Updated: 7/29/2022

Rh Disease

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  • Snapshot
    • A 30-year-old G2P1 woman presents to the emergency room with contractions at 37 weeks. She previously had a baby boy via spontaneous vaginal delivery without complications. She had this delivery done in a foreign country, and obstetric records are not available. Her prenatal care has also been limited. On fetal ultrasound, it is noted that the fetus has ascites and soft tissue edema. She is immediately prepped for delivery.
  • Introduction
    • Overview
      • Rh hemolytic disease of the newborn is caused by Rh incompatibility
      • maternal anti-Rh IgG antibodies cross the placenta and destroy fetal Rh-positive red blood cells
  • Epidemiology
    • Incidence
      • 15% of the population is Rh-negative
    • Risk factors
      • history of prior blood transfusion
      • previous pregnancy
      • mother is Rh-negative, and father is Rh-positive or unknown
      • prior administration of Rh IgG (RhoGam)
      • history of invasive obstetric procedures
  • ETIOLOGY
    • Pathogenesis
      • mechanism
        • Rh factor is a red blood cell antigen
        • when a Rh-negative mother is pregnant with a Rh-positive fetus, the mother is exposed to Rh-positive red blood cells and leads to maternal antibody production (IgG) against the foreign Rh antigen
        • as IgG can cross the placenta, subsequent pregnancy with Rh-positive fetus will result in fetal alloimmune induced hemolytic anemia
        • development of antibody depends on volume of transplacental crossover of red blood cells, concurrent presence of ABO incompatibility, and extent of maternal immune response
        • breakdown of red blood cells causes elevation of bilirubin
  • Presentation
    • Symptoms
      • hemolytic anemia
    • Physical exam
      • inspection
        • jaundice
        • pallor
  • Imaging
    • Fetal ultrasound
      • indication
        • suspected Rh incompatibility
      • findings
        • fetal ascites and edema
  • Studies
    • Serum labs
      • hyperbilirubinemia
      • low hematocrit
      • elevated reticulocyte count
      • positive direct Coombs test
    • Rosette test
      • to detect fetal-maternal hemorrhage
    • Kleihauer-Betke test
      • if Rosette test is positive, can conduct this test
      • measures fetal red blood cells in utero in maternal circulation to determine dose of RhoGAM
  • Differential
    • ABO incompatibility
      • key distinguishing factor
        • typically less severe
  • Treatment
    • Medical
      • maternal anti-D immune globulin (Rh IgG or RhoGAM) administration
        • indication
          • only if mother is Rh-negative and has not been sensitized previously, given at 28th week of pregnancy, if possible, and within 72 hours after birth
          • external cephalic version
          • amniocentsis
          • ectopic pregnancy
      • exchange transfusion
        • indications
          • erythroblastosis fetalis
          • hydrops fetalis
          • kernictus
  • Complications
    • Kernicterus secondary to hyperbilirubinemia
      • loss of Moro reflex
      • posturing
      • poor feeding
      • seizures
    • Erythroblastosis fetalis
      • most severely, can manifest as hydrops fetalis with high output cardiac failure, edema, and death
      • indication for immediate delivery and exchange transfusion
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Questions (3)

(M2.OB.17.4817) A 31-year-old G2P1001 presents to the labor floor for external cephalic version (ECV) due to breech presentation at 37 weeks gestation. Her pregnancy has been complicated by an episode of pyelonephritis at 14 weeks gestation, treated with intravenous ceftriaxone. The patient has not had urinary symptoms since that time. Otherwise, her prenatal care has been routine and she tested Rh-negative with negative antibodies at her first prenatal visit. She has a history of one prior spontaneous vaginal delivery without complications. She also has a medical history of anemia. Current medications include nitrofurantoin for urinary tract infection suppression and iron supplementation. The patient’s temperature is 98.5°F (36.9°C), pulse is 75/min, blood pressure is 122/76 mmHg, and respirations are 13/min. Physical exam is notable for a fundal height of 37 centimeters and mild pitting edema in both lower extremities. Cardiopulmonary exams are unremarkable. Bedside ultrasound confirms that the fetus is still in breech presentation. Which of the following should be performed in this patient as a result of her upcoming external cephalic version?

QID: 109396

Complete blood count

11%

(4/35)

Urinalysis

11%

(4/35)

Fibrinogen level

6%

(2/35)

Urine protein to creatinine ratio

3%

(1/35)

Rhogam administration

69%

(24/35)

M 7 D

Select Answer to see Preferred Response

(M2.OB.15.4672) A 29-year-old G1P0 female at 32 weeks gestation presents to the emergency department with vaginal bleeding. She has had minimal prenatal care to-date with only an initial visit with an obstetrician after a positive home pregnancy test. She describes minimal spotting that she noticed earlier today that has progressed to larger amounts of blood; she estimates 30 mL of blood loss. She denies any cramping, pain, or contractions, and she reports feeling continued movements of the baby. Ultrasound and fetal heart rate monitoring confirm the presence of a healthy fetus without any evidence of current or impending complications. The consulted obstetrician orders blood testing for Rh-status of both the mother as well as the father, who brought the patient to the hospital. Which of the following represents the best management strategy for this situation?

QID: 107196

If mother is Rh-negative and father is Rh-positive then administer RhoGAM

94%

(30/32)

If mother is Rh-negative and father is Rh-negative then administer RhoGAM

0%

(0/32)

If mother is Rh-positive and father is Rh-negative then administer RhoGAM

3%

(1/32)

If mother is Rh-negative and father is Rh-positive, RhoGAM administration is not needed

0%

(0/32)

After 28 weeks gestation, administration of RhoGAM will have no benefit

0%

(0/32)

M 7 E

Select Answer to see Preferred Response

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