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| Evaluation of posterior fossa in normal fetuses at the 11~13+6 gestational weeks |
| LI Shun-zhen1, HU Xing-rong1, LI Qiang1, LIU Zhi-yi1, LI Yang2 |
| 1. The Central Hospital of Enshi Autonomous Prefecture, Enshi Hubei 445000, China;2. Department of Radiology, the Second Hospital of Shandong University, Jinan 250011, China |
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Abstract Objective: To establish the normal reference ranges of the posterior fossa structure in normal fetuses at the 11~13+6 gestational weeks. Methods: Two hundreds and thirty-eight normal fetuses at the gestational age 11 to 13+6 weeks were selected. Maternal and fetal factors were analyzed which would affect the posterior fossa’s appearance. The parameters of the posterior fossa were measured in mid-sagittal plane. We compared the parameters with the crown-rump length(CRL), used linear regression analysis to get the linear regression equation and drew scatter diagram. Thirty randomly selected cases were reviewed for intraobserver and interobserver reliability. Results: In the 238 normal fetuses, intracranial translucency was seen in 222(93%). The main factors influencing the image quality were obesity(n=13), fetal position(n=10), retroverted uterus(n=5) and cesarean scar(n=3). With increasing CRL, there was a significant increase in brain stem diameter, intracranial translucency diameter and brain stem-occipital bone diameter. The brain stem diameter-to-brain stem-occipital bone diameter ratio decreased with increasing CRL. Intraobserver intraclass correlation coefficients of BS, IT, BSOB were 0.621 3, 0.696 2 and 0.936 1. Intreobserver intraclass correlation coefficients of BS, IT, BSOB were 0.581 3, 0.812 5 and 0.960 1. Conclusions: To obtain clear fetal posterior fossa structures’ sonogram, we not only need to standardize the training of the ultrasound physician, but also need to avoid the influence of maternal and fetal adverse factors on image quality. The measurement of posterior fossa structures is reproducible, and it will be useful for the future of early pregnancy screening for fetal malformation.
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Received: 29 October 2014
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Corresponding Authors:
LI Yang
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2015, Vol. 26 
