A P diameter is maximum in which type of pelvis?
**Core Concept**
The pelvic diameter refers to the dimensions of the pelvis, which is a crucial factor in childbirth. The P diameter, specifically, is the interspinous diameter, measuring the distance between the ischial spines. This diameter is significant in obstetrics as it determines the passage of the fetal head during labor.
**Why the Correct Answer is Right**
The P diameter is indeed maximum in the android pelvis. This type of pelvis has a heart-shaped inlet, with the ischial spines being closer together. This configuration allows for a larger P diameter, which is essential for a smoother delivery process. The android pelvis is one of the four main types of pelvises, along with the anthropoid, platypelloid, and gynaecoid types.
**Why Each Wrong Option is Incorrect**
**Option A:** The anthropoid pelvis has a more oval-shaped inlet, which actually increases the anteroposterior diameter but not necessarily the P diameter.
**Option B:** The gynaecoid pelvis is considered the "female" pelvis, with a rounded inlet, but it does not necessarily have the largest P diameter.
**Option C:** The platypelloid pelvis has a flat, broad inlet, which increases the transverse diameter but not the P diameter.
**Clinical Pearl / High-Yield Fact**
Remember that the type of pelvis can significantly affect the delivery process. A larger P diameter in an android pelvis can facilitate a smoother delivery, but an abnormally small P diameter in other types of pelvises can lead to complications.
**Correct Answer:** D. Android pelvis.