Influence of Imaging Angle in Measurement of Cisterna Magna

Study Overview
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Brief Summary
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The aim of this study is to determine the effect of imaging angle on the measurement of fetal cisterna magna (CM) in the second trimester. Fetal CM will be prospectively measured in women at 18-24.6 weeks' gestation. Measurements will be made on different angles between the transducer and fetal cerebellar axial plane with internal landmarks. Design: Observative, cross sectional

Detailed Description
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Patients and methods: women with low risk single pregnancy will be studied. Fetuses with multiple pregnancies, maternal chronic disease and severe congenital anomalies except mega cisterna magna (MCM) will be excluded from the study. Measurements will be performed on the axial cerebellar plane.The anteroposterior measurement will be made between the posterior border of the cerebellar vermis and the internal face of the occipital bone. The primary outcome variables will be cisterna magna length measured on different angles between the transducer and the axial cerebellar plane of the fetal head. Cisterna magna length measurement related to fetal presentation and gender will be secondary outcomes.

Official Title
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Influence of Imaging Angle in Measurement of Cisterna Magna in the Second Trimester

Conditions
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Fetal Cisterna Magna Length, Ultrasonography

Intervention / Treatment
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* Diagnostic Test: Ultrasonographic Measurement on Fetal cisterna magna length


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant women between the 18th and 24th weeks. Confirmed gestational age by regular menstrual cycle or determined from crown- rump length at first trimester ultrasonography for those with unknown menstruation date . Exclusion Criteria: Uncertain gestational age Twin or multiple pregnancy. Increased risk for aneuploidy determined by first trimester screening. Absence of intracranial translucency in first trimester ultrasound examination. Fetal malformations identified EXCEPT megacisterna magna. Karyotype anomaly. Chronic maternal diseases such as arterial hypertension, diabetes mellitus, hypothyroidism and hyperthyroidism. Failure to obtain accurate measurement for technical reasons.
Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: Ultrasonographic Measurement on Fetal cisterna magna length|The length measurement on the fetal cisterna magna (CM) with an angle of 0° between the transducer and the axial cerebellar plane of the fetal head (midline structures will be perpendicular to the ultrasound beam). After that, CM will be measured again after moving the transducer approximately 30° towards the fetal occiput. Measurements will be performed on the axial cerebellar plane using internal landmarks including the cavum septi pellucidi, thalamus, third ventricle, cerebral peduncles and cerebellar hemispheres.The anteroposterior measurement will be made between the posterior border of the cerebellar vermis and the internal face of the occipital bone. All the ultrasonography examinations were performed abdominally, using 3-5 megahertz (MHz) transducers.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cisterna Magna length | The length measurement on the CM with an angle of 0° between the transducer and the axial cerebellar plane of the fetal head (midline structures will be perpendicular to the ultrasound beam). After that, CM will be measured again after moving the transducer approximately 30° towards the fetal occiput. Measurements of the anteroposterior diameter Will be obtained along straight lines between the posterior border of the cerebellar vermis and the internal face of the occipital bone. | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cisterna Magna length according to fetal presentation | The length measurement on the CM with an angle of 0° between the transducer and the axial cerebellar plane of the fetal head (midline structures will be perpendicular to the ultrasound beam). After that, CM will be measured again after moving the transducer approximately 30° towards the fetal occiput. Measurements will be made in fetuses with cephalic and breech presentation. Another measurement will be made in fetuses with cephalic presentation that had converted to breech presentation or viceversa in less than 24 hours. | 24 hours | 
| Cisterna Magna length according to fetal sex | The length measurement on the cisterna magna (CM) with an angle of 0° between the transducer and the axial cerebellar plane of the fetal head (midline structures will be perpendicular to the ultrasound beam). After that, CM will be measured again after moving the transducer approximately 30° towards the fetal occiput. Those measurements will be compare between male and female fetuses. | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cisterna magna length, ultrasound