Correct Answer: C

Rationale: The correct answer is C: Improve fetal oxygenation. Oxygen at 4 liters/minute is given to increase oxygen levels which can help improve oxygenation to the fetus during a cord prolapse scenario. This can be crucial in preventing fetal distress and hypoxia. Explanation for Incorrect Choices: A: Relieve maternal distress - Oxygen is primarily given in this scenario to benefit the fetus, not to relieve maternal distress. B: Promote her relative rest - Oxygen is not administered to promote rest, but to address the immediate concern of fetal oxygenation. D: Achieve the effect of tocolysis - Oxygen does not have a role in tocolysis, which is the inhibition of uterine contractions.

Correct Answer: B

Rationale: The correct answer is B: Cyclosporine. Cyclosporine is an immunosuppressant medication commonly used post-bone marrow transplant to prevent graft-versus-host disease. It works by inhibiting T-cell activation and proliferation, reducing the risk of the donor's immune cells attacking the recipient's tissues. Immune globulin (A) is used for passive immunization, not prevention of graft-versus-host reaction. Prophylactic antibiotics (C) are used to prevent infections post-transplant, not graft-versus-host disease. Systemic corticosteroids (D) may be used to treat graft-versus-host disease but are not the first-line prophylactic medication.

Correct Answer: A

Rationale: The correct statement about shoulder dystocia is A: It’s an impaction of the anterior shoulder after delivery of the head. This is accurate as shoulder dystocia occurs when the anterior shoulder becomes impacted behind the maternal pubic symphysis. This can lead to difficulty delivering the shoulders after the head is delivered. B is incorrect as shoulder dystocia involves the anterior shoulder, not the posterior. C is incorrect as shoulder dystocia is not related to compound presentation. D is incorrect as shoulder dystocia is an obstetric emergency that requires prompt intervention to prevent complications for both the mother and the baby.

Correct Answer: B

Rationale: Breech presentation refers to the bottom or feet-first position of the baby in the uterus. This is the correct answer (B) because it accurately defines breech presentation. Choice A (head-first presentation) is incorrect as it describes the typical vertex presentation. Choices C (oblique lie) and D (transverse lie) are also incorrect as they refer to other abnormal fetal positions that are different from breech presentation.

Correct Answer: D

Rationale: The correct answer is D (>90%). Mr. Mettenberger had a reexpansion of his second spontaneous pneumothorax this year, indicating a high recurrence risk. Spontaneous pneumothorax recurrence rates are high, especially in young males. Factors such as smoking history, gender, and prior occurrences contribute to increased risk. Mr. Mettenberger's cessation of smoking reduces but does not eliminate the risk. Choices A, B, and C are too low, given his history and current situation. Choice D is the most appropriate due to the high likelihood of recurrence based on his medical history and risk factors.