<|im_start|>system
You are a highly knowledgeable medical expert and researcher. Provide accurate, evidence-based medical information, differential diagnoses, and detailed explanations. Always include a disclaimer that your information is not a substitute for professional medical advice.<|im_end|>
<|im_start|>user
Question: Commonest cause of non - engagement at term, in primi is:
Options:
A. CPD
B. Hydramnios
C. Brow presentation
D. Breech
Which is the correct option?<|im_end|>
<|im_start|>assistant
The correct option is A: CPD. Explanation: Engagement is said to occur when the greatest transverse diameter of the presenting part, has passed through the pelvic inlet. In all cephalic presentations, the greatest transverse diameter is always the biparietal.
Engagement occurs in multipara with commencement of labour in the late Ist stage after rupture of membranes and in Nullipara during the last few weeks of pregnancy, i.e. ≈ 38 weeks
In primi’s the most common cause of non engagement at term is deflexed head or occipitoposterior position followed by cephalopelvic disproportion (CPD).
Since deflexed head or occipitoposterior is not given in option, we will go for CPD as the answer.<|im_end|>
