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control), and methemoglobin levels will be elevated up to 65% (normal 0% to
2%). Hemoglobin electrophoresis will be normal (except in rare cases of
hemoglobin M), as is the glucose-6-phosphate dehydrogenase assay in most
cases. With appropriate treatment, the methemoglobin level returns to normal.
However, death can occur from methemoglobinemia in infants if not treated
promptly.
Kernicterus, or bilirubin encephalopathy (see Chapter 96 Neonatal
Emergencies ), should be considered in the septic-appearing infant with
neurologic findings. This usually occurs in the first week of life in jaundiced
neonates due to the deposition of indirect bilirubin in the basal ganglia and
brainstem nuclei. Premature infants are more susceptible to kernicterus, but the
majority of infants who develop kernicterus are healthy, term infants who
predominantly breast-feed. Lethargy and decreased feeding present early, and
with progression the infant will develop respiratory distress and neurologic signs,
including decreased reflexes, a high-pitched cry, arching, opisthotonic posturing,
twitching of the extremities, and convulsions. The neonate can even develop a
bulging fontanel, making it difficult to differentiate from meningitis on clinical
examination. Laboratory evaluation is crucial; obtain total and direct bilirubin
counts, a CBC, blood typing, and Coombs test. Kernicterus usually does not
develop until the total bilirubin level has exceeded 25 to 30 mg/dL, but toxicity
has occurred at levels as low as 20 mg/dL.

Gastrointestinal Disorders (See Chapter 91 Gastrointestinal
Emergencies )
Gastroenteritis in an infant can rapidly lead to profound dehydration and shock.
Hypoglycemia is also common in these young infants and can cause lethargy and
coma. Bacterial infections such as Salmonella may cause sepsis in a young infant,
and viral agents may mimic this. A history of bloody diarrhea suggests bacterial
gastroenteritis. A CBC with many band forms despite a normal white blood cell
(WBC) count suggests Shigella infection. Stool cultures will diagnose infections,
but a few days are needed for bacterial isolation and viral isolation takes even

longer. Rapid PCR detection of common gastrointestinal pathogens in stool is
available at many institutions. Fluid resuscitation may improve the infant’s
appearance and make dehydration the likely diagnosis.
There are several intra-abdominal surgical emergencies that mimic sepsis. The
underlying pathophysiology is some combination of hypovolemia, electrolyte
disturbances, hypoglycemia, and/or metabolic acidosis. Small bowel obstruction
(SBO) caused by volvulus , intussusception , or incarcerated hernia will generally