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Rh Negative or D Negative

By AdminPosted On 05-Oct-2016

1. Routine Antenatal anti-D Prophylaxis (RAADP)

All previously non-sensitized, D negative, pregnant women are offered routine antenatal anti-D Ig prophylaxis (RAADP). However, the disadvantage of this approach is that approximately 40% of D negative women who are carrying an D negative child will be given routine prophylactic anti-D Ig unnecessarily. Is there any test available to detect fetal D type during pregnancy?

a) Yes
b) No

Correct Answer: a) Yes. In recent years, advancements in fetal blood group genotyping using cell free fetal DNA (cffDNA) from maternal blood samples taken at 16–20 week gestation, have made it possible to determine fetal D type with a diagnostic accuracy of around 96%. The risk of a false negative result (i.e. missing an D positive fetal blood group) by this technique, is small and currently estimated to be around 0·08 to 0·16%. Routine fetal RHD typing for all D negative pregnant women has been introduced in Denmark and The Netherlands to allow selective use of RAADP.

2. Sensitising Event

Routine Antenatal Anti-D Ig Prophylaxis Should be regarded as a separate entity and administered regardless of, and in addition to, any anti-D Ig that may have been given for a potentially sensitising event.

a) True
b) False

Correct Answer: a) True. Use of routine antenatal anti-D Ig prophylaxis should not be affected by previous anti-D Ig prophylaxis administered for a sensitising event earlier in the same pregnancy. The RAADP (Routine antenatal anti-D Ig prophylaxis) scheme should be regarded as supplementary to any anti-D Ig administered for sensitising episodes. (Ref: RCOG)

3. Dose of anti-D Ig

If using the two-dose regimen, a minimum dose of anti-D Ig 500 IU is recommended at 28 and 34 weeks. Alternatively, a single dose of anti-D Ig, 1500 IU should be administered between 28 and 30 weeks.

a) True
b) False

Correct Answer: a) True. The single dose regimen of 1500 IU may be more cost effective, potentially enabling better compliance and providing logistic benefits.Use of routine antenatal anti-D Ig prophylaxis should not be affected by previous anti-D Ig prophylaxis administered for a sensitising event earlier in the same pregnancy. (Ref: RCOG)

4. Dose of Anti-D after 20 weeks

For potentially sensitising events after 20 weeks gestation, a minimum anti-D Ig dose of --------- should be administered within 72 h of the event.

a) 100 IU
b) 250 IU
c) 300 IU
d) 500 IU

Correct Answer: d) 500 IU. For potentially sensitising events after 20 weeks gestation, a minimum anti-D Ig dose of 500 IU should be administered within 72 h of the event, regardless of whether the woman has already received RAADP at 28 weeks.Additional dose(s) of anti-D Ig will be necessary if the volume of FMH exceeds that covered by the standard anti-D Ig dose in use. A follow-up blood sample should be taken at 48 h following each IV dose of anti-D and 72 h following each IM dose of anti-D to check if fetal cells have cleared. (Ref: RCOG)

5. Anti-D Deadline

Following potentially sensitising events, anti-D Ig should be administered as soon as possible and always within 72 h of the event. If, exceptionally, this deadline has not been met some protection may be offered if anti-D Ig is given up to ----- after the sensitising event.

a) 5 days
b) 7 days
c) 10 days
d) 14 days
e) Should not be administered after 3 days

Correct Answer: c) 10 days. Following potentially sensitising events, anti-D Ig should be administered as soon as possible and always within 72 h of the event. If, exceptionally, this deadline has not been met some protection may be offered if anti-D Ig is given up to 10 days after the sensitising event. (Ref: RCOG Guidelines)

6. Dose of Anti-D <12 weeks

In pregnancies following ectopic pregnancy, molar pregnancy, therapeutic termination of pregnancy and in cases of uterine bleeding where this is repeated, heavy or associated with abdominal pain. The minimum dose should be ------

a) 50 IU
b) 100 IU
c) 250 IU
d) 300 IU
e) 500 IU

Correct Answer: c) 250 IU. In pregnancies <12 weeks gestation, anti-D Ig prophylaxis is only indicated for potentially sensitising events. The minimum dose should be 250 IU. A test for fetomaternal haemorrhage (FMH) is not required, (Ref: RCOG Guidelines)

7. Previously Sensitized D Negative

All D negative pregnant women who have not been previously sensitized should be offered routine antenatal prophylaxis with anti-D Ig either with a single dose regimen at around 28 weeks, or two-dose regimen given at 28 and 34 weeks.

a) True
b) False

Correct Answer: a) True. If using the two-dose regimen, a minimum dose of anti-D Ig 500 IU is recommended at 28 and 34 weeks.Alternatively, a single dose of anti-D Ig, 1500 IU should be administered between 28 and 30 weeks. The single dose regimen may be more cost effective, potentially enabling better compliance and providing logistic benefits. (Ref: RCOG)

