Which of the following is called flat pelvis?

Appeared in: RIMS Nursing Officer - 2022

Explanation

The Platypelloid pelvis is anatomically defined as the 'flat pelvis'.
Its key feature is a pelvic inlet that is wide in the transverse diameter but significantly shortened in the anteroposterior (AP) diameter, giving it a flattened, kidney-like shape.
This shape is the least common, occurring in about 5% of women.
During labor, the fetal head must engage in a transverse position, which can lead to difficulty in descent and rotation, increasing the risk of obstructed labor and the need for cesarean delivery.

Option A: The Gynaecoid pelvis is the classic 'female' pelvis. Its inlet is round or slightly oval, which is the most favorable shape for a vaginal birth.
Option B: The Anthropoid pelvis has an oval-shaped inlet that is longer in the anteroposterior diameter than the transverse diameter. It is often associated with delivery in the occiput-posterior position.
Option C: The Android pelvis is the typical 'male' pelvis, characterized by a heart-shaped or triangular inlet and a narrow pubic arch. It is not favorable for vaginal delivery and is associated with labor dystocia.

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 types as background academic context rather than a clinical decision trigger.
Assessment of the pelvic shape (clinical pelvimetry) helps the obstetrician and nurse anticipate potential difficulties during labor and delivery.
A woman with a platypelloid or android pelvis is at a higher risk for cephalopelvic disproportion (CPD), where the fetal head is too large to pass through the pelvis, often necessitating a cesarean section.
Nurses should be vigilant in monitoring labor progress in women with non-gynaecoid pelvises, watching for signs of arrest of descent or failure to progress, and be prepared for potential interventions.

How to Approach the Question

First, identify the key term in the question: 'flat pelvis'.
Recall the Caldwell-Moloy classification, which categorizes the female pelvis into four main types based on the shape of the inlet.
Associate the descriptive term 'flat' with the anatomical characteristics of each pelvic type.
The term 'Platy' means flat or broad. Therefore, 'Platypelloid' directly relates to a flat pelvis.
Eliminate the other options: Gynaecoid (round, female-type), Android (heart-shaped, male-type), and Anthropoid (long oval).
Confirm that the Platypelloid pelvis has a shortened anteroposterior diameter and a wide transverse diameter, consistent with a 'flat' shape.

Concept Tested & Keywords

QGrCimzAH3qlK2_y1CG2G5

E6 Midwifery Obstetrics and Gynecology Nursing Sandeep Kaur p. 38-46

E6 Obstetrics Williams p. 16-32

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