What is the diagonal conjugate in obstetrics?

What is the diagonal conjugate in obstetrics?

• A. Measurement to see pelvis is adequate for vaginal delivery
• B. Measurement of fetal heart rate
• C. Measurement of pelvic width
• D. Measurement of cervix dilation

Answer: (A)

The diagonal conjugate is a pelvic inlet measurement used to judge whether the birth canal is adequate for vaginal delivery. It is measured transvaginally from the inferior border of the pubic symphysis to the sacral promontory, and it estimates the obstetric (true) conjugate—the smallest anteroposterior diameter the fetal head must pass through during labor. A larger diagonal conjugate suggests more space for the head to descend, supporting a vaginal delivery plan, while a smaller measurement raises concern for cephalopelvic disproportion. This concept is distinct from fetal heart rate, general pelvic width in other planes, or cervical dilation, which are not assessed by this measurement.

The diagonal conjugate is a pelvic inlet measurement used to judge whether the birth canal is adequate for vaginal delivery. It is measured transvaginally from the inferior border of the pubic symphysis to the sacral promontory, and it estimates the obstetric (true) conjugate—the smallest anteroposterior diameter the fetal head must pass through during labor. A larger diagonal conjugate suggests more space for the head to descend, supporting a vaginal delivery plan, while a smaller measurement raises concern for cephalopelvic disproportion. This concept is distinct from fetal heart rate, general pelvic width in other planes, or cervical dilation, which are not assessed by this measurement.