SUCCESS! In Clinical Laboratory Science - Immunohematology: Hemolytic Disease (Hemolytic Disease of the Newborn, Immune Hemolytic Anemia)

A neonate with a positive direct antiglobulin test (DAT) indicates that there was an incompatibility between a mother and her fetus. The system that is most commonly associated with an incompatibility is A. ABO B. Rh C. Kell D. Kidd

A. ABO A. Although the ABO system is most often implicated in fetomaternal incompatibilities, it very rarely causes clinical symptoms. ABO-HDN generally occurs when group O mothers have group A or B children. Although Rh-HDN can be prevented, there is no prevention for ABO-HDN, and generally there is none needed because exchange transfusion is rarely necessary.

A patient being treated with alpha-methyldopa has a 4+ DAT result. You would expect an eluate from his red cells to react most likely with A. All the untreated panel cells tested B. Just the untreated D-positive cells tested C. All panel cells treated with a-methyldopa D. All panel cells when a-methyldopa is added to the eluate

A. All the untreated panel cells tested A. The drug a-methyldopa (Aldomet®), a blood pressure medication that is no longer frequently used, induces autoantibody formation that is indistinguishable from antibody produced in WAIHA. The antibody produced usually reacts with all panel cells tested. Some of the other drugs that induce autoantibody formation are L-dopa, procainamide, and some nonsteroidal anti-inflammatory drugs.

Which of the following is not considered a useful predictor of hemolytic disease of the newborn (HDN) during the gestational period? A. Anti-A B. Anti-D C. Anti-Fya D. Anti-U

A. Anti-A A. Prenatal testing for all pregnant women should include ABO, Rh, and antibody screening to exclude the presence of unexpected antibodies with the potential for causing hemolytic disease of the newborn (HDN). The presence of an unexpected antibody does not indicate that the infant will be affected. Testing the red blood cells of the father, to determine whether the corresponding antigen is expressed and, if so, whether he is a homozygote or heterozygote, should indicate the probability for the presence of the antigen on infant cells. ABO-HDN is not predictable until postpaitum, when the blood type of the infant is determined.

An antibody screen was performed on a 25- year-old male referred to the hospital for elective surgery. Refer to the gel reactions below seen in an antibody screen test. (SC = screening cell, AC = autocontrol) SCI = Diffused throughout SCII = button at bottom SC III = Button at bottom What has happened to the matrix in SC I that caused a difference in its appearance from that of SCII? A. Antibody-coated cells have been trapped in the gel matrix of SC I. B. A too heavy red cell suspension was used in SC I; correct suspensions were used in SCII and AC. C. Hemolysis is occurring in SC I, but not in SCII or AC. D. SC II shows a mixed-field reaction.

A. Antibody-coated cells have been trapped in the gel matrix of SC I. A. When centrifuged, unagglutinated cells, like those in SC II, fall completely through the gel matrix and form a pellet at the bottom of the microtube. The agglutinated cells in SC I have been trapped in the gel according to the size of the agglutinates. The gel matrix is porous and will suspend antigen-antibody agglutinates in the gel when they are too large to fall further through the matrix.

A 64-year-old female is seen in the emergency department with a hemoglobin value of 8.9 g/dL. The resident sends down a request for 2 units of packed red cells. She types as group O, D-positive using monoclonal antisera. Her ABO group and Rh type match previous records. She has not been transfused in the past 5 years. However, her antibody screen produces the following results: -SCI/SCII/SC III/Auto-control IS: 0 / 0 / 0 / 0 37 C LISS: 0 / 0 / 0 / 0 AHG: 4 + / 4 + / 4 + / 4 + CC: NT* / NT / NT / NT *NT = not tested To demonstrate whether the antibody(ies) has/have become attached this patient's red blood cells in vivo, which of the following tests would be most useful? A. Direct antiglobulin test B. Complement fixation test C. Elution procedure D. Indirect antiglobulin test

A. Direct antiglobulin test A. The direct antiglobulin test (DAT) is the easiest and the quickest wayto detect in vivo sensitization of red blood cells. The indirect antiglobulin test is used to detect in vitro sensitization of red blood cells and is most commonly used in antibody detection tests and crossmatching. Uses of the direct antiglobulin test include investigation of hemolytic disease of the newborn, autoimmune hemolytic anemia, transfusion reactions, and drug-induced sensitization of red blood cells.

