[27] Parvovirus Infection In Pregnancy

Question 1

What is parvovirus B19?

Answer 1

A single stranded DNA virus (Parvoviridae family)

Question 2

How common is parvovirus B19 infection in pregnancy?

Answer 2

Approx. 1 in 400 women become infected during their pregnancy

Question 3

In what % of cases of parvovirus B19 infection in pregnancy does vertical transmission to the fetus occur?

Answer 3

33%

Question 4

In what % of cases of fetal parvovirus B19 infection does spontaneous miscarriage or intrauterine fetal death occur?

Answer 4

9%

Question 5

How is parvovirus B19 spread?

Answer 5

Primary by infected respiratory droplets, but blood-borne transmission has also been reported

Question 6

When do symptoms of parvovirus B19 infection begin?

Answer 6

4-20 days after exposure

Question 7

How long do symptoms of parvovirus B19 infection last?

Answer 7

About a week

Question 8

When are people with normal immune systems infectious for parvovirus B19?

Answer 8

Before becoming symptomatic, but not after

Question 9

When is parvovirus B19 common?

Answer 9

In primary school age children during outbreaks in winter and spring months

Question 10

Can anyone become ill with parvovirus B19?

Answer 10

Yes

Question 11

How does parvovirus B19 most commonly present?

Answer 11

Infection in adults is usually asymptomatic

Question 12

What is the most common clinical feature of parvovirus B19 infection, if present?

Answer 12

Asymmetrical arthralgia, typically of proximal interphalangeal joints and/or knees

Question 13

How can infection be determined in cases where the mother has potentially come into contact with parvovirus B19?

Answer 13

Viral serology can be performed

Question 14

What indicates recent parvovirus infection on viral serology?

Answer 14

Parvovirus specific IgM antibodies

Question 15

What indicates past infection and therefore immunity to parvovirus on viral serology?

Answer 15

Parvovirus specific IgG antibodies

Question 16

What is involved in the maternal management of parvovirus B19 infection?

Answer 16

Parvovirus infection is self-limiting, and does not require treatment, but anti-pyretics and analgesia can be given

Question 17

What is the main risk of fetal parvovirus B19 infection?

Answer 17

Fetal hydrops

Question 18

What is fetal hydrops?

Answer 18

Abnormal accumulation of fluid in 2 or more fetal compartments

Question 19

How is it assessed if a fetus with parvovirus B19 infection is showing signs of fetal hydrops?

Answer 19

Serial ultrasound scans and Doppler assessment

Question 20

When do serial ultrasound scans in parvovirus B19 infection start?

Answer 20

4 weeks post infection, or at 16 weeks

Question 21

How often are serial ultrasound and Doppler scans for fetal parvovirus B19 repeated?

Answer 21

Every 1-2 weeks, until 30 weeks gestation

Question 22

What action should be taken if there is evidence of fetal hydrops on ultrasound?

Answer 22

Patient should be referred to a tertiary centre for intrauterine erythrocyte transfusion

Question 23

How is fetal hydrops diagnosed?

Answer 23

Ultrasound scan

Question 24

What are the features of fetal hydrops on ultrasound scan? (6)

Answer 24

• Ascites
• Subcutaneous oedema
• Pleural effusion
• Pericardial effusion
• Scalp oedema
• Polyhydraminos

Question 25

How does parvovirus B19 cause fetal hydrops?

Answer 25

Parvovirus B19 has an affinity for the erythroid system, and replicates within the erythroid progenitor cells of the liver and bone marrow

Question 26

What does the replication of parvovirus B19 in the liver and bone marrow of the fetus induce?

Answer 26

Severe anaemia

Question 27

What does the severe anaemia caused by parovirus B19 result in? (2)

Answer 27

• High output cardiac failure

- Increased extrahepatic and hepatic erythropoiesis

Question 28

What does increased extrahepatic and hepatic erythropoiesis in fetal parvovirus B19 infection result in?

Answer 28

• Portal hypertension

- Hypoproteinaemia with subsequent ascites

Question 29

What are the other fetal complications of parvovirus B19 infection?

Answer 29

• Hepatitis
• Severe anaemia
• Inflammation of heart muscle and cardiac failure