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
In the pelvic inlet, which is the shoest anteroposterior diameter? 
Select and explain. 
A. True conjugate, B. Obstetric conjugate, C. Anatomical conjugate, D. Bispinous diameter
B: Obstetric conjugate
Answer: B: Obstetric conjugate 
Explanation: Ans: B. Obstetric conjugate In pelvic inlet shoest anteroposterior diameter - Ostetric conjugate (10 cm).Pelvic inlet:Four diameters:Anteroposterior, transverse & two oblique diameters.Anteroposterior diameter:Distinct with specific landmarks.Most cephalad - Hence, true conjugate.Extends from upper- most margin ofthe symphysis pubis to sacral promontory.Clinically impoant obstetrical conjugate is shoest distance between the sacral promontory and the symphysis pubis. Normally 10 cm or more.