The serum and eluate from a male patient with a 3+ DAT on a-methyldopa therapy demonstrates anti-e specificity. The patient denies knowledge of having received blood transfusions. To determine whether the anti-e is an auto- or alloantibody, one should A. Type the patient's red cells with a low protein anti-e reagent B. Adsorb the serum with the patient's red cells C. Adsorb the eluate with R2R2 red cells D. Adsorb the eluate with rr red cells

A. Type the patient's red cells with a low protein anti-e reagent A. Autoantibodies are directed against antigens present on the patient's own red blood cells. The easiest way to determine whether the anti-e is auto or allo when the patient has not been recently transfused is to type the patient's red cells with a low-protein anti-e reagent. A high-protein reagent should not be used, since a false positive reaction is likely to occur. The preparation of an eluate when patients have no history of recent transfusion is not necessary; it is presumed that the eluate contains only autoantibody.

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Female D-negative; miscarriage at 11 weeks A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

A. Yes, 50-ug dose A. Whenever doubt exists as to the weak D status of the infant or the origin of the anti-D, postpartum RhIG should be administered. . The 50-ug dose of RhIG is used only when a female of 12-weeks gestation or less suffers a miscarriage.

Which of the following antibodies present in a multitransfused obstetric patient would be most likely to cause HDN in her infant? A. Anti-Lea B. Anti-c C. Anti-Pj D. Anti-K

B. Anti-c B. Neither anti-P, nor anti-Lea is likely to cause HDN. They are almost exclusively IgM antibodies (cannot cross the placenta), and the corresponding antigens are not well developed on neonatal red blood cells. Both anti-K and anti-c are almost exclusively IgG antibodies and are capable of causing serious HDN. However, the K antigen has a much lower frequency (<10%) in the population than the c antigen (>80%), so the infant is much more likely to be c+.

A 64-year-old female is seen in the emergency department with a hemoglobin value of 8.9 g/dL. The resident sends down a request for 2 units of packed red cells. She types as group O, D-positive using monoclonal antisera. Her ABO group and Rh type match previous records. She has not been transfused in the past 5 years. However, her antibody screen produces the following results: -SCI/SCII/SC III/Auto-control IS: 0 / 0 / 0 / 0 37 C LISS: 0 / 0 / 0 / 0 AHG: 4 + / 4 + / 4 + / 4 + CC: NT* / NT / NT / NT *NT = not tested How would you identify the antibody(ies) on this woman's cells? A. Autoabsorption followed by a panel on the absorbed serum B. Elution followed by a panel on the eluate C. Enzyme-treated panel on her serum D. Perform a panel on the serum

B. Elution followed by a panel on the eluate B. The only method that can be used to identify an antibody coating red blood cells is to perform an elution on those cells and then test the eluate against a panel. Autoabsorption of the patient's serum and then a panel on the autoabsorbed serum would be the method of choice for the identification of alloantibodies in her serum because she has not been recently transfused. Any panel on her serum would simply react with all panel cells tested because of the presence of the autoantibody.

Which two of the following conditions are the most serious immediate consequences of HDN? A. Anemia and a positive DAT B. Hyperbilirubinemia and anemia C. Hyperbilirubinemia and j aundice D. Hyperbilirubinemia and kernicterus

B. Hyperbilirubinemia and anemia B. During the first few hours of life, the primary risk to a baby with hemolytic disease of the newborn is heart failure caused by severe anemia. After the first 24 hours, in which the anemia can be compensated, the highest risk to the infant comes from hyperbilirubinemia. Kernicterus, which is brought on by hyperbilirubinemia (generally >18 mg/dL of unconjugated bilirubin) in a full-term infant in the first days of life, can cause irreversible brain damage. Depending on the severity of the hyperbilirubinemia, one or more exchange transfusions may be needed.

A patient with WAIHA has a history of an anti-Jka in her autoabsorbed serum, and an anti-e in her eluate. Her autoabsorbed serum today is not showing anti-Jka on prewarmed panel, but the eluate is still showing anti-e. What blood would be selected for crossmatching packed red cells today? A. e-Negative B. Jk(a-) C. Jk(a-) and e-negative D. No screening is necessary because all transfused cells will be destroyed anyway.

