Alloimmunization

Question 1

What is alloimmunisation?

Answer 1

Alloimmunisation is when a Rh-negative pregnant mother is exposed to Rh-positive fetal red blood cells, leading to the production of Rh Immunoglobulin G (IgG) antibodies that can cross the placenta and destroy fetal erythrocytes, causing hemolytic anemia in the fetus.

Question 2

What are the common causes of fetomaternal hemorrhage leading to alloimmunisation?

Answer 2

Common causes include miscarriage, trauma, invasive obstetric procedures, and normal delivery. Sensitization most often occurs during delivery.

Question 3

What is the importance of screening for alloimmunisation in Rh-negative mothers?

Answer 3

Screening is important because sensitization can lead to serious complications in future pregnancies, such as hydrops fetalis, icterus gravis neonatorum, and congenital anemia in the fetus.

Question 4

What is the preventive management of Rh alloimmunisation?

Answer 4

Preventive management includes administering Rh immunoglobulin (RhIg) to Rh-negative mothers after sensitizing events, at 28 weeks gestation, and within 72 hours of delivery if the infant is Rh-positive.

Question 5

What dose of Rh immunoglobulin is recommended after a sensitizing event before 20 weeks of gestation?

Answer 5

150 μg of Rh immunoglobulin is recommended for events occurring before 20 weeks of gestation.

Question 6

What is the recommended dose of Rh immunoglobulin for events occurring after 20 weeks of gestation or within 72 hours of delivery?

Answer 6

300 μg of Rh immunoglobulin should be administered after events occurring after 20 weeks of gestation or within 72 hours of delivery.

Question 7

What should be done if Rh immunoglobulin is not administered within the recommended immediate postpartum period?

Answer 7

It should still be given up to 28 days postpartum.

Question 8

What is the management for a sensitized maternal patient (positive Coombs test in Rh-negative woman)?

Answer 8

Management includes referral to a specialist, monthly ultrasound for fetal weight, MCA Doppler to detect fetal anemia, possible early delivery if severe anemia is detected, and consideration of caesarean delivery for severely affected or preterm fetuses.

Question 9

What is the management approach for fetomaternal hemorrhage to minimize the risk of alloimmunisation?

Answer 9

Avoid manual removal of the placenta, immediately clamp the cord, and keep the cord of the fetus long for possible transfusion.

Question 10

What key historical details should be gathered when assessing a patient for alloimmunisation risk?

Answer 10

Important history includes gravidity, parity, previous abortions/miscarriages, history of blood transfusions, and the blood group of the pregnant woman and her partner.

Question 11

What laboratory tests should be ordered to assess for alloimmunisation?

Answer 11

Blood tests should include hemoglobin (Hb), blood group, Direct Coombs test, syphilis test, and HIV.

Question 12

How often should Rh-negative mothers be tested for antibodies during pregnancy?

Answer 12

Rh-negative mothers should be tested for antibodies three times during pregnancy: at the first antenatal visit, at 28 weeks gestation, and at delivery.

Question 13

What should be tested in potentially affected infants of Rh-negative mothers at the time of delivery?

Answer 13

The Rh type and antibodies should be tested from the umbilical cord at the time of delivery.

Question 14

What is the role of ultrasound (US) in the diagnosis and monitoring of alloimmunisation?

Answer 14

Ultrasound is used for dating the pregnancy and performing serial ultrasounds to diagnose and monitor the fetus for signs of hemolytic disease.

Question 15

What is the Direct Coombs test used for in the context of alloimmunisation?

Answer 15

The Direct Coombs test is used to detect the presence of maternal antibodies bound to fetal red blood cells.

Question 16

When should serial ultrasounds be conducted in Rh-negative mothers?

Answer 16

Serial ultrasounds should be conducted throughout the pregnancy to monitor the fetus for signs of hemolytic anemia and other complications associated with alloimmunisation.

Question 17

Why is it important to monitor antibody titers in sensitized Rh-negative mothers?

Answer 17

Monitoring antibody titers helps assess the risk of fetal hemolytic anemia and guides the timing and management of delivery.

Question 18

What is the primary method for preventing Rh alloimmunisation in Rh-negative pregnant women?

