Measurement of Carboxyhemoglobin by Gas Chromatography as an Index of Hemolysis
Measurement of Carboxyhemoglobin by Gas Chromatography as an Index of Hemolysis
The purpose of this research study is to more accurately measure the amount of true red blood
 cell breakdown (hemolysis) in newborn babies with potentially problematic blood type mismatch
 with their mothers (ABO incompatibility), and to examine how the true level of red blood cell
 destruction relates to other laboratory tests obtained in newborns with jaundice.

 A better understanding of the true amount of red blood cell destruction that is caused by
 blood type mismatch, as well as how it relates with other laboratory tests ordered for ABO
 incompatibility and red blood cell destruction, would help avoid unnecessary testing,
 treatment and prolonged hospital stays in such babies.
Clinically severe jaundice due to ABO incompatibility can occur when infants with blood type
 A or B are born to mothers with type O blood. An estimated 20 percent of pregnancies are ABO
 incompatible, but only a very small proportion of blood type A or B babies born to O type
 mothers develop overt ABO hemolytic disease. Despite the relative rarity of ABO hemolytic
 disease, it is common practice among pediatricians and family practice physicians to perform
 routine blood typing and antibody screening on all newborns born to type O mothers.

 A very accurate and reliable laboratory measure of red blood cell destruction is the plasma
 carboxyhemoglobin level (COHb). COHb levels can be determined using a minute amount of blood,
 obtained at the same time the newborn's heel is pierced to obtain blood for the mandatory
 newborn screen (performed on all newborns prior to discharge) in order to avoid an additional
 invasive procedure.

 Our hope is to determine whether routine blood typing and anti-globulin testing of infants
 born to type O mothers is necessary, or if these tests should instead be obtained only in the
 context of significant visible jaundice. This would help clarify the proper management of a
 very common problem in the newborn, and minimize the potential for subjecting infants of type
 O mothers to unnecessary blood tests, unwarranted treatment, and prolonged hospitalizations.
Inclusion Criteria:

 -  written informed consent

 -  mother blood type O

 -  mother Rh +

 -  healthy infants

 -  ≥37 wks gestation

 -  ≥ 2500 gm birth weight

 -  Apgar ≥5 at 1 and 5 minutes

 Exclusion Criteria:

 -  major anomalies

 -  infants evaluated for sepsis or infants with transitional respiratory problems
 requiring >6 hrs observation in the NICU

 -  significant birth trauma with continued bruising and/or sequestration of blood still
 evident at the time of discharge

 -  known perinatal blood loss with hemodynamic consequences such as persistent
 tachycardia, need for fluid boluses or supplemental oxygen

 -  neonatal anemia with Hb<13.5g/dL

 -  known family history of hereditary hemolytic disease such as G6PD deficiency,
 hereditary spherocytosis or hereditary elliptocytosis