Perinatal Bloodwork

Platelets

Platelet normally 150-400 x 109/L

Platelets are acute phase reactants, so a low count may suggesr sepsis or coagulopathy (ie pregnancy-induced hypertension in HELLP syndrome - hemolysis, elevated liver enzymes, low platelets)

<150 warrants mention and <100 is concerning; if platelets are less than 40x 109/L, spontaneous bleeding can occur, ie into the neonatal cerebral ventricles.

A count higher than 400 may indicated fungal infection in those susecptible

Hemoglobin

Hgb

adult females 120-145 g/L

neonates 160-200 g/L

In a situation of acute hemorrhage, the hgb will be unchanged. It will take 3-12 h for fluid volume to be replaced and hgb to drop

RBC, hematocrit, MCV, MCH, MCHC not as helpful acutely, but can assist with explanation of type of anemia.

White Blood Cell Count

WBC

women in labour have a higher WBC (10-21) due to the stress reaction

sepsis in labour can lead to 16-24

Neonates

first 24 hours of life: up to 24x109 (stress reaction)
24-48h: 12-20
after 48h: 4-12
a corrected WBC neonatal count is the manual count of WBCs; an automated count may include nucleated RBCs due to the stress of birth

Manual Differential

A manual differential will give band count.

An infection will lead to neutrophils

Neutrophils

The more immature cells circulating, the more concerning the situation.

If there is a major blood loss

Other

Kleihauer test

indicated percentage of fetal RBCs in the mother's circulation. Normal 0-0.2%.

If mother needs WinRho therapy, and the Kleihauer result exceeds 0.2%, the dosage of WinRho must be adjusted upwards.

It is normally only requested in Rh-negative mothers, but also can be ordered on any mother in whom fetal-maternal hemorrhage is suspected (ie abruption).

ABO/Rh type

read carefully to see whether it refers to mother's blood or cord (CD) blood

DAT Direct Antibody Test

measures presence of antibodies

WinRho A/D suggests antibodies have been triggered by WinRho, not infant.

A positive result in an infant suggests increased risk of hemolytic hyperbilirubinemia.

Blood Chemistries

Cord Gases

arterial - reflects neonate's status at moment of delivery

venous - reflects mother's status at that time, so is almost always more normal than the arterial result.

pH arterial:

normal adult: 7.35-7.45
infant at birth: >7.2
neonate: 7.32-7.42

pCO2 arterial:

normal adult: ~40 mmHg
infant at birth: <60 mmHg
neonate: 30-45 mmHg

BE

HCO3

pO2: always very low in a cord arterial sample

irrelevant in a cpillary heel stick sample

Bilirubin

total = conjugated plus unconjugated
babies almost always have unconjugated

protein

total protein = albumin, immunoglobulins, etc
TProt correlates with albumin
albumin transports unconjugated bilirubin, preventing it from crossing the BBB
a low albumin leads to increased risk of kernicterus, even though bilirubin levels can be normal
albumin levels will be low in neonates who are preterm, small for gestational age, or otherwise malnourished

ESR and CRP

non-specific; may be elevated in hemolysis or injury
CRP faster than ESR