Cephalopelvic disproportion

1. Big picture

Cephalopelvic disproportion (CPD) means the fetal presenting part, usually the head, is too large, poorly positioned, or poorly adapted to pass safely through the maternal pelvis.

The examiner wants you to think clinically:

CPD is suspected when labour does not progress despite adequate contractions, especially with poor descent, increasing caput, moulding, and fetal/maternal distress.

The key danger is treating mechanical obstruction as weak labour.

Slow labour
   ↓
Assess contractions
   ↓
Adequate contractions + no descent/progress
   ↓
Think CPD or malposition
   ↓
Do NOT blindly give oxytocin
   ↓
Senior review → operative delivery, usually c