26. Cephalopelvic disproportion and its consequences

Question 1

what is cephalopelvic disproportion (CPD)?

Answer 1

A disproportion in the size of the fetus relative to the maternal pelvis can result in failure to progress in the second stage
a subjective clinical assessment based on physical examination and course of labor

Question 2

potential etiologies of CPD?

Answer 2

fetal malposition, (persistent OT or OP position), fetal malpresentation (mentum posterior or brow presentation), macrosomia, small pelvis, or deformed pelvis (ex. pelvic trauma).

Question 3

what complications are seen in CPD?

Answer 3

1. increased incidence of peripartum sepsis for mother and baby
2. maternal- uterine rapture, pathologic retraction ring of Bandl, fistula formation (rare), pelvic floor injury
3. perinatal- caput succedaneum and molding, mechanical trauma such as nerve injury, fractures, and cephalohematoma

Question 4

what is a contracted pelvic inlet?

Answer 4

The pelvic inlet shortest AP diameter is <10cm or if the greatest transverse diameter is < 12cm

Question 5

what are the consequences of a contracted pelvic inlet?

Answer 5

Early spontaneous rupture of membrane, Delayed labor, abnormal presentation

Question 6

what is the most common pelvic contraction?

Answer 6

contracted midpelvis
because the capacity of the midpelvis is smaller than that of the inlet

Question 7

is disproportion between the fetal head and the pelvic outlet cause dystocia?

Answer 7

no, but it may play an important part in perineal tears.