Shoest diameter of true pelvis amongst the following is: September 2008
**Core Concept**
The true pelvis is the part of the pelvis that forms the pelvic cavity, which is the space where vital organs such as the bladder, rectum, and reproductive organs are located. The dimensions of the true pelvis are critical in obstetrics to determine the ease of vaginal delivery.
**Why the Correct Answer is Right**
The shortest diameter of the true pelvis is the interspinous diameter, which is the distance between the ischial spines. This diameter is significant because it is the smallest diameter of the pelvis and is often used to determine the pelvic capacity for vaginal delivery. The interspinous diameter is approximately 10-12 cm in adults and is an important consideration in obstetrics to assess the potential for cephalopelvic disproportion.
**Why Each Wrong Option is Incorrect**
* **Option A:** The ischial tuberosity diameter is larger than the interspinous diameter, typically measuring around 13-15 cm.
* **Option B:** The obstetric conjugate is the distance between the promontory of the sacrum and the symphysis pubis, which is typically around 10-12 cm, but it's not the shortest diameter of the true pelvis.
* **Option D:** The subpubic angle is an important consideration in obstetrics, but it's not a diameter and is not the shortest diameter of the true pelvis.
**Clinical Pearl / High-Yield Fact**
In obstetrics, the interspinous diameter is an important consideration in determining the potential for vaginal delivery, and a diameter of less than 10 cm may indicate cephalopelvic disproportion.
**Correct Answer: C. Interspinous diameter.**