This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetal Skull and Maternal Pelvis, Subject name: Gynaecology & Obstetrics
Smallest diameter of p elvis is? 
Select and explain. 
A. Interspinous diameter, B. True conjugate, C. Diagonal conjugate, D. Intertuberous diameter
A: Interspinous diameter
Answer: A: Interspinous diameter 
Explanation: ANSWER: (A) Interspinous diameterREF: Clinical Obstetrics 10th edition by S. Gopalan, Sarala & Jain, Vanita Page 4, Manual of Obstetrics, 3e by Shirish N Daftary Page 11-12, Manual Of Obstetrics (2Nd Edition) by Daftary Page 16-18"Interspinous diameter (transverse diameter of midpelvis = 10 cm or somewhat more) is the smallest diameter of pelvis" REF: Williams's obstetric 22nd edition page 34Measurements of Pelvis AnterioposteriorObliqueTransverseInletTrue conjugate11 cm12 cm13 cmObstetric conjugate10.5 cmDiagonal conjugate12 cmMid pelvisPlane of greatest dimension12 cm12 cm12 cmPlane of least dimension10 cm10 cm10 cm(interspinous)Outlet13 cm12 cm11 cmShortest anteroposterior diameter of inlet of pelvis is obstetrical conjugateInterspinous diameter, 10 cm or somewhat more, is usually the smallest diameter of the pelvisPelvic inlet is an adequate size for a normal fetus if the diagonal conjugate is 12 cm or greater