CLINICAL ACTIONS:

According to SMFM recommendations, mild cerebral ventriculomegaly is identified on a prenatal ultrasound report when the atrium measures between 10-12 mm.  Next steps include

• Detailed anatomical study
• Refer for genetic counseling
• Consider diagnostic testing for aneuploidy
  • ACOG/SMFM  guidance recommends offering invasive testing using microarray in the setting of fetal structural anomalies seen on prenatal ultrasound
• Consider maternal toxoplasmosis and cytomegalovirus (CMV) testing regardless of whether the patient is aware of previous exposure
• Consider fetal MRI for detection of associated cortical anomalies or signs of cerebral infection
  • May be of less value if a patient has already had an ultrasound examination by a professional with expertise in fetal brain imaging on ultrasound
• Deliver based on standard clinical indications
• If no abnormal findings detected on thorough examination, prognosis is favorable and the newborn is expected to be normal
• Repeat ultrasound in the 3rd trimester, (30-34 weeks gestation)
  • Prognosis is better if measurement remains stable or improves/resolves
  • Serial ultrasounds unlikely to be helpful
• Antepartum fetal testing not likely to be beneficial
• Antiplatelet antibodies if intracranial hemorrhage also present

SYNOPSIS:

Mild/moderate ventriculomegaly may be seen in approximately 1% of fetuses. While mild cerebral ventriculomegaly may resolve or be of no consequence, clinical work-up is required to determine whether there is any physical obstruction, decreased cerebral volume or conditions that may alter production, reabsorption or cerebral spinal fluid (CSF) flow within the cerebral ventricles.  Measurements of the lateral cerebral ventricles are obtained from an axial plane at the level of the thalamic nuclei.

KEY POINTS:

• ‘Fetal cerebral ventriculomegaly’ is present if the atrial diameter is ≥10mm and the SMFM further refines this definition as follows
  • Mild: 10-12 mm
  • Moderate: 13-15 mm
  • Severe: >15 mm
• Ventriculomegaly is found in 0.15%-0.7% of chromosomally normal/euploid fetuses
• When isolated, the incidence of an abnormal karyotype is 3.8% although some centers report higher rates
• If patient opts for invasive testing, microarray is critical as copy number variants (CNVs) have been found in 8.3% of isolated cases following normal karyotype and were highly correlated with neurodevelopmental disorders
• Ventriculomegaly is also associated with genetic syndromes, brain malformations, feto-neonatal alloimmune thrombocytopenia and congenital infections
  • Often, no cause will be found
• Postnatal follow-up by pediatric neurologists and specialists should be considered
  • While children with a prenatal diagnosis of mild ventriculomegaly will overall have a very good prognosis, a few may still have abnormal neurodevelopment, dependent on associated anomalies and etiology
• When only one ventricle is mildly enlarged and there are no other findings, chromosomal work up is more likely to be normal
  • There is still a risk of congenital infections (8.2%) and additional brain abnormalities (5% prenatal and 6.4% postnatal), as well as a risk of neurodevelopmental delay of 5.9%

Learn More – Primary Sources:

Mild fetal cerebral ventriculomegaly: prevalence, characteristics, and utility of ancillary testing in cases presenting to a tertiary referral center

Copy Number Variations with Isolated Fetal Ventriculomegaly

ACOG Practice Bulletin No. 162: Prenatal Diagnostic Testing for Genetic Disorders

ACOG Practice Bulletin No. 226: Screening for Fetal Chromosomal Abnormalities

Society for Maternal-Fetal Medicine (SMFM) Consult Series #45: Mild fetal ventriculomegaly: Diagnosis, evaluation, and management

Fetal Mild Ventriculomegaly: Still a Challenging Problem

Perinatal and Long-term Outcome in Fetuses Diagnosed With Isolated Unilateral Ventriculomegaly: Systematic Review and Meta-analysis

Locate a genetic counselor or genetics services:

Genetic Services Locator-ACMG

Genetic Services Locator-NSGC

Genetic Services Locator-CAGC

Related ObG Topics: