Rhesus Antigen and Pathophysiology Quiz
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Rhesus Antigen and Pathophysiology Quiz

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Questions and Answers

What is a major consequence of severe anemia in the fetus?

The fetus may die in utero due to heart failure.

What treatment is provided to unsensitized Rh-negative women during pregnancy to prevent Rh incompatibility?

Rh-immune globulin (Rh Ig) 300 mcg is administered between 28-32 weeks gestation.

What factors could lead to the failure of prophylaxis in Rh incompatibility?

Too small a dose or administering the dose later than 72 hours post-delivery.

How does the Indirect Coombs test assist in detecting Rh incompatibility?

<p>It identifies the presence of cell-destroying antibodies in the mother's plasma.</p> Signup and view all the answers

What does a positive Kleihauer-Betke test indicate in terms of fetomaternal hemorrhage?

<p>It determines the percentage of fetal blood cells in the maternal circulation.</p> Signup and view all the answers

What is the significance of measuring bilirubin concentration in amniotic fluid?

<p>It indirectly measures the degree of hemolysis of fetal red blood cells.</p> Signup and view all the answers

During which weeks of gestation are maternal antibody titers recommended to be monitored for sensitized patients?

<p>Titers are repeated every month until 24 weeks and more frequently in the third trimester.</p> Signup and view all the answers

What indication suggests that a fetus in Zone III may require immediate intervention?

<p>Zone III indicates severe disease that may require transfusion or delivery.</p> Signup and view all the answers

What is the main immunogenic Rh antigen responsible for Rh incompatibility and why is it considered significant?

<p>The main immunogenic Rh antigen responsible for incompatibility is the D antigen, significant due to its ability to induce strong immunologic reactions in Rh-negative individuals.</p> Signup and view all the answers

How does the mother’s immune response develop upon exposure to the Rh D antigen during pregnancy?

<p>Upon exposure to the Rh D antigen, an Rh-negative mother perceives it as a foreign threat, activating immune pathways that produce anti-D antibodies.</p> Signup and view all the answers

What factors influence the likelihood of an Rh-negative mother carrying an Rh-positive fetus?

<p>The likelihood depends on the partner's Rh status; if the partner is Rh-positive, there's a 100% chance if homozygous and 50% if heterozygous.</p> Signup and view all the answers

What is hydrops fetalis and what causes it?

<p>Hydrops fetalis is an abnormal accumulation of fluid in fetal tissues and cavities, commonly caused by hemolytic anemia, congenital heart defects, and chromosomal anomalies.</p> Signup and view all the answers

What is the significance of the timing of feto-maternal hemorrhage in relation to Rh incompatibility?

<p>Feto-maternal hemorrhage is only 5% in the first trimester but increases to 47% in the third trimester, influencing primary sensitization risks.</p> Signup and view all the answers

How is the degree of fetal anemia assessed using Doppler ultrasound?

<p>The degree of fetal anemia is assessed by measuring ductus venosus blood flow and the peak systolic velocity of the fetal middle cerebral artery using Doppler ultrasound.</p> Signup and view all the answers

What is hydrops fetalis and how is it related to Rh isoimmunization?

<p>Hydrops fetalis is a severe condition characterized by fetal edema, often resulting from extensive hemolysis caused by maternal anti-D antibodies.</p> Signup and view all the answers

What is the significance of amniocentesis in cases of suspected fetal anemia?

<p>Amniocentesis is significant as it allows for the measurement of bilirubin levels in amniotic fluid, which helps assess the severity of fetal anemia quantitatively using the 'Liley' curve.</p> Signup and view all the answers

Explain the potential outcomes for a fetus if the mother produces anti-D antibodies during pregnancy.

<p>If the mother produces anti-D antibodies, the fetus may experience hemolysis leading to anemia, jaundice, or hydrops fetalis.</p> Signup and view all the answers

What conditions may warrant intrauterine blood transfusion in a preterm fetus?

<p>Intrauterine blood transfusion is warranted for a preterm fetus with significant fetal anemia and evidence of hydrops fetalis, particularly if the mother's blood sample shows Hb &gt;1g/dL.</p> Signup and view all the answers

What role does the placenta play in the transfer of bilirubin in cases of Rh isoimmunization?

<p>The placenta facilitates the transfer of bilirubin from fetal blood to maternal circulation, helping to manage bilirubin levels.</p> Signup and view all the answers

What factors should be considered when preparing blood for exchange transfusion?

<p>For exchange transfusion, the blood must be less than a week old, Rh and ABO compatible with both mother and baby, and tested for CMV and hepatitis viruses.</p> Signup and view all the answers

How can Rh incompatibility be prevented in at-risk pregnancies?

<p>Prevention involves early identification of Rh status and administering Rh immunoglobulin to Rh-negative mothers during and after pregnancy.</p> Signup and view all the answers

What are the treatment options for a sensitized patient with hyperbilirubinemia?

<p>Treatment options include phototherapy for mild jaundice and exchange blood transfusion for moderate to severe jaundice.</p> Signup and view all the answers

What is the role of dexamethasone in the management of preterm fetuses?

<p>Dexamethasone is administered to enhance lung maturity in preterm fetuses, particularly when there are concerns about potential respiratory complications.</p> Signup and view all the answers

What family planning advice should be given to a sensitized mother with high levels of D antibodies?

<p>The sensitized mother should receive advice regarding family planning, especially if the father is homozygous for the Rh gene, as there is a 100% chance of having an Rh positive baby.</p> Signup and view all the answers

What distinguishes immune hydrop fetalis from non-immune hydrop fetalis?

