Alloimmunization Flashcards
when can transplacental hemorrhage of fetal Rh-positive red blood cells into circulation of Rh-negative mother occur?
following a number of obstetric procedures and complications, such as amniocentesis, chorionic villus sampling, spontaneous/threatened abortion, ectopic pregnancy, dilation and evacuation, placental abruption, antepartum hemorrhage, preeclampsia, Cesarean delivery, manual removal of placenta and external version
What is ABO incompatibility?
immune system response that occurs when blood from two different and incompatible blood types are mixed together
What is the risk of isoimmunization?
2% antepartum, 7% after full term delivery and 7% with subsequent pregnancy, so less than 20% total
What is a method for noninvasive diagnosis of fetal anemia?
doppler ultrasonography; use of middle cerebral artery peak systolic velocity in the management of fetuses at risk for anemia because of red cell alloimmunization has emerged as the best test for the noninvasive diagnosis of fetal anemia
What on fetal ultrasound can be explained by Rh disease?
fetal hydrops is easily diagnosed on ultrasound and develops in the presence of decreased hepatic protein production; it is defined as collection of fluid in two or more body cavities, such as ascites, pericardial and/or pleural fluid and scalp edema; on occasion when extramedullary hematopoiesis is extensive, there will be evidence of hepatosplenomegaly
what amount of fetal blood is neutralized by 300mcg dose of RhoGAM?
30cc fetal blood, this is equivalent to 15cc of fetal red blood cells
What are Lewis antibodies?
IgM antibodies that do not gross the placenta, therefore are not associated with isosensitization or hemolytic disease in fetus
What is the mnemonic device for risk posed by atypical antibodies?
“Lewis Lives, Duffy Dies, and Kell Kills”
What color is the amniotic fluid in presence of severely erythroblastic fetus and why?
fluid is stained yellow; yellow pigment is bilirubin, which can be quantified by spectrophotometric measurements
What test can be used to quantitate volume of fetomaternal hemorrhage?
Kleihauer-Betke test
