Prenatal screening for microcephaly: an update after three decades.

Area of Science:

• Obstetrics and Gynecology
• Fetal Medicine
• Diagnostic Imaging

Background:

• Recent Zika virus outbreaks have increased focus on fetal and neonatal microcephaly.
• Established 1984 criteria for prenatal microcephaly diagnosis (≤3 standard deviations from mean) lack recent reevaluation.
• Modern ultrasound technology has advanced significantly since the original criteria were proposed.

Purpose of the Study:

• To assess the applicability of the 1984 Chervenak et al. microcephaly diagnostic criteria.
• To evaluate these criteria using current ultrasound technology and patient populations.
• To determine if reevaluation is necessary given medical advancements.

Main Methods:

• Retrospective analysis of 27,697 ultrasound examinations.
• Data collected from 18 to 40 weeks' gestation.
• Comparison of current gestational age-specific mean head circumference and standard deviations with 1984 data.

Main Results:

• No statistically significant differences were found in gestational age-specific mean head circumference between the current and historical datasets.
• Standard deviations differed due to the larger size of the current dataset.
• The 1984 criteria for microcephaly diagnosis were found to be applicable.

Conclusions:

• The 1984 ultrasound criteria for diagnosing microcephaly are still considered valid.
• Clinicians can utilize the established 3 standard deviation cutoff.
• Alternatively, new population-specific datasets with statistical validation can be developed.