[Contracted pelvis determined from a three-dimensional viewpoint--2 step X-ray pelvimetry]

Area of Science:

• Obstetrics and Gynecology
• Radiology
• Pelvic Anatomy

Background:

• Current definitions of contracted pelvis focus solely on the pelvic inlet.
• A three-dimensional perspective is crucial for accurately assessing contracted pelvis in Japanese women.

Purpose of the Study:

• To propose a refined definition of contracted pelvis using pelvic inlet area and sacral shape.
• To evaluate the diagnostic utility of pelviography in identifying contracted pelvis and guiding clinical decisions.

Main Methods:

• Analysis of 108 sets of superior-inferior and lateral pelviographs.
• Measurement of pelvic inlet area and assessment of sacral shape.
• Correlation of pelvic measurements with Cesarean section (c/s) rates and delivery outcomes.

Main Results:

• Pelvic inlet area > or = 110 cm² excludes contracted pelvis.
• Inlet area < 100 cm² indicates contracted pelvis with a high c/s incidence.
• Inlet area 100-110 cm² defines 'relative contracted pelvis,' requiring lateral pelviography to assess sacral deformity and guide delivery method.

Conclusions:

• A 3D approach incorporating pelvic inlet area and sacral shape improves contracted pelvis diagnosis.
• This method helps stratify risk and optimize delivery strategies, reducing unnecessary Cesarean sections.
• Accurate assessment of pelvic dimensions and sacral morphology is vital for predicting delivery outcomes.