Correct Answer: D

Rationale: The engagement of the fetus refers to the baby's head moving down into the mother's pelvis in preparation for birth. This factor is not typically used to distinguish between true and false labor because it is a sign of progress in labor rather than a defining characteristic of true labor. In contrast, the factors that are commonly used to differentiate between true and false labor include contractions (e.g., regularity, intensity, duration), cervical changes observed through vaginal examination (e.g., effacement and dilation), and monitoring vital signs.

Correct Answer: D

Rationale: Spiral CT angiography is the most appropriate test for confirming the diagnosis of pulmonary embolism (PE) in a patient with suspected PE. It is a non-invasive imaging modality that can detect filling defects within the pulmonary vasculature indicative of a clot. This diagnostic test has high sensitivity and specificity for diagnosing PE, making it a valuable tool in the management of patients with suspected PE.

Correct Answer: D

Rationale: In a 55-year-old postmenopausal woman presenting with vaginal bleeding and a healthy cervix on examination, the most likely cause would be a cervical polyp. Cervical polyps are benign growths that can occur on the cervix and are often asymptomatic but can occasionally cause postmenopausal bleeding. Their appearance on examination would typically be a non-malignant finding with no cervical motion tenderness. Cervical cancer, endometrial cancer, and vaginal cancer would typically present with different examination findings and risk factors.

Correct Answer: D

Rationale: The presentation described in the question – sudden-onset unilateral headache along with ipsilateral ptosis, miosis, and anhidrosis – is characteristic of Horner syndrome. Horner syndrome is caused by disruption of the sympathetic nerve pathway and can occur in trigeminal neuralgia. Trigeminal neuralgia is a painful condition affecting the trigeminal nerve commonly characterized by sudden and severe facial pain that can be triggered by various stimuli. The involvement of the sympathetic pathway in trigeminal neuralgia can lead to Horner syndrome symptoms such as ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face. Cluster headaches usually involve severe unilateral pain around the eye, but they do not typically present with Horner syndrome symptoms. Migraine and tension-type headaches also do not typically present with Horner syndrome symptoms.

Correct Answer: D

Rationale: A subarachnoid hemorrhage is characterized by bleeding within the subarachnoid space, the area between the arachnoid mater and the pia mater surrounding the brain. Patients typically present with a sudden-onset severe headache, altered mental status, and focal neurological deficits due to the mass effect of the blood in the subarachnoid space. Imaging, such as a CT scan, can confirm the presence of the hemorrhagic lesion. Ischemic stroke results from a blockage in the blood vessels supplying the brain, leading to tissue infarction and neurological deficits. Subdural hematoma is a collection of blood between the dura mater and the arachnoid mater, commonly seen following head trauma. Intracerebral hemorrhage involves bleeding within the brain tissue itself, often leading to focal neurological deficits.