Which among the following is the smallest diameter of true pelvis?
Interspinous or bispinous diameter is the distance between the tip of the two ischial spines. It measures 10.5 cm. Diagonal conjugate is the distance between the lower border of symphysis pubis to the midpoint on the sacral promontory. It measures 12 cm. True conjugate or anatomical conjugate or conjugate vera is the distance between the midpoint of the sacral promontory to the inner margin of the upper border of symphysis pubis. It measures 11 cm. Inteuberous diameter is the distance between the inner borders of ischial tuberosities. It measures 11 cm. Ref: Textbook of Obstetrics by D C Dutta, 6th edition, Page 91.
Interspinous diameter
Diagonal conjugate
True conjugate
Inteuberous diameter