This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetus, Subject name: Gynaecology & Obstetrics
IUGR cannot be detected by USG using : 
Select and explain. 
A. Estimated Fetal weight, B. BPD, C. SDP, D. Head circumference
C: SDP
Answer: C: SDP 
Explanation: Ultrasound is the best method to diagnose IUGR not only to diagnose the growth restriction but also to identify a fetus of symmetrical or asymmetrical one. The biometric measures are: Biparietal diameter Head circumference Femur length Abdominal circumference Estimated fetal weight HC/AC and FL/AC ratio Above all AC is the single most sensitive parameter to detect IUGR. TEXT BOOK OF OBSTETRICS,Sheila Balakrishnan,2nd edition,page no.204,205.