FETAL DISORDERS Flashcards
FETAL DISORDERS etiology
- May be ACQUIRED - Alloimmunization
- May be GENETIC - Congenital Adrenal Hyperplasia, 4alpha Thalassemia
- May be SPORADIC - Structural abnormalities
One of the most frequent causes of
fetal anemia
RED CELL ALLOIMMUNIZATION
Results from transplacental passage of
maternal antibodies that destroy fetal
red cells
RED CELL ALLOIMMUNIZATION
RED CELL ALLOIMMUNIZATION will lead to
overproduction of immature fetal and neonatal red cells ERYTHROBLASTOSIS FETALIS)
RED CELL ALLOIMMUNIZATION detected by
Blood type and Antibody screening during 1 st
PNCU
RED CELL ALLOIMMUNIZATION dx test
- Unbound antibodies detected by INDIRECT COOMB’S TEST
- IgG antibodies are assessed since these are the ones that cross the placenta
- Critical titer for anti D ≥1:16 can cause significant fetal anemia
D negative mother and D positive fetus
increased chance of alloimmunization
- Absence of D Antigen
- Sensitized after single exposure of 0.1 mL of fetal RBCs
D NEGATIVITY
D Sensitization also may occur following
- first trimester pregnancy complications
- prenatal diagnostic procedures
- maternal trauma
Five Red Cell Antigens
c, C, D, E, e
have lower immunogenicity but can cause
hemolytic disease
C, c, E and e Antigens
CDE most common blood group incompatibility
Anti E alloimmunization
greater need for fetal or neonatal transfusion
Anti c alloimmunzation
current pregnancy is jeopardized by maternal antibodies that were initially provoked by his or her grandmother’s erythrocytes
Grandmother effect
Most common cause of hemolytic disease with A and B Blood group antigens
ABO BLOOD GROUP INCOMPATIBILITY
ABO vs CDE Incompatibility
- ABO incompatibility seen in first born
- ABO rarely become more severe in successive pregnancy
- ABO more of pediatric concern
- Most ABO Antibodies don’t cross the placenta (IgM)
- Fetal cells are less immunogenic due to less A and B antigenic sites
ALLOIMMUNIZED PREGNANCY will develop in what
- Mild to moderate hemolytic anemia
- Hydrops fetalis
MANAGEMENT OF ALLOIMMUNIZED PREGNANCY
- Monitoring of titer, repeated every 4 weeks if below the critical level
- If within critical level , further evaluation should be done and no benefit with repeating the titer level
25% to 30% D alloimmunized will develop
mild to moderate hemolytic anemia
25% of alloimmunized pregnancy will develop
hydrops fetalis
MANAGEMENT: DETERMINE FETAL RISK
-40% risk for D Negative mother to have D Negative fetus
-Amnestic Response - Patient is sensitized from previous exposure but titer may be elevated with
current pregnancy even if the fetus is D Negative
-Initial evaluation
*Determine paternal erythrocyte antigen status
*Paternal zygosity
*Fetal genotype
MANAGEMENT: ALLOIMMUNIZED PREGNANCY
-Individualized
-Monitoring
*Accurate fetal aging is critical
*Aging when anemia develops
*Maternal antibody titer surveillance
*Sonographic monitoring of Middle Cerebral Artery (MCA) peak systolic
velocity
*Amniotic fluid bilirubin studies
*Fetal blood sampling and blood transfusion
PREVENTION OF ANTI D ALLOIMMUNIZATION
-Administration of anti D immune globulin
at 28 weeks gestation
-Routine postpartum administration within 72 hours of delivery lowers the alloimmunization by 90%
-Anti D Immune globulin
*Rosette test: positive
*Kleihauer Betke Test: (+) fetal cells in maternal blood
- Approximately, 2/3 provoke an Antigen-Antibody reaction
- Incidence directly proportional to AOG
FETAL HEMORRHAGE INCIDENCE
FETAL HEMORRHAGE causes
- Placenta previa
- Placental chorioangioma
- Vasa previa
FETAL HEMORRHAGE ssx
Decreased fetal movement
FETAL HEMORRHAGE seen in diagnostics
- Sinusoidal fetal heart rate pattern
- Elevated MCA Peak Systolic Velocity on Ultrasound
No significant effect on fetal heart rate unless fetus is moribund
CHRONIC ANEMIA
- Poorly tolerated by the fetus
- May cause profound neurologic impairment from cerebralhypoperfusion, ischemia and infarction
ACUTE ANEMIA
*Most commonly used quantitative test for
fetal red cells in the maternal circulation
*Hemoglobin F is resistant to acid elution
(darker)
* “Ghosts” –> maternal RBCs