B. Jk(a-) B. A patient with a history of having had anti-Jka in her serum must always be given Jk(a-) blood. Anti-Jka in the plasma often drops to below detectable levels of antibody in the absence of stimulus. However, if Jk(a+) cells were to be given to the patient, the antibody would quickly rebound to high levels and cause a delayed hemolytic transfusion reaction. It is difficult to procure e negative blood because -80% of the population is e+. Add that to the need for Jk(a-) blood and the likelihood of finding suitable units drops. It is much more important to avoid transfusing against the alloantibody, anti-Jka, than the autoantibody. The autoantibody will destroy transfused cells at the same rate it is destroying the patient's RBCs; however, the alloantibody will destroy the transfused cells more rapidly

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother D-negative with anti-Fya; infant D-positive A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

B. Yes, 300-ug dose B. . The presence of antibodies other than anti-D in the pre- or postpartum serum does not preclude a D-negative woman from receiving RhIG.

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother D-negative, with anti-D, titer 2, history of RhIG injection postamniocentesis procedure at 30 weeks; infant Dpositive A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

B. Yes, 300-ug dose B. Most obstetricians routinely inject RhIG at 28 weeks antenatally to prevent sensitization during a third-trimester fetal bleed. This injected anti-D is sometimes detectable postpartum and does not preclude additional administration of RhIG at childbirth

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother D-negative; infant weak D A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

B. Yes, 300-ug dose B. Mothers who are not candidates to receive Rh immune globulin (RhIG) are (1) D-positive, (2) D-negative giving birth to a D-negative infant, or (3) D-negative who have produced alloanti-D. For purposes of determining RhIG candidacy, the weak D phenotype is considered to be D-positive

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother D-negative; twin #1 D-negative, twin #2 D-positive A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

B. Yes, 300-ug dose B. When only one of the infants in a multiple birth is D-positive and the other(s) is (are) D-negative, the mother is a candidate for RhIG

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother group O, D-negative; infant group A, DAT = 2+, monoclonal antiD-negative at immediate spin, weak D test not performed A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

B. Yes, 300-ug dose B. When the infant's red cells are DAT+, it may be difficult to determine the correct Rh status. Because RhIG is a low-risk product, experts recommend a fail-safe approach and give RhIG when in doubt.

An antibody screen was performed on a 25- year-old male referred to the hospital for elective surgery. Refer to the gel reactions below seen in an antibody screen test. (SC = screening cell, AC = autocontrol) SCI = Diffused throughout SCII = button at bottom SC III = Button at bottom Which of the following is the correct interpretation of the reaction in SC I? A. 0 B. 1 + C. 2+ D. 3 +

C. 2+ C. The reaction in screening cell I is 2+. This reaction is characterized by the presence of some agglutinates in the bottom of the gel microtube along with antigen-antibody complexes that are distributed throughout the gel. The 2+ reaction represents agglutinates of many different sizes. This is different than a 1+ reaction in which all of the agglutinates are confined to the lower half of the gel microtube. Larger agglutinates are trapped at the top of the gel, and the smaller the agglutinates, the further they fall through the matrix.

A Kleihauer-Betke acid elution stain for postpartum fetomaternal hemorrhage (FMH) is reported to be 1.3%. With this amount of FMH, how many vials of a standard dose of RhIG should be administered to the mother within 72 hours of childbirth? (Presume the infant to be D-positive.) A. 1 B. 2 C. 3 D. 4

C. 3 C. One standard dose of Rh immune globulin (300 (jg) protects the mother from a 30-mL bleed. Because the precision of a KleihauerBetke stain is poor, a margin of safety is employed to prevent RhIG prophylaxis failure. The total bleed in milliliters is divided by the level of protection in one dose (30 mL). For decimals less than five, round down and add one dose (e.g., 2.3 rounds down to 2 + 1 dose = 3 vials total dose); for decimals five or greater, round up and add one dose (e.g., 2.6 rounds up to 3 + 1 dose = 4 vials total dose). 65 mL bleed / 30 mL = 2.2; give 3 vials RhIG

A patient has a 2+mf DAT with anti-IgG. He was transfused 1 week ago with 2 units of RBCs during surgery. His eluate would most likely contain A. No antibody B. Autoantibody C. Alloantibody D. Drug-related antibody

C. Alloantibody C. When a patient has been recently transfused, a mixed-field positive DAT may indicate the presence of clinically significant alloantibody attached to circulating donor's cells. A positive DAT may also reflect autoantibody attached to patient's ordonor's csells, either because of drug sensitivity or secondary to clinical disease, which i less likely in this case. It is important to obtain information, including diagnosis, clinical condition, medication history, and laboratory data such as hematocrit, bilirubin, haptoglobin, and reticulocyte count, both pre- and posttransfusion to determine whether a delayed hemolytic transfusion reaction (DHTR) has occurred. A DHTR commonly demonstrates a mixed-field DAT result.

