Cephalopelvic Disproportion (CPD): Causes, Signs and Management

Cephalopelvic Disproportion is anatomical disproportion between fetal head and maternal pelvis. It may be as a result of big head, small pelvis or combination of both.

It occurs when the head of the fetus does not fit in to the mother’s pelvis or a delivery condition in which the mother’s pelvis is too small or too misshapen to allow the fetal head to pass through. It can be classified as mild, moderate or severe.

Causes of CPD

These may be divided into maternal and fetal causes.

Maternal causes

• Women of small stature less than 1.6m leading to jus to minor pelvis.
• Type of pelvis e.g., android pelvis
• Congenital or acquired pelvic abnormalities e.g. fractured pelvis, contracted pelvis
• Pelvic tumors, e.g. fibroids

Fetal Causes

• Fetal abnormality like obstructive hydrocephalus
• Fetal macrosomia(big baby)
• Malposition e.g. occipito-posterior position leading to deflexion of the head with larger diameter presenting.
• Malpresentations: Face or brow presentation

Contracted Pelvis

This is when the one or more pelvic diameters are reduced by1 centimeter or more centimeters.

Signs of contracted pelvis

• In multigravida, prolonged and difficult labour with history of still births, instrumental delivery and neonatal deaths
• In primigravida – pendulous abdomen
• Woman is small – under 150 cm with short fingers and small feet
• Bony deformity of spine , hip and leg
• Pelvic assessment will reveal contracted pelvis

Degrees of contracted pelvis

• Mild: Where the anterior parietal bone is at level with symphysis pubis.
• Moderate: The head slightly overlaps at the edge of the
  pubis
• Severe:  The head bulges over the symphysis pubis

Signs of CPD

• Slow progress or actual arrests despite good uterine contraction.
• Failure of the fetal head to engage
• During vagina examination there is severe moulding and excessive caput.
• Presenting part is poorly applied to the cervix.

Methods of Determining Cephalopelvic Disproportion

• Determining the degree of overlap by placing the fingers on the symphysis pubis while pressing the head down and with the other.
• Head fitting – Sitting patient up method – patient lies on the bed. Place the patient to set up by her own effort. The effort should force the head into the pelvis and the midwife will feel its slip past her hand.
• Head filling – left hand grip method – Grasp head with left hand and    push it downward and backward if a sense of “giveness” felt there is no overlap or C.P.D.

Management of CPD

• In mild to moderate CPD augmentation of labour with oxytocin is carried out in a primigravida in a setting with facility for caesarian section. That’s trial of labour.
• Augmentation must not be used in a multiparous woman with suspected CPD
• Caesarean section is carried out in severe CPD or in a multiparous woman.