Kleihauer-Betke Test (Acid Elution)
resistant to acid elution (darker)
Hemoglobin F
Hemorrhage Quantification for fetal hemorrhage
- Computation of FBV from
result of KB test - Flow Cytometry
- Uses monoclonal antibodies to hemoglobin F or D antigen
- Followed by quantification of fluorescence
- More sensitive and More accurate
- Unaffected by maternal blood cells
Flow cytometry
-Most common cause of Severe Thrombocytopenia
-also known as FNAIT (Fetal and Neonatal Alloimmune
Thrombocytopenia) or NAIT (Neonatal Alloimmune Thrombocytopenia)
Alloimmune Thrombocytopenia (AIT)
- Caused by maternal alloimmunization to paternally inherited fetal platelet antigens
- Maternal antiplatelet antigens cross the placenta
- Maternal platelet alloimmunization is usually against human platelet antigen 1a (HPA 1a)
FETAL AND NEONATAL ALLOIMMUNE THROMBOCYTOPENIA (FNAIT)
FETAL AND NEONATAL ALLOIMMUNE
THROMBOCYTOPENIA (FNAIT) diagnosis
Upon delivery of a neonate, when there is severe and unexplainable thrombocytopenia from a
mother with normal platelet count
FETAL AND NEONATAL ALLOIMMUNE
THROMBOCYTOPENIA (FNAIT) diagnosis
- Intravenous Immune globulin (IVIG) and Prednisone:
- Increases Platelet count by 50,000 u/L or 80% increase if used in combination
- Side effects of IVIG : fever, headache, myalgia, nausea/vomiting and rash
FETAL AND NEONATAL ALLOIMMUNE
THROMBOCYTOPENIA (FNAIT) mode of delivery
- CS for term or near term
* Non instrumental vaginal delivery if Platelet count is >100,000/ uL
IMMUNE THROMBOCYTOPENIA pathogenesis
- Antiplatelet IgG antibodies that attack platelet glycoproteins
- Crosses the placenta and causes fetal thrombocytopenia (mild)
IMMUNE THROMBOCYTOPENIA also known as
Immune Thrombocytopenic Purpura (ITP)
IMMUNE THROMBOCYTOPENIA mode of delivery
- Vaginal
- CS for Obstetric indications
- Excessive accumulation of serous fluid
- Edema of the fetus
- Associated with placentomegaly and hydramnios
- Skin thickness >5 mm and placental thickness of at least 4 cm (2nd trimester) and 6 cm (3rd trimester)
HYDROPS FETALIS
prenatal diagnosis of hydrops fetalis
Ultrasound
- 2 or more fetal effusions
- Pleural
- Pericardial
- Ascites
- 1 effusion plus Anasarca
HYDROPS FETALIS: IMMUNE TYPE results from
Transplacental passage of maternal antibodies that destroy fetal red cells
HYDROPS FETALIS: IMMUNE TYPE Associated with
Red Cell Alloimmunization
Incidence declined dramatically due to
- Anti D Immune globulin administration
- MCA Doppler Studies for early detection
- Fetal Blood transfusion
HYDROPS FETALIS: IMMUNE TYPE
HYDROPS FETALIS: IMMUNE TYPE Pathophysiology
- Decreased colloid oncotic pressure
- Increased hydrostatic pressure
- Enhanced vascular permeability
HYDROPS FETALIS: IMMUNE TYPE complications
-anemia –> stimulates marrow erythroid hyperplasia and extramedullary hematopoiesis in the
spleen and liver
*usually severe (Hgb < 5g/dL)
-Tissue hypoxia –> may increase capillary permeability causing fluid accumulation in the thorax, abdominal cavity and subcutaneous tissue
- 90% of cases of hydrops fetalis
- Etiology is identified depending of age of gestation
- Prenatally (Aneuploidy, Cardiovascular abnormalities, Infections (Parvovirus B19)
- Prognosis depends on etiology
HYDROPS FETALIS: NON IMMUNE TYPE
Causes of fetal hydrops
Fetal anemia Fetal arrhythmia Structural abnormality Aneuploidy Placental abnormality Monochorionic twinning complications
fetal hydrops
-Initial Evaluation
*Indirect Coomb’s test for alloimmunization
*Targeted sonographic fetal and placental
evaluation
–Detailed anatomic survey
–MCA Peak Systolic Velocity
–Fetal echocardiogram
*Amniocentesis and TORCH evaluation
*Kleihauer Betke test
*Thalassemia work up
- Association of fetal hydrops and development of maternal edema
- “Triple Edema”: fetus, mother and placenta all edematous
- Form of Severe preeclampsia
- 90% edema
- 60% hypertension
- 40% proteinuria
- 20% elevated liver enzymes
- 15% headache and visual disturbance
MIRROR SYNDROME
Triple edema
edematous:
- fetus
- mother
- placenta
Management of mirror syndrome
Prompt Delivery and Resolution of maternal edema