A 23-year-old gravida 3 para 1 at 28 weeks gestation whose blood type is O-negative is antibody positive (D antibody) on a routine 28-week screen.
Which one of the following best describes the clinical significance of this finding?
Correct Answer C: When a person is Rh negative, this indicates that they do not have type D antigen on their red blood cells. If a woman is exposed to Rh D antigen-positive red blood cells, she can have an immune response of variable strength. This may occur in the setting of pregnancy (transplacental fetomaternal transfusion), or exposure outside of pregnancy (e.g., transfusion with mismatched blood).
If a maternal antibody screen for D antigen is positive, this indicates that the current fetus MAY be at risk for hemolytic disease. The level of risk is determined by the antibody titer. For example, an antibody titer of 1:4 poses much less risk to the fetus than a titer of 1:64.
Determination of the blood type of the father is helpful if paternity is certain. If the father is homozygous Rh negative, there is no risk of alloimmunization to the fetus and the fetus is NOT at risk for hemolytic disease. In this scenario, maternal sensitization occurred either from a prior pregnancy with a different partner or from another source (e.g. transfusion). If the father is heterozygous Rh positive, then the fetus IS at risk. If paternity is uncertain, a polymerase chain reaction can be performed on 2 mL of amniotic fluid or 5 mL of chorionic villi to accurately determine the fetal Rh status.
A young woman with phenylketonuria (PKU) has not been following her diet over the past several years. She comes to you in her first trimester of pregnancy.
Which one of the following congenital abnormalities would the baby most likely develop?
Correct Answer A:
Phenylketonuria (PKU) is an autosomal recessive genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase. This enzyme is necessary to metabolize the amino acid phenylalanine to the amino acid tyrosine. When it is deficient, phenylalanine accumulates and is converted into phenyl ketones, which are detected in the urine.
Left untreated, this condition can cause problems with brain development, leading to progressive mental retardation and seizures. However, PKU is one of the few genetic diseases that can be controlled by diet. A diet low in phenylalanine and high in tyrosine can be a very effective treatment. There is no cure. Damage done is irreversible so early detection is crucial.
For women affected with PKU, it is essential for the health of their child to maintain low phenylalanine levels before and during pregnancy. Though the developing fetus may only be a carrier of the PKU gene, the intrauterine environment can have very high levels of phenylalanine, which can cross the placenta. The result is that the child may develop congenital heart disease, growth retardation, microcephaly and mental retardation.
Which of the following congenital birth defects could most likely occur when a woman using Accutane (isotretinoin) for acne becomes pregnant and keeps the baby?
Correct Answer A: Accutane (isotretinoin) is a powerful drug used to combat the most serious and complicated cases of acne. One of the most serious complications of accutane is its effect on pregnant women and their unborn fetuses. Birth defects that have been documented following isotretinoin exposure include abnormalities of the face, eyes, ears, skull, CNS, cardiovascular system, and thymus and parathyroid glands.
Cardiovascular abnormalities observed have included interrupted aortic arch, ventricular septal defect, atrial septal defect, transposition of the great vessels, and Tetralogy of Fallot.
Ear abnormalities have included anotia, micropinna, and small or absent external auditory canals. Central nervous system abnormalities have included cerebral abnormalities, cerebellar malformation, hydrocephalus, microcephaly, and cranial nerve deficit.
Craniofacial abnormalities have frequently included occipital vaulting, and/or a sharply sloping, narrow forehead, widespaced eyes, small chin, and flat, depressed nasal bridge.
A 24-year-old female at 36 weeks gestation plans to breastfeed her infant. She has a history of bipolar disorder, but is currently doing well without medication, and also has a history of frequent urinary tract infections. She asks you about medications that she may need to take after delivery, and how they may affect her newborn.
Which one of the following would be contraindicated if she decided to breastfeed her infant?
Correct Answer D:
Of the drugs listed, the only maternal medication that affects the infant is lithium. Breastfed infants of women taking lithium can have blood lithium concentrations that are 30% - 50% of therapeutic levels.
A 78-year-old white female notices a scant milky secretion from her breast.
Which one of the following medications can cause this symptom?
Many medications can cause galactorrhea, including the dopamine receptor blocker risperidone. Additional drugs that cause this condition include cimetidine, verapamil, and morphine. The other drugs listed do not cause galactorrhea.
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