Fever of Uncertain Source (0-60 Days Old)

Your baby has a fever above 100.4°F (38°C), and the reason for the fever is not obvious. Many things can cause a fever. The most common causes are bacterial or viral infections.

What Can I Expect When I Take My Baby to the Doctor?

A caregiver will ask you questions about your baby’s illness. Then, the caregiver will examine your baby. If the caregiver is concerned that your baby may have a serious infection, we will do tests on your baby’s urine, blood or spinal fluid. This can help find the cause of the fever.

How will urine be collected?

The area where your infant urinates will be cleaned.  We will place a small, flexible tube, or catheter, into your baby’s bladder to get urine. We will take the catheter out as soon as we collect the urine sample. This specimen will tell the doctor if your baby may have an infection in his or her urine.

How will blood be collected?

We will place a thin plastic tube, called an IV, into a vein to collect some blood. We may leave this IV in the vein so we can give your baby fluids and medicines.  This specimen will tell the doctor if your baby may have an infection in his or her blood.

How is spinal fluid collected?

A spinal tap is also called a lumbar puncture. It is done to remove a small amount of spinal fluid. Someone will hold your baby still during the procedure to keep him or her safe.  The caregiver will clean your baby’s back and then place a needle between the bones in the lower part of the spine. The needle does not enter the spinal cord. The needle goes into the lower back below the level of the spinal cord. A small amount of fluid will drip into tubes. We will remove the needle as soon as the fluid is collected.  A small bandage will be placed over the area.

We will test all the fluid we collected to see if bacteria and / or viruses are present. Early test results will be available within two hours. Other tests, called cultures, check to see if bacteria grow from the blood, urine or spinal fluid samples. It takes 36 hours to find out if there are any bacteria growing.

There are many types of bacteria that can cause infections. These bacteria can be found in the urine, blood or spinal fluid. Your baby may be treated with antibiotics through the IV while you are waiting for the test results.

Like bacteria, there are many different viruses that can cause a fever. Most viruses cannot be treated with medications. Antibiotics work only on bacteria.

It can help your child's caregiver to know:

  • How awake or sleepy your baby is
  • If your baby has a fever
  • If your baby is fussy or irritable
  • How well your baby is eating
  • If your baby is vomiting or having diarrhea
  • How many wet diapers your baby has had in the past 24 hours
  • If your baby has a rash or bumps on the skin
  • If your baby is having any breathing problems
  • If anyone in your household has recently been sick, has had a rash or has had cold sores

Last Updated 11/2012