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: B

Rationale: The correct answer is B: Face presentation. Vaginal delivery is possible in face presentation as the baby's head is extended, allowing for descent through the birth canal. Brow presentation (A) and shoulder presentation (C) may require cesarean delivery due to the atypical presentation of the baby. Unstable lie (D) refers to the baby being in a transverse position, which also necessitates a cesarean section. Face presentation is the only option where vaginal delivery may be possible due to the extended position of the baby's head.

Correct Answer: B

Rationale: The correct answer is B: Myelomeningocele. McEwen sign refers to the characteristic scalloping of the frontal bones due to pressure from the expanding brain in individuals with myelomeningocele. This sign is specific to myelomeningocele and is not associated with hydrocephalus (A), microcephaly (C), or encephalocele (D), which have different clinical manifestations and imaging findings. Myelomeningocele is a neural tube defect where the spinal cord and its coverings protrude through an opening in the spine, leading to neurological deficits and associated signs like McEwen sign.

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: D

Rationale: Step-by-step rationale for why D is correct: 1. Hyperemesis gravidarum is severe nausea and vomiting during pregnancy. 2. Prolonged vomiting can lead to electrolyte imbalances and nutritional deficiencies. 3. Vitamin B deficiency, specifically thiamine, can result in Wernicke’s encephalopathy. 4. Mallory-Weiss syndrome can occur due to repeated retching and vomiting. 5. Therefore, hyperemesis gravidarum can lead to both Wernicke’s encephalopathy and Mallory-Weiss syndrome. Summary: A: Placenta praevia is related to abnormal placental placement, not vomiting. B: Hypertensive disorders are associated with high blood pressure, not vomiting-related complications. C: Vitamin B deficiency can lead to Wernicke’s encephalopathy but is not directly caused by hyperemesis gravidarum.