Deep transverse arrest occurs in which type of pelvis:
**Core Concept**
Deep transverse arrest is a type of fetal malpresentation during labor, where the fetal head is unable to progress beyond the ischial spines in the pelvis. This occurs due to a mismatch between the size and shape of the fetal head and the maternal pelvis.
**Why the Correct Answer is Right**
A deep transverse arrest is more likely to occur in a pelvis with a small or irregularly shaped pelvis, particularly in cases of a contracted pelvis or a pelvis with a narrow subpubic arch. The ischial spines act as a barrier to the fetal head, preventing it from moving further in the pelvis. In such cases, the fetal head will often assume a transverse position, unable to progress further.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify a type of pelvis associated with deep transverse arrest.
**Option B:** This option is incorrect as it refers to a different obstetric complication, where the fetal head is unable to rotate from a transverse position to an occipito-anterior position.
**Option C:** This option is incorrect as it refers to a different type of pelvis, which is typically associated with a different obstetric complication.
**Clinical Pearl / High-Yield Fact**
A deep transverse arrest is often associated with a contracted pelvis, which can be a result of pelvic fractures, pelvic tumors, or congenital conditions such as a narrow subpubic arch.
**Correct Answer: D. Anthropoid pelvis.**