Pelvimeter

Quick Answer: A pelvimeter is a calliper-type instrument for measuring external diameters of the pelvis between bony landmarks. It is used in midwifery, obstetrics and anatomy teaching to locate pelvic landmarks and demonstrate pelvic measurement.

External Pelvic Measurements

The instrument looks like a large pair of curved callipers with rounded tips, hinged at one end, with a graduated scale to read the distance between the tips. The external measurements usually taught are the interspinous diameter (between the anterior superior iliac spines), the intercristal diameter (the widest distance between the iliac crests) and the external conjugate, also called Baudelocque’s diameter. Some designs are made for the pelvic outlet, measuring between the ischial tuberosities.

External pelvimetry has limited value in predicting how labour will progress, and modern obstetric practice relies on clinical assessment and, where needed, imaging. It remains useful in teaching, because it makes students find and palpate the bony landmarks they will use throughout midwifery and anatomy.

Practise first on a female pelvis structural model, where landmarks are easy to see, before palpating landmarks on a classmate over clothing.

Specifications

Applications

• Midwifery and obstetric teaching on pelvic landmarks and diameters
• Anatomy practicals comparing male and female pelves on skeletal models
• Physical anthropology and anthropometry measurements
• Instrument identification in obstetrics viva sessions

Care & Handling

• Check that the hinge moves freely and the scale reads zero when the tips meet.
• Wipe the tips and arms with disinfectant between users.
• Store the pelvimeter closed in its case so the arms are not bent, which would make readings wrong.

Why Choose LabEquip

Nursing and midwifery schools, obstetrics departments and anatomy labs order this instrument for practical teaching. LabEquip lists it in the Biology Lab Products range; enquire about quantity and pattern through the contact page.

Frequently Asked Questions

What does a pelvimeter measure?

Distances between bony landmarks of the pelvis measured from outside the body, such as the interspinous and intercristal diameters and the external conjugate.

Is external pelvimetry still used in obstetrics?

It is used much less than in the past, because it predicts labour outcome poorly. It is still taught as a way of learning the pelvic landmarks.

Where are the tips placed for the interspinous diameter?

On the outer edges of the two anterior superior iliac spines, the bony points felt at the front of the hips.

What is Baudelocque’s diameter?

Another name for the external conjugate: the distance from the upper front edge of the pubic symphysis to the spinous process of the fifth lumbar vertebra.

Can the instrument be used on skeletal models?

Yes. Measuring a model or a skeletal pelvis is a good way to learn the landmarks and compare male and female pelvic shapes.

How do I check that it reads correctly?

Close the tips together and confirm the scale reads zero. If it does not, the arms may be bent, and readings will be offset.

Last Updated: September 2026