Correct Answer: A

Rationale: Metronidazole is the correct choice for treating bacterial vaginosis as it is the first-line medication recommended for this condition. Metronidazole works by disrupting the DNA structure of bacteria, making it an effective treatment. Choice B, Fluconazole, is an antifungal medication primarily used for treating fungal infections, not bacterial vaginosis. Choice C, Acyclovir, is an antiviral medication used to treat viral infections, not bacterial vaginosis. Choice D, Clindamycin, is also used to treat bacterial infections but is not the first-line treatment for bacterial vaginosis, making it an incorrect choice in this scenario.

Correct Answer: B

Rationale: A sonogram, also known as an ultrasound, is a procedure that utilizes sound waves to generate images of a developing embryo or fetus. This imaging technique is commonly used in prenatal care to monitor fetal development and identify any potential abnormalities. Choices A, C, and D are incorrect because a phenotype refers to an individual's observable traits resulting from genetic and environmental influences, a genotype is an individual's genetic makeup, and an alpha-fetoprotein (AFP) assay is a blood test used to screen for certain birth defects.

Correct Answer: A

Rationale: Uterine atony is significant hypotonia of the uterus and is the leading cause of postpartum hemorrhage. It results in the inability of the uterus to contract effectively after delivery, leading to excessive bleeding. Uterine inversion is a rare but serious complication that involves the turning inside out of the uterus, leading to hemorrhage, but it is not the most likely cause of profuse bleeding in this scenario. Vaginal hematoma may cause bleeding but is typically associated with pain as a primary symptom rather than profuse bleeding. Vaginal lacerations can cause bleeding, but in the presence of a firm, contracted uterine fundus, uterine atony is a more likely cause of ongoing profuse bleeding in the postpartum period.

Correct Answer: B

Rationale: Placenta previa, a condition where the placenta covers the cervix, can cause painless, bright red vaginal bleeding in the third trimester. In this scenario, the absence of contractions and pain, along with the presence of significant bright red bleeding, is more indicative of placenta previa rather than abruptio placenta or a ruptured vessel. A normal bloody show typically occurs closer to the onset of labor and is not associated with the amount of bleeding described in the question.

Correct Answer: D

Rationale: The correct answer is D, TORCH screening. TORCH screening is done to detect infections such as toxoplasmosis, which can be contracted from handling cat litter and is harmful during pregnancy. Biophysical profile (choice A) is a prenatal ultrasound evaluation. Fern test (choice B) is used to assess for amniotic fluid leakage. Amniocentesis (choice C) involves taking a sample of amniotic fluid to test for genetic abnormalities and certain infections, not specifically related to toxoplasmosis from cat litter.