Which of the following would not be included when routine testing is performed early in a pregnancy? A. ABO and Rh testing B. Antibody screening C. Amniocentesis D. Weak D testing on apparent Rh negative patients

C. Amniocentesis C. ABO testing, Rh testing (for weak D when applicable), and antibody screening should all be performed early in a pregnancy. Amniocentesis should be done only when clinically indicated. Furthermore, amniocentesis generally is not done before the third trimester, although in recent years the procedure has been done as early as 14 weeks.

If a patient's red blood cells are DAT+ due to penicillin antibody, the A. Serum will react if penicillin is added to the test system B. Serum will react with all red cells C. Eluate will react with penicillin-coated red cells D. Eluate will react with all red cell

C. Eluate will react with penicillin-coated red cells C. Antibody directed against drugs may be suspected if patients present a positive DAT with a nonproductive eluate. The eluate and serum antibody may demonstrate reactivity only with reagent red cells coated with the appropriate drug and not with uncoated red cells. A current medication history and demonstration of eluate reactivity against the appropriate drug-coated red cells confirm the cause of the positive DAT. Drug-related antibodies are seldom clinically significant, and elaborate testing usually is not performed unless the patient shows symptoms of active hemolysis.

What is the most important consideration in patients suffering from life-threatening anemia and whose serum contains warm autoantibodies? A. Determine the specificity of the autoantibody. B. Determine the immunoglobulin class of the autoantibody. C. Exclude the presence of alloantibody(ies). D. Avoid transfusion

C. Exclude the presence of alloantibody(ies). C. Although it is best to avoid transfusing patients with warm autoantibodies, life-threatening anemia may develop, which necessitates them to receive blood. The primary concern in patients demonstrating serum warm autoantibody is to detect and identify the presence of underlying alloantibodies that may be masked by the reactions of the autoantibody. One must be certain to differentiate between auto- and alloantibodies. If the autoantibody appears to have a simple specificity such as anti-e, alloantibody identification can be accomplished by testing reagent red cells that are e-negative and antigen positive for the alloantibodies to be excluded. Alternatively, when sufficient e-negative panel cells are not available to do a thorough rule out, warm autoadsorption of the serum with the untransfused patient's red cells will remove autoantibody but not alloantibody. Alloantibodies will cause the transfused RBCs carrying the corresponding antigen to be removed from the recipient's circulation even more rapidly than the patient's own RBCs and will not provide the oxygen-carrying capacity the patient requires.

If during a Donath-Landsteiner test there is hemolysis in both the test and control tubes at the conclusion of the test, this indicates that the test is A. Positive B. Negative C. Invalid D. False negative

C. Invalid C. The Donath-Landsteiner (D-L) test is a diagnostic test for PCH. A characteristic of the antibody involved is that it will bind to red blood cells at cold temperatures; at 37°C it will cause red blood cell lysis. In the D-L test, a tube with the patient's serum and test cells is incubated at 4°C whereas a control tube is incubated at 37°C. After the 4°C incubation, the tube is placed in the 37°C incubator. After incubation, the tubes are centrifuged and examined for hemolysis. If there is hemolysis noted in the test and none in the control, the test is positive. If no hemolysis is noted in either tube, the test is negative, and if hemolysis is present in both tubes, the test is invalid.

In which of the following blood group systems may the red blood cell typing change during pregnancy? A. P B. MNS C. Lewis D. Duffy

C. Lewis C. The Lewis typings of a pregnant woman may appear to be Le(a-b-), even though the original typing may have been Le(a-b+). When women are pregnant, they have an increased plasma volume and increased amount of lipoprotein in relation to red blood cell mass. Because Lewis antigens are adsorbed onto red cells and lipoprotein from plasma, the dilutional effect and greater lipoprotein mass would lead to less adsorption of Leb onto red cells. After the pregnancy, the woman will return to her original type.

A newborn is group O, D-positive and has a 3+ DAT. The mother's antibody screening test is negative. Assuming the antibody detection test is valid, one should consider HDN due to an antibody directed against A. Fyb antigen B. K antigen C. Low-incidence antigen D. A or B antigen

C. Low-incidence antigen C. Given that all prenatal and neonatal testing is valid, one should consider an antibody against a low-incidence antigen. The low incidence antigen was of paternal origin, and it stimulated the mother to form an IgG antibody. To prove this theory, an eluate from the baby's cells should be tested with the father's cells. Also, the mother's serum and the baby's eluate could be tested with a panel of cells positive for various low-incidence antigens to identify the specificity of the antibody.

