RH Isoimmunization Flashcards
Rh (Rhesus group D antigen): antigens called C, D, and E. if the Rh factor D antigen is present on the cells, the person is Rh ____. If there is no Rh factor antigen, the person is rH____
Rh (Rhesus group D antigen): antigens called C, D, and E. if the Rh factor D antigen is present on the cells, the person is Rh +. If there is no Rh factor antigen, the person is rH-
how is rH factor genetically determine?
its dominant
+/+: rh positive, +/-: rH positive , -/-: rh negative.
Rh positivity is more common in basques and north american caucasians
Overall, 10% of all pregnancies are rh incompatible.
WHEN RHOGAM SHOULD BE GIVEN
1st and 2nd Trimester: __, __, __, __
___ weeks: routine prophylaxis after screening for antibodies
3rd trimester: __, __, ___
Post partum: within 72 hours if baby is rH ___.
1st and 2nd Trimester: bleeding, abortion, CVS, amniocentesis
28 weeks: routine prophylaxis after screening for antibodies
3rd trimester: bleeding, abruption, ECV
Post partum: within 72 hours if baby is rH positive.
T/F give rhogam to rH positive woman
false. only rh negative women
describe RH Sensitization
Fetal RBCs can enter maternal circulation (mom is rh -), and maternal antibody production is stimulated against the RH antigen.
Usually the first baby is not affected, but antibodies will be present for the second pregnancy, causing hemolytic disease.
key symptom at birth that indicates hemolytic disease of the fetus
Often presents with severe jaundice in the neonatal period due to hemolysis.
risk factors for signigicant fetal maternal bleed
Asymptomatic transplacental passage of fetal red blood cells (RBCs), happens more with advancing gestation (and delivery).
Risk factors for significant fetal maternal bleed: C-section, antepartum bleed (abruption, bleeding previa), manual removal of placenta, intrauterine manipulation (external cephalic version)
FMB can also occur at the time of aboriton (spontaneous and therapeutic), ectopic pregnancy, and amniocentesis or CVS.
In an rH negative patient that is sensitized after critical tire, you can continue to monitor through:
Ultrasound of middle cerebral artery of the fetus to detect hydrops
If ultrasound suggests that the baby is at risk of severe anemia, the next step is:
fetal blood sampling from the umbilical cord: measure the hematocrit and do a possible transfusion if the fetus is anemic.
If the baby is close to term, delivery rather than transfusion may be indicated.
Pediatric Surveillance from Birth
Cord blood bilirubin and hematocrit
Phototherapy
Exchange transfusion if severe
Top-up transfusions are frequently needed→ follow the hematocrit level!
Managing a sensitized patient:
Managing sensitized patient: Rhogam is ___ in preventing
hemolytic disease of the fetus when the mother is already sensitized
o Determine partners blood type (including if heterozygous or
homozygous +ve)
o Determine fetal blood type (if father is heterozygous):
amniocentesis, cell free DNA
o If the fetus is at risk_, do __ t___itres at monthly intervals
(until 28wks and then q2wk)_
§ Once critical threshold crossed (1:16), now you must
monitor fetus for development of __
o Monitor: ultrasound (to detect hydrops), amniocentesis (can assess degree of hemolysis) +/- fetal blood sampling (fetal hematocrit measurement for anemia)
§ If the baby is anemic, fetus needs a __
• Pediatric Surveillance: cord blood __/__, phototherapy, exchange transfusion if
severe
Managing sensitized patient: Rhogam is ineffective in preventing
hemolytic disease of the fetus when the mother is already sensitized
o Determine partners blood type (including if heterozygous or
homozygous +ve)
o Determine fetal blood type (if father is heterozygous):
amniocentesis, cell free DNA
o If the fetus is at risk_, do antibody titres at monthly intervals
(until 28wks and then q2wk)_
§ Once critical threshold crossed (1:16), now you must
monitor fetus for development of anemia
o Monitor: ultrasound (to detect hydrops), amniocentesis (can assess degree of hemolysis) +/- fetal blood sampling (fetal hematocrit measurement for anemia)
§ If the baby is anemic, fetus needs a transfusion
• Pediatric Surveillance: cord blood bilirubin/hematocrit, phototherapy, exchange transfusion if
severe
