The shape of the brim in anthropoid pelvis is?

Appeared in: AIIMS Patna NO - 2020

Explanation

The anthropoid pelvis is defined by its oval-shaped brim.
This oval shape is elongated in the anteroposterior (front-to-back) diameter, distinguishing it from other pelvic types.
The transverse diameter is shorter than the anteroposterior diameter.
This pelvic shape is considered favorable for vaginal delivery and is found in about 25% of women.

Option A: A triangular or heart-shaped brim with the base towards the sacrum is characteristic of the android pelvis, not the anthropoid pelvis.
Option B: Square is not a shape used in the standard Caldwell-Moloy classification of pelvic types.
Option C: A well-rounded or round brim is the defining feature of the gynecoid pelvis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Caldwell-Moloy classification of pelvic shapes as background academic context rather than a clinical decision trigger.
Assessing the pelvic shape helps nurses and obstetricians anticipate the mechanism of labor and potential for dystocia (difficult labor).
An anthropoid pelvis, while generally favorable, often leads to the fetus engaging in an occiput-posterior (OP) position. Nurses should be prepared to assist with maternal positioning changes (e.g., hands and knees) to facilitate rotation to an occiput-anterior (OA) position.
What if? If a woman has a platypelloid pelvis, the fetal head may have difficulty engaging because the anteroposterior diameter is short. This often leads to a transverse arrest of labor, requiring a cesarean section.

How to Approach the Question

First, identify the key terms in the question: 'shape of the brim' and 'anthropoid pelvis'.
This is a direct recall question that requires knowledge of the anatomical classification of the female pelvis.
Recall the four main pelvic types described by Caldwell and Moloy: Gynecoid, Android, Anthropoid, and Platypelloid.
Mentally associate the characteristic brim shape with each type: Gynecoid (round), Android (heart/triangular), Anthropoid (long oval), and Platypelloid (flat oval).
Compare the options to your recalled knowledge. 'Oval' directly matches the description of the anthropoid pelvis.
Eliminate the other options: 'Triangular' is Android, 'Well-rounded' is Gynecoid, and 'Square' is not a standard type.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 16-32

E6 Midwifery Obstetrics and Gynecology Nursing Sandeep Kaur pp. 38-46, 37-45

Practise the full AIIMS Patna NO - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.