Distal lateral ventricular atrium: reevaluation of normal range.
OBJECTIVE
To reassess the mean size of the lateral cerebral ventricular atrium in the fetus.


METHODS
Measurements were obtained from axial ultrasound (US) images of 500 fetuses by using the standard criteria, and they were reviewed for consistency. Eleven fetuses had ventricular atrial measurements of 10 mm or more, and they were also followed up. Postnatal evaluation consisted of US examinations of the head in three patients and clinical examination of all 11 patients.


RESULTS
The mean size of the ventricular atrium was 6.6 mm with a standard deviation (SD) of 1.4 mm. However, the mean plus 2.5 SD would yield an upper normal limit of 10.1 mm. Findings at the postnatal examinations of the 11 fetuses with isolated lateral ventriculomegaly (three with measurements of 13 mm or less and eight with measurements at 10 mm) were normal.


CONCLUSIONS
Use of 10 mm (mean from this study plus 2.5 SD) as the upper limit of normal for the ventricular atrial measurement should be continued. Measurements of 10 mm or above should prompt a careful search for associated fetal abnormalities and consideration of amniocentesis.
Alagappan
R
R
Department of Radiology, University of California Davis Medical Center, Sacramento 95817.
Browning
P D
PD
Laorr
A
A
McGahan
J P
JP
D001927:Brain Diseases / Q000000981:diagnostic imaging; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging* / Q000196:embryology; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D012016:Reference Values; D016216:Ultrasonography, Prenatal