At this stage of pregnancy, your baby measures approximately 25 cm from head to toe and has reached half their birth size. In contrast, they only weigh approximately 500 g. Their small size means that they can begin to move with ease while you still feel relatively little movement. They sleep nearly all the time and, although they cannot see yet, their sense of touch is highly developed. Their appearance is also developing fast; their arms and legs are clearly visible and they have fingers, feet measuring 4 cm, a heart that is the size of a cherry and even a nose... Your baby is really taking shape.
Your second trimester ultrasound scan is performed at around 22 weeks pregnant. Our main aim is to look for morphological or anatomical abnormalities and a specialist will focus on a wide range of organs and structures. The test is carried out on several dozen parameters, using a precise and methodical visual analysis of your whole baby, for example:
- The shape and structure of your baby’s head and brain are examined in order to detect certain serious, but extremely rare, brain problems.
- The facial elements are checked in order to detect abnormalities, such as a cleft lip. However, cleft palates, located inside the mouth, are not visible. The presence of two sockets, nostrils and tongue as well as the size of the nose, neck and ear bones are all checked.
- The spine is thoroughly examined in order to check the vertebrae are complete and correctly aligned.
- The abdominal wall is also checked to ensure it properly covers all internal organs.
- The size, form and function of the heart are assessed: the four chambers should be symmetrical and the two atrioventricular valves should be well formed. Heart rate and development of the pulmonary arteries and aorta are monitored.
- The stomach is also examined because your baby swallows amniotic fluid, making the organ visible.
- The test then focuses on the renal system: the presence and function of two kidneys as well as good urine flow in the bladder are assessed. If your baby’s bladder is empty, you will see it fill up during the ultrasound scan as they have been urinating every 30 minutes for several months now.
- The arms, hands, legs and feet are all examined.
- Your baby’s growth is assessed using various measurements of the skull, abdomen and limbs.
The second ultrasound scan can also predict the sex of your baby with a high degree of accuracy.
External structures are also examined:
- Placenta, including wall thickness, position and structure
- Umbilical cord, including the three blood vessels
- Amniotic fluid
A Doppler ultrasound scan is usually performed to monitor blood flow in high-risk pregnancies or in the event of complications, such as:
- High blood pressure (hypertension) and pre-eclampsia
- Foetal distress
- Foetal abnormality
- Abnormal amniotic fluid
- Gestational diabetes
- Intrauterine growth restriction (IUGR)
- History of vascular disease in previous pregnancies, such as a detached placenta or pre-eclampsia
- Monochorionic twin pregnancy (single placenta)
- Health problems affecting the mother-to-be, such as lupus, kidney disease, high blood pressure
It is important to remember that in the vast majority of cases, pregnancies are healthy and your baby will be growing wonderfully. Any abnormalities are also usually a little easier to detect than in the first trimester.
However, there is the rare possibility that abnormalities may not be found. This is the case if some areas of your baby cannot be accessed and viewed during the scan due to their position, or because your baby has a progressive abnormality and it has not developed by the time of the second trimester ultrasound scan. Other defects are also only determined after birth, such as autism or cerebral palsy.
However, we do everything we can to ensure you have the most complete picture of your pregnancy. In the rare event a problem does occur, the team at our EchoFemme ultrasound centre will carefully review the situation with you and provide you with everything you need to know, so that you can understand the problem and make the best decision possible with the support of our network of health professionals and your usual doctors.