If you are preparing to take the United States Medical Licensing Examination® (USMLE®) Step 1 exam this spring—as many second-year medical students are—you might want to know which questions are most often missed by test-prep takers.

Over the years, AMA Wire® has run dozens of example questions from Kaplan Medical. Here’s a look at our most popular USMLE Step 1 stumpers. Each of them comes with an expert explanation of the answer. Also check out all posts in this series.

A 41-year-old woman comes to the physician because of a recent history of joint pain in her hands and knees, in addition to some mild weight loss and fatigue. She has a two-week history of swelling behind her left knee. She states that the swelling has been progressively growing, and she has pain and difficulty in flexing the knee.

Her serum is positive for rheumatoid factor. Physical examination shows an erythematous, fluid-filled mass in the left lateral popliteal fossa overlying the tendon of the biceps femoris. During aspiration of the cyst, a structure immediately adjacent to the tendon is injured. Can you predict the loss she will experience?

A 75-year-old man comes to the physician because of nocturia, urinary urgency and a feeling that he cannot completely empty his bladder. He voids six times per day and four times per night. He has a strong desire to void, and when he reaches the toilet he can only void with a weakened stream with straining.

Digital rectal examination shows a firm, enlarged prostate measuring approximately 30 grams. Post-void residual by ultrasound is 300 mL. Bone scan shows multiple osteoblastic lesions in the vertebral bodies. Elevation of which of the following bone metabolites is most strongly associated with these lesions?

A 16-year-old girl is brought to the emergency department because of acute abdominal pain and diarrhea. She has had three similar episodes, but no cause has been found. She also complains of burning on urination. The patient appears diaphoretic and in pain. Her temperature is 102 °F (38.8 °C) and pulse is 95 beats per minute. Physical examination shows there is diffuse abdominal tenderness, especially around the suprapubic area. First percussion over the costovertebral angle elicits exquisite pain on the right. What is the likeliest cause of the pain?

A 54-year-old man comes to the physician for a follow-up examination because of progressive rheumatoid arthritis unresponsive to high dose nonsteroidal anti-inflammatory drugs (NSAIDs). Treatment with prednisone and hydroxychloroquine was started six weeks earlier.

The patient is concerned about steroid-induced osteoporosis, because his father, a type 2 diabetic, recently fell and broke his hip. Laboratory studies and a dual energy x-ray absorptiometry (DEXA) test of the spine and hip are ordered to address the patient's concerns. Which additional tests would be recommended for this patient?

The AMA selected Kaplan as a preferred provider to support you in reaching your goal of passing the USMLE® or COMLEX-USA®. AMA members can save 30 percent on access to additional study resources, such as Kaplan’s Qbank and High-yield courses. Learn more.

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