Radiology
Parvovirus B19 Infection During Pregnancy
Built from Obstetric Imaging
What’s inside
11 sections · 70 slides
Overview
- Scope of this presentation
The virus and how it spreads
What parvovirus B19 is, who is already immune, and how often infection reaches the fetus.
- Parvovirus B19 and erythema infectiosum
- Parvovirus particles under the electron microscope
- Routes of transmission
- Period of infectivity
- 50%-60%
- Immunity and reinfection
- Attack rates after household and school exposure
- Risk of transmission to the fetus
- Incubation period and maternal illness
- Lacelike rash of erythema infectiosum
- Aplastic crisis
What the virus does to the fetus
How parvovirus B19 crosses the placenta, stops red cell production, and strains the fetal heart.
- Transplacental transmission
- Pathophysiology of fetal parvovirus B19 infection
- P antigen as the viral receptor
- Red blood cell precursors
- Fetal myocarditis and cardiomyopathy
- Natural course of fetal infection
- Congenital malformations
Hydrops fetalis
The most obvious and most serious manifestation, what it looks like on ultrasound, and how the risk changes with gestational age.
- Hydrops fetalis: definition
- Fluid collections that define hydrops fetalis
- Ultrasound appearances of fetal hydrops
- Fetal ascites on ultrasound
- Fetal pleural effusion on ultrasound
- Fetal skin edema on ultrasound
- Frequency of hydrops in affected pregnancies
- Risk of hydrops by gestational age at infection
- Intrauterine fetal death without hydrops
- Hydrops and fetal haematocrit
Confirming infection in the mother
Serologic tests, their limits, and how to read an IgM and IgG result.
- Serologic tests for maternal infection
- Limitations of parvovirus B19 serology
- Reading the maternal antibody result
- Interpretation of Maternal Serologic Findings
- “
Confirming infection in the fetus
Fetal blood and amniotic fluid testing, and the ultrasound surveillance that follows.
- Tests that confirm fetal infection
- Amniocentesis under ultrasound guidance
- Ultrasound surveillance schedule
- Grayscale ultrasound assessment
- Other causes of hydrops sought on the anatomic survey
Middle cerebral artery Doppler
The non-invasive test that detects fetal anaemia, the 1.5 MoM threshold, and how to measure it correctly.
- Amniotic fluid spectrophotometry in parvovirus anaemia
- Middle cerebral artery peak systolic velocity
- The 1.5 multiples of the median threshold
- Middle cerebral artery Doppler measurement
- Circle of Willis on colour Doppler
- Obtaining the correct plane for MCA Doppler
- Sample volume position and insonation angle
- MCA Doppler after previous intrauterine transfusion
- From an abnormal Doppler result to treatment
- Cordocentesis and its exception
Differential diagnosis of fetal hydrops
Immune and non-immune causes that must be excluded before hydrops is put down to parvovirus B19.
- Causes of fetal hydrops
- Immune hydrops
- Other causes of non-immune hydrops
Treatment
Intrauterine transfusion, the blood product used, and the platelet problem that goes with it.
- Intrauterine transfusion
- Blood product used for intrauterine transfusion
- Fetal thrombocytopenia during transfusion
- Transfusion or delivery
Outcome after intrauterine infection
What happens to babies who survive parvovirus B19 infection in the womb.
- Long-term outcome of survivors
- Neurodevelopmental outcome after intrauterine transfusion
What the referring physician needs to know
The four questions the clinician must answer, and the key points to carry away.
- Maternal blood type and indirect Coombs testing
- Maternal parvovirus B19 immunity status
- Determining the time of exposure
- Gestational age at the time of exposure
- Key points: the virus and its effects
- Key points: detection and treatment
- References
- References (continued)
- References (continued)
- References (continued)
- Suggested readings
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition