This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in obstetrics, Subject name: Gynaecology & Obstetrics
Increased acidosis and hypoxaemia is associated with : 
Select and explain. 
A. Normal Doppler wave form, B. Increased fetal diastolic flow in the middle cerebral aery with absent diastolic flow in the aoa, C. Presence of the notch' in the uterine aery, D. absent umbilical aery
B: Increased fetal diastolic flow in the middle cerebral aery with absent diastolic flow in the aoa
Answer: B: Increased fetal diastolic flow in the middle cerebral aery with absent diastolic flow in the aoa 
Explanation: MIDDLE CEREBRAL AERY DOPPLER Normally,middle cerebral vessels have a very little diastolic flow and hence an increased resistance .A brain sparing effect is seen in IUGR with a reduction in the resistance indices in the middle cerebral vessels due to shunting of blood to brain in IUGR.This occurs after umbilical aery flow becomes abnormal and is called cephalisation of flow.Once the middle cerebral aery flow is abnormal the fetal outcome is worse and is indication for delivery.In fetal anemia due to Rh isoimmunisation the peak systolic velocity in the middle cerebral aery is increased. TEXTBOOK OF OBSTETRICS,SHEILA BALAKRISHNAN,Pg no:513,2nd edition