Evolving understanding and treatment of labour dystocia.

The objective of the review is to critically review the diagnosis and management of dystocia in the first stage of labour. We conducted a narrative review of research since 1998. Eight studies were identified, four about the onset and duration of active phase of the first stage of labour, one on the diagnosis of dystocia, and three focused on the treatment of dystocia. The review demonstrates that current understandings of dystocia rest on outdated definitions of active first stage of labour, its progress and on treatments with an equivocal evidence base. These include the cervical dilatation threshold for active first stage, uncertainty over whether a reduced rate of dilatation and reduced strength of uterine contractions always represent pathology and the effectiveness of amniotomy/oxytocin for treating dystocia. Prospective studies should evaluate the impact of defining the active phase of the first stage of labour as commencing at 6 cm dilated and should test this definition in combination with Zhang's revised partogram.