Common NICU tests

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

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.

  • Blood tests can tell if a baby is anemic or if bilirubin levels are too high. Bilirubin is formed when red blood cells break down. Jaundice occurs when the liver can't remove bilirubin from the blood.
  • They show whether a baby has low blood sugar (hypoglycemia), high blood sugar (hyperglycemia), salt or water imbalances, or nutritional needs (such as problems with protein, liver and kidney function)—all of which can cause problems if not corrected.
  • Blood tests also can help determine if your baby has an infection and which antibiotic should be used to treat it.
  • If your baby is very sick, she may need blood tests several times an hour to measure the levels of blood gases (oxygen and carbon dioxide). This may be done on a blood sample taken from an artery, because arteries carry oxygen to all parts of the body. The sample can be taken through the umbilical catheter, if a baby has one in place, or from an artery in the wrist or foot.

Your baby may have a blood test to check blood gases soon after she is admitted to the NICU, to see whether she needs additional oxygen or mechanical ventilation. This test is repeated often to see if the baby is getting enough oxygen or whether the level needs to be adjusted.

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 your 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. Your 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. Your 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 28 weeks of gestation or weighing less than 1,500 grams (3 1/3 pounds). The test is generally performed about 4 to 6 weeks after birth, or when your baby reaches 31 to 33 weeks gestational age (weeks since the mother's last menstrual period). An ophthalmologist (eye doctor) examines your baby's eyes with a special scope (ophthalmoscope). Before the examination, the doctor places drops in her eyes so the doctor can see her retina and determine whether the blood vessels are developing normally. If your baby has any signs of ROP, the doctor will repeat this test regularly to see if the condition is clearing up on its own, or whether treatment is necessary.


Ultrasound takes a picture of a baby's organs using sound waves, rather than X-rays. 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 your baby has an infection.


Your 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 your baby's lungs and other internal organs. These pictures help your baby's doctor plan her treatment and monitor her progress. Your 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 your baby's health now or in the future. Your baby will not need to be moved to the radiology department for this test; it is done right at her incubator.

August 2009

Most common questions

Is it OK to hold my baby in the NICU?

It depends on your baby's health overall. Some newborn intensive care units (NICUs) will encourage you to hold your baby from birth onward. Other NICUs will want you to wait until your baby's health is stable. Ask your NICU staff about its policy on kangaroo care (holding your baby on your bare chest). Kangaroo care has benefits for both you and your baby. The skin-to-skin contact is a precious way to be close to your baby. You may be afraid you'll hurt him by holding him. But you won't. Your baby knows your scent, touch and the rhythms of your speech and breathing, and he’ll enjoy feeling that closeness with you.

My baby was born full term. Why is she in the NICU?

Not all newborn intensive care unit (NICU) babies are born premature. Some babies, even those born full term, may need special care. Your baby may need to spend some time in the NICU if she had a difficult delivery, has breathing problems, has infections or has birth defects.

Most babies leave the NICU just fine. Others may need more special care once they're home.

©2013 March of Dimes Foundation. The March of Dimes is a non-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3).