This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
All of the following are ultrasonographic fetal growth parameters except : 
Select and explain. 
A. Biparietal diameter, B. Head circumference, C. Transcerebeller diameter, D. Femur length
C: Transcerebeller diameter
Answer: C: Transcerebeller diameter 
Explanation: Ans. is c i.e. Transcerebellar diameter Ultrasonographic 'fetal measurements' commonly used are : -- Crown Rump length Biparietal diameter -- Head circumference Abdominal circumference -- Femur length. All the parameters given above are : Primary biometric parameters. Transcerebeller diameter is a Secondary biometric parameter. Other secondary biometric parameters are : -- Binocular distance -- Cerebellar distance Clavicle length -- Radius length Ulnar length -- Tibia length Foot length. Best parameter for dating of pregnancy - Measurement of CRL in 1st trimester. Most sensitive parameter for assessment of fetal growth is abdominal circumference. Best age for assessment of gestation age in second trimester 14-20 weeks. Prediction of fetal gestational age using ultrasound biometric parameters