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Qualitative and quantitative study of fetal posterior fossa during the first trimester in a Chinese population
Li Feng1,2, Lijuan Sun1,2, Jingjing Wang1,2
1Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, P. R. China.
Insights
This study establishes normal reference ranges for fetal posterior fossa parameters in the first trimester Chinese population. Measurements of cisterna magna (CM), intracranial translucency (IT), brain stem (BS), and brain stem to occipital bone (BSOB) correlate with crown-rump length (CRL).
Area of Science:
- Prenatal imaging and fetal development
- Obstetrics and Gynecology
- Medical Ultrasound
Background:
- First-trimester ultrasound screening is crucial for fetal development assessment.
- Establishing normative data for fetal posterior fossa parameters is essential for early detection of abnormalities.
- Limited data exists for the Chinese population regarding these specific measurements.
Purpose of the Study:
- To determine normal reference ranges for fetal posterior fossa parameters in the first trimester among the Chinese population.
- To analyze the correlation between these posterior fossa parameters and crown-rump length (CRL).
Main Methods:
- A cohort of 1663 singleton pregnancies in the first trimester (11–13+6 weeks) with Chinese parents was studied.
- Measurements of cisterna magna (CM), intracranial translucency (IT), brain stem (BS), brain stem to occipital bone (BSOB), and BS/BSOB were performed.
- Reproducibility was assessed through intra- and inter-operator measurements.
Main Results:
- High intra- and inter-operator reproducibility was achieved for all measured parameters (ICCs ranging from 0.772 to 0.991).
- Linear correlations were observed between CRL and CM, IT, BS, and BSOB.
- Specific regression equations were derived for CM, IT, BS, BSOB, and BS/BSOB in relation to CRL.
Conclusions:
- Quantitative assessment of the fetal posterior fossa is feasible and reliable in the first trimester.
- Normal reference ranges for CM, IT, BS, BSOB, and BS/BSOB were established for the Chinese population.
- CM, IT, BS, and BSOB show positive correlation with CRL, while BS/BSOB exhibits a negative correlation.
Background:
To establish the normal reference ranges for parameters related to the fetal posterior fossa in the first trimester (11 ~ 13+6 weeks of gestation) and to analyze the relationship between them and crown-rump length (CRL) among the Chinese population.
Methods:
Singleton pregnancies of 11 ~ 13+6 weeks (CRL:45 ~ 84 mm) with both parents from China were randomly selected from January 2021 to November 2021. The related parameters of the posterior fossa including cisterna magna (CM), intracranial translucency (IT), brain stem (BS), brain stem to the occipital bone (BSOB), and brain stem/brain stem to occipital bone (BS/BSOB) were evaluated and measured in nuchal translucency (NT) mid-sagittal section clearly by an experienced sonographer (operator 1). To assess the reproducibility of the measurements, we randomly selected 50 pregnant women. According to the blind method, operators 1 and 2 respectively screened and measured relevant parameters. In addition, operator 1 examined and measured relevant parameters again 2 h after the first.
Results:
This study included 1663 fetuses. All fetuses can clearly show the three spaces of the fetal posterior fossa. The ICCs (95% CI) of intra-operator reproducibility of CM, IT, BS, BSOB, BS/BSOB were 0.981 (0.952 ~ 0.991, P < 0.001), 0.929 (0.866 ~ 0.961, P < 0.001), 0.970 (0.946 ~ 0.983, P < 0.001), 0.991 (0.974 ~ 0.996, P < 0.001), 0.939 (0.892 ~ 0.965, P < 0.001), respectively; The ICCs (95% CI) of inter-operator reproducibility 0.926 (0.860 ~ 0.960, P < 0.001), 0.810 (-0.083 ~ 0.940, P < 0.001), 0.820 (0.645 ~ 0.904, P < 0.001), 0.804 (0.656 ~ 0.888, P < 0.001), 0.772 (0.599 ~ 0.871, P < 0.001), respectively. There was a linear correlation between CRL and the parameters related to the posterior fossa (CM, IT, BS, BSOB, BS/BSOB). CM (mm) = -1.698 + 0.532 × CRL (cm) (r = 0.829, P < 0.001); IT (mm) = 0.701 + 0.179 × CRL (cm) (r = 0.548, P < 0.001); BS (mm) = 0.403 + 0.349 × CRL (cm) (r = 0.716, P < 0.001); BSOB (mm) = -0.277 + 0.719 × CRL (cm) (r = 0.829, P < 0.001); BS/BSOB = 0.747-0.021 × CRL (cm) (r = 0.196, P < 0.001).
Conclusions:
Qualitative and quantitative assessment of the fetal posterior fossa structure was feasible in the first trimester. We constructed the normal reference ranges of CM, IT, BS, BSOB, and BS/BSOB. Furthermore, CM, IT, BS, and BSOB were positively correlated with CRL, but BS/BSOB was negatively correlated with CRL.
