Febrile Infants: When Can We Skip the Lumbar Puncture?

Christopher J. Chiu, MD;   Justin L. Berk, MD, MPH,


December 08, 2021

This transcript has been edited for clarity.

Christopher J. Chiu, MD: Welcome back to The Cribsiders and our Medscape video recap of our pediatric medicine podcast. Justin, what are we talking about today?

Justin L. Berk, MD, MPH, MBA: We're talking about febrile infants and our recent podcast, When Babies Are Too Hot. We talked with Dr Paul Aronson, who joined us to interpret the AAP’s new febrile infant guidelines that came out in July 2021. This was a great way to go through them systematically and figure out how they might change our practice.

Chiu: Give us a little background. Why do we worry about these patients?

Berk: Febrile infants are often seen in pediatric emergency rooms and pediatric hospitals. In any infant under the age of 90 days, we worry about invasive bacterial infections such as meningitis or bacteremia. The term "serious bacterial infection" has fallen out of favor.

We learned about the breakdown of infections seen in young infants. Urinary tract infections are the most common bacterial infections, accounting for about 10% of all febrile infants. Bacteremia, however, really only occurs in 2%, and meningitis in only 1% of febrile infants. Those numbers go down with each day that the child gets older.

Chiu: You said that these guidelines just came out in July. What are the newest points in the guidelines that we should be aware of?

Berk: These guidelines apply to well-appearing, full-term infants ages 8-60 days old, with a temperature greater than 38.0 °C in the past 24 hours. That's the context of the guidelines. Essentially, they divided well-appearing febrile infants into three groups:

  • Age 8-21 days

  • Age 22-28 days

  • Age 29-60 days

The first group (8-21 days) should receive the standard workup, including blood, urine, and cerebrospinal fluid studies. This doesn't really change what we're already doing. The 22- to 28-day-old infant is the new frontier. In this group, we're reassessing how many invasive tests really need to be performed by looking at inflammatory markers. The 22- to 28-day-old febrile infant should be tested for procalcitonin, absolute neutrophil count, and C-reactive protein (CRP) to help determine whether there is serious inflammation that might signal an invasive bacterial infection. This can help determine the need for a lumbar puncture. If these markers are normal, the guidelines suggest that the infant can be sent home after a single dose of ceftriaxone. Shared decision-making can be used to determine whether antibiotics or a lumbar puncture are needed for febrile infants in this age group.

Chiu: What helps us with the shared decision-making?

Berk: If your institution has access to procalcitonin, Dr Aronson recommended using either the PECARN or Step-by-Step algorithm, which helps risk-stratify and also includes other inflammatory markers like absolute neutrophil count and CRP. But if your institution doesn't have procalcitonin testing, then both absolute neutrophil count and CRP should be done. If all of these inflammatory markers are normal, the risk for invasive bacterial infection is considered to be very low, and that can help guide some of those shared-decision-making conversations.

Chiu: Okay. What about the 29- to 60-day-old group?

Berk: The 29- to 60-day-old group is one that can usually avoid the lumbar puncture entirely if the inflammatory markers are normal. We are becoming more confident in avoiding the lumbar puncture in these infants, whereas in the 22- to 28-day-old group there's a little bit more ambiguity. So you can put that needle away and sleep soundly knowing that the infant is at extremely low risk for an invasive bacterial infection.

Chiu: Hey, I always love criteria that tell me I don't have to do a lumbar puncture.

Berk: Absolutely.

Chiu: Thanks for joining us for another Medscape recap video of The Cribsiders pediatric medicine podcast. You can download full episodes on any podcast player or visit us at The Cribsiders.

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