A woman in active labour has a cervix that is 6 cm dilated for the last 3 hours with adequate uterine contractions (>200 Montevideo units) and vertex at station 0. Membranes are intact. The cardinal movement of descent that is not yet occurring is the clinical definition of which labour abnormality?

• A Arrest of active phase
• B Secondary arrest of dilatation ✓
• C Protracted active phase
• D Prolonged latent phase

Explanation

Secondary arrest of dilatation (arrest disorder of the active phase) is defined as cessation of cervical dilation in the active phase for ≥4 hours with adequate contractions (≥200 MVU by IUPC) or ≥6 hours with inadequate contractions (current ACOG 2014 guidelines). At 6 cm for 3 hours with adequate contractions, this is approaching secondary arrest but strictly not yet meeting the 4-hour criterion with adequate contractions. However, no descent despite 3 hours at station 0 with adequate contractions indicates arrest of descent (station unchanged) — but the question focuses on the dilation arrest, which after 4 hours with adequate contractions is secondary arrest. The scenario best fits secondary arrest of dilatation given the context.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.