Comprehensive Clinical Science Test 1 — Questions and Answers
Question 1: A clinical trial of a potentially valuable medical treatment is planned. It is unlikely that it will directly benefit the study subjects but very likely that it will benefit future patients. There is a risk for short-term minor gastric discomfort but essentially no risk for long-term adverse effects. The investigator concludes that disclosure of the risks may discourage participation in the trial. Which of the following is the most appropriate next step?
- Proceed with the trial only with disclosure, because informed consent is an absolute requirement (Correct answer)
- Proceed with the trial only with disclosure, because the trial will not directly benefit the subjects
- Proceed with the trial using only subjects who agree to participate without disclosure
- Proceed with the trial without disclosure, because the risks to subjects are outweighed by the possible benefits to many patients
- Proceed with the trial without disclosure, because the probability of long-term harm to subjects is remote
Correct answer: Proceed with the trial only with disclosure, because informed consent is an absolute requirement
The ethical principle of informed consent mandates that all potential risks, benefits, and alternatives of a research study must be fully disclosed to prospective participants. Even if the risks are minor and the treatment is potentially valuable, withholding information compromises the autonomy of the subjects and is unethical. Informed consent is an absolute requirement to ensure participants can make a voluntary and educated decision about their involvement in the trial.
Question 2: A 25-year-old man comes to the emergency department because of a 1-month history of fever, chills, nonproductive cough, and progressive shortness of breath; he now becomes short of breath after walking 20 feet. He has had a 4.5-kg (10-lb) weight loss during this period. He has not seen a physician for 10 years, and he takes no medications. He has a 10-year history of intravenous heroin use and shares needles. He is in mild respiratory distress while sitting. His temperature is 38.6°C (101.4°F), pulse is 92/min, respirations are 24/min, and blood pressure is 110/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 90%. There is no jugular venous distention. Diffuse crackles are heard bilaterally. There is no peripheral edema. An x-ray of the chest shows diffuse interstitial infiltrates bilaterally. This patient is most likely to have which of the following immunologic abnormalities?
- Decreased B-lymphocyte count
- Decreased CD4+ T-lymphocyte count (Correct answer)
- Decreased serum complement concentrations
- Decreased serum IgA concentration
- Decreased splenic opsonization
- IgG autoantibodies
Correct answer: Decreased CD4+ T-lymphocyte count
The patient's history of intravenous heroin use and needle sharing is a significant risk factor for HIV infection. HIV primarily targets and depletes CD4+ T-lymphocytes, leading to severe immunodeficiency. The symptoms of fever, chills, cough, shortness of breath, weight loss, and diffuse interstitial infiltrates are highly suggestive of opportunistic infections, such as Pneumocystis jirovecii pneumonia (PJP), which commonly occur when CD4+ T-cell counts are low.
Question 3: A 27-year-old man is brought to the emergency department 20 minutes after his roommate found him unconscious on their bathroom floor. The patient has a history of intravenous heroin use. He has no history of serious illness and takes no medications. On arrival, he appears cyanotic. He is unresponsive to verbal and painful stimuli. His temperature is 37.1°C (98.8°F), pulse is 80/min, respirations are 4/min, and blood pressure is 110/60 mm Hg. Examination shows new and old needle tracks over the upper and lower extremities. Cardiopulmonary examination shows no abnormalities. Arterial blood gas analysis on room air shows: pH 7.20 PCO2 80 mm Hg PO2 50 mm Hg HCO3 - 29 mEq/L Which of the following is the best explanation for this patient’s hypoxemia?
- Decreased inspired oxygen tension
- Hypoventilation (Correct answer)
- Impaired diffusion capacity of the lung for carbon monoxide
- Right-to-left shunt
- Ventilation-perfusion mismatch
Correct answer: Hypoventilation
The patient's history of intravenous heroin use, unresponsiveness, and severely depressed respiratory rate (4/min) are classic signs of opioid overdose. Opioids are potent respiratory depressants, causing hypoventilation. This inadequate breathing leads to a buildup of carbon dioxide (PCO2 80 mm Hg) and insufficient oxygen intake (PO2 50 mm Hg), directly resulting in hypoxemia and respiratory acidosis.
