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
[{'content': 'A primigravida is posted for cesarean section due to insufficient pelvis. Pelvic inlet usually is considered to be contracted, when: \nSelect and explain. \nA. The shoest anteroposterior diameter is less than 10 cm, B. The greatest transverse diameter is less than 12 cm, C. Diagonal conjugate of less than 11.5 cm, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The pelvic inlet usually is considered to be contracted if its shoest anteroposterior diameter is less than 10 cm or if the greatest transverse diameter is less than 12 cm. The anteroposterior diameter of the inlet is commonly approximated by manually measuring the diagonal conjugate, which is approximately 1.5 cm greater. Therefore, inlet contraction usually is defined as a diagonal conjugate of less than 11.5 cm. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 20. Abnormal Labor. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.', 'role': 'assistant'}]