NECROTIZING ENTEROCOLITIS LAB STUDIES
Category: Pediatric Surgery
Abstract : Lab Studies of necrotizing enterocolitis: • Initial presentation usually
includes subtle signs of feeding intolerance, such as gastric residuals,
abdominal distention, and/or grossly bloody stools. Abdominal imaging studies
are crucial at this stage. Laboratory studies are pursued if the abdominal
studies are worrisome or the baby is manifesting any systemic signs. •
Lab Studies of necrotizing enterocolitis:
• Initial presentation usually
includes subtle signs of feeding intolerance, such as gastric residuals,
abdominal distention, and/or grossly bloody stools. Abdominal imaging studies
are crucial at this stage. Laboratory studies are pursued if the abdominal
studies are worrisome or the baby is manifesting any systemic signs.
•
Complete blood count with manual differential to look for signs of infection,
anemia, and thrombocytopenia is usually repeated at least every 6 hours if the
patient continues to deteriorate.
o White blood cell count:
Marked
elevation may be worrisome (<20,000 depending on whether treatment includes
systemic steroids for lung disease), but leukopenia (<5000) is even more
concerning. Although elevated mature and/or immature neutrophil counts may not
be good indicators of neonatal sepsis after the first 3 days of life, moderate
neutropenia (absolute neutrophil count [ANC] <1500) strongly suggests
evolving sepsis.
o Red blood cell count:
Premature infants are prone
to anemia from iatrogenic blood draws as well as anemia of prematurity; however,
blood loss from hematochezia and/or a developing consumptive coagulopathy can
manifest as an acute decrease in hematocrit.
o Platelet
count:
Platelets are an acute phase reactant, and thrombocytosis can
represent physiologic stress to an infant, but acute NEC is more commonly
associated with thrombocytopenia (<100,000). Thrombocytopenia may become more
profound and alarming in severe cases that become complicated with consumption
coagulopathy. Consumption coagulopathy is characterized by prolonged prothrombin
time (PT), prolonged activated partial thromboplastin time (aPTT), and
decreasing fibrinogen and increasing fibrin degradation products
concentrations
o Blood culture:
Drawing a blood culture is recommended
before beginning antibiotics in any patient presenting with any signs/symptoms
of sepsis or NEC. Although blood cultures do not grow any organisms in most
cases of NEC, sepsis is one of the major conditions that mimic NEC and it should
be considered in the differential diagnosis. Therefore, identification of a
specific organism can aid and guide further therapy.
• Serum electrolytes
can show some characteristic abnormalities. Obtain a panel of basic electrolytes
during the initial evaluation, followed serially at least every 6 hours
depending on the acuity of the patient's condition. o Serum sodium: Hyponatremia
is a worrisome sign that can suggest the initial stages of a developing
capillary leak. Depending on the baby's age and feeding regimen, baseline sodium
levels may be low-normal or subnormal, but an acute decrease (<130 mEq/dL) is
alarming and heightened vigilance is warranted. o Metabolic acidosis: Low serum
bicarbonate (<20) in a baby with a previously normal acid-base status also is
concerning.
• Arterial blood gasses o Depending on presentation acuity
and the baby's respiratory status, an arterial blood gas can reveal whether the
baby needs respiratory support and the developing acid-base status. o Acute
acidosis with baseline carbon dioxide pressure is worrisome (as is apnea).
Metabolic acidosis results from decreased cardiac output (as in cardiovascular
collapse and shock), leading to poor perfusion of peripheral tissues and lactic
acidosis.
• An arterial blood sample is a convenient way to
simultaneously obtain a blood culture, CBC, serum electrolytes, and ABG for the
initial evaluation (note that arterial blood has a lower yield for demonstrating
bacteremia than venous blood). Depending on presentation acuity, inserting a
peripheral arterial line while peripheral perfusion and intravascular volume is
still good may be prudent. This peripheral arterial line facilitates serial
blood sampling and invasive blood pressure monitoring that is essential if the
baby's condition deteriorates.
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