Cytomegalovirus (CMV) in pregnancy

Definition

• Congenital cytomegalovirus infection results from intrauterine transmission of cytomegalovirus (CMV, human herpesvirus 5) from the pregnant woman to the fetus.

Classification

• A distinction is made between maternal primary infection and non-primary infection due to reactivation or reinfection with a different CMV strain.

Occurrence & epidemiology

Initial Situation

• The pathogen: cytomegalovirus (CMV), a herpesvirus.
• Significance: most common congenital infection.
• Particularly useful for: women with toddlers (<3y) & daycare staff.

Epidemiology

• CMV is regarded as the most common viral cause of congenital infection and the leading cause of non-hereditary sensorineural hearing loss in children.

Aetiopathogenesis

Transmission and Risk

• Main route of transmission to the pregnant woman: saliva and urine of young children.
• Greatest risk of severe fetal damage: maternal primary infection in 1st trimester.
• Probability of transmission to the fetus: rises with gestational age, severity falls.

Aetiology and pathogenesis

• The virus is found in saliva, urine, genital secretions, breast milk and blood, among others; children shed it intermittently in urine and saliva.
• After primary infection in the first trimester, the virus is transmitted in about 20%, and more than half of infected fetuses suffer severe permanent damage.

Clinical features

What is seen in the child

• Ultrasound findings: microcephaly, periventricular calcifications.
• Also possible: growth restriction, hepatosplenomegaly.
• Confirmation of fetal infection: CMV PCR from amniotic fluid (after infection).
• Most common long-term sequela in a seemingly healthy newborn: progressive sensorineural hearing loss.

Clinical features and complications

• In immunocompetent pregnant women, infection is usually asymptomatic or causes non-specific, flu-like symptoms.
• 85–90% of congenitally infected newborns are asymptomatic at birth.
• Typical sequelae, often not yet recognisable after birth, are hearing impairment, delayed growth, intellectual disability and microcephaly.

Diagnosis

• Primary infection is ideally demonstrated by seroconversion; low-avidity IgG antibodies indicate infection within roughly the preceding three months.
• Prenatally, fetal infection is best detected by PCR of amniotic fluid, which may be falsely negative if performed too soon after infection.
• In the newborn, PCR detection of the virus in saliva or urine is the most sensitive method, as CMV IgM is undetectable in up to 80%.

Keep learning in the app

Further reading (selection)

1. Robert Koch Institute, RKI-Ratgeber (German): Zytomegalievirus-Infektion
2. StatPearls: Congenital Cytomegalovirus Infection (NCBI Bookshelf)
3. DocCheck Flexikon, Zytomegalie

Cross-references