Answer 18

The primary method is the administration of Rh immunoglobulin (RhIg) at specific times during pregnancy and after delivery.

Question 19

When should Rh immunoglobulin be administered during pregnancy to prevent alloimmunisation?

Answer 19

Rh immunoglobulin should be administered at 28 weeks gestation and within 72 hours of delivery if the infant is Rh-positive

Question 20

What dose of Rh immunoglobulin is recommended at 28 weeks gestation?

Answer 20

A dose of 300 μg (1500 IU) of Rh immunoglobulin is recommended at 28 weeks gestation.

Question 21

What should be done if a sensitizing event occurs before 20 weeks of gestation?

Answer 21

If a sensitizing event occurs before 20 weeks, administer 150 μg of Rh immunoglobulin

Question 22

What is the protocol if Rh immunoglobulin is not administered within the recommended postpartum period?

Answer 22

Rh immunoglobulin should still be given up to 28 days postpartum if not administered within the immediate postpartum period.

Question 23

What are some examples of sensitizing events that require administration of Rh immunoglobulin?

Answer 23

Sensitizing events include vaginal bleeding, abortion/miscarriage, ectopic pregnancy, molar pregnancy, chorionic villus sampling, amniocentesis, blunt trauma to the abdomen, fetal death, and external cephalic version

Question 24

What is the role of Rh immunoglobulin in cases of fetal death?

Answer 24

Rh immunoglobulin should be administered at the time that fetal death is diagnosed, rather than waiting until delivery.

Question 25

What management strategies are used for minimizing fetomaternal hemorrhage during delivery?

Answer 25

Strategies include avoiding manual removal of the placenta, immediate clamping of the cord, and keeping the cord of the fetus long for possible transfusion

Question 26

How should a sensitized maternal patient with a positive Coombs test be managed?

Answer 26

The patient should be referred to a specialist, undergo regular ultrasounds, and MCA Doppler if available, to monitor for fetal anemia. Delivery should be planned based on the severity of anemia and fetal viability.

Question 27

Why is it important to counsel women affected by alloimmunisation about future pregnancies?

Answer 27

Women should be informed that future pregnancies are generally more severely affected, necessitating close monitoring and early intervention.

Question 28

How should fetal well-being be monitored in a sensitized pregnancy?

Answer 28

Regular ultrasounds should be performed to monitor fetal growth and check for signs of hydrops fetalis (e.g., fetal edema, accumulation of fluid in fetal compartments).

Question 29

What advanced monitoring technique is used to detect fetal anemia in sensitized pregnancies?

Answer 29

Doppler ultrasound of the middle cerebral artery (MCA) is used to detect fetal anemia, with a threshold value of 1.5 multiples of the median (MoM) indicating moderate to severe anemia.

Question 30

What is the recommended action if severe fetal anemia is detected via MCA Doppler?

Answer 30

Consider early delivery if the fetus is viable; if not, the situation may warrant more intensive monitoring and preparation for potential interventions.

Question 31

What is the delivery plan for a fetus affected by alloimmunisation?

Answer 31

Caesarean delivery is recommended for severely affected or preterm fetuses. If the fetus is less than 34 weeks, antenatal corticosteroids like dexamethasone should be administered prior to delivery to enhance fetal lung maturity.

Question 32

How should newborns affected by alloimmunisation be managed immediately after birth?

Answer 32

Newborns with hemoglobin levels ≤ 12 g/dL, a positive direct Coombs test, or bilirubin levels ≥ 5 mg/dL should be considered for transfusion

Question 33

What medication can be given prior to delivery to enhance hepatic maturity in the fetus?

Answer 33

Oral phenobarbital may be administered 7 to 10 days prior to delivery to improve hepatic maturity and enhance the conjugation of bilirubin.

Question 34

When is it appropriate to induce labor in a pregnancy complicated by alloimmunisation?

Answer 34

Induction of labor can be considered around 37-38 weeks gestation or earlier if fetal lung maturity is documented, especially in consultation with a specialist.

Question 35

Why is it important to monitor for hydrops fetalis in sensitized pregnancies?

Answer 35

Hydrops fetalis is a severe and potentially life-threatening condition characterized by high-output cardiac failure, edema, ascites, and pericardial effusion, which requires immediate medical attention and management.

