Everything You Need To Know About Prenatal Ultrasound


The basic principle of prenatal ultrasound is to transmit video or photographic images to figure out information regarding health, position, gender, etc. about the foetus. The process is carried out with the help of a device called a transducer which is moved around on the lower abdomen in a gel medium. 

While most ultrasounds take place typically on the surface of the skin, an alternative could be the transvaginal ultrasound which involves inserting a probe into the vagina to inspect the foetus. This produces images of better quality and is also used to assess cervix problems if any. 

Overview of the procedure

The standard procedure is to make the expectant mother lie on a table, where a kind of a gel is applied on her abdomen. A device called the transducer produces high frequency waves when moved around the abdomen covered with gel. These waves, which are inaudible to the human ear, reflect off the foetal structures and give an idea with the help of moving pictures displayed on a screen. There are not any preparatory measures that need to be taken, but a few doctors prefer the mother to drink a few glasses of water before the prenatal ultrasound

This makes sure the bladder remains full which, in turn, enhances the quality of the pictures and helps to discern the required facts. A minor discomfort might be felt during the test because they are refrained from urinating until the completion of the test. The doctor might also ask the mother to hold their breath a few times. The entire procedure takes about 30 minutes. 

Different stages of Ultrasound

The prenatal ultrasound is carried out during different stages of pregnancy. The level I ultrasound is usually taken around 5-6 weeks of pregnancy. It shows images of the amniotic sac, placenta and the ovaries, and helps to determine whether there are any problems. By this time, the foetal heartbeat and its movements can also be determined. 


Level II ultrasound, usually carried out around 18-20 weeks, measures the level of the amniotic fluid, the position of the placenta, the size of the baby, its expected weight and the condition of its vital organs. The gender of the baby can also be determined during this stage of the ultrasound. 

Determining the gender of the baby

While determining the gender is quite complicated, there are a few common signs that sonographers look out for. For the baby to be a girl, the hamburger sign (from the appearance of the clitoris and the labia) and the sagittal sign (the angle of the lower end of the spine) are observed. The sagittal sign is common for a boy, but the angle is different. The other signs that are observed are the direction of the flow of urine and the presence of the male genitalia. 

Risks of prenatal ultrasound

There is a certain risk in all medical procedures, but evidence shows that there are no risks in prenatal ultrasounds when performed by a medical professional. The high frequency waves are not UV radiation as in case of X-rays, and, thus, pose no threat to the mother or their baby. 


Comments are closed.