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MFM Written/Oral Boards > Parvovirus B19 > Flashcards

Parvovirus B19 Flashcards

1
Q

How is maternal infection with parvovirus diagnosed

A

IgM+ (within 7 days of infection)

IgM- and IgG - then 4 weeks later IgM + or Ig + (within 7-120 days ago)

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2
Q

Do you recommend screening for parvovirus routinely in pregnancy?

A

no.
- Incidence of seroconversion is low
- Variable risk of fetal transmission (17-33%)
- Variable risk of subsequent sequelae

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3
Q

How do you counsel a patient with a positive parvovirus IgM and negative IgG results?

A
  • 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)
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4
Q

How do you counsel a patient with a positive parvovirus IgM and positive IgG results?

A

Recent acute infection

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5
Q

How is parvovirus infection transmitted?

A

Direct exposure to respiratory secretions and hand to mouth contact and blood transfusion

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6
Q

What are maternal risks of parvovirus infection?

A

Child care, classroom

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7
Q

What are maternal symptoms of parvovirus infection?

A
  • Fever
  • Body rash
  • Joint pain
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8
Q

What percentage of patients infected with parvovirus are symptomatic?

A

20%

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9
Q

What ultrasound findings suggest possible in utero parvovirus infection?

A
  • Fetal growth restriction
  • Placentomegaly
  • Cardiomegaly
  • Hydrops
  • Ascites
  • High MCA PSV
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10
Q

How is in utero parvovirus infection confirmed?

A

Amniocentesis

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11
Q

If performing amniocentesis for suspected parvovirus, what tests will you order on the amniotic fluid?

A

PCR (100% sensitive)

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12
Q

Which trimester of pregnancy is the greatest risk of fetal infection for parvovirus?

A

Second trimester due to viral placental transport and due to increased hematopoiesis during this period

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13
Q

Which patients are candidates for parvovirus serology?

A
  • Known exposure
  • Ultrasound findings such as placentomegaly, cardiomegaly, ascites, hydrops, growth restriction
  • Symptoms
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14
Q

How do you follow a patient if in utero parvovirus infection is suspected or confirmed?

A

every 1-2 weeks for 8-12 weeks

-assess for cardiomegaly, placentomegaly, ascites

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15
Q

How frequently do you perform MCA doppler studies if in utero parovirus infection is suspected or confirmed?

A

q weekly x 12 weeks

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16
Q

How long will you continue performing MCA dopplers if in utero parvovirus infection is suspected or confirmed?

A

Until MCA PSV is greater 1.5MoM if confirmed and 8-12 weeks if suspected

17
Q

Describe how you perform an MCA Doppler study.

A

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

18
Q

How do you interpret MCA doppler study findings?

A

1.5 MoM correlates with severe fetal anemia

19
Q

What does an MCA PSV >1.5MoM indicate?

A

Hbg 6

20
Q

How do you counsel a patient if she has an MCA PSV >1.5MoM?

A
  • 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
21
Q

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

A

10 fold increase risk of mortality with IUT before 22 weeks

22
Q

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

A
  • Administer BMZ

- IUT

23
Q

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

A
  • Administer BMZ if not done before

- Delivery

24
Q

How do you counsel a patient regarding long term neonatal outcomes in the setting of fetal parvovirus infection?

A

There is an increased risk of:

  • myocarditis
  • chronic fetal hepatitis
  • neurodevelopmental impairment particularly in the setting of hydrops
25
Q

Are patients at risk of parvovirus infection by transmission from puppies who have received parvovirus vaccination?

A

Parvovirus B19 infects only humans

MFM Written/Oral Boards (127 decks)

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