Purpose
Projection of the relationship between fetal head and maternal pelvic bones.
Diagnosis of Cephalopelvic Disproportion (CPD).
Measurement of the maximum transverse and maximum anteroposterior diameters of the pelvic inlet.
Prior confirmation
Confirming patient’s understanding of radiation exposure levels.
Considering the lower-exposure Colcher-Sussman method or CT.
Remove any obstacles.
Positioning
Semisitting position (50-55°).
Align the external conjugate line (posterior edge of the pubic symphysis to L5 spinous process) parallel to the cassette.
Use a support device (backrest) or support the body with both hands.
Align the mid-sagittal plane with the central axis of the cassette.
Place the measurement ruler on the thigh in a position parallel to the cassette. Ideally, position the measurement ruler at the level of the upper margin of the pubic symphysis.
-> Alternatively, in the absence of the patient after imaging, place a centimeter grid at the height of the patient’s external conjugate line and perform double exposure.
Align the X-ray center with the cassette center.
CR, distance, field size
CR : Perpendicular entry directed towards a point 3 fingerwidths cranial from the greater trochanter in the medial sagittal plane.
Distance : 115-200 cm.
Field size : Includes iliac crest and measurement ruler.
Exposure condition
103kV / 30mAs
Grid ( + )
Full expiration
Image, check-point
Normal
Inability to observe bilateral obturator foramina.
Ischial spines are projected symmetrically on both sides.
Clear visibility of entrance anteroposterior diameter, interischial spine diameter, inlet transverse diameter, and fetal head with sufficient contrast.
The ruler markings are readable and distinguishable, with measurements of 10cm or more.
Absence of motion blur due to movement.
Videos
Related materials
