Standardized method for comparing fetal size with the respective maternal pelvis
Fetal head & abd. circumference by USG
Maternal pelvic inlet & midpelvic circumference by X-ray pelvimetry
" Fetal - pelvic index " number based upon differences in the pelvis & fetal circumference.
Maternal pelvic dimensions & fetal abd. circumference were related to C/S for CPD.
c.f.) Fetal head circumference was not identified as a cause of dystocia.
3. Presentation & position of the fetus
Contracted pelvic inlet play an important part in the production of abnormal presentation
ex) In women with contracted pelvis.
Face & shoulder presentation : *3 inc
Prolapse of the cord and of the extremity : * 4~ 6 inc
4. Course of labor
Course of labor is prolonged, often, effective labor is never achieved.
--> result in serious maternal & fetal effects.
5. Maternal effect
1) Abnormalities in dilatation of the cervix
Normally, at unrupture membrane, hydrostatic action --> facilitated cervical dilatation.
after rupture, by direct application of the P.P. against the cervix.
Contracted pelvis --> early SROM
--> absence of pressure by fetal head against the cervix & lower ut. segment.
--> less effective ut. contraction
--> cervical dilatation may proceed very slowly or not at all
Cervical response to labor provides a prognostic view of the outcome of labor in women with inlet
contraction.
2) Danger of Uterine rupture
Pathologic retraction ring
: felt as a transverse or oblique ridge extending across the uterus somewhere between the
symphysis & the umbilicus.
: danger of ut. rupture --> prompt delivery or C/S
3) Production of fistula
P.P dose not advance --> excessive pressure to pelvic wall --> impaired circulation