A D-negative woman who received antepartum RhIG gave birth to a Dpositive infant and received one vial of RhIG the same day. Because of postpartum hemorrhage, her physician ordered two units of RBCs for her 2 days later. The antibody screening test was positive, but the crossmatches were both compatible. The most likely cause for the positive antibody screening test was the presence of a(an) A. Clinically significant anti-K B. Actively acquired anti-D C. Passively acquired anti-D D. Rh antibody other than anti-D

C. Passively acquired anti-D C. The most likely cause for the positive antibody screening test is the presence of a passively acquired anti-D. Because the mother received antepartum Rh immune globulin (RhIG), anti-D from that injection may still be present at childbirth. Depending on how the RhIG was injected postpartum, the anti-D could already be present in the patient's serum. Because antepartum RhIG was given, it is unlikely that active immunization has occurred. Passively acquired anti-D rarely has an antiglobulin titer above 4 and should be entirely IgG. When in doubt about whether anti-D is passive or represents active immunization, it is always better to administer RhIG at the appropriate time. The crossmatches are compatible because D-negative RBCs would have been chosen for transfusion.

A patient with drug-induced hemolytic anemia has the following DAT results: Poly specific AHG =3+ Anti-IgG =3+ Anti-C3d = 0 Which of the following drugs is most likely to be the cause? A. Phenacetin B. Quinidine C. Penicillin D. Tolmetin

C. Penicillin C. Of the drugs listed, only penicillin has the observed DAT profile. IgG alone is also generally seen when a-methyldopa and cephalosporins are the implicated drugs. When phenacetin, quinidine, and tolmetin are the drugs in question, only C3 (complement) is usually detected on the patient's red cells. Antibody in the patient's serum and/or eluate will not react with reagent red cells unless the RBCs are first treated with penicillin. This occurs because the antibody produced by the patient reacts with epitopes formed by the penicillin coating the RBCs.

A 64-year-old female is seen in the emergency department with a hemoglobin value of 8.9 g/dL. The resident sends down a request for 2 units of packed red cells. She types as group O, D-positive using monoclonal antisera. Her ABO group and Rh type match previous records. She has not been transfused in the past 5 years. However, her antibody screen produces the following results: -SCI/SCII/SC III/Auto-control IS: 0 / 0 / 0 / 0 37 C LISS: 0 / 0 / 0 / 0 AHG: 4 + / 4 + / 4 + / 4 + CC: NT* / NT / NT / NT *NT = not tested What is the best treatment for this woman's anemia? A. Transfusion with packed red cells B. Infusion of fresh-frozen plasma C. Steroid administration D. Plasma exchange

C. Steroid administration C. Most patients having warm autoimmune hemolytic anemia (WAIHA) respond well to steroids, which decrease the autoantibody production. Transfusing these individuals usually will cause the autoantibody to be produced in greater amounts. Transfusion in these cases isoften counterproductive because the donor cells are destroyed as quickly as the patient's own cells and the expected increment in hemoglobin from the transfusion does not occur. Because this woman needs more oxygen-carrying capacity, transfusion with FFP will not be of help to her. Plasma exchange may remove antibody from her circulation but will not provide any oxygen-carrying capacity.

The cord blood of an infant of a D negative mother with anti-D, titer 2048, is submitted to the laboratory along with a sample of maternal blood with a request to select blood for possible exchange transfusion. The neonate appears to be D-negative. The weak D status cannot be determined because the DAT result is positive (4+). What is the most likely explanation for this? A. Wharton's jelly contaminated the sample. B. The baby has ABO HDN. C. The baby has a "blocked D" antigen. D. A different antibody is causing the positive DAT

C. The baby has a "blocked D" antigen. C. When D+ red blood cells are sufficiently coated with antibody, leaving no or few remaining sites to react with D antiserum, the cells are referred to as having a "blocked D" and may react weakly or not at all with a low-protein anti-D reagent. One may suspect this phenomenon, confirmed by elution of anti-D from the red cells, when the DAT is strongly positive. Enough antibody may be removed either with a gentle heat elution (45 °C) or using chloroquine diphosphate to permit accurate D typing of the coated red cells

How is cold hemagglutinin disease (CHD) different from paroxysmal cold hemoglobinuria (PCH)? A. PCH is a common form of cold autoimmune anemia whereas CHD is rare. B. PCH is a warm autoimmune hemolytic anemia. C. The offending antibody in PCH is an IgG antibody unlike the IgM antibody in CHD. D. The offending antibody in PCH is an IgM antibody while an IgG antibody is common in CHD.

