1. بسم الله الرحمن الرحيم

2. Management of Rh alloimmunization

3. CDE (Rhesus) System Includes c, C, D, e, E
D negativity defined as absence of D antigen

4. Antibodies Associated with
Anti-c, Anti-D, Anti-E, and Anti-Kell
Anti-D-immunoglobulin prophylaxis reduced the hemolytic disease caused by anti-D, but not the others

5. Minor RBC Antigens causes hemolyisis
Kell is most common of minor
Responsible for 10% of cases of severe antibody-mediated anemia
**Transfuse women with Kell(-) blood**

6. Inert Antibodies
Antigens such as A, P, Le (a), M, I, IH, and Sd (a) are innocuous
Mostly are IgM
Lewis antibodies is the commonest one detected

7. Sensitization rate 16 percent without prophylaxis
2 percent with routine postpartum administration
0.1 percent with routine antenatal administration

8. Causes of Rh isoimmunization
Delivery
Induced abortion
Spontaneous abortion
Ectopic pregnancy
Partial molar pregnancy
Chorionic villus sampling
Cordocentesis

9. Amniocentesis
External cephalic version
Abruptio placenta
Antenatal hemorrhage
Maternal abdominal trauma
Spontaneous
Needles
Blood and blood product

10. Clinical Management Routine booking blood group &Antibodies screen
Rh –v Ab –v
Determine father’s RhBC status if
-v No risk

11. If the father is +ve for-D-antigen, fetus is at RISK
- Repeat Antibodies screen at 28 weeks for Rh-ve women prior to receiving Anti-D immunoglobulin
-Determine father’s RBC antigen status and zygosity

12. Clinical Management If Antibody screen is +ve, identify antibody type
Identify the risk factors for alloimmunization (past pregnancies, transfusions, shared needles)

13. Clinical Management
Obtain antibody titer from the mother if the past history is not significant for an affected pregnancy.
**Titers less reliable after a sensitized pregnancy**
Consider invasive testing at titer of 1:16 or greater by indirect Coombs

14. Clinical Management
If Antibodies titer remains below critical titer- invasive testing is not indicated and the patient can be followed up by serial Antibodies titter
Serial titers before weeks not necessary

15. If Antibodies titer is above the critical level or the past history is positive regardless of the antibodies titer - invasive testing is indicated

16. Clinical Management
Amniocentesis for amniocytes at 15 weeks by (PCR) to determine fetal blood type if father is heterozygous.
Free fetal DNA in maternal circulation.

17. Fetal antigenic determination
Amniocentesis, CVS, cordocentesis samples can be used
to determine fetal antigen status by DNA typing
100% accuracy in 390 samples
Bennett et al. 1993
Molecular analysis of maternal plasma: fetal DNA for RhD
100% accuracy in 45 fetuses second/third trimester
Lo et al. N Engl J Med 1998;339:

18. Possible utility in embryo selection for sensitized mothers
PCR from cell free DNA in maternal serum
100% accuracy in 137 fetuses (including 21 female fetuses)
Finning et al. Transfusion 2002;42:
Possible utility in embryo selection for sensitized mothers

19. Clinical Management
Serial amnio to measure delta OD450 and plot values on Liley or Queenan graph

20. Delta OD450
Spectral analysis of amniotic fluid at 450 nm proposed in 1961 by Liley- measures change in OD
Measures the level of bilirubin and predicts severity of hemolytic disease after 27 weeks
Delivery or intrauterine transfusion if delta OD450 falls into zone III or upper zone II

22. Queenan Curve Proposed another method of using delta OD450
Suggested four zones and extended the gestational age to 14 weeks

24. Limitations of Amniocentesis
May give a falsely elevated bilirubin level in presence of mec or blood
May be low after exposure to light or in Kell alloimmunization

25. Cordocentesis Gold standard for detection of fetal anemia
Complications!
2.7% total risk of fetal loss
Reserved for patients with increased MCA-PSV or delta OD450

26. MCA-PSV Velocity of blood flow in brain increased with anemia
1. Increased cardiac output
2. Vasodilatation in the brain
3. Decreased blood viscosity

27. MCA & FETAL ANEMIA
The MCA PSV correlated well with hematocrit and hemoglobin concentrations and is useful for predicting the severity of fetal anemia
(Mari G. 1995)
The MCA PSV increases in fetuses with anemia
(Roberts AB. 2001)

28. FETAL ANEMIA Fetal anemia  blood viscosity  Cardiac output
peripheral vasodilatation
 Blood flow to the Brain,
Heart and Adrenal gland
Mari G. 1990
Many A. 1996
HecherK. 1995
Bahauddin Sallout

29. Correct Technique for MCA Doppler
Fetus resting
Circle of Willis imaged in axial image using color Doppler
Entire length of MCA
Close to origin of internal carotid artery

30. MCA LOCALIZATION
In a transverse axial view of the fetal head at a slightly more caudal plane than the one used for BPD
At this level, which include the cerebral peduncles, the MCA can be seen as a major lateral branch of the circle of Willis
Bahauddin Sallout

31. MIDDLE CEREBRAL ARTERY
Transverse view of the fetal head with color Doppler showing the circle of Willis
Flow velocity waveforms from the MCA at 32 wk

32. MIDDLE CEREBRAL ARTERY
Normal flow in 1º trimester
Normal flow in 2º & 3º trimester

33. MCA-PSV
I would like to review our technique for measuring the middle cerebral artery peak systolic velocity, using the following steps:
Identification of the circle of Willis by color Doppler on an axial section of the brain slightly superior to the thalami and cavum septum pellucidum.
Then, identification of the middle cerebral arteries flowing anteriorly and outward; just behind the orbits.
The sample volume line is placed as close as possible to 0 degrees; parallel to the walls of the vessel, in the proximal middle cerebral artery, close to its origin but not incorporating the internal carotid artery.
The middle cerebral artery peak systolic velocity is then measured at the highest point of the Doppler waveform. The MCA-PSV is measured multiple times and the highest peak systolic velocity is recorded.

