Fetal Morphology – What Is It & What Role Does It Play

As a mother-to-be, you want to be sure that your baby is developing exactly as it should. That's why there are several examinations recommended during pregnancy which make it possible to detect potential anatomical malformations or congenital disorders at an early stage. The fetal anomaly scan (organ screening) is one of these examinations.

The scan is usually carried out in the second trimester of pregnancy, but it can be performed in any trimester. Read on to find out how it works, what information it provides and how to prepare for a fetal anomaly scan!

What is a fetal anomaly scan?

A fetal anomaly scan is a medical examination consisting of an ultrasound that allows the doctor to assess the development of your future baby, the placenta, the umbilical cord and the volume of amniotic fluid, as well as to detect serious anatomical malformations or congenital disorders, should any be present.

During an anomaly scan, the doctor can examine the baby's skull, spine, limbs, heart, lungs, kidneys and bladder in detail to make sure there is no abnormal development. The same examination also allows the baby's heartbeat to be observed – and, if you'd like to know, you can also find out the baby's sex at this point.

How does a fetal anomaly scan work? 

In principle, the fetal anomaly scan is a pain-free examination that can be carried out abdominally, but also transvaginally or using a combination of both if the abdominal ultrasound doesn't provide an optimal view.

With the abdominal approach, you lie on the couch while the doctor applies a special gel to your abdomen. They then place the ultrasound probe on your abdomen and move it downwards in order to assess the baby's organs and structure precisely. To improve the view, they may apply gentle pressure.

If the abdominal ultrasound doesn't allow an accurate assessment of the placenta and cervix, the doctor may additionally recommend a transvaginal ultrasound. This is also pain-free and generally takes no longer than 5 minutes.

When is a fetal anomaly scan recommended?

The fetal anomaly scan is typical of the second trimester of pregnancy and is most commonly carried out then, although it can be performed in any of the three trimesters.

Fetal anomaly scan in the first trimester 

The first-trimester scan takes place between weeks 11 and 14 of pregnancy, that is, after at least 6 weeks without a period. It is usually carried out at the same time as the serological test, which is why it is also referred to as the double test.

The ultrasound at this stage provides information about the age of the fetus based on its measurements, the estimated due date, and any possible abnormalities of the skull, heart or limbs. Multiple pregnancies can also be identified at this point.

Fetal anomaly scan in the second trimester

Ideally carried out at week 22, the second-trimester anomaly scan can take place between weeks 20 and 24 depending on your doctor's individual recommendation, and can confirm or rule out the findings of the first-trimester scan (e.g. the risk of Down's syndrome, Edwards' syndrome, etc.).

The images from this examination now show the face, limbs, spine, chest and diaphragm in considerably greater detail. The doctor can also tell you the baby's sex at this point, if you'd like to know.

In addition, the doctor can follow the baby's movements in real time and create a 3D or 4D reconstruction, as well as assess the placenta and umbilical cord in order to detect any potential complications early on.

Fetal anomaly scan in the third trimester

In the third trimester, the anomaly scan is carried out between weeks 30 and 32. Even though the baby's position and size make visibility more difficult at this stage, the examination is worthwhile for detecting possible problems with the central nervous system or heart defects that appear later on.

Which anomalies can a fetal anomaly scan detect?

Since the fetal anomaly scan makes it possible to view the baby's structure and organs in every trimester of pregnancy – from the skull to the upper and lower limbs – the following abnormalities can be detected:

• Facial malformations (cleft palate, chin malformations or cleft lip)
• Malformations in the chest area (ventricular septal defect, malformations of the blood vessels around the heart)
• Problems with the diaphragm (diaphragmatic hernia)
• Abdominal malformations (duodenal stenosis, oesophageal atresia, hyperechogenic bowel)
• Malformations of the urinary tract (megaureter, ureteropelvic junction obstruction)
• Malformations of the skull (hydrocephalus, encephalocele, holoprosencephaly)
• Problems with the spine (spina bifida, diastematomyelia)
• Heart defects
• Limb malformations (polydactyly, joint anomalies, skeletal dysplasias)
• Edwards' syndrome or Patau's syndrome

Does the fetal anomaly scan detect chromosomal abnormalities?

No, the fetal anomaly scan does not detect chromosomal abnormalities and cannot replace genetic testing.  It only allows the structure and organs of the fetus to be observed as it develops.

If the doctor finds indications of chromosomal abnormalities, they may recommend genetic tests to investigate them further.

Benefits of the fetal anomaly scan

Anomaly scans have many benefits, but the most important is that they allow potential abnormalities to be detected at an early stage. This means there is a chance to take action in good time and to plan appropriate medical care for the fetus, and for the mother too. Here is a list of the main benefits of the anomaly scan:

• It makes it possible to detect structural or congenital anomalies and to intervene in good time
• It confirms that  the pregnancy is progressing normally
• It reveals the baby's sex
• The examination is non-invasive, pain-free and involves no radiation exposure

How do you prepare for a fetal anomaly scan?

If you have a fetal anomaly scan coming up, there's no need to worry. No special or complicated preparations are required, just a few simple recommendations:

• Avoid using creams or oils on your abdomen for 24 hours before the ultrasound.
• For the second- and third-trimester scans, you should eat something beforehand, as this encourages the fetus to move and makes its structures easier to assess.
• It's recommended that you empty your bladder before the anomaly scan – as with any ultrasound.

When and how do you receive the results?

In most cases, you'll receive the results of the fetal anomaly scan on the same day, once the doctor has carefully reviewed them.

Depending on the case, after the second- and third-trimester scans, when the fetus is more clearly visible, you may receive a CD containing images relevant to the specialist – along with photographs you can keep as a memento.

What happens after the fetal anomaly scan?

After the examination, the doctor reviews the results. If everything is fine, you simply continue with your next scheduled appointments.

If the ultrasound results give the doctor cause for concern, they may recommend additional investigations, such as genetic tests – the only way to diagnose a chromosomal abnormality or determine the risk of one.

 Is the fetal anomaly scan compulsory?

Anomaly scans are not compulsory, but they are carried out on the recommendation of the doctor overseeing your care, as they allow a detailed assessment of the baby's structures and provide a wealth of precise information for the early detection of possible anomalies.