True pelvis is also known as:
A. Android pelvis
B. Platypelloid pelvis
C. Gynecoid pelvis
D. Anthropoid pelvis
Correct Answer: C. Gynecoid pelvis
Explanation
True pelvis is also known as the lesser pelvis.
Explanation:
- The pelvis is divided into two parts:
- False pelvis (greater pelvis) – the upper, wider part above the pelvic brim.
- True pelvis (lesser pelvis) – the lower, narrow part below the pelvic brim.
- The true (lesser) pelvis:
- Contains the pelvic cavity
- Forms the birth canal in females
- Is clinically important in obstetrics because it determines whether the fetal head can pass during labor
👉 Therefore, true pelvis = lesser pelvis.
Other Options Details
These are the four classical types of female pelvis described by Caldwell and Moloy. Each type has characteristic shape and obstetric significance.
A. Android pelvis
- Shape: Heart-shaped pelvic inlet (similar to male pelvis)
- Anteroposterior diameter: Reduced
- Transverse diameter: Narrow
- Side walls: Convergent
- Ischial spines: Prominent
- Sacrum: Flat and inclined forward
- Obstetric significance:
- Unfavorable for vaginal delivery
- Commonly associated with deep transverse arrest and prolonged labor
- Frequency: ~20–30%
B. Platypelloid pelvis
- Shape: Flat, kidney-shaped inlet
- Anteroposterior diameter: Markedly reduced
- Transverse diameter: Increased (wide)
- Side walls: Wide
- Sacrum: Flat
- Obstetric significance:
- Engagement of the fetal head is difficult
- Head often enters in transverse position
- Frequency: Least common (~5%)
C. Gynecoid pelvis ✅ (Most favorable)
- Shape: Rounded pelvic inlet
- Anteroposterior diameter: Adequate
- Transverse diameter: Adequate
- Side walls: Straight
- Ischial spines: Not prominent
- Sacrum: Well curved
- Obstetric significance:
- Ideal pelvis for normal vaginal delivery
- Least obstetric complications
- Frequency: Most common (~50%)
D. Anthropoid pelvis
- Shape: Oval pelvic inlet (anteroposteriorly long)
- Anteroposterior diameter: Increased
- Transverse diameter: Narrow
- Side walls: Slightly convergent
- Sacrum: Long and deeply curved
- Obstetric significance:
- Occipito-posterior position common
- Vaginal delivery often possible
- Frequency: ~20–25%
Summary Table
Pelvis Type Inlet Shape Obstetric Outcome Gynecoid Rounded Best for normal delivery Android Heart-shaped Difficult labor Anthropoid AP oval OP position common Platypelloid Flat Engagement difficult
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Writer: Vandita Singh, Lucknow (GS India Nursing Group