34. MCA & FETAL ANEMIA Fetal anemia due to maternal alloimmunization
Bahauddin Sallout

35. MCA ABSENT DIASTOLIC FLOW
Severe hydrops (kell antibody)
Bahauddin Sallout

36. Rh Alloimmunization management
If using MCA-PSV, and initial is less than 1.5 MoM, weekly testing
Cordocentesis or delivery depends on the gestational age once the MCA-PSV reaches 1.5 MoM

37. Several prospective studies have found that elevated middle cerebral artery peak systolic velocities as measured by Doppler ultrasonography correlate with the presence of fetal anemia in alloimmunized pregnancies.
Work by Mari et al., published in 1995, - not only correlated elevations in middle cerebral artery peak systolic velocities with fetal anemia, but also established a nomogram for the normal range of middle cerebral artery peak systolic velocity as a function of gestational age.
Mari et al. N Eng J Med 2000

38. Advantages of MCA-PSV Non-invasive
Mother not put at risk for worsening alloimmunization
Can be used with all antibodies other than RhD, including anti-Kell antibodies

39. Disadvantages of MCA-PSV
Need skill
Done weekly
Accuracy decreases after 35 weeks
False +ve results 12 percent

40. Current evidence supporting MCA-PSV Doppler velocimetry
Initial prospective study of 16 fetuses: 14 anti-D, 2 anti-c
Mari et al. Ultrasound Obstet Gynecol 1995;5:400-5.
Since then several prospective and retrospective studies: over 200 additional cases
Rbc alloimmunization and parvovirus B19
1-Scott et al. Prenat Diagn 1998;18:
2-Teixeira et al. Ultrasound Obstet Gynecol 2000;15:205-8.
3-Delle Chiaie et al. Ultrasound Obstet Gynecol 2001;18:232-6.
4-Mari et al. N Eng J Med 2000;342:9-14.
5-Zimmermann et al. Br J Obstet Gynecol 2002;109:
6-Mari et al. Ultrasound Obstet Gynecol 2002;99:

41. Current evidence supporting MCA-PSV Doppler velocimetry
Sensitivity %
Specificity %
PPV %
NPV %
Data combined from 7 studies: rbc alloimmunization and parvovirus B19

42. Prediction of fetal anemia by MCA-PSV Doppler compared to Amniocentesis
4 Comparative Studies
N = 28 Nishie EN, et al. Am J Obstet Gynecol ;188:214-9
N = Pereira L et al. Am J Obstet Gynecol ;189:1002-6
N = 38 Bullock ,et al. Ultrasound Obstet Gynecol 2005
N = 165 Oepkes D, et al. N Engl J Med 2006;355:

43. Current evidence MCA-PSV Doppler Amniocentesis
Sensitivity
Specificity
PPV
NPV
N =259
Cumulative ranges from 4 trials

44. Conclusion
MCA-PSV accurately predicted moderate to severe fetal anemia
Compared to conventional management, MCA-PSV may have a better predictive accuracy for moderate or severe anemia in alloimmunization
Management by MCA-PSV may eliminate the need for amniocentesis and reduce the number of PUBS performed in alloimmunized pregnancies

45. Potential Benefits of Management by MCA-PSV
14,000 cases of alloimmunization per year in the U.S.
Avoid 24,500 amniocenteses and 900 PUBS
Avoid 1 pregnancy loss/preterm delivery for every
100 patients; 142 nationwide per year
Avoid worsening sensitization from procedure
related bleeding complications – TPH risk 2-10% following amniocentesis, 50% following PUBS
It is possible that management with MCA-PSV Doppler will reduce the number of invasive procedures and minimize procedure related losses.
In the U.S there are approximately 14,000 cases of alloimmunization annually.
If we applied the trend we observed to the U.S population, we could avoid 24,500 amniocenteses and 980 PUBS per year by using MCA-PSV.
With a complication rate of 0.5% for amniocentesis and a conservative estimate of 2% for PUBS you would avoid 1 pregnancy loss or preterm delivery per 100 patients (over 140 annually) using MCA-PSV over conventional management - and these would likely occur in a mildly anemic or non-anemic fetuses.
Furthermore, an additional benefit would occur from avoiding procedure related bleeding complications which increase sensitization and worsen disease.

46. Prevention of Alloimmunization
Doses of ani-D-immuonoglubuline for Rh-ve)
50 mcg dose protects against 2.5 ml of Rh (+) RBC’s
300 mcg dose protects against 15 ml of RBC’s or 30 ml of Rh (+) blood
20 mcg per ml RBC

47. Prevention standard recommendations
300 mcg dose within 72 hrs of delivery to unsensitized Rh (-) women (Rh positive infant) 13 days , 28 days
300 mcg at 28 weeks UNLESS father known to be Rh (-)
Repeat Antibody Screen before giving the prophylactic dose?

48. Indications for administration of anti-(D) immune globulin
At 28 weeks of gestation
Spontaneous abortion, threatened abortion, induced abortion
Ectopic pregnancy
Invasive procedures: genetic amniocentesis; chorionic
villus sampling; multi-fetal reduction; fetal blood sampling
Hydatidiform mole

49. Fetal death in the second or third trimester
Blunt trauma to the abdomen
Antepartum hemorrhage in the second or third trimester (eg, placenta previa or abruption)
External cephalic version

50. Prevention
Test for excessive fetal-maternal hemorrhage after blunt trauma, abruption, cordocentesis, and bleeding assoc. with previa
Kleihauer Betke

51. Thank you