In which type of provis ala of both sides are absent:
A. Roberts pelvis
B. Kyphotic pelvis
C. Naegles pelvis
D. None of the above
Correct Answer: A. Roberts pelvis
Explanation
You’re asking: “In which type of pelvis are the alae (wings) on both sides absent?” Let’s break this down carefully.
- Understanding the terms:
- The ala (plural: alae) refers to the broad, wing-like lateral parts of the ilium, which are part of the pelvic bone. They are prominent in normal pelvic anatomy.
- In some abnormal pelvis shapes, these alae can be poorly developed or absent, affecting the shape of the pelvic inlet and the mechanics of childbirth.
- Types of female pelvis:
- Gynecoid: Most common, rounded/well-proportioned; alae present.
- Android: Heart-shaped, narrow; alae present.
- Anthropoid: Oval, elongated anteroposteriorly; alae present.
- Platypelloid: Flattened anteroposteriorly, wide transverse diameter; this is the type where the alae are very reduced or absent, leading to a flat, broad pelvic brim.
✅ Answer: Platypelloid pelvis – in this type, the alae of both sides are essentially absent or extremely reduced.
Why it matters:
- Absence or flattening of alae makes the pelvic inlet wide transversely but shallow anteroposteriorly.
- This can cause transverse arrest of the fetal head during labor because the head may not align properly in the shallow AP dimension.
Other Options Details
Here’s a detailed explanation of the pelvis types you’ve listed:
A. Robert’s Pelvis
- Definition: A rare type of contracted pelvis.
- Key Features:
- Severe anteroposterior (AP) shortening of the pelvis.
- Symphysis pubis is unusually high.
- Often associated with cephalopelvic disproportion (difficulty in vaginal delivery).
- Clinical Significance: Vaginal delivery is usually very difficult; often requires cesarean section.
B. Kyphotic Pelvis
- Definition: Pelvis affected due to spinal deformity, typically kyphosis of the lumbar spine.
- Key Features:
- Forward angulation of the sacrum, changing the pelvic inlet shape.
- Reduced anterior-posterior diameter.
- Clinical Significance: Can lead to malpresentation of the fetus (e.g., brow or face presentation) and difficult labor.
C. Naegele’s Pelvis
- Definition: A type of contracted pelvis, often considered a variety of platypelloid pelvis.
- Key Features:
- Transverse narrowing of the pelvic outlet.
- Often seen in rickets or skeletal deformities.
- Clinical Significance: May result in obstructed labor, particularly during the engagement of the fetal head.
D. None of the Above
- This option is usually included in multiple-choice questions to test recognition or exclusion if none of the listed options match a description or definition.
✅ Summary Table: Pelvis Type Main Feature Clinical Significance Roberts Severe AP shortening Vaginal delivery difficult Kyphotic Forward angulation of sacrum Malpresentation, obstructed labor Naegele’s Transverse outlet narrowing Obstructed labor None of the above – –
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Writer: Vandita Singh, Lucknow (GS India Nursing Group