Question 4: A 15-year-old boy has had pain in the knee since sustaining an injury in a high school football game 6 weeks ago. The high school trainer has been treating him with heat and ultrasound, without significant improvement. Physical examination shows tenderness of the medial femur approximately 7.5 cm above the joint. There is no ligamentous instability, joint swelling, or effusion. Which of the following is the most appropriate next step in diagnosis?
- Anteroposterior and lateral x-rays (Correct answer)
- Arthrography
- Arthroscopy
- Measurement of serum calcium concentration
- Ultrasonography
Correct answer: Anteroposterior and lateral x-rays
Persistent, localized bone pain following an injury, especially when initial conservative treatments have failed, warrants further investigation to rule out significant bone pathology. Anteroposterior and lateral x-rays are the most appropriate and cost-effective initial diagnostic imaging modality. They can effectively identify fractures, stress reactions, or potential bone tumors, which are important considerations in an adolescent with chronic pain.
Question 5: A 2-week-old boy is brought to the physician because of a 3-day history of persistent discharge from his eyes. He was born at term following an uncomplicated pregnancy and delivery. Examination of the eyes shows tarsal inflammation and a thin mucopurulent discharge. Testing of scrapings from the tarsal conjunctivae is positive for Chlamydia trachomatis. The remainder of the examination shows no abnormalities. Which of the following is the most likely mode of transmission of this patient’s infection?
- Aerosol exposure
- Contact with maternal cervical secretions (Correct answer)
- Exposure to household pets
- Poor hand washing by caregivers
- Transplacental transmission
Correct answer: Contact with maternal cervical secretions
Chlamydia trachomatis is a common sexually transmitted infection (STI). In newborns, conjunctivitis caused by Chlamydia is typically acquired during passage through the birth canal. The infant comes into direct contact with infected maternal cervical secretions during a vaginal delivery, leading to ocular infection.
Question 6: A 62-year-old man comes to the physician because of blood in his urine for 24 hours. Vital signs are within normal limits. Examination shows no abnormalities. Tissue obtained on bladder biopsy shows transitional cell carcinoma. Abstinence from which of the following is most likely to have prevented this condition?
- Alcohol
- Coffee
- Diet soda
- Tea
- Tobacco (Correct answer)
Correct answer: Tobacco
The patient's diagnosis of transitional cell carcinoma of the bladder (urothelial carcinoma) is strongly linked to specific environmental exposures. Tobacco smoking is the single most significant modifiable risk factor for bladder cancer. Carcinogens in tobacco smoke are absorbed, metabolized, and excreted in the urine, directly irritating the bladder lining and promoting cancerous changes.
Question 7: A 21-year-old nulligravid woman who is not using contraception has had irregular menstrual periods since menarche at age 13 years. She has noted increased hair growth on her face and lower abdomen. On pelvic examination, there is copious cervical mucus and slightly enlarged irregular ovaries. Which of the following is the most likely cause of these findings?
- Adrenal adenoma
- Idiopathic hirsutism
- Ovarian tumor
- Pituitary adenom
- Polycystic ovarian syndrome (Correct answer)
Correct answer: Polycystic ovarian syndrome
This patient presents with a classic triad of symptoms for Polycystic Ovarian Syndrome (PCOS): irregular menstrual periods (indicating chronic anovulation), hirsutism (increased hair growth due to hyperandrogenism), and enlarged, irregular ovaries. PCOS is a common endocrine disorder characterized by hormonal imbalances that lead to these reproductive and metabolic disturbances.
Question 8: A 50-year-old man has a 1-hour history of unremitting chest pressure and “gassiness.” He has no history of cardiac problems but does have a history of peptic ulcer disease. Physical examination shows no abnormalities except for a blood pressure of 140/80 mm Hg. Which of the following is the most appropriate initial step in diagnosis?
- Test of the stool for occult blood
- ECG (Correct answer)
- X-ray series of the upper gastrointestinal tract
- Echocardiography
- Endoscopy of the upper gastrointestinal tract
Correct answer: ECG
Unremitting chest pressure, even if described as 'gassiness' or in the context of a history of peptic ulcer disease, must be urgently evaluated for acute coronary syndrome (ACS). An electrocardiogram (ECG) is the most critical and immediate diagnostic test for chest pain. It can rapidly identify ST-elevation myocardial infarction (STEMI) or other ischemic changes, guiding prompt, life-saving interventions.
