CASE Pregnant woman with positive hepatitis B surface antigen
A 27-year-old primigravida at 9 weeks 3 days of gestation tests positive for the hepatitis B surface antigen at her first prenatal appointment. She is completely asymptomatic.
- What additional tests are indicated?
- Does she pose a risk to her sexual partner, and is her newborn at risk for acquiring hepatitis B?
- Can anything be done to protect her partner and newborn from infection?
Meet our perpetrator
Hepatitis is one of the more common viral infections that may occur during pregnancy. Two forms of hepatitis, notably hepatitis A and E, pose a primary threat to the mother. Three forms (B, C, and D) present dangers for the mother, fetus, and newborn. This article will review the epidemiology, clinical manifestations, perinatal implications, and management of the various forms of viral hepatitis. (TABLE 1).
Hepatitis A
Hepatitis A is caused by an RNA virus that is transmitted by fecal-oral contact. The disease is most prevalent in areas with poor sanitation and close living conditions. The incubation period ranges from 15 to 50 days. Most children who acquire this disease are asymptomatic. By contrast, most infected adults are acutely symptomatic. Clinical manifestations typically include low-grade fever, malaise, anorexia, right upper quadrant pain and tenderness, jaundice, and claycolored stools.1,2
The diagnosis of acute hepatitis A infection is best confirmed by detection of immunoglobulin M (IgM)-specific antibodies. The serum transaminase concentrations and the serum bilirubin concentrations usually are significantly elevated. The international normalized ratio, prothrombin time, and partial thromboplastin time also may be elevated.1,2
The treatment for acute hepatitis A largely is supportive care: maintaining hydration, optimizing nutrition, and correcting coagulation abnormalities. The appropriate measures for prevention of hepatitis A are adoption of sound sanitation practices, particularly water purification; minimizing overcrowded living conditions; and administering the hepatitis A vaccine for both pre and postexposure prophylaxis.3,4 The hepatitis A vaccine is preferred over administration of immune globulin because it provides lifelong immunity.
The hepatitis A vaccine is produced in 2 monovalent formulations: Havrix (GlaxoSmithKline) and Vaqta (Merck & Co, Inc). The vaccine should be administered intramuscularly in 2 doses 6 to 12 months apart. The wholesale cost of the vaccine varies from $66 to $119 (according to http://www.goodrx.com). The vaccine also is available in a bivalent form, with recombinant hepatitis B vaccine (Twinrix, GlaxoSmithKline). When used in this form, 3 vaccine administrations are given—at 0, 1, and 6 months apart. The cost of the vaccine is approximately $150 (according to http://www.goodrx.com). TABLE 2 lists the individuals who are appropriate candidates for the hepatitis A vaccine.3,4
Hepatitis B
Hepatitis B is caused by a DNA virus that is transmitted parenterally or perinatally or through sexual contact. Four genotypes have been identified: A, B, C, and D.
Acute hepatitis B affects 1 to 2 of 1,000 pregnancies in the United States. Approximately 6 to 10 patients per 1,000 pregnancies are asymptomatic but chronically infected.4 The natural history of hepatitis B infection is shown in the FIGURE. The diagnosis of acute and chronic hepatitis B is best established by serology and polymerase chain reaction (PCR; TABLE 3).
All pregnant women should be routinely screened for the hepatitis B surface antigen.5,6 If they are seropositive for the surface antigen alone and receive no immunoprophylaxis, they have a 20% to 30% risk of transmitting infection to their neonate. Subsequently, if they also test positive for the hepatitis Be antigen, the risk of perinatal transmission increases to approximately 90%. Fortunately, 2 forms of immunoprophylaxis are highly effective in preventing perinatal transmission. Infants delivered to seropositive mothers should receive hepatitis B immune globulin within 12 hours of birth. Prior to discharge, the infant also should receive the first dose of the hepatitis B vaccine. Subsequent doses should be administered at 1 and 6 months of age. Infants delivered to seronegative mothers require only the vaccine series.1
Although immunoprophylaxis is highly effective, some neonates still acquire infection perinatally. Pan and colleagues7 and Jourdain et al8 demonstrated that administration of tenofovir 200 mg orally each day from 32 weeks’ gestation until delivery provided further protection against perinatal transmission in patients with a high viral load (defined as >1 million copies/mL). In 2016, the Society for Maternal-Fetal Medicine endorsed the use of tenofovir in women with a high viral load.6
Following delivery, women with chronic hepatitis B infection should be referred to a hepatology specialist for consideration of direct antiviral treatment. Multiple drugs are now available that are highly active against this micro-organism. These drugs include several forms of interferon, lamivudine, adefovir, entecavir, telbivudine, and tenofovir.1
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