The measurements of the pelvic outlet can be described using the following diameters:

Anatomical anteroposterior diameter
- From: inferior border of the pubic symphysis, inferior pubic ligament
- To: tip of the coccyx
- Average length: 4.3 inches (11 cm)
Obstetric anteroposterior diameter
- From: inferior border of the pubic symphysis, inferior pubic ligament
- To: sacrococcygeal symphysis (the coccyx moves backward during the second stage of labor)
- Average length: 5.1 inches (13 cm)

Please note that anteroposterior dimeters can vary significantly due to the mobility of the coccyx.

Transverse (intertuberous, bituberous) diameter
- Between: inner aspects of the ischial tuberosities
- Average length: 4.3 inches (11 cm)

In males, all these diameters are slightly shorter relative to body size compared to females. The measurements of the female pelvis are important in pelvimetry, and these diameters increase during labor to ease the delivery of the fetus through the pelvic outlet.

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Pelvic outlet diameters