Contracted pelvis and disproportion

Abstract

A contracted pelvis is one in which either the shape or size is sufficiently abnormal to cause difficulty in the delivery of a normal-sized fetus. Disproportion is a term which embraces a wider group and indicates any disparity in size between the fetus and pelvis that will lead to difficulties in labour, or dystocia. Thus, even when the patient has a normal pelvis, disproportion will exist if the fetus presents by the brow, has hydrocephalus or is excessively large. A badly flexed occipito-posterior position may also cause disproportion.