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OD450 in zone 3

Queenan Curve
The main limitation of the Liley's curve is that it starts at 26 weeks of gestation and extrapolation of the lines to earlier gestational ages is inaccurate. Queenan have developed a curve for fetal assessment from 14 to 40 weeks, divided into 4 zones.


  1. IUT: Fresh O-negative blood is given to the fetus by doing a cordocentesis. The amount of blood required to be transfused is calculated by various formulas depending upon fetal Hct and donor Hct.
  2. Nicolaides and coworkers recommend that transfusions be commenced when the hemoglobin is at least 2 g/ dl below the mean normal fetuses of corresponding gestational age. Other clinicians perform transfusions when the fetal Hct is below 30%, which is 2 standard deviations below the mean at all gestational ages.

Middle cerebral artery Doppler

Fetal anemia can be predicted noninvasively using middle cerebral artery Doppler. The anemic fetus shunts blood preferentially to the brain to maintain adequate oxygenation. This response can be identified by measuring PSV in the middle cerebral artery. Nowadays this method is preferred over amniocentesis. If the above the cutoff (more than 1.5 MOM) IUT is recommended depending upon the weeks of gestation.

Kell Sensitization

  1. As with COE antigens, Kell sensitization also can occur as a result of the maternal-fetal incompatibility. Maternal Kell sensitization is different from D-sensitization because anti-Kell antibodies also attach to fetal erythrocyte precursor cells directly in the bone marrow, thus preventing a hemopoietic response to anemia. This process can cause a more rapid and severe anemia than with anti-Desensitization. Because fewer erythrocytes are produced, there is less hemolysis and less amniotic fluid bilirubin. As a result, severe anemia may not be predicted by either the maternal anti-Kell titer or the level of amniotic fluid bilirubin.
  2. Because of this disparate severity of Kell sensitization, some investigators recommend evaluation when the maternal anti-Kell titer is 1:8 or greater. In addition, the initial evaluation should be accomplished by cordocentesis instead of amniocentesis, because fetal anemia from Kell sensitization is usually more severe than indicated by the amniotic fluid bilirubin level.

Kleihauer-Betke (KB) Test (Acid Elution Test)

  1. Principle: HbF is more resistant to acid elution than HbA.
  2. Acid will elute the adult hemoglobins but not the fetal haemoglobin from the red cells. Hence the fetal red cells appear stained dark red, unlike the light coloured maternal red cells or ghost cells.
  3. The number of fetal red cells in 50 low power fields is assessed.
  4. If there are 80 fetal red cells in 50 low power fields, it represents a fetomaternal bleed of 4 ml of fetal blood.
  5. 100 μg of anti-D will neutralize 4 ml of fetomaternal bleed.
  6. If FMH >30ml the dose of anti-D is calculated as 10μg for every 1 ml of fetal whole blood.

Using basic physiological principles, the amount of fetal hemorrhage may be calculated form the results of a Kleihauer-Betke (KB) stain using the formula:



where MBV = maternal blood volume (about 5000 mL in normal-sized normotensive women at term) and Hct = hematocrit.



It is an IgG antibody that is given by i.m. route.


It binds to fetal RBCs so that they cannot stimulate the maternal immune system

  1. 300 pg will protect the mother from fetal hemorrhage of up to 15 mL of D-positive red cells or 30 mL of fetal whole blood.
  2. It should be given at 28 weeks to all unsensitized Rh-negative mother and postpartum within 72 h if the baby's blood group is Rh positive.
  3. It should also be given after abortion, MTP, and ectopic pregnancy.

Indications and Recommended Dose of Anti, D



Recommended Dose (μg)

First trimester abortion/MTP


First trimester ectopic pregnancy


Second trimester abortion/MTP


Second trimester amniocentesis


Prophylaxis at 28 weeks


After delivery


Follow diagram of management of Rh negative non immunized mother:



Follow diagram of management of Rh negative immunized mother (First affected pregnancy):



Follow diagram of management of Rh negative immunized mother (Multiple affected pregnancy)


Causes of Nonimmune Hydrops Fetalis (NIHF) and Associated Clinical Conditions









Urethral stenosis or atresia


Congenital heart block


Posterior neck obstruction


Anatomical defects (ASD/VSD, TOF,


Prune belly


hypoplastic left heart, pulmonary valve




insufficiency, Ebstein subaortic stenosis,




and single ventricle)




Trisomies, Turner syndrome, and triploidy


Jejunal atresia




Midgut volvulus




Malrotation of intestines




Duplication of intestinal tract




Meconium peritonitis


Thanatophoric dwarfism


Antepartum indomethacin (taken


Arthrogryposis multiplex congenital


to stop preterm labor, causing fetal


Osteogenesis imperfecta


ductus closure and secondary




nonimmune hydrops fetalis)


α-Thalassemia = MC cause of








Arteriovenous shunts (vascular tumors)








Kasabach-Merritt syndrome



Twin pregnancy

Twin-twin transfusion syndrome




Acardiac twin syndrome




Diaphragmatic hernia


Amniotic band syndrome


Cystic adenomatous malformation


Cystic hygroma


Pulmonary hypoplasia


Congenital lymphedema




Congenital neuroblastoma




Tuberous sclerosis




Sacrococcygeal teratoma

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