obstetric conjugate

true conjugate

[TA]
the diameter that represents the shortest diameter through which the head must pass in descending into the superior strait and measures, by means of x-ray, the distance from the promontory of the sacrum to a point on the inner surface of the symphysis a few millimeters below its upper margin.

ob·stet·ric con·ju·gate

(ob-stet'rik kon'jŭ-găt)
The shortest diameter through which the fetal head must pass in descending into the superior strait; as measured by x-ray, the distance from the promontory of the sacrum to a point on the inner surface of the symphysis a few millimeters below its upper margin.
References in periodicals archive ?
T1 gradient echo sequences were taken to compare the positions in terms of the obstetric conjugate, sagittal outlet, and the interspinous, intertuberous, and transverse diameters.
The only measurement that was smaller in the squatting position, compared with the supine position, was the obstetric conjugate (12.