Correct Answer: C

Rationale: The presentation of severe testicular pain with a red, tense scrotum, and absent cremasteric reflex on one side is highly concerning for testicular torsion. Testicular torsion is a urologic emergency that occurs when the spermatic cord twists, leading to compromised blood flow to the testicle. The affected testicle can become ischemic and necrotic within hours, necessitating prompt diagnosis and intervention to avoid permanent damage or loss of the testicle.

Correct Answer: C

Rationale: The presentation of severe testicular pain with a red, tense scrotum, and absent cremasteric reflex on one side is highly concerning for testicular torsion. Testicular torsion is a urologic emergency that occurs when the spermatic cord twists, leading to compromised blood flow to the testicle. The affected testicle can become ischemic and necrotic within hours, necessitating prompt diagnosis and intervention to avoid permanent damage or loss of the testicle.

Correct Answer: B

Rationale: Research studies have shown that for every increment of 20 mm Hg in systolic blood pressure and 10 mm Hg in diastolic blood pressure, the cardiovascular risk approximately doubles. Therefore, the cardiovascular risk increases by 50% for each increment of 20 mm Hg systolic and 10 mm Hg diastolic in blood pressure. This underlines the importance of maintaining healthy blood pressure levels to reduce the risk of cardiovascular diseases.

Correct Answer: A

Rationale: When examining a patient with known peripheral vascular disease in the legs, it is important to note the size, symmetry, and skin color of the lower extremities. These aspects can provide valuable information about the circulation and potential complications related to the disease. Changes in size, such as muscle wasting or atrophy, can indicate poor circulation and muscle ischemia. Asymmetry between the two legs may point to a significant difference in blood supply to the limbs. Skin color changes, such as pallor or cyanosis, can suggest impaired blood flow. Monitoring and documenting these findings are crucial for assessing the progression or improvement of the disease and guiding treatment interventions.

Correct Answer: D

Rationale: The most likely cause of the 19-year-old college sophomore's joint pain is Lyme disease. The presentation of a red spot shaped like a target (erythema migrans) that spreads, along with joint pain, is classic for Lyme disease. Additionally, the history of camping in an area known to have ticks and the history of using insect repellent support the likelihood of a tick-borne illness like Lyme disease.