THE ATRIA OF THE FETAL LATERAL VENTRICLES - A SONOGRAPHIC STUDY OF NORMAL ATRIAL SIZE AND CHOROID-PLEXUS VOLUME

OBJECTIVE. Evaluation of the cerebral ventricular system is a routine part of all fetal sonographic examinations. Ventriculomegaly and decre ased choroid volume are indicators of poor fetal outcome, so it is imp ortant to know the normal variation of these parameters, The present s tudy describes the normal size of the fetal lateral ventricular atrium and the normal amount of choroid plexus within the atrium during the second and third trimesters. SUBJECTS AND METHODS. Six hundred eight c onsecutive, healthy, singleton fetuses from 13 to 42 weeks' menstrual age were examined prospectively, The atrium of the lateral ventricle w as measured in the axial and coronal planes. For each axial measuremen t, the width of the choroid plexus was determined. RESULTS, An axial a trial measurement was obtained in 88% of the fetuses, and a coronal at rial measurement was obtained in 84%, The mean measurement and one sta ndard deviation are 6.5 +/- 1.5 mm in the axial plane and 6.6 +/- 1.5 mm in the corona[ plane, Ninety-eight percent of all measured atria we re at least 60% filled by choroid plexus, and in all cases the atria w ere at least 50% filled, Complete filling by choroid plexus occurred i n 58% of cases. CONCLUSION. This large prospective study confirms prev ious observations of mean atrial size, However, four standard deviatio ns above the mean is 12 mm, suggesting currently used cutoffs for norm al atrial size are too low. Other parameters, such as choroid plexus f illing, may be helpful markers of normalcy in fetuses with atrial meas urements between 8 and 12 mm.