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CBCs and Infection
Are Complete Blood Cell Counts Useful in
the Evaluation of Asymptomatic Neonates Exposed to Suspected Chorioamnionitis?
Jackson GL, Engle WD, Sendelbach DM, et al. PEDIATRICS (May 2004); 113:
1173-1180.
Objective.
Chorioamnionitis complicates 1% to 10% of pregnancies and increases the risk of
neonatal infection. Women with chorioamnionitis receive intrapartum antibiotics,
often resulting in inconclusive neonatal blood cultures. Peripheral neutrophil
values are used frequently to assist in the diagnosis of neonatal infection and
to determine duration of antibiotics; we sought to determine the utility of this
approach.
Methods. A
prospective observational study was performed in 856 near-term/term
neonates who were exposed to suspected chorioamnionitis. Each
received antibiotics for 48 hours unless clinical infection or
positive blood cultures occurred. Peripheral neutrophils were
measured serially and analyzed using the reference ranges of Manroe
et al; an additional analysis of only the initial neutrophil values
used the normal ranges of Schelonka et al. Results of neutrophil
analyses were not used to determine duration of therapy. Fifty
percent of asymptomatic neonates were seen post discharge to
ascertain recurrent infection. Local patient charges were examined.
Results.
Ninety-six percent of neonates were asymptomatic and had negative
cultures, and antibiotics were discontinued at 48 hours. A total of
2427 neutrophil counts were analyzed. Although abnormal neutrophil
values were more frequent in infected or symptomatic neonates, 99% of
asymptomatic neonates had 
1
abnormal value. The specificity and negative predictive values
for abnormal neutrophil values ranged between 0.12 and 0.95 and 0.91
and 0.97, respectively; sensitivity was 0.27 to 0.76. Significant
differences in interpretation of the initial neutrophil values were
noted, depending on the normal values used. Follow-up was performed
for 373 asymptomatic neonates until 3 weeks’ postnatal age. Eight
required rehospitalization; none had evidence of bacterial infection.
If neutrophil values had been used to determine duration of
antibiotics, then local costs would have increased by $76 000 to
$425 000 per year.
Conclusions.
Single or serial neutrophil values do not assist in the diagnosis of
early-onset infection or determination of duration of antibiotic
therapy in asymptomatic, culture-negative neonates who are 35
weeks’ gestation and are delivered of women with suspected
chorioamnionitis.
Comment. There is no good test to rule out sepsis in infants
born to mothers with chorioamnionitis. Blood culture results are usually
tainted by the presence of intrapartum antibiotic treatment. We now learn that
99% of these infants have at least 1 abnormal value in their neutrophil
counts. I’m impressed that the authors were comfortable enough to
stop antibiotics in 48 hours in 96% of these babies. We need a more
discriminating test than the CBC for this purpose. Perhaps the CRP at 48
hours will fit the bill. ABK.
Additional Comments:
Date: 23 May 2004
Time: 07:39:22
There is no day in our practice in which we don't have to decide whether to
start/stop antibiotics in a baby whose mother had fever during labor. We are
searching for lab tests to help us in this decision. Arguably, the "clinical"
determination is in this article, and for many of us, the 'golden standard'
(save a positive blood culture). If we base our decision in our "clinical"
judgement, would the lawyers/jury accept it as a "valid argument" in the 1/100
case who we would miss if we ignore that abnormal CBC's and determine that a
'malpractice' has not occurred?
UserName: Felix A. Estrada, MD
Institution: Parkway Regional Medical Center
telephone: 305-654-5612
email: felixaestradamd@pol.net
Date: 13 Jun 2004
Time: 22:47:46
In this era of increasing resistance to antibiotics we need to start using the
antibiotics more responsibly. Over use of antibiotics in pregnant women has
already made our decisions more difficult by selecting for more invasive and
resistant e. coli in the newborns. I think that over and over again it has been
shown that CBC does not have high specificity for infection, therefore "treating
numbers instead of patients" should be considered an act of a nervous
physician. Moreover, I think most institutions overdiagnose choriamnionitis and
not all institutions report CBCs in the same fashion, therefore it may be more
important to look at the signs and symptoms correlating with positive infections
and treating them instead of the CBC numbers. As long as our actions are
"standard of care" the lawyers/jury should have no problem accepting them as
valid treatments. Lets not make our future more difficult by creating more
resistant bugs.
Thank you
UserName: Pranav Patel
Institution: Westchester Medical Ctr
email: dok4kidz@yahoo.com
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