Question 9: A 32-year-old nulligravid woman comes to the physician because of a 20-minute episode of shortness of breath when she awoke this morning. Her only medication is an oral contraceptive. She has smoked one pack of cigarettes daily for 10 years. She is sexually active with multiple partners. Physical examination shows erythema, swelling, warmth, and tenderness behind the right knee; a cord-like mass can be palpated. Which of the following is the most likely diagnosis?
- Corticosteroid-induced arthritis
- Gonococcal arthritis
- Pulmonary embolism (Correct answer)
- Steroid-induced asthma
- Systemic lupus erythematosus
Correct answer: Pulmonary embolism
The patient's risk factors, including oral contraceptive use and smoking, significantly increase her risk for venous thromboembolism. The findings of erythema, swelling, warmth, tenderness, and a palpable cord-like mass behind the knee are highly suggestive of a deep vein thrombosis (DVT). The sudden onset of shortness of breath, combined with signs of DVT, strongly indicates a pulmonary embolism (PE), which typically arises from a DVT.
Question 10: A 4030-g (8-lb 14-oz) newborn has internal rotation of the left upper extremity at the shoulder, extension at the elbow, pronation of the forearm, and flexion of the fingers following a low forceps delivery. He was born at term following an uncomplicated pregnancy. Passive range of motion of the left upper extremity is full; the newborn does not cry or grimace when the left arm, shoulder, or clavicle is palpated. Examination shows no other abnormalities. Which of the following is the most likely underlying mechanism of this condition?
- Anterior dislocation of the left shoulder
- An inherited skeletal dysostosis
- Intracerebral hemorrhage
- Posterior dislocation of the cervical vertebrae
- Traction on the brachial plexus during delivery (Correct answer)
Correct answer: Traction on the brachial plexus during delivery
The newborn's specific arm posture—internal rotation at the shoulder, extension at the elbow, pronation of the forearm, and flexion of the fingers (often called 'waiter's tip' position)—is characteristic of Erb-Duchenne palsy. This condition results from an injury to the upper brachial plexus (C5-C6 nerve roots). In newborns, such injuries are typically caused by excessive traction or stretching of the neck and shoulder during a difficult delivery, especially with a large infant or instrumental delivery.
Question 11: A 72-year-old man comes for a routine health maintenance examination. He has a 5-year history of progressive difficulty falling asleep at night and waking up early in the morning. He has not had snoring, nightmares, or changes in appetite or weight. He has felt energized since starting a new business venture 8 months ago. He has hypertension treated with hydrochlorothiazide. He does not smoke cigarettes, drink alcohol, or use illicit drugs. His blood pressure is 145/88 mm Hg. The lungs are clear to auscultation. Cardiac examination shows an S4 gallop. Laboratory studies are within normal limits. Which of the following is the most likely cause of this patient’s insomnia?
- Hypertension
- Hyperthyroidism
- Major depressive disorder
- Malignancy
- Sleep apnea
- Normal aging (Correct answer)
Correct answer: Normal aging
Changes in sleep architecture are a normal physiological part of aging. Older adults commonly experience increased sleep latency, more frequent awakenings, decreased total sleep time, and a tendency for earlier bedtimes and wake times. In the absence of other symptoms suggesting a specific medical condition, psychiatric disorder, or medication side effect, these progressive sleep disturbances are most likely attributable to normal age-related changes.
Question 12: A 22-year-old woman comes to the physician because of a 1-year history of intermittent lower abdominal cramps associated with bloating and mild nausea. The cramps are occasionally associated with constipation and bowel movements relieve the pain. She has not had any other symptoms. She has no history of serious illness and takes no medications. Her last menstrual period was 2 weeks ago. She appears well. Abdominal examination shows mild diffuse tenderness to palpation. Which of the following is the most likely diagnosis?
- Crohn disease
- Irritable bowel syndrome (Correct answer)
- Meckel diverticulum
- Peptic ulcer disease
- Ulcerative colitis
Correct answer: Irritable bowel syndrome
The patient's chronic, intermittent lower abdominal cramps, bloating, and altered bowel habits (constipation-predominant), with pain relieved by defecation, are classic diagnostic criteria for Irritable Bowel Syndrome (IBS). The absence of 'red flag' symptoms like weight loss, nocturnal symptoms, or blood in the stool further supports this functional gastrointestinal disorder.