<p>Immune hydrops fetalis is primarily caused by blood group incompatibility, while non-immune hydrops fetalis arises from other medical conditions affecting fluid regulation.</p> Signup and view all the answers

List two potential causes of non-immune hydrops fetalis.

<p>Cardiac defects and fetal anemia are two potential causes of non-immune hydrops fetalis.</p> Signup and view all the answers

What diagnostic methods are commonly used to identify hydrops fetalis?

<p>Ultrasound and fetal blood sampling are commonly used to diagnose hydrops fetalis.</p> Signup and view all the answers

What are the key factors influencing the treatment of hydrops fetalis?

<p>The baby's overall health, gestational age, extent of the disease, and cause of hydrops are key factors in treatment.</p> Signup and view all the answers

Explain the prognosis for babies diagnosed with non-immune hydrops fetalis.

<p>The prognosis is poor, with a perinatal mortality rate greater than 85%, especially for those diagnosed early or with structural abnormalities.</p> Signup and view all the answers

What maternal risks increase due to the presence of hydrops fetalis?

<p>Maternal risks include rapid onset or unusual types of preeclampsia and postpartum hemorrhage.</p> Signup and view all the answers

Name two symptoms that a newborn with hydrops fetalis might exhibit after birth.

<p>Common symptoms include severe abdominal swelling and respiratory distress.</p> Signup and view all the answers

What role does ABO incompatibility play in pregnancy regarding hemolytic diseases?

<p>ABO incompatibility can lead to hemolytic disease in the newborn, where maternal antibodies attack fetal red blood cells.</p> Signup and view all the answers

Study Notes

Rhesus Antigen

  • Rhesus factor is a protein found on the surface of red blood cells.
  • Rh positive individuals have the protein, while Rh negative individuals do not.
  • Blood type is indicated with a + or - symbol after the blood type to denote Rh status.
  • Rh status is inherited as an autosomal dominant trait.
  • There are 5 Rh antigens (D, C, c, E, e) but Rh positivity or negativity is determined by the presence or absence of the D antigen.
  • The D antigen is the most immunogenic.
  • Approximately 15% of the population is Rh negative.
  • Rh negativity is more common in Caucasians than Africans or Asians.

Pathophysiology

  • Rh-negative mothers may develop antibodies against Rh-positive fetal blood cells.
  • Exposure to Rh-positive blood can occur during pregnancy, delivery, or miscarriages.
  • Antibodies produced cross the placenta and attack the fetus, leading to hemolysis (destruction) of fetal red blood cells.

Prevention

  • Rh-immune globulin (RhIg) is the primary method of prevention.
  • RhIg is administered to Rh-negative mothers to suppress antibody production.
  • RhIg is given at 28-32 weeks of gestation and within 72 hours of delivery if the baby is Rh positive.
  • RhIg is also recommended following miscarriages, ectopic pregnancies, amniocenesis, and other procedures that may expose the mother to fetal blood.

Diagnosis

  • Indirect Coombs test detects the presence of Rh antibodies in the maternal blood.
  • Kleihauer-Betke (KB) test measures the percentage of fetal blood cells in maternal circulation.
  • Amniocentesis can be used to determine the bilirubin level in the amniotic fluid, which indicates the severity of hemolysis.

Management

  • Regular monitoring of maternal antibody levels through indirect Coombs testing.
  • Possible fetal blood sampling to determine Rh status.
  • Ultrasound examination to assess fetal well-being, including amniotic fluid volume, hydrops fetalis, and Doppler measurements.
  • Consideration of intrauterine blood transfusions for severe hemolytic disease.
  • Delivery at term.

Fetal Hydrops

  • Fetal hydrops is a serious condition characterized by fluid accumulation in fetal tissues, including ascites, pleural effusion, and edema.
  • It can be either immune or non-immune.
  • Immune hydrops is caused by Rh incompatibility.
  • Non-immune hydrops can be caused by cardiac defects, fetal anemia (like alpha thalassemia), lung defects, and genetic disorders.

Diagnosis

  • Ultrasound examination to assess fetal fluid accumulation, placental thickening, organ size, and ascites.
  • Fetal blood sampling for karyotyping, virology, and blood count.
  • Doppler ultrasound for middle cerebral artery (MCA) flow.
  • Amniocentesis for bilirubin level and other tests.
  • Fetal echocardiography.

Treatment

  • Supportive measures, including management of respiratory status, fluid and electrolytes, and nutrition.
  • Management of arrhythmias.
  • Treatment of fetal anemia with intrauterine blood transfusions.

ABO Incompatibility

  • Hemolytic disease of the newborn can also occur due to ABO incompatibility.
  • This is less common and less severe than Rh incompatibility.

Prognosis

  • The prognosis for Rh incompatibility is good with appropriate management.
  • The prognosis for fetal hydrops depends on the underlying cause and can be variable.
  • Premature birth and intrauterine growth restriction are possible in severe cases.

Key Considerations

  • Rh incompatibility is preventable with proper management.
  • RhIg is essential for preventing sensitization in Rh-negative mothers.
  • Early diagnosis and treatment are important for fetal well-being.
  • Careful monitoring and prompt intervention are crucial for both mother and fetus in cases of Rh incompatibility and fetal hydrops.

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Rh Incompatibility in Pregnancy PDF

Description

Test your understanding of the Rhesus antigen, its inheritance, and its medical implications during pregnancy. Learn about Rh-negative mothers and the possible complications with Rh-positive fetuses. This quiz will cover key concepts related to Rh factors and their significance in blood typing.

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