Mom & Baby test

Question 1

Prenatal type & screen

Answer 1

• Early in the pregnancy
• ABO & Rh: to determine RhIG and for weak D
• Screen: For other unexpected RBC antibodies

Question 2

RhIg program

Answer 2

• For Rh negative parent
• At 28 weeks with a presumption that baby is Rh pos
• Following miscarriage, abortion, trauma, invasive procedure
• Within 72 hrs of delivery:
  + Baby: D pos, weak D pos, unknown Rh
  + Parent is not already sensitized D antigen
• Show up in AbSC
• Prenatal sample collected prior to RhIG administration

Question 3

If a prenatal AbSC is positive

Answer 3

• Perform Ab ID
• Titer Ab if IgG: serial dilution, homozygous cell, significant if > 16 ( for K, significant >8), repeat throughout the pregnancy
• Paternal phenotype (uncommon)

Question 4

Methods to monitor the fetus

Answer 4

• Ultrasound: check hydrops (increase body fluid)
• Amniocentesis: phenotype the baby, measure the amniotic fluid at OD 450nm (for bilirubin) –> increase risk of miscarriage
• Cordocentesis: measure the Hgb in the cord blood –> increase the risk

Question 5

Intrauterine transfusion (IUT)

Answer 5

• Baby lost blood due to HDFN
• Indication: OD450nm in zone 2, 3 / Hgb < 10g/dL / fetal hydrops detected
• Try to give fetus more time

Question 6

Requirements for IUT

Answer 6

• Irradiated (prevent TA-GvHD)
• Leukoreduced
• < 5 days old
• O neg
• Antigen compatible with parent
• Hgb S neg
• Modification (volume reduction, wash)

Question 7

Postnatal test

Answer 7

• TSCR on the parent: in case need to transfusion
• Baby: ABO/D & Weak D for baby Rh neg (confirmation) and parent is a candidate for RhIg
• Sample from baby: cord cell, heel stick, line draw

Question 8

Challenge for newborn testing

Answer 8

• Parental contamination
• Mixed field in ABO: contamination and incomplete expression of A & B antigen
• Parental Antibodies coat baby’s cells –> Invalid ABO due to positive control.

Question 9

DAT on baby

Answer 9

• Only IgG concern
• May detect ABO HDFN: mom is O and makes anti-A,B Ab. DAT on baby can be weak due to incompleted antigen
• DAT is positive –> perform eluate
• Elution: use cord cells –> test with AbSC and AbID

Question 10

Test for Rh- parent and Rh+ baby

Answer 10

• Determine candidacy for RhIg therapy
• Optimal: 1 hour post-delivery
• Screening test: Fetal bleed screen
• Enumeration test: KB or Flow cytometry
• Determine RhIg dosage

Question 11

FBS (Rosette test)

Answer 11

• Will detect > 10ml of fetal blood in parental circulation
• Use parent’s blood
• Chemically modified Anti-D
• Incubate - Wash - Add indicator cells - Observe on microscope
• Positive (> 5 agglutinin in 5 fields)
• -> perform enumeration test: KB or Flow cytometry
• Negative (< 5 agglutinin in 5 fields)
• -> 1 dose of RhIG
• Can’t use of parent or baby is weak D (false negative result)

Question 12

KB test

Answer 12

• Acid destroy parental Hgb but not fetal cells –> stain on smear. Fetal cell: pink & adult cells: ghost
• Count total 2000 cells –> % of fetal cells
• Cons: error due to fetal cells & lymphocytes, not precise, Hgb F can cause false elevated

Question 13

Flow cytometry

Answer 13

• Anti-Hgb F
• Precise
• Expensive
• Can used for Rh pos parent

Question 14

RhIG

Answer 14

• 1 dose (300mcg) = 30mL WB or 15mL packed RBC
• Given within 72 hours and not exceed 5 doses (IM per 24 hour). If need larger dose –> IV
• Cleared within 6 months
• RhIG at delivery: 2% make alloAb
• RhIG at w28 and delivery: 0.2% make alloAb
• Mini dose (50mcg): effective only 1st trimester

