A 4-hour-old infant is evaluated in the neonatal intensive care unit. The infant was born at 37 weeks gestation via cesarean delivery to a healthy 33-year-old primigravid woman. Apgar scores were 6 and 8, at 1 and 5 minutes, respectively. The delivery was complicated by arrest of descent and nonreassuring fetal heart rate. The mother's laboratory testing from the first prenatal visit demonstrated negative IgG titers to rubella but was otherwise normal. Fetal anatomy ultrasound at 20 weeks gestation showed no abnormalities. The mother traveled to South America at 15 weeks gestation for a family emergency and returned 2 weeks later. She smoked half a pack of cigarettes a day throughout the pregnancy but did not use alcohol or illicit drugs. She declined influenza and tetanus-diphtheria-acellular pertussis vaccines during pregnancy. The infant's vital signs are normal. Height and weight are at the 20th percentile; head circumference is at the 95th percentile. Cardiac examination reveals a normal rate and regular rhythm. Abdominal examination reveals hepatomegaly but no other palpable masses. A head CT scan reveals hydrocephalus and diffuse intracranial calcifications. Which of the following best explains this infant's examination findings?

Question

A 4-hour-old infant is evaluated in the neonatal intensive care unit.  The infant was born at 37 weeks gestation via cesarean delivery to a healthy 33-year-old primigravid woman.  Apgar scores were 6 and 8, at 1 and 5 minutes, respectively.  The delivery was complicated by arrest of descent and nonreassuring fetal heart rate.  The mother's laboratory testing from the first prenatal visit demonstrated negative IgG titers to rubella but was otherwise normal.  Fetal anatomy ultrasound at 20 weeks gestation showed no abnormalities.  The mother traveled to South America at 15 weeks gestation for a family emergency and returned 2 weeks later.  She smoked half a pack of cigarettes a day throughout the pregnancy but did not use alcohol or illicit drugs.  She declined influenza and tetanus-diphtheria-acellular pertussis vaccines during pregnancy.  The infant's vital signs are normal.  Height and weight are at the 20th percentile; head circumference is at the 95th percentile.  Cardiac examination reveals a normal rate and regular rhythm.  Abdominal examination reveals hepatomegaly but no other palpable masses.  A head CT scan reveals hydrocephalus and diffuse intracranial calcifications.  Which of the following best explains this infant's examination findings?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c17b_81be_8f63_3322eefd8be6_MD0005_00 Hydrocephalus, intracranial calcifications, and hepatomegaly are signs of congenital toxoplasmosis, which is acquired by transplacental transmission. Maternal infection is acquired via inadvertent ingestion of Toxoplasma gondii from cat feces, contaminated soil on fruits/vegetables, or undercooked meat; infection rates are highest in South America, where more virulent strains exist. Routine screening is not undertaken in the United States. Although toxoplasmosis infection is typically asymptomatic in an immunocompetent adult, it can cause severe consequences in the fetus or newborn. After maternal ingestion, tachyzoites transmitted through the placenta invade developing fetal cells, most commonly in the muscle and brain. Classic congenital manifestations include eye abnormalities (eg, chorioretinitis), neurologic findings (eg, intracranial calcifications, hydrocephalus), and hearing impairment. When infection is suspected prenatally, diagnosis is made via maternal serology or amniocentesis. When the infection is suspected in a newborn, diagnosis is with neonatal serology. Treatment is with antiparasitic therapy (ie, pyrimethamine and sulfadiazine) and supplemental folate for a year. (Choice B) Pertussis vaccination in pregnancy is recommended to promote passive immunity against this respiratory illness. Influenza vaccination is recommended because influenza causes more severe illness in pregnancy and has been associated with miscarriage and preterm labor. Both illnesses cause a symptomatic illness in adults, not seen in this infant's mother. (Choice C) Folic acid deficiency is correlated with neural tube defects, which are not seen in this infant. neural tube defects (Choice D) Rubella infection in pregnancy is more commonly symptomatic (eg, fever, maculopapular rash) than toxoplasmosis infection. Congenital rubella typically manifests as congenital heart defects, eye abnormalities, and hearing impairment. Intracranial calcifications are not seen. (Choice E) Although sexually transmitted infections can cause illness in infants (eg, syphilis resulting in hepatosplenomegaly), none are associated with the intracranial calcifications seen in this infant. Educational objective: Inadvertent consumption by pregnant women of the toxoplasmosis parasite in cat feces, undercooked meat, or contaminated soil may be associated with congenital disease, which may manifest as eye abnormalities, neurologic findings, and hearing impairment. References: Diagnosis, treatment, and prevention of congenital toxoplasmosis in the United States. (http://www.ncbi.nlm.nih.gov/pubmed/28138010)

A 4-Hour-Old Infant Is Evaluated in the Neonatal Intensive Care