the upper lip due to the incomplete joining of the lip tissues, is the scan’s other finding.
  • The scan can reveal Exomphalos or an abnormality in your baby’s abdomen wall. In this condition, your baby’s abdominal organs, the bowel, liver, or stomach, grow in a sac.
  • An anomaly scan is also beneficial in detecting Gastroschisis, where your baby’s intestines grow beyond the abdomen via a hole near the belly button.
  • It can also diagnose another birth deficit known as Open Spina Bifida, where the spinal column lay malformed or unformed, leaving a gap in your baby’s spine.
  • Your doctor can find a Diaphragmatic Hernia or a congenital condition where your baby has a hole in the diaphragm.
  • An anomaly scan can identify serious cardiac abnormalities in your baby growing inside the womb, such as a hole in the heart, a narrowed artery, or valves that cannot open and close appropriately.
  • It can also identify Lethal Skeletal Dysplasia, i.e., genetic disorders where your baby’s bones and cartilage grow and develop abnormally.
  • Doctors may also want to check if there is a Bilateral Renal Agenesis, where your baby’s kidney fails to develop. An anomaly scan can diagnose this abnormality in the fetus.
  • An anomaly scan can likewise detect Edwards’ Syndrome, a genetic condition where your baby has a third additional chromosome 18 and therefore grows abnormally inside your womb.
  • The scan can show Patau’s Syndrome too, where there’s an additional chromosome 13 in your baby’s gene, and hence develop absurdly with deformities.

Besides, an anomaly scan can help assess the placenta’s location, cervix length, and amniotic fluids around the baby. If and when a defect lay detected, this scan report can help your doctor plan an early surgery before due time to save the baby!

Do you know that an anomaly scan can even display the sex of your fetus? That’s right! However, your doctor is not likely to reveal it to you to avoid female feticide.

How Accurate Is an Anomaly Scan?

Records confirm that an anomaly scan is nearly 90 to 95% accurate in diagnosing birth defects during the mid-trimester of your pregnancy. According to the statistics compiled by CRANE, an anomaly scan on the 20th week of pregnancy can detect cleft lips for 81% of the cases.

The National Center for Biotechnology Information (NCBI)  states that an anomaly ultrasound scan can serve with 94.7 % sensitivity and 98.3% specificity in diagnosing open Spina bifida in fetuses. Studies also demonstrate that an anomaly ultrasound can detect congenital heart diseases in the mid-trimester of pregnancy for around 60% to 70% of the cases.

As per the NHS Anomaly Screening Program, a mid-pregnancy anomaly scan is able to diagnose congenital diaphragmatic hernia in 60% of the cases. Researches even highlight that an anomaly scan during the 14th to 21st week of pregnancy holds an accuracy rate of 90% in detecting Edwards’ syndrome.

Concluding Thoughts

This brings us to the end part of our article, where it is quite visible to us that which week of pregnancy is best for an anomaly scan depends on various factors.

Yes, from what your doctor aims to identify to when can an anomaly rightly shows up during the pregnancy tenure, many things shall determine when to up-take the ultrasound. So, it is a little advice from us, www.mrichandigarh.com, to follow what your doctor says!

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About author
Hi, I am Alka Tiwari, Founder & Patient Care Executive at MRIChandigarh.com. Helping you get the diagnostics scans services like MRI, CT Scan, UltraSound & PET Scan, etc at the best price. At MRIChandigarh's blog, I will be writing to create awareness and to educate you about how and where to get diagnostic scans done in Chandigarh at the best price with best-in-class services.
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