Question 15

Monitoring of baby

Answer 15

• Anemia, bilirubin –> prevent kernicterus (bilirubin > 25 mg/dL)
• Treatment: bili-light (no effective if bilirubin rises at a rate 0.5-2.0mg/dL/h). Exchange transfusion (perform when serum bilirubin at 18-20mg/dL)

Question 16

Transfusing baby

Answer 16

• Same with IUT
• Pedi-pack or aliquot
• 90% low birth weight and 58% of preterm infant
• Exchange transfusion: reconstituted RBC (mix RBC and plasma)

Question 17

Hydrop fetalis

Answer 17

• Hight cardiac output –> accumulation of extracellular fluid
• 30% mortality: stillbirth or neonatal

Question 18

Newborn jaundice

Answer 18

• Jaundice
• Bilirubin pass though blood/brain barrier
• Acute bilirubin encephalopathy
• Kernicterus

Question 19

Cause of maternal fetal hemorrhage

Answer 19

• term, preterm delivery
• miscarriage
• Abortion
• ectopic pregnancy
• chronic villi sampling
• amniocentesis
• vaginal bleeding

Question 20

Titer prenatal testing

Answer 20

• Report as too weak or 1:2, 1:4, 1:8
• Titer value: the reciprocal of the last tube dilution that demonstrates a positive agglutinin reaction
• Critical titer: titer at which there’s a significant risk for hydrops fetalis (at UW 1:8)
• If < 1:8, perform monthly titer during pregnancy, except anti-K

Question 21

Other prenatal tests

Answer 21

• Type parent’s partner (homozygous, heterozygous)
• Fetal testing
• Cell free DNA: fetal Rh status 96-99%, use maternal blood
• Amniocentesis

Question 22

Postnatal test

Answer 22

• Incompatible blood types mom & baby
• Hemolysis?
• Antibody-mediated hemolysis

Question 23

Ultrasound

Answer 23

• Anemia cause increased cardiac output
• Lower blood viscosity –> increase blood velocity
• Measure o the fetal middle cerebral artery (MCA)
• Value > 1.5 MoM –> moderate to severe fetal anemia
• Start at 18-20 weeks (after 35w, maybe false positive)
• Non-invasive and can be used for Kell

Question 24

Intrauterine Transfusion

Answer 24

• O neg, CMV negative, irradiated
• Fresh unit has higher 2,3 DPG
• HCT 70-80
• Fetal monitoring
• Transfuse 40-100 cc
• Lab: opening and closing HCT
• Transfuse q2 weeks for 1st two and q3 weeks up to 35 weeks

Question 25

Neonatal Management after IUT

Answer 25

- IUT will suppress fetal erythropoesis - Deliver at 37-38 weeks - At birth need: IAT, DAT, HCT, Reticulocyte count, bilirubin - Follow up HCt & reticulocyte counts until recovery of hematopoietic function (4-6 weeks)

Question 26

ABO-induced disease

Answer 26

- Infant A, B from O mom - Can occur in 1st pregnancy - 15% of all pregnancies (only 0.6% need treatment)

Question 27

Neonatal Management (hemolysis)

Answer 27

- Oral hydration - Phototherapy - Blue light (420-470) - Converts bilirubin to lumirubin (soluble --> excreted into bile and urine) - Simple transfusion - Immunoglobulin therapy - Exchange transfusion

Question 28

Postpartum hemorrhage

Answer 28

- Within 24 hrs after delivery (> 1000mL) - Secondary if happen after 24 hrs to 6-12 weeks - 1-5% of deliveries - Uterine atony most common

Question 29

Invasive Placentation

Answer 29

- Abnormal placentation: attachment of placenta to uterine lining - Directly attach to myometrium - Risk: previous C-section, uterine surgery, placenta previa

Question 30

Placenta abruption

Answer 30

- Premature separation of placenta from the uterus | - Bleeding leads to placental separation

Question 31

Obstetric Bleeding Emergency Protocol

Answer 31

RBC: FFP:PLT ( 6 unit each) and 10 unit of cryoprecipitate

Question 32

Transfusion Indication for Obstetric

Answer 32

- Massive hemorrhage: RBC, 4u FFP if needed - PLT < 100K: 6 packs - Fibrinogen < 125: 6 unit cryo - INR > 1.5: 4 unit FFP