Cytomegalovirus (CMV), parvovirus B19, varicella zoster, and toxoplasmosis infection in pregnancy: Clinical sciences

Cytomegalovirus, or CMV, parvovirus B19, varicella zoster, and toxoplasma are infectious organisms that can cause congenital infection in pregnancy. These conditions often have nonspecific maternal symptoms; however, they can lead to congenital anomalies or even fetal demise depending on the timing and severity of infection.

Let’s first take a look at when a patient presents a chief concern of CMV, you should first obtain a focused history and physical exam, as well as an obstetric ultrasound.

Patients are usually asymptomatic but might report headaches, fatigue, and muscle or joint pains. You may find risk factors like childcare or healthcare workers that are exposed to body fluids, including urine, saliva, nasopharyngeal secretions, and tears.

Physical exam could show a low-grade fever, runny nose, pharyngitis, or hepatomegaly. Lastly, obstetric ultrasound may reveal periventricular calcifications, ventriculomegaly, hepatic calcifications, echogenic bowel, growth restriction, microcephaly, and hepatosplenomegaly.

Based on these findings, suspect that vertical transmission of CMV has resulted in infection and order CMV IgM and IgG antibody testing. If both IgM and IgG antibodies are negative, repeat testing in 2 to 4 weeks to ensure no seroconversion. If antibodies remain negative, consider an alternate diagnosis. Now, if IgM is negative but IgG is positive, that suggests remote CMV infection. These carry a low risk of fetal transmission from viral reactivation or infection with a new strain. Counsel the patient and offer fetal diagnostic testing via amniocentesis and PCR of the amniotic fluid if ultrasound is suspicious for fetal infection.

If both IgM and IgG antibodies are positive, then check CMV IgG avidity to determine if the infection is recent.

If there’s high avidity, IgG has been present for a significant amount of time, meaning the infection is remote. Inform your patient that there’s a lower risk of fetal transmission, but offer diagnostic amniocentesis and PCR if the ultrasound is concerning. On the flip side, low IgG avidity suggests recent conversion from IgM to IgG, meaning the infection is recent.

Counsel these patients that there’s a higher risk of transmission to the fetus and that, although the highest rate of transmission occurs during the third trimester, there’s a higher risk of serious sequelae with first trimester infection. Offer diagnostic testing via amniocentesis and PCR, and order follow-up growth ultrasounds, including repeat assessment of fetal anatomy, particularly looking at the brain, which could show ventriculomegaly.

Alright, let’s move on to Parvovirus B19 infection. These patients are usually asymptomatic but might report joint pain. The greatest risk for exposure is through respiratory secretions and hand-to-mouth contact, such as with childcare or healthcare workers.

Physical exam might reveal a “slapped cheek” facial rash; though a “lace-like” erythematous rash on the trunk and extremities is more common. If labs are drawn, a transient aplastic crisis could be seen, especially in patients with hemoglobinopathy.

Ultrasound might show fetal hydrops, which is a collection of interstitial fluid in 2 or more compartments of the fetal body, specifically affecting the abdominal cavity, heart, or lungs. As such, you may observe transient isolated fetal pleural or pericardial effusions, and ascites. Other possibilities include possible cardiomegaly and placentomegaly.

Based on these findings, suspect Parvovirus B19 infection. Next, order Parvovirus IgM and IgG antibody testing. You can also consider sending PCR of maternal blood in cases where there’s high suspicion for infection. If both IgM and IgG are negative, repeat testing 2 to 4 weeks later. If antibodies remain negative, and if PCR returns negative, consider an alternate diagnosis. However, if IgM is negative but IgG is positive, that’s a remote infection. With Parvovirus B19, remote infection doesn’t carry a risk of reinfection, so you can continue with routine prenatal care. Now, if IgM is positive, regardless of IgG status, or if PCR is positive, you can diagnose recent Parvovirus B19 infection.

Counsel these patients that there’s a higher risk of fetal transmission, and offer diagnostic testing with amniocentesis and PCR of the amniotic fluid.

Further management is based on gestational age. If gestation is less than 18 weeks, inform the patient that fetal infection may result in fetal loss, as the highest risk of fetal mortality is in the first half of pregnancy. On the other hand, if the gestational age is 18 weeks or more, perform an ultrasound to look for fetal hydrops, and check middle cerebral artery, or MCA, Doppler for fetal anemia.

If the ultrasound shows no hydrops and MCA Doppler is normal, continue surveillance weekly for at least 8 to 12 weeks from the time of infection.