A 32-year-old pregnant woman presents with painless vaginal bleeding at 10 weeks of gestation. On ultrasound, a gestational sac with no embryo is visualized within the uterus. Which of the following conditions is most likely to be responsible for these findings?

Correct Answer: C

Rationale: In a missed abortion, the embryo has died, but the products of conception remain in the uterus, leading to the visualization of a gestational sac without an embryo on ultrasound. This is a type of missed miscarriage where the woman may not have any symptoms initially and the diagnosis is made during a routine ultrasound. The most common presenting symptom is painless vaginal bleeding. The absence of an embryo within the gestational sac can be confirmed through serial ultrasound examinations showing no fetal growth or cardiac activity. It is important for healthcare providers to provide appropriate counseling and management options to support the patient through this emotional experience.

Correct Answer: B

Rationale: Cervical intraepithelial neoplasia (CIN) is a precancerous condition of the cervix characterized by the presence of abnormal cells on the surface of the cervix. These abnormal cells are often classified as low-grade squamous intraepithelial lesions (LSIL) on cytology. CIN is not yet cervical cancer but can progress to invasive cancer if left untreated. LSIL is indicative of mild dysplasia or cervical intraepithelial neoplasia 1 (CIN 1), which is considered a precancerous lesion. Therefore, the presence of abnormal cervical cells classified as LSIL is more likely to be associated with CIN rather than cervical cancer, cervicitis, or cervical polyps.

Correct Answer: A

Rationale: Natural killer (NK) cells play a vital role in the innate immune response by identifying and eliminating virus-infected cells, as well as tumor cells, without the need for prior exposure or activation. NK cells are able to detect abnormal cells by recognizing changes in the cell surface molecules, such as downregulation of MHC class I molecules. Once activated, NK cells release cytotoxic granules containing perforin and granzyme, leading to the destruction of the target cell. This direct killing mechanism is crucial for controlling viral infections and preventing the development of tumors. NK cells do not produce antibodies (option B), present antigens to T cells (option C), or release cytokines to recruit other immune cells (option D) as their primary function in the immune response.

Correct Answer: A

Rationale: T helper cells (Th cells) are primarily responsible for coordinating and regulating immune responses by producing cytokines that direct the activities of other immune cells. These cytokines help in activating cytotoxic T cells, B cells, macrophages, and other cells involved in the immune response. Th cells play a crucial role in mounting an effective immune response against infections and diseases by providing the necessary signals to activate and control various immune cells. Thus, T helper cells are considered the central coordinators of the immune system.

Correct Answer: A

Rationale: Albuterol (salbutamol) is a short-acting beta agonist bronchodilator commonly used for quick relief of bronchoconstriction in patients with COPD. It works by relaxing the smooth muscles in the airways, allowing for easier breathing and improved airflow. The patient's increased dyspnea, wheezing, and productive cough are indicative of bronchoconstriction, and albuterol is the most appropriate medication to provide rapid bronchodilation and symptom relief in this situation. Diphenhydramine (Benadryl) is an antihistamine and not typically used for bronchodilation in COPD. Montelukast (Singulair) is a leukotriene receptor antagonist that may be used in the maintenance treatment of COPD but is not the initial choice for acute symptom relief. Prednisone is a cortic