8. Anti-D Ig in APH

Anti-D Ig should be given to all non-sensitised RhD-negative women after any presentation with Antepartum haemorrhage.

a) True
b) False

Correct Answer: a) True. For potentially sensitising events after 20 weeks gestation, a minimum anti-D Ig dose of 500 IU should be administered within 72 h of the event. A test for FMH is required and additional dose(s) of anti-D Ig should be administered as necessary. For potentially sensitising events between 12 and 20 weeks gestation, a minimum dose of 250 IU should be administered within 72 h of the event. A test for FMH is not required. (Ref: RCOG Guidelines)

9. Anti-D Ig following delivery

Following birth, ABO and Rh D typing should be performed on cord blood and if the baby is confirmed to be D positive. All D negative, previously non-sensitised, women should be offered at least ------- of anti-D Ig within 72 h following delivery.

a) 50 IU
b) 100 IU
c) 250 IU
d) 300 IU
e) 500 IU

Correct Answer: e) 500 IU. Maternal samples should be tested for FMH and additional dose(s) given as guided by FMH tests. If an FMH >4 mL is detected, follow-up samples are required at 48 h following an IV dose of anti-D or 72 h following an IM dose to check for the clearance of fetal cells. (Ref: RCOG)

10. FMH

A dose of 500 IU, IM is considered sufficient to treat a FMH (Feto-maternal haemorrhage) of up to ----- fetal red cells.

a) 2 mL
b) 4 mL
c) 8 mL
d) 10 mL
e) 15 mL

Correct Answer: b) 4mL. A dose of 500 IU, IM is considered sufficient to treat a FMH of up to 4 mL fetal red cells (WHO Technical Report 468, 1971). Where it is necessary to give additional doses of anti-D Ig, as guided by tests for FMH.

11. Intrauterine death in D Negative

In the event of an intrauterine death (IUD), where no sample can be obtained from the baby, an appropriate dose of prophylactic anti-D Ig should be administered to D negative, previously non-sensitised women within 72 h of delivery.

a) True
b) False

Correct Answer: b) False. Answer is within 72 h of the diagnosis of IUD, irrespective of the time of subsequent delivery. It should be noted that the diagnosis of IUD is the sensitising event rather than delivery. (Ref: RCOG)

12. D negative platelet

D negative platelets should be transfused to D negative girls or women of child bearing potential, who need a platelet transfusion.

a) True
b) False

Correct Answer: a) True. Whenever possible, D negative platelets should be transfused to D negative girls or women of child bearing potential, who need a platelet transfusion. Occasionally, if the appropriate product is not available or its availability would cause unacceptable delay, it may be necessary to transfuse D positive platelets. In these circumstances, prophylaxis against possible sensitisation to the D antigen by red cells contaminating the platelet product should be given.A dose of 250 IU anti-D immunoglobulin should be sufficient to cover up to five adult therapeutic doses of D positive platelets given within a 6-week period.

13. D positive platelet

It is not necessary to administer anti-D Ig to D negative females without childbearing potential, or males who receive D positive platelets.

a) True
b) False

Correct Answer: a) True. It is not necessary to administer anti-D Ig to D negative females without childbearing potential, or males who receive D positive platelets.

14. Kleihauer-Betke test

28-year-old primi at term with labour pains. Her prenatal course was remarkable for her being Rh negative and antibody negative. Her husband is Rh positive. She delivered normally in next 5 hours. The placenta required manual removal. To determine the correct amount of anti-D immune globulin that should be given, which of the following is the most appropriate laboratory test?a) Complete blood count b) Kleihauer-Betke c) Liver function tests d) Prothrombin time e) Serum potassiumCorrect Answer: b) Kleihauer-Betke test Women who are Rh negative are at risk for developing Rh isoimmunization. The amount of anti-D immune globulin, that is usually given after the delivery of an Rh-positive fetus is 300 µg. This amount is sufficient to cover a fetal to maternal hemorrhage of 30 mL (or 15 mL of fetal cells). However, some women will have a fetal to maternal hemorrhage that is in excess of this 30 mL-especially in cases such as manual removal of the placenta or placental abruption. To determine the amount of fetal to maternal hemorrhage that occurred, it is necessary to perform a Kleihauer-Betke test. This acid-dilution procedure allows fetal red blood cells to be identified and counted. Knowing the amount of fetal to maternal hemorrhage that took place allows the correct amount of anti-D immune globulin to be given.

15. A positive Kleihauer test may be found in all of the following EXCEPT

a) In men with sickle cell anemia.b) In Woman with homozygous beta-thalassemia .c) Following feto-maternal hemorrhage .d) During adult hood period. e) Following normal delivery.Correct Answer: d) During adult hood period. In those with positive Kleihauer-Betke test, follow up testing at a postpartum check should be done to rule out the possibility of a false positive. This could be caused by a process in the mother which causes persistent elevation of fetal hemoglobin, e.g. sickle cell or thalassemia.

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