- Serves to both support and protect the reproductive and other support organs. Its bones are ilium, ischium, pubis, sacrum and coccyx.
- For obstetrical purposes, the subdivisions are:
- False pelvis - the superior half, supports the uterus during late months of pregnancy and aids in directing fetus to the true pelvis.
- True pelvis - the inferior half, facilitates true delivery of fetus.
- Inlet - the entrance to the true pelvis or the upper ring of the bone through which the infant must pass to deliver vaginally.
- Outlet - the inferior portion of the pelvis, bounded in the back by the coccyx; greatest diameter is the antero-posterior part.
- Pelvic cavity - the space between the inlet and outlet. Its curve slows and control the speed of birth.
Internal Measurements are:
- Diagonal Conjugate - the distance between the anterior surface of the sacral prominence and the anterior surface of the inferior margin of the symphysis pubis; suggestive of antero-posterior diameter of inlet; it should be 12.5 cm to be adequate.
- True Conjugate/ Conjugate Vera - the distance between the anterior surface of the sacral prominence and posterior surface of the inferior margin of the symphysis pubis; to get this just subtract the usual depth of symphysis pubis from diagonal conjugate, it should be 10.5-11.0 cm.
- Ischial tuberosity diameter - the distance between ischial tuberosities or the transverse diameter of the outlet ; 11.0 measurement is adequate.
TYPES OF PELVIS:
Gynecoid - transversely rounded and slightly ovoid.
Android - angulated, resembles male pelvis round shaped.
Anthropoid - oval, wider anteroposterior diameter.
Platypelloid - flat anteroposterior diameter, wide transversely.
