New guidance from the Society for Maternal-Fetal Medicine (SMFM) recommends a thorough testing regime for pregnant women at high risk for the hepatitis C virus (HCV) and a prescriptive set of recommendations on screening workups for this disease. The guidance was reviewed and endorsed by the American College of Obstetricians and Gynecologists (ACOG).

Screening for high risk patients should take place at the first prenatal visit, the two groups advised. Even if this initial test is negative, a second screening may be warranted at a later stage of the pregnancy if new or persistent HCV factors arise, such as the use of intranasal or injected illicit drugs.

The estimated prevalence of antenatal HCV infection is low in the United States, about 1-2.5%, although some researchers suggest that it’s as high as 4%, according to the guidance. SMFM and ACOG recommended against screening all pregnant women for HCV, citing a lack of data on the cost-effectiveness of universal screening and the fact that no antiviral therapies for HCV have yet been approved for use in pregnancy.

The guidance recommends HCV prenatal testing for women with certain high risk factors, such as illegal drug use, unregulated tattoos, those on long-term hemodialysis or a history of incarceration, or who received blood products from a donor who eventually tested positive for HCV. Women who received transfusions or organ transplants prior to July 1992 and clotting factor concentrates produced before 1987 should also get screened.

Clinicians use anti-HCV antibody tests to screen for this disease. Positive results can mean one of several things: an acute or chronic HCV infection, a past infection that has since resolved, or a false positive result. SMFM and ACOG recommend that a quantitative nucleic acid test for HCV RNA follow any positive result for HCV antibodies. “If a patient who tested negative for HCV RNA within the past 6 months is newly found to be viremic, acute HCV infection is confirmed,” they advised.

If a never-before screened patient tests positive for anti-HCV antibodies and HCV RNA, clinicians shouldn’t solely use these results to assess whether this woman has an acute versus chronic case of HCV. “If the anti-HCV antibody test result is positive and the HCV RNA test result is negative, distinguishing a false-positive antibody test from a true infection requires testing for anti-HCV antibody with a different antibody assay platform,” the authors indicated. This should be conducted in accordance with Centers for Disease Control and Prevention (CDC) recommendations.

In other screening recommendations, SMFM and IDSA advised that clinicians follow up with HCV RNA testing in patients exposed to HCV within a 6-month period who have tested negative for anti-HCV antibodies. This is necessary because these antibodies might not have become detectable at the time of initial testing.

In the absence of formal, pregnancy-specific guidelines on lab testing for HCV, the guidance authors ended up adapting guidelines from the American Association for the Study of Liver Disease/Infectious Diseases Society of America. “For pregnant women with confirmed active HCV infection, a quantitative HCV RNA test should be done to determine the baseline viral load,” they recommended. Basic lab tests such as platelet count, bilirubin albumin, and alanine aminotransferase should be conducted to assess for liver disease, as well as HCV genotype testing to inform future treatment.

HCV-positive pregnant women also should get tested for sexually transmitted diseases such as HIV, syphilis, gonorrhea, chlamydia, and hepatitis B virus. Patients who request invasive prenatal diagnostic testing should be notified about the limited data available on the risks of vertical transmission, and that amniocentesis is a preferred method over chorionic villus sampling.

In other recommendations, the authors advised against relying on cesarean delivery to indicate HCV.

No antiviral therapies have been approved to treat HCV infection in pregnant women. For this reason, the authors suggested that direct acting antiviral therapy regimens should either be deferred for postpartum use, or used in a clinical trial environment. As a best practice, patients with HCV, including pregnant women, should be advised not to drink alcohol.

For babies born to HCV-positive women, the guidance refers to American Academy of Pediatrics and CDC recommendations, which call for screening for anti-HCV antibodies at >18 months of age or for HCV RNA on two occasions in infants >1 month of age. “The rationale for the timing of the diagnosis relates to the fact that maternal antibodies can persist for months in infants leading to false positive diagnoses. It is also possible that an infant can clear virus from the mother so the requirement for HCV RNA twice after the age of one month is to avoid false positive diagnoses,” Brenna Hughes, MD, the guidance’s lead author, told CLN Stat.

Additional studies on HCV during pregnancy would help improve understanding of the virus and treatment options, said ACOG Vice President of Practice Activities, Christopher M. Zahn, MD, in a statement. “With further information, obstetric care providers will be able to adequately screen for HCV and counsel pregnant women who are HCV-positive.”