Parvovirus B19 In Pregnancy

Question 1

What is the route of transmission of parvovirus?

Answer 1

Respiratory droplets

Question 2

What is the percentage of women at childbearing age who aren’t immune to PVB19 ?

Answer 2

50%

Question 3

What is the diseases caused by parvovirus B19 ?

Answer 3

fifth disease:
1- in adults: erythema infectiosum - fever - malaise
2- in children: mild illness - typical facial rash ( slapped face )

Question 4

If the fetus is infected with PVB19 what is the main feature of infection?

Answer 4

HYDROPS: due to fetal hemolytic anaemia 👉 cardiac failure 👉 fetal death

Question 5

What is the incubation period for PVB19 ? How long the patient will be infectious?

Answer 5

Incubation period: 4 - 21 days
Patient is infectious 10 days post exposure or until the rash appears

Question 6

What is the clinical presentation of parvovirus B19 infection?

Answer 6

👉symptoms peak around day 9
1- The rash may appear up to 18 days after the exposure - slapped cheek
[ on the cheeks with pallor around the mouth sparing the nasolabial fold , forehead ,mouth]
2- fever-headache nausea- diarrhea
3- lace - like on trunk & extremities
ℹ the rash exacerbates by sunlight - heat - stress

Question 7

What is the transplacental transmission rate at each trimester of pregnancy?

Answer 7

< 15 w 👉 15%
15 - 20 w 👉 25 %
> 20 w towards term 👉 70%

Question 8

What are the fetal outcomes of maternal PVB19 infection ?

Answer 8

1- miscarriage
2- IUFD
3- fetal anaemia
4- nonimmune hydrops **
NO EVIDENCE OF TERATOGENESIS

Question 9

What is the teratogenicity of fetus infection with PVB19?

Answer 9

NO EVIDENCE OF TERATOGENESIS

Question 10

What is the risk of fetal loss in maternal PVB19 infection?

Answer 10

Overall risk 10% most deaths occur 4 - 6 w following the onset of maternal symptoms ( may occur 3 months later)
ℹ before 20 w 👉9% excess fetal loss

Question 11

What is the risk of fetal hydrops in maternal PVB19 ininfection? What is the fatality rate in that case ?

Answer 11

The risk of hydrops is low 3 %
The fatality rate is high 50%

Question 12

How is maternal PVB19 infection diagnosed?

Answer 12

1- serology in paired samples
2- DNA - PCR

Question 13

What are the serological changes in maternal PVB19 infection?

Answer 13

IgM : detected after 10 days and persist < 4w ( short lived )
ℹ If the rash is present + IgM undetectable 👉 PVB19 infection is excluded
IgG : detectable 12 - 14 days after the infection - lifelong immunity
ℹ IgG seroconversion confirms the diagnosis

Question 14

What is the management in each case of PVB19 infection;
1- IgG +ve / IgM -ve
2- IgM+ve regardless IgG
3- IgG -ve / IgM -ve

Answer 14

1- reassure
2- review reference sample
Or send sample for confirmatory
Testing
3- repeat after 1 month

Question 15

After confirmation maternal PVB19 how to monitor the fetus?

Answer 15

Serial US with MCA-PSV ( to detect fetal anaemia)
Starting 4 w after the onset of illness or the seroconversion & every 1-2w up to 12 weeks

Question 16

Fetal hydrops secondary to PVB19:
- What is the percentage of spontaneous resolution?
- what is the percentage of resolution after blood transfusion?

Answer 16

• Spontaneous resolution: 1/3
• resolution after blood transfusion 94% within 6 w

Question 17

When intrauterine fetal blood sampling may indicated in fetal PVB19 infection?

Answer 17

1- ascites or hydrops
2- MCA-PSV > 1.5 multiples of the median
ℹ intrauterine blood transfusion if fetal hemoglobin is below the gestational age

Question 18

If confirmed maternal PVB19 infection in first 20 w of pregnancy what is the management?

Answer 18

US after 4 w 👉 findings of hydrops
Refer to fetal medicine
👉 NO findings of hydrops
Repeat US every 1 - 2 w until
30 w of pregnancy or 12 w of
monitoring then you can reassure