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
Which of the following is NOT true about amniotic fluid index (AFI)? 
Select and explain. 
A. It is calculated by adding the veical depths of the largest pocket in each of four equal uterine quadrants, B. Fluid restriction may lower the AFI, C. Significant hydramnios is defined by an index greater than 24 cm, D. There is steady increase in AFI after 36 weeks
D: There is steady increase in AFI after 36 weeks
Answer: D: There is steady increase in AFI after 36 weeks 
Explanation: Amniotic fluid index (AFI) is calculated by adding the veical depths of the largest pocket in each of four equal uterine quadrants. Significant hydramnios is defined by an index greater than 24 cm. Fluid restriction or dehydration may lower the AFI. Peak AFI is seen at approximately 32 weeks followed by a steady decline until 42 weeks. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 21. Disorders of Amnionic Fluid Volume. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.