The presenting diameter in brow presentation is

Correct Answer: A

Rationale: The presenting diameter in brow presentation is the submentobregmatic diameter. This is because in brow presentation, the fetal head is partially extended, causing the forehead (bregma) to be the presenting part. The submentobregmatic diameter is the distance between the chin (mentum) and the highest point of the forehead (bregma). This diameter is crucial for successful delivery in brow presentation as it is the smallest diameter that must pass through the maternal pelvis. Summary of other choices: B: Suboccipitofrontal - This diameter is not relevant in brow presentation as it involves the back of the head. C: Occipitalfrontal - This diameter is the distance between the back of the head and the forehead, also not relevant in brow presentation. D: Mentovertical - This diameter is the distance between the chin and the vertex of the head, not the forehead.

Correct Answer: C

Rationale: The correct answer is C: 4 hours. This is based on the definition of prolonged second stage in nulliparous women, which is labor lasting more than 4 hours. This duration is considered abnormal and may lead to increased risk of maternal and fetal complications. Choice A (1 hour) is too short and does not meet the criteria for prolonged second stage. Choice B (2 hours) is also insufficient based on the established timeframe. Choice D (8 hours) exceeds the duration for prolonged second stage, indicating a more advanced stage of labor. Therefore, the most appropriate and accurate timeframe for prolonged second stage in nulliparous women is 4 hours.

Correct Answer: D

Rationale: In True cephalopelvic disproportion, the baby's head is too large to pass through the mother's pelvis. This condition often requires operative delivery (C-section) as a vaginal birth is not possible. Choice D is correct because operative delivery is indeed needed to safely deliver the baby. Choice A is incorrect as not all patients with cephalopelvic disproportion will necessarily require operative delivery. Choice B is also incorrect as the issue cannot generally be overcome during labor due to physical constraints. Choice C is incorrect as operative delivery is usually necessary in cases of true cephalopelvic disproportion to prevent complications.

Correct Answer: A

Rationale: The correct answer is A: Submentovertival, bitemporal. In a face presentation, the presenting diameters are submentovertival (chin to vertex) and bitemporal (temple to temple). This is because the fetus is in a face-first position with the chin presenting first. Option B is incorrect because submentobregmatic is not a recognized presenting diameter in face presentation. Option C is incorrect as biparietal refers to the widest transverse diameter of the fetal head, not relevant in face presentation. Option D is incorrect as mentovertical is not a valid presenting diameter in face presentation.

Correct Answer: A

Rationale: The correct answer is A because an estimated fetal weight below 3500 grams indicates a lower risk of complications during childbirth. Higher fetal weight increases the likelihood of shoulder dystocia and birth injuries. Maternal body mass index, gestational age, and maternal age do not directly impact the likelihood of a favorable outcome during a trial of scar.