[27] Parvovirus Infection In Pregnancy Flashcards
What is parvovirus B19?
A single stranded DNA virus
How common is parvovirus B19 infection in pregnancy?
Approx. 1 in 400 women become infected during their pregnancy
In what % of cases of parvovirus B19 infection in pregnancy does vertical transmission to the fetus occur?
33%
In what % of cases of fetal parvovirus B19 infection does spontaneous miscarriage or intrauterine fetal death occur?
9%
How is parvovirus B19 spread?
Primary by infected respiratory droplets, but blood-borne transmission has also been reported
When do symptoms of parvovirus B19 infection begin?
4-20 days after exposure
How long do symptoms of parvovirus B19 infection last?
About a week
When are people with normal immune systems symptomatic for parvovirus B19?
Before becoming symptomatic, but not after
When is parvovirus B19 common?
In primary school age children during outbreaks in winter and spring months
Can anyone become ill with parvovirus B19?
Yes
How does parvovirus B19 most commonly present?
Infection in adults is usually asymptomatic
What is the most common clinical feature of parvovirus B19 infection, if present?
Asymmetrical arthralgia, typically of proximal interphalangeal joints and/or knees
How can infection be determined in cases where the mother has potentially come into contact with parvovirus B19?
Viral serology can be performed
What indicates recent parvovirus infection on viral serology?
Parvovirus specific IgM antibodies
What indicates past infection and therefore immunity to parvovirus on viral serology?
Parvovirus specific IgG antibodies
What is involved in the maternal management of parvovirus B19 infection?
Parvovirus infection is self-limiting, and does not require treatment, but anti-pyretics and analgesia can be given
What is the main risk of fetal parvovirus B19 infection?
Fetal hydrops
What is fetal hydrops?
Abnormal accumulation of fluid in 2 or more fetal compartments
How is it assessed if a fetus with parvovirus B19 infection is showing signs of fetal hydrops?
Serial ultrasound scans and Doppler assessment
When do serial ultrasound scans in parvovirus B19 infection start?
4 weeks post infection, or at 16 weeks
How often are serial ultrasound and Doppler scans for fetal parvovirus B19 repeated?
Every 1-2 weeks, until 30 weeks gestation
What action should be taken if there is evidence of fetal hydrops on ultrasound?
Patient should be referred to a tertiary centre for intrauterine erythrocyte transfusion
How is fetal hydrops diagnosed?
Ultrasound scan
What are the features of fetal hydrops on ultrasound scan?
- Ascites
- Subcutaneous oedema
- Pleural effusion
- Pericardial effusion
- Scalp oedema
- Polyhydraminos
How does parvovirus B19 cause fetal hydrops?
Parvovirus B19 has an affinity for the erythroid system, and replicates within the erythroid progenitor cells of the liver and bone marrow
What does the replication of parvovirus B19 in the liver and bone marrow of the fetus induce?
Severe anaemia
What does the severe anaemia caused by parovirus B19 result in?
- High output cardiac failure
- Increased extrahepatic and hepatic erythropoiesis
What does increased extrahepatic and hepatic erythropoiesis in fetal parvovirus B19 infection result in?
- Portal hypertension
- Hypoproteinaemia with subsequent ascites
What are the other fetal complications of parvovirus B19 infection?
- Hepatitis
- Severe anaemia
- Inflammation of heart muscle and cardiac failure
