<prompt> Which among the following is the smallest diameter of the pelvis in the midplane?Interspinous diameterTrue conjugateDiagonal conjugateInteuberous diameter  <response>: The smallest diameter of the midpelvis or midplane is the transverse or interspinous diameter 10cm or more which is between the two ischial spines. True conjugate obstetric conjugate is the distance between the midpoint of the sacral promontory to prominent bony projection in the midline on the inner surface of the symphysis pubis. Diagonal conjugate is the distance between the lower border of symphysis pubis to the midpoint on the sacral promontory. The transverse or inteuberous diameter is the distance between the inner borders of the ischial tuberosities. Ref: Clinical Obstretics 10Th Edn. By S. Gopalan, Sarala Jain, Vanita eds., 2005, Page 5; 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; Williamss obstetric, 22nd edition, Page 34 