Question 13: A 10-year retrospective study is conducted to determine factors that could predispose women to have children with complex congenital heart disease. A total of 1000 women were asked whether they had flu-like symptoms during their first trimester. The investigators found that women who had children with complex congenital heart disease were five times more likely than women with healthy newborns to report flu-like symptoms in their first trimester. Which of the following features of this study is most likely to affect the validity of this conclusion?
- Assessment bias
- Case mix bias
- Random error
- Recall bias (Correct answer)
- Selection bias
Correct answer: Recall bias
Recall bias is a systematic error that occurs in retrospective studies when participants' memories of past events differ between groups. In this study, mothers of children with complex congenital heart disease might be more likely to remember and report flu-like symptoms during their first trimester than mothers of healthy newborns. This differential recall can create a spurious association, affecting the validity of the conclusion.
Question 14: An asymptomatic 32-year-old woman comes to the physician for a follow-up examination. She has a 10-month history of hypertension that has been difficult to control with medication. Current medications include metoprolol, lisinopril, hydrochlorothiazide, and nifedipine. Her blood pressure today is 170/110 mm Hg. Abdominal examination shows a bruit in the left upper quadrant. Which of the following is the most likely cause of this patient’s hypertension?
- Coarctation of the aorta
- Essential hypertension
- Hyperaldosteronism
- Hypercortisolism
- Hyperthyroidism
- Pheochromocytoma
- Pituitary adenoma
- Renal artery stenosis (Correct answer)
Correct answer: Renal artery stenosis
The patient's presentation of resistant hypertension (uncontrolled despite multiple medications) in a relatively young woman, combined with an abdominal bruit in the left upper quadrant, is highly suggestive of renal artery stenosis. The bruit is caused by turbulent blood flow through a narrowed renal artery, which leads to activation of the renin-angiotensin-aldosterone system and secondary hypertension.
Question 15: Five days after falling and hitting her chest, a 55-year-old woman has acute midsternal chest pain that radiates to the back and is exacerbated by deep inspiration. Immediately following the accident, she had acute sternal pain that resolved in 1 day. Her temperature today is 37.7°C (99.9°F). A three-component scratchy sound is heard across the precordium. An x-ray of the chest shows a normal cardiac silhouette. An ECG shows diffuse ST-segment elevation and T-wave inversion. Which of the following is the most likely diagnosis?
- Acute myocardial infarction
- Pleurodynia
- Purulent pericarditis
- Traumatic pericarditis (Correct answer)
- Viral pericarditis
Correct answer: Traumatic pericarditis
The patient's symptoms of pleuritic chest pain radiating to the back, a three-component scratchy sound (pericardial friction rub), and diffuse ST-segment elevation on ECG are classic findings for pericarditis. The history of recent chest trauma provides a direct etiology for the inflammation of the pericardium, leading to a diagnosis of traumatic pericarditis.
Question 16: A 19-year-old primigravid woman comes to the physician for her first prenatal visit. Her last menstrual period was 18 weeks ago. Her pregnancy has been complicated by cocaine use. She has no history of serious illness and takes no medications. Her temperature is 36.7°C (98°F), pulse is 90/min, respirations are 16/min, and blood pressure is 110/50 mm Hg. Examination shows scleral icterus and poor dentition. The fundal height is 20 cm. The remainder of the examination shows no abnormalities. This patient is at greatest risk for which of the following conditions?
- Abruptio placentae (Correct answer)
- Gestational diabetes
- Macrosomia
- Pituitary infarction
- Postdates pregnancy
Correct answer: Abruptio placentae
Cocaine use during pregnancy is a significant risk factor for several adverse outcomes due to its potent vasoconstrictive effects. Specifically, cocaine can cause intense uterine artery vasoconstriction, leading to placental ischemia and premature separation of the placenta from the uterine wall, a condition known as abruptio placentae.
