“It’s is really a complete anatomical survey of the baby,” says Jacki Weidman, Director of the Family Maternity Center at West Valley Medical Center.

One thing to keep in mind is that, legally, the ultrasound tech can’t provide you with any information beyond the sex of the baby, which is great. But this test is looking at so much more.

So, it’s important to speak with the radiologist or your obstetrician to ask for preliminary information.

Here are 5 things the radiologist will be looking for when she reviews your 20-week ultrasound scans.

4 things your 20-week ultrasound can tell you about your baby

How big is your baby?

The 20-week ultrasound helps doctors determine whether your baby is growing at a normal rate, Jacki explains.

If you have been using any popular resources comparing fetal growth to various fruits and vegetables, you may be interested to know that at 20 weeks, your little one is probably around six inches long—about size of banana.

Are her organs developing at a normal rate?

Jacki also points out that, at the 20-week ultrasound appointment, the physician can check out the growth rate for your baby’s heart, brain, spine, kidneys, bladder and more.

Here are some of the conditions your doctor will be on the lookout for—and many of these are very rare.

  • Cleft lip
  • Abdominal wall defects
  • Limb malformations or missing limbs
  • Defect of the spinal cord (spina bifida)
  • Major kidney problems
  • Chromosomal abnormalities
  • Major heart problems (defects of chambers, valves or vessels)

Location of the placenta

The 20-week ultrasound also provides information about the location of the placenta, Jacki says.

1 in 200 women experience a condition called placenta previa. This is when the placenta is growing in the lowest part of the uterus and covering all or part of the cervix, which is the opening of the birth canal, according to the National Institutes of Health (NIH).

At 20 weeks, this isn’t a big deal. But, eventually, placenta previa may prevent a safe, vaginal delivery.

If the doctor sees that you do have placenta previa, it’s likely that your physician will want to monitor you. For many women, the issue resolves itself.

Down Syndrome

1 in every 691 babies in the U.S. is born with Down syndrome, according to the National Down Syndrome Society.

At your 20-week appointment, the ultrasound can detect certain markers that could indicate Down Syndrome, Those markers include:

  • mild kidney swelling
  • bright spots in the heart
  • shortening of an arm bone or thigh bone
  • increased thickness of the back of the neck

Source: January 2013 study in the journal Ultrasound in Obstetrics & Gynecology

The 20-week ultrasound is an exciting appointment. If you are having your ultrasound with a technician rather than with your physician, ask to speak to the radiologist to get a preliminary reading.