A pregnant woman presents to your clinic with classical thyrotoxicosis signs and symptoms. Which of the following drugs is contraindicated?

Correct Answer: D

Rationale: The correct answer is D, Radioactive iodine. Radioactive iodine is contraindicated in pregnant women due to its teratogenic effects on the developing fetus. It can cause fetal thyroid dysfunction and increase the risk of thyroid cancer later in life. Sodium iodide (A) and potassium iodide (C) are safe to use in pregnancy for managing thyrotoxicosis. Propylthiouracil (B) is also considered safe and is often the preferred treatment choice in pregnant women.

Correct Answer: A

Rationale: The correct answer is A: seminiferous tubules. Sperm production begins in the seminiferous tubules of the testes through a process called spermatogenesis. This is where immature germ cells called spermatogonia undergo multiple divisions to eventually form mature sperm cells. The other choices, B: epididymis, C: vas deferens, and D: ejaculatory duct, are incorrect as they are not sites of sperm production but rather play roles in sperm maturation, storage, and transportation during ejaculation.

Correct Answer: A

Rationale: The correct answer is A: endometrium. The endometrium is the innermost layer of the uterine wall that thickens in preparation for potential implantation of a fertilized egg. If fertilization does not occur, this layer is shed during menstruation. The myometrium (B) is the middle layer responsible for uterine contractions during labor. Epimetrium (C) is not a recognized term relating to the uterine wall. Choice D is incorrect as the endometrium is indeed the layer that sheds during menstruation.

Correct Answer: B

Rationale: The correct answer is B: cervix. The cervix is the structure between the uterus and the vagina. It functions as a passageway for sperm to travel to the uterus and for menstrual blood to flow out of the uterus. The other choices are incorrect because: A: Uterine tube (fallopian tube) connects the ovary to the uterus, not between the uterus and vagina. C: Vulva refers to the external genitalia, not the internal structure between the uterus and vagina. D: Hymen is a thin membrane at the vaginal opening, not the structure between the uterus and vagina.

Correct Answer: B

Rationale: The correct answer is B: Hypoglycemia. Phenytoin is an anticonvulsant medication that commonly causes side effects such as ataxia, hirsutism, and gum hypertrophy. However, hypoglycemia is not a known side effect of phenytoin. It is important to monitor blood sugar levels in patients taking anticonvulsants, as some medications may lead to hyperglycemia rather than hypoglycemia. Therefore, choice B is the correct answer. Choices A, C, and D are incorrect as they are common side effects associated with phenytoin use.