C. The offending antibody in PCH is an IgG antibody unlike the IgM antibody in CHD C. Paroxysmal cold hemoglobinuria (PCH) isthe rarest form of cold autoimmune hemolytic anemia. It is characterized by an IgG antibody that usually exhibits anti-P specificity. The antiP attaches to the RBC during exposure to cold and then activates complement when the patient rewarms, causing hemolysis. A diagnostic test used to aid in the identification of PCH is the Donath-Landsteiner test. CHD is usually caused by anti-I, which is IgM.

A patient has a positive DAT due to cephalosporin therapy and a negative antibody screening test result. Two units of RBCs have been ordered. In order to crossmatch this patient, one should crossmatch with A. The eluate from the patient's red cells and donor cells B. Autoadsorbed patient's serum and untreated donor cells C. Untreated patient's serum and untreated donor cells D. Cephalosporin-treated donor cells and untreated patient's serum

C. Untreated patient's serum and untreated donor cells C. Cephalosporin antibodies will generally not react with red blood cells unless the RBCs have been treated with the drug. The negative antibody screening test indicates that crossmatches will be similarly compatible. An eluate from the patient's red cells would be expected to be nonreactive with untreated RBCs as well. An eluate would not be prepared unless the patient had been recently transfused and a DHTR was suspected.

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother D-negative; infant D-positive; rosette test = 1—2 rosettes per field A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

C. Yes, additional testing necessary to determine dose. C. The preferred method for determining fetomaternal hemorrhage (FMH) is the rosette test, which is more sensitive than a microscopic weak D test. The rosette test will detect FMH of >10 mL. A positive test would show one or more rosettes per field when an enhancing medium is used. Additional testing must be performed to quantify the amount of FMH to prevent sensitization to the D antigen. The Kleihauer-Betke acid elution stain is the standard technique available to determine whether a bleed of more than 15 mL red cells (30 mL whole blood) occurred, necessitating additional 300-ug doses beyond the standard one-vial dose.

A Kleihauer-Betke acid elution stain for postpartum fetomaternal hemorrhage (FMH) is reported to be 1.3%. What is the total volume of FMH? A. 6.5 mL B. 13mL C. 26 mL D. 65 mL

D. 65 mL D. The Kleihauer-Betke acid elution stain is used to estimate the amount of fetal red blood cells present in the circulation of a D-negativemother postpartum. Failure to quantify the FMH may result in the administration of insufficient Rh immune globulin. Sensitization to the Rh antigen may occur, leading to HDN in subsequent pregnancies. The fetal bleed is calculated using the formula: KB% X 50 = milliliters fetal blood present or 1.3 X 50 = 65 mL.

What is the principle of the Kleihauer Betke stain? A. Fetal hemoglobin is more resistant to alkaline buffer than adult hemoglobin. B. Adult hemoglobin is more resistant to alkaline buffer than fetal hemoglobin. C. Fetal hemoglobin is more resistant to erythrosin and hematoxylin staining than adult hemoglobin. D. Adult hemoglobin is more soluble in acid buffer than fetal hemoglobin

D. Adult hemoglobin is more soluble in acid buffer than fetal hemoglobin D. The Kleihauer-Betke acid elution stain is used to quantify the amount of fetal cells present in the maternal circulation postpartum to calculate the correct dose of RhIG to administer. Adult hemoglobin is soluble in acid buffer, whereas fetal hemoglobin is resistant to acid elution. A thin blood smear is subjected to acid elution, pH 3.2, and then is stained with erythrosin B and Hams hematoxylin. Normal adult cells appear as pale ghosts microscopically; fetal cells are bright pink. The number of fetal cells in 2000 maternal cells is calculated. The volume of fetal hemorrhage is calculated as follows: (Number of fetal cells/number of maternal cells ) X Material blood volume (estimate 5000m:) = fetal bleed This is equivalent to: Fetal cells expressed as a percentage of maternal cells X 50 = mL of fetal whole blood. One vial of a standard 300-ug dose protects the D-negative mother against sensitization to the D antigen for a 30-mL bleed. Therefore, the fetal hemorrhage volume is divided by 30 to determine the number of vials

