[Pelvimetry using computerized tomography. I. Theoretical and methodical fundamentals]

The first part of our article deals with the basic aspects of using computed tomography in obstetrical pelvimetry. A macerated osseous female pelvis was used to measure the true conjugate, the transverse plane of the pelvic inlet, the interspinous line and the distance between the ischial tuberosities. The same pelvis was then examined computed tomographically. A lateral and a posterior-anterior scan, and a single scan through the iliac spines were performed. The results of the direct measurement agreed highly with the values achieved computed tomographically if the phantom was positioned exactly on the mid-line of the examination-table, if not, the true conjugate was elongated. Measurements of the superficial and the intravaginal radiation dose in patients demonstrated a significantly lower risk in computed tomography than in conventional x-ray methods. We recommend computed tomography in obstetrics as a safe, accurate and reliable method.