Parvovirus B19 Flashcards
How is maternal infection with parvovirus diagnosed
IgM+ (within 7 days of infection)
IgM- and IgG - then 4 weeks later IgM + or Ig + (within 7-120 days ago)
Do you recommend screening for parvovirus routinely in pregnancy?
no.
- Incidence of seroconversion is low
- Variable risk of fetal transmission (17-33%)
- Variable risk of subsequent sequelae
How do you counsel a patient with a positive parvovirus IgM and negative IgG results?
- False positive
- Acute infection
- Not all are transmitted
- See symptoms (ascites, placentomegaly, cardiomegaly, hydrops, decrease fetal growth restriction) in fetus within 8 weeks of infection (follow fetus every 1-2 weeks for 8-12 weeks)
How do you counsel a patient with a positive parvovirus IgM and positive IgG results?
Recent acute infection
How is parvovirus infection transmitted?
Direct exposure to respiratory secretions and hand to mouth contact and blood transfusion
What are maternal risks of parvovirus infection?
Child care, classroom
What are maternal symptoms of parvovirus infection?
- Fever
- Body rash
- Joint pain
What percentage of patients infected with parvovirus are symptomatic?
20%
What ultrasound findings suggest possible in utero parvovirus infection?
- Fetal growth restriction
- Placentomegaly
- Cardiomegaly
- Hydrops
- Ascites
- High MCA PSV
How is in utero parvovirus infection confirmed?
Amniocentesis
If performing amniocentesis for suspected parvovirus, what tests will you order on the amniotic fluid?
PCR (100% sensitive)
Which trimester of pregnancy is the greatest risk of fetal infection for parvovirus?
Second trimester due to viral placental transport and due to increased hematopoiesis during this period
Which patients are candidates for parvovirus serology?
- Known exposure
- Ultrasound findings such as placentomegaly, cardiomegaly, ascites, hydrops, growth restriction
- Symptoms
How do you follow a patient if in utero parvovirus infection is suspected or confirmed?
every 1-2 weeks for 8-12 weeks
-assess for cardiomegaly, placentomegaly, ascites
How frequently do you perform MCA doppler studies if in utero parovirus infection is suspected or confirmed?
q weekly x 12 weeks
How long will you continue performing MCA dopplers if in utero parvovirus infection is suspected or confirmed?
Until MCA PSV is greater 1.5MoM if confirmed and 8-12 weeks if suspected
Describe how you perform an MCA Doppler study.
Angle of insonation as close to zero degrees as much as possible (30 degrees or less), 2mm above branching of the MCA from the circle of willis
How do you interpret MCA doppler study findings?
1.5 MoM correlates with severe fetal anemia
What does an MCA PSV >1.5MoM indicate?
Hbg 6
How do you counsel a patient if she has an MCA PSV >1.5MoM?
- High chance of severe fetal anemia
- Intrauterine transfusion until 35 weeks with anticipated delivery between 37-38 weeks gestation
- Second transfusion (moderate - severe anemia MCA PSV >1.32 MoM), MCA cannot be used for the third transfusion can be every 3 weeks
Describe your management of a patient with confirmed or suspected in utero parvovirus infection with an MCA PSV >1.5 MoM at 20 weeks gestation
10 fold increase risk of mortality with IUT before 22 weeks
Describe your management of a patient with confirmed or suspected in utero parvovirus infection with an MCA PSV >1.5 MoM at 30 weeks gestation
- Administer BMZ
- IUT
Describe your management of a patient with confirmed or suspected in utero parvovirus infection with an MCA PSV >1.5 MoM at 36 weeks gestation
- Administer BMZ if not done before
- Delivery
How do you counsel a patient regarding long term neonatal outcomes in the setting of fetal parvovirus infection?
There is an increased risk of:
- myocarditis
- chronic fetal hepatitis
- neurodevelopmental impairment particularly in the setting of hydrops
Are patients at risk of parvovirus infection by transmission from puppies who have received parvovirus vaccination?
Parvovirus B19 infects only humans