A patient's preoperative antibody screening test is negative, but the autocontrol is positive. A DAT performed on his red cells is 2+ with anti-IgG. His last transfusion was 9 months ago, and he has a negative drug history. Which of the following would most likely be present in his eluate? A. No antibody B. Alloantibody C. Alloantibody and autoantibody D. Autoantibody

D. Autoantibody D. Autoantibody(ies) directed against self-antigens may attach to a patient's own red blood cells in vivo, resulting in a positive DAT. A variety of elution techniques can remove this antibody from the red cells for testing. When a patient has not been transfused recently (within 3 to 4 months), it may be presumed that only autoantibody is present in the eluate. If recently transfused, donor's cells may be present in the patient's circulation. Alloantibody may be attached to donor cells, and autoantibody may be attached to patient's or donor's cells. When this is the case, alloantibody and autoantibody both could be recovered in the eluate

A patient with cold hemagglutinin disease (CHD) has a positive DAT when tested with a polyspecific AHG. Which of the following would most likely be detected on her red cells? A. IgM B. IgG C. IgA D. C3

D. C3 D. Although the cold autoagglutinin is generally IgM, complement is usually the only protein detected on the red blood cells. The IgM antibody binds complement at lower temperatures in the extremities (such as fingers exposed to cold temperatures) and then dissociates when the red cells circulate. The polyspecific AHG is not required to have anti-IgM but must have antiIgG and anti-C3d.

A premature infant with hydrops fetalis and a bilirubin of 20 mg/dL is referred to an intensive care unit. The neonatologist wants to perform an exchange transfusion to correct anemia and prevent kernicterus. No blood specimen from the mother is available. The infant's serum has a positive antibody screen. The DAT is 4+. What would be the best approach in this situation? A. Identify the antibody in the serum and crossmatch blood negative for the offending antigen, using the serum in a crossmatch. B. Issue group O, D-negative blood for the exchange. C. Refuse to issue blood for exchange until a sample can be obtained from the mother. D. Identify the antibody in the serum and eluate and crossmatch blood negative for the offending antigen, using both the serum and eluate in a crossmatch

D. Identify the antibody in the serum and eluate and crossmatch blood negative for the offending antigen, using both the serum and eluate in a crossmatch D. A positive DAT on the infant's red blood cells indicates that IgG antibody has crossed the placenta and coated the neonate's red cells. Identification of the antibody in the maternal serum and elution of the same antibody from the infant's red cells confirms the specificity of the offending antibody. In lieu of a maternal blood sample, the identity of the antibody may be confirmed by testing the infant's eluate and serum. The eluate contains the antibody(ies) responsible for the clinical HDN; the serum may contain additional maternal antibody(ies) directed against antigens absent on the infant's cells but present on the donor's cells. Blood compatible with both serum and eluate should be prepared for exchange transfusion

Which is the class of immunoglobulin uniquely associated with hemolytic disease of the newborn (HDN)? A. IgA B. IgD C. IgE D. IgG

D. IgG D. IgG is the only immunoglobulin that is transported across the placenta. It does not cross the placenta because of low molecular weight or simple diffusion, as evidenced by higher concentrations of antibody present in cord than in maternal serum. IgG molecules are actively transported via the Fc portion beginning in the second trimester. Therefore, potentially any IgG blood group antibody produced by the mother could cause HDN, if the fetus possesses a well developed corresponding antigen. The disease varies widely in severity, being dependent on multiple factors

The most conclusive way to demonstrate the antibody that is causing a positive DAT in a newborn is to perform an antibody A. Titration using the mother's serum B. Panel using the mother's serum C. Panel using an eluate from the mother's red cells D. Panel using an eluate from the baby's red cells

D. Panel using an eluate from the baby's red cells D. An antibody panel performed on an eluate made from the baby's red blood cells is the most conclusive way to identify positively the antibody causing the positive DAT. This would be especially helpful in a case where the mother has several antibodies that could cause hemolytic disease of the newborn. However, RBCs for transfusion in the neonatal period should be negative for any antigen corresponding to any IgG antibody that crossed the placenta

Which of the following is not true of an exchange transfusion when an infant is suffering from HDN? A. Removes unconjugated bilirubin B. Reduces the amount of incompatible antibody in the baby's circulation C. Removes antibody-coated red blood cells D. Provides red blood cells of the baby's type

D. Provides red blood cells of the baby's type D. Providing blood of the baby's type is exactly what one does not want to do. This would defeat the purpose of the exchange transfusion. For example, if a D+ infant was suffering from HDN because of an anti-D, the transfusion of D-positive cells would allow transfused cells to be coated with anti-D. The transfused cells would then be removed from the circulation by the RES and would have decreased survival.

