Book of Medical Disorders in Pregnancy - Tintash

Chapter No: 16
X-Ray Pelvimetry - X-Ray Pelvimetry
is a valuable aid in predicting the course
of labour by providing assessment of
tube pelvic capacity. This can be possible
if the procedure is performed by an
experienced person who is fully aware of
the danger of radiation to the fetus and,
the films are interpreted jointly by the
obstetrician and the radiologist.
Fig16.1: Shows X-ray of pelvis AP
views.
There is considerable danger of exposing
the fetus and the maternal gonads to the
hazards of radiation therefore this
examination should be done with great
reservation and only when absolute
indications are present. Certain clinical
circumstances can point to the
probability of pelvic contraction or potential
dystocia. It is only in such cases
that the X-Ray pelvimetry should be
done. The type of pelvis and measurements
of its diameters, the size of the
fetal head, its presentation and position
can all be determined with this method.
This information is very vital for the
obstetrician in making decision for a safe
vaginal delivery. With this information
at hand the physician is forewarned and
therefore forearmed to deal with
problems arising due to faults in pelvic
capacity. He can avoid unnecessary use
IMMAGING IN PREGNANCY
206
of oxytocin to correct faults of forces
and thus stop trial of labour at proper
time.
There is no place for routine pelvimetry
in modern obstetrical practice. The
student must appreciate that; for a full
radiological pelvimetry four films are
taken i.e. one lateral film in standing
position, the supero-inferior view of the
brim (Thom's view), the anteroposterior
view and the subpubic arch or outlet
view. Generally Thom's superoinferior
view is not taken in routine pelvimetry,
this helps to reduce the amount of
radiation.
Since the information provided by good
radiographs of the pelvis can be of great
help in the conduct of a trial of labour or
of a trial of forceps, pelvimetry has a
definite place in cases where genuine
indication is present.
It provides opportunity for measurement
of various pelvic diameters which can
not be determined by other means.
Measurement of transverse dia-meter of
the inlet and the antero-post-erior Nd
interspinous diameters of the mid pelvis
and the outlet is very im-portant since it
is at these points where the arrest in
progress of labour usually occurs and
their precise me-asurement can be very
helpful in guiding the phy-sician, who is
contemplating difficult forceps operation.
In any given case the progress of labour
can be predicted on the basis of the size
and shape of the bony pelvis, the size of
the fetal head; the force of the uterine
contraction and the presentation and