Feasibility of combining anterior and posterior fontanelle acoustic windows for median sagittal plane in fetal cranial ultrasound scanning

Abstract

Objective To explore the feasibility of combining anterior and posterior fontanelle acoustic windows for fetal median sagittal plane cranial scanning in prenatal ultrasound.Methods From July 5 to August 25 in 2012,200 pregnant women in Huai'an First Hospital at 22 to 24 gestational weeks accepted transabdominal uhrasonography,with anterior fontanelle,longitudinal suture and posterior fontanelle as acoustic windows to obtain the median sagittal plane.In the mean time,ten aborted or induced fetuses (with malformations or maternal complications) underwent cranial ultrasound with the same acoustic windows.The successful rates of obtaining median sagittal plane were calculated.Data were analyzed by Chi-square test.Results (1) Among the ten aborted or induced fetuses,all median sagittal planes were successfully obtained through anterior,posterior fontanelle,or longitudinal suture alone.(2) Among the 200 cases of prenatal uhrasonography,the successful rate of obtaining median sagittal plane through posterior fontanelle alone was 76.0％(152/200),which was higher than that through anterior fontanelle alone [59.5％ (119/200),x2=12.5,P＜0.01].The successful rate was 95.5％ (191/200) when combining the anterior and posterior fontanelle,which was higher than that through anterior fontanelle or posterior fontanelle alone (x2 =74.3 and 31.1,both P＜0.01).The successful rate of obtaining median sagittal plane through posterior fontanelle was 67.3％ (65/102) in cephalic presentation,which was also higher than that through anterior fontanelle [37.3％ (38/102),x2 =14.3,P＜0.01].The successful rate was 88.8％ (87/98) through posterior fontanelle in non-cephalic presentation,which was similar to that through anterior fontanelle [82.7％(81/98),x2 =1.5,P＞0.05].When both anterior and posterior fontanelle applied,the successful rate in cephalic presentation was 9.8％ (10/102),lower than that in non-cephalic presentation fetuses [71.4％ (70/98),x2 =79.1,P＜0.01].Conclusions The successful rate in obtaining median sagittal plane through posterior fontanelle is higher than that through anterior fontanelle,and might be increased when both anterior and posterior fontanelle were used. Key words: Skull; Parietal bone; Cranial sutures; Foramen megnum; Ultrasonography,prenatal; Nervous system malformations