Question 36

What is the management approach for an unsensitized Rh-negative pregnant woman

Answer 36

Administer routine antenatal anti-D prophylaxis (RAADP) to prevent sensitization.

Question 37

When should Rh immunoglobulin be administered to an unsensitized Rh-negative pregnant woman during pregnancy?

Answer 37

Rh immunoglobulin should be administered at 28 weeks gestation

Question 38

What dose of Rh immunoglobulin is given at 28 weeks gestation for unsensitized Rh-negative mothers?

Answer 38

A dose of 300 μg (1500 IU) of Rh immunoglobulin is given at 28 weeks gestation.

Question 39

What should be done if an unsensitized Rh-negative pregnant woman experiences a sensitizing event before 20 weeks gestation?

Answer 39

Administer 150 μg of Rh immunoglobulin for events occurring before 20 weeks gestation.

Question 40

How should sensitizing events occurring after 20 weeks gestation be managed in an unsensitized Rh-negative pregnant woman?

Answer 40

Administer 300 μg of Rh immunoglobulin for events occurring after 20 weeks gestation.

Question 41

What should be done if an unsensitized Rh-negative mother has recurrent antepartum hemorrhage after 20 weeks gestation?

Answer 41

Administer anti-D immunoglobulin at least every 6 weeks to prevent sensitization.

Question 42

What is the protocol if the pregnancy is non-viable and the mother is Rh-negative but unsensitized?

Answer 42

Administer anti-D immunoglobulin within 72 hours of diagnosis, regardless of the timing of delivery.

Question 43

What tests should be conducted at the time of delivery in an unsensitized Rh-negative mother?

Answer 43

Test the infant’s Rh type and perform a Direct Coombs test from the umbilical cord blood.

Question 44

What should be done if the newborn of an unsensitized Rh-negative mother is Rh-positive?

Answer 44

Administer 300 μg of Rh immunoglobulin to the mother within 72 hours of delivery.

Question 45

Why is it important to administer Rh immunoglobulin even if no sensitization has occurred by the end of pregnancy?

Answer 45

To prevent sensitization in future pregnancies, which could lead to severe complications such as hemolytic disease of the fetus and newborn.

Question 46

How often should antibody titers be monitored in a sensitized Rh-negative pregnant woman?

Answer 46

Antibody titers should be monitored every 4 weeks until 28 weeks gestation, and then every 2 weeks until delivery.

Question 47

What fetal monitoring technique is crucial in sensitized pregnancies to assess for anemia?

Answer 47

Middle Cerebral Artery (MCA) Doppler ultrasound should be performed weekly from 16-18 weeks gestation to detect fetal anemia

Question 48

What is the management if the MCA Doppler indicates severe fetal anemia?

Answer 48

Consider early delivery if the fetus is viable; otherwise, more intensive monitoring and potential in-utero treatments may be necessary.

Question 49

At what gestational age should delivery be considered in a sensitized pregnancy?

Answer 49

Delivery should be considered at 37-38 weeks gestation, or earlier if there is evidence of fetal compromise or if fetal lung maturity is confirmed.

Question 50

What should be administered to the mother if delivery is planned before 34 weeks in a sensitized pregnancy?

Answer 50

Administer antenatal corticosteroids (e.g., dexamethasone) to enhance fetal lung maturity before delivery.

Question 51

What neonatal management is indicated immediately after delivery in sensitized pregnancies?

Answer 51

Test the newborn for hemoglobin levels, perform a Direct Coombs test, and measure bilirubin levels. Consider transfusion if hemoglobin is ≤ 12 g/dL, Coombs test is positive, or bilirubin is ≥ 5 mg/dL.

Question 52

What are the potential complications for the fetus or newborn in a sensitized pregnancy?

Answer 52

Complications can include hemolytic anemia, hydrops fetalis, and severe jaundice leading to kernicterus.

Question 53

What is the role of phenobarbital in the management of sensitized pregnancies?

Answer 53

Oral phenobarbital may be considered in the 7 to 10 days prior to delivery to improve hepatic maturity and enhance bilirubin conjugation in the newborn.