A 2-month-old boy is brought to the office by his parents for well-child care. The infant was born at term via spontaneous vaginal delivery to a primigravid mother who developed acute hepatitis B infection during the third trimester. Both parents have a history of intravenous heroin use, and the father also has chronic, active hepatitis B. The parents entered a detoxification program after her diagnosis and no longer use illicit substances. The parents say, "We are terrified that he might develop hepatitis, too - it's all we can think about." The infant received hepatitis B immunoglobulin and vaccination at birth. The patient is gaining weight well and is formula feeding exclusively. Since his last visit, he has begun making cooing sounds and smiling. Vital signs are normal. Abdominal examination, including liver size, is unremarkable. The sclerae are white. The remainder of the physical examination is unremarkable. Which of the following is the most appropriate next step in this infant's care?

Question

A 2-month-old boy is brought to the office by his parents for well-child care.  The infant was born at term via spontaneous vaginal delivery to a primigravid mother who developed acute hepatitis B infection during the third trimester.  Both parents have a history of intravenous heroin use, and the father also has chronic, active hepatitis B.  The parents entered a detoxification program after her diagnosis and no longer use illicit substances.  The parents say, "We are terrified that he might develop hepatitis, too - it's all we can think about."  The infant received hepatitis B immunoglobulin and vaccination at birth.  The patient is gaining weight well and is formula feeding exclusively.  Since his last visit, he has begun making cooing sounds and smiling.  Vital signs are normal.  Abdominal examination, including liver size, is unremarkable.  The sclerae are white.  The remainder of the physical examination is unremarkable.  Which of the following is the most appropriate next step in this infant's care?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c171_487a_8f63_914d92155a22_MD0005_00 Infants born to mothers with active hepatitis B infection are at risk for acquiring hepatitis B either in utero or, more commonly, during delivery due to exposure to infected genital secretions. Maternal viral load is the primary risk factor and directly correlates with the risk of vertical transmission to the infant. However, with prompt administration of hepatitis B vaccine and immunoglobulin to the infant, the risk for infection decreases to <5%. Infants who are vertically infected with hepatitis B generally develop chronic infection in an immune-tolerant phase. These infants characteristically have very high viral loads and positive HBeAg, but remain asymptomatic and have normal or minimally elevated liver enzymes. Therefore, liver function tests cannot be used to detect infection (Choice E). Instead, exposed infants should receive the hepatitis B vaccine and immunoglobulin within 12 hours of birth, followed by completion of the normal hepatitis B series (at age 0, 2, and 6 months). Serology should be obtained at the subsequent well-child visit, usually at age 9 months. If HBsAg is not detected at that time, the infant is uninfected. (Choice A) Hepatitis B immunoglobulin should be given to exposed infants as soon as possible after delivery. Efficacy of immunoglobulin is markedly reduced beyond 12 hours; there is no role for immunoglobulin at age 2 months. (Choices C and D) Serology should be obtained 3 months after completion of the primary hepatitis B vaccine series. Early serology may be falsely positive (HBsAg remains positive for up to a month after immunization, and the immunoglobulin can persist for 6-8 months). However, as anti-HBs decreases over time, serology obtained after age 12 months may incorrectly identify children as vaccine nonresponders even if their anti-HBs levels were appropriate at age 9-12 months. Educational objective: Infants born to mothers with active hepatitis B infection should receive the hepatitis B vaccine and immunoglobulin within 12 hours of delivery. Exposed infants should receive the normal hepatitis B series, and serology should be obtained approximately 3 months after the final hepatitis B vaccine. Detection of HBsAg at that time is consistent with vertical infection. References: Update: shortened interval for postvaccination serologic testing of infants born to hepatitis B-infected mothers. (http://www.ncbi.nlm.nih.gov/pubmed/26447601) Vertical transmission of hepatitis B virus: challenges and solutions. (http://www.ncbi.nlm.nih.gov/pubmed/24966696)

A 2-Month-Old Boy Is Brought to the Office by His