The specificity of the antibody in warm autoimmune hemolytic anemia (WAIHA) is most often associated with which of the following blood group systems? A. ABO B. Kell C. Kidd D. Rh

D. Rh D. Most antibodies in WAIHA have specificitythat appears to be directed foward the Rh blood group system antigens. Sometimes the antibody has a simple specificity; anti-e is the most common warm autoantibody of simple specificity. Usually the antibody has a broad specificity, reacting with blood cells of most Rh phenotypes except for rare phenotypes such as Rhnuir In addition, there are mimicking or relative specificities—for example, an apparent auto anti-e that can be adsorbed onto e-negative red cells.

Indicate whether the women are candidates for Rh immune globulin (RhIG) prophylaxis. Assume that D-negative mothers have a negative test for weak D and a nonreactive antibody screening test unless noted: Mother weak D (strong); infant D-positive A. Yes, 50-ug dose B. Yes, 300-ug dose C. Yes, additional testing necessary to determine dose. D. RhIG is not indicated.

D. RhIG is not indicated. D. If the mother is D-negative and has not made anti-D, she must receive RhIG when giving birth to a D-positive or weak D phenotype infant.

A 64-year-old female is seen in the emergency department with a hemoglobin value of 8.9 g/dL. The resident sends down a request for 2 units of packed red cells. She types as group O, D-positive using monoclonal antisera. Her ABO group and Rh type match previous records. She has not been transfused in the past 5 years. However, her antibody screen produces the following results: -SCI/SCII/SC III/Auto-control IS: 0 / 0 / 0 / 0 37 C LISS: 0 / 0 / 0 / 0 AHG: 4 + / 4 + / 4 + / 4 + CC: NT* / NT / NT / NT *NT = not tested What is the most likely cause for these results? A. Polyagglutination B. Rouleaux C. Transfusion reaction D. Warm autoantibody

D. Warm autoantibody D. A positive autocontrol reacting at the antiglobulin phase of testing indicates that the patient has a positive DAT. All screening cells react at the same strength at the same phase of testing as the autocontrol. This indicates the presence of a warm (IgG) autoantibody, both on the patient's cells and in her semm. This patient's serum would be expected to react 4+ at AHG with all cells tested. Polyagglutinable cells will not react in the autocontrol, because the patient will lack the antibody corresponding to the antigen causing the poly agglutination. Rouleaux will not be present in the antiglobulin phase because all of the serum proteins are washed away before the AHG is added. A transfusion reaction may demonstrate a positive autocontrol and/or antibody screen; however, the reaction will be mixed field, because the patient's cells will not react with her alloantibody but the donor cells will react with the patient's antibody

A massive fetomaternal hemorrhage in a D-negative woman who had a D-positive infant should be suspected if the A. Infant is premature B. Infant has a positive acid elution slide test C. Mother requires a transfusion following childbirth D. Weak D test on the maternal blood shows a mixed-field reaction microscopically

D. Weak D test on the maternal blood shows a mixed-field reaction microscopically D. A mixed-field weak D test on maternal blood indicates the presence of D-positive baby cells circulating with the mother's D-negative cells, suggestive of a large fetomatemal hemorrhage. If a mother does demonstrate a positive weak D test when previously it was negative, a KleihauerBetke acid elution test should be done on the mother's red blood cells. This test is used to quantify the amount of the fetal blood that has entered the mother's circulation. The results of the test will determine how many vials of Rh immune globulin should be administered to the patient. One vial will protect against approximately 30 mL of fetal blood (or 15 mL of red cells) that have entered the mother's circulation. A more sensitive method to identify fetomatemal hemorrhage (FMH) than the test for weak D is the rosette test. A maternal red cell suspension is incubated with an anti-D of human source, allowing antibody to coat D+ fetal cells. D+ indicator cells are added that bind to the coated D+ cells, forming rosettes. This is a qualitative test and must also be followed by a quantitative test, such as the Kleihauer-Betke acid elution test.