Common NICU tests

Your baby will have a number of different test during his stay in the neonatal intensive care unit (NICU). 

These tests help determine what your baby's problems may be and how they should be treated. Tests also help monitor his progress. Your baby's doctor will tell you what tests are recommended and inform you of the results. If your baby needs a major test, the doctor will ask you to sign a consent form before the test is done.

What tests are common in the NICU?

These are some of the tests done in the NICU. Your baby may need additional specialized tests, depending on his medical condition.

Blood tests

These are among the most frequent procedures done in the NICU. Blood tests provide crucial information on how your baby is doing. They alert doctors to potential problems before they become more serious. Here are some problems blood tests can find:

  • Anemia
  • High levels of bilirubin (possible jaundice)
  • Low blood sugar
  • Salt or water levels that are out of balance
  • Infection
  • Low oxygen or high carbon dioxide levels (blood gases)

Computed tomography (CAT or CT scan)

A CT scan is an advanced form of imaging that often can produce a more precise image of tissue than an X-ray or ultrasound examination. It focuses a beam of energy on the tissue the doctor wants to see, and uses computers to create a full picture (two-dimensional image). The baby will need to be taken to the radiology department and possibly sedated (so he doesn't move) for this test.


A specialized form of ultrasound examination that is used to study the heart. It can detect structural problems (heart defects) and problems with how the heart works.

Hearing test

Premature and other sick babies are at increased risk of hearing problems. Before a baby goes home, she probably will have a hearing test called a "brainstem auditory evoked response test." A tiny earphone will be placed in her ear to deliver sound. Small sensors, which are taped to the baby's head, will relay information to a machine that measures the electrical activity in her brain in response to sound. The baby's doctor will discuss the results of the hearing test with you and whether any follow-up will be necessary. If your baby responds normally, she probably has normal hearing. It is important to detect hearing problems early, in order to help prevent speech and language problems.

Magnetic resonance imaging (MRI)

Like a CT scan, an MRI can produce a very detailed picture that may be difficult to see on an X-ray or ultrasound. The MRI gives a more detailed view than a CT scan, using powerful magnets and computers to create an image. This test is painless and safe for babies. There are no X-rays involved. The baby will need to be moved to the radiology department for this test and may have to be sedated.

Newborn screening test

Also called a PKU or NBS test, newborn screening is a test performed by pricking a baby's heel to obtain a few drops of blood on a filter paper. It tests babies for serious hereditary disorders. Most states screen for more than 20 conditions. New technologies have made it possible to test for many disorders at one time.

Retinopathy of prematurity (ROP) examination

This test usually is done for babies born at or before 30 weeks of gestation or weighing less than 1,500 grams (3 1/3 pounds). The eye doctor, also called an opthamologist, will check to see if the blood vessels in the baby's eyes are developing the right way. If there are signs of any problems, the doctor will keep checking the baby's eyes on a regular basis to see if the condition is getting better or needs treatment. 


An ultrasound uses sound waves and a computer screen to show a picture of your baby inside the womb. A small hand-held device called a transducer is rubbed back and forth over the area that the doctor wants to see. An ultrasound examination is painless and done at the baby's incubator. It often is done to determine if a baby has any bleeding in the brain. A head ultrasound or “head sonogram” is the routine test to diagnose bleeding in the brain.

Urine tests

Like blood tests, urine tests can tell a great deal about a baby's overall condition. Urine tests can help determine how well the kidneys are functioning, and whether the baby has an infection.


A baby is weighed soon after delivery, then at least once a day while he is in the NICU. Don't be alarmed if your baby loses some weight in the first days or weeks after birth. This is normal, especially for very small babies. When a premature baby starts gaining weight at a steady rate, it is an encouraging sign that he is doing well.


X-rays provide pictures of a baby's lungs and other internal organs. These pictures help the baby's doctor plan her treatment and monitor her progress. The baby may receive several lung X-rays each day if she has serious breathing problems. She will be exposed to a little radiation from these X-rays. But the amount is so low it should not affect the baby's health now or in the future. The baby will not need to be moved to the radiology department for this test; it is done right at her incubator.

Last reviewed: August, 2014