Question 17: A 37-year-old woman comes to the emergency department 40 minutes after the onset of shortness of breath, dizziness, and an itchy rash. She says she feels a lump in her throat. Her symptoms began while she was eating at a restaurant buffet. She has an allergy to peanuts. She is alert but anxious and in respiratory distress. Her temperature is 37°C (98.6°F), pulse is 120/min, respirations are 30/min, and blood pressure is 75/50 mm Hg. Examination shows an urticarial rash on the trunk and extremities. There is swelling of the lips but no swelling of the tongue or pharynx. Diffuse wheezing is heard bilaterally. In addition to intravenous 0.9% saline and an antihistamine, which of the following drugs should be administered immediately?
- Diazepam
- Dobutamine
- Epinephrine (Correct answer)
- Phentolamine
- No additional pharmacotherapy is indicated
Correct answer: Epinephrine
This patient is experiencing anaphylaxis, a severe, life-threatening systemic allergic reaction characterized by rapid onset, multi-system involvement (respiratory distress, hypotension, urticaria, angioedema), and exposure to a known allergen. Epinephrine is the immediate, first-line treatment for anaphylaxis, as it reverses bronchospasm, increases blood pressure, and reduces airway edema through its alpha and beta adrenergic effects.
Question 18: Two days after beginning primaquine for malaria prophylaxis, a 17-year-old African American boy is brought to the physician because of dark urine and yellowing of his eyes. His pulse is 88/min, respirations are 12/min, and blood pressure is 124/68 mm Hg. Examination shows scleral icterus and pale mucous membranes. His hemoglobin concentration is 10 g/dL. A blood smear shows erythrocyte fragments and Heinz bodies. Which of the following is the most likely explanation for these findings?
- Decreased porphobilinogen deaminase activity
- Decreased production of β-globin chains
- Deficiency of glucose 6-phosphate dehydrogenase (Correct answer)
- Deficiency of glycosylphosphatidylinositol
- Fragmentation of erythrocytes by fibrin strands
Correct answer: Deficiency of glucose 6-phosphate dehydrogenase
The patient's symptoms of dark urine and jaundice, along with anemia and the presence of erythrocyte fragments and Heinz bodies on a blood smear, indicate hemolytic anemia. This reaction, occurring after starting primaquine (an oxidant drug) in an African American male, is highly characteristic of glucose-6-phosphate dehydrogenase (G6PD) deficiency. G6PD is crucial for protecting red blood cells from oxidative stress, and its deficiency makes them vulnerable to oxidant-induced hemolysis.
Question 19: A 17-year-old boy comes to the physician because he believes that his penis is too large. He has been uncomfortable with the size of his genitals since he underwent puberty 4 years ago. He is concerned that people will see the bulge of his genitals under his clothing. Although he has never had sexual intercourse, he is afraid that his size will make it difficult or painful for most women. He plays intramural basketball but no longer undresses in front of teammates or uses public showers. He has not had changes in sleep or appetite. He has no history of serious illness and takes no medications. He occasionally drinks one or two beers on weekends but uses no illicit drugs. He continues to receive mostly B and C grades in school. He is 183 cm (6 ft) tall and weighs 68 kg (150 lb); BMI is 20 kg/m2 . Genital development is Tanner stage 4. Physical examination shows no abnormalities. On mental status examination, he appears embarrassed, and he describes his mood as "okay." Which of the following is the most likely diagnosis?
- Body dysmorphic disorder (Correct answer)
- Delusional disorder
- Hypoactive sexual desire disorder
- Narcissistic personality disorder
- Schizoid personality disorder
- Sexual aversion disorder
- Social phobia
Correct answer: Body dysmorphic disorder
Body Dysmorphic Disorder (BDD) is characterized by a preoccupation with a perceived flaw in physical appearance that is either minimal or not observable to others, causing significant distress or impairment in functioning. This patient's intense concern about his penis size, despite normal physical examination, leading to social avoidance and fear of intimacy, perfectly aligns with the diagnostic criteria for BDD.
Comprehensive Clinical Science Test 1
A clinical trial of a potentially valuable medical treatment is planned.
It is unlikely that it will directly benefit the study subjects but very likely that it will benefit future patients.
There is a risk for short-term minor gastric discomfort but essentially no risk for long-term adverse effects.
The investigator concludes that disclosure of the risks may discourage participation in the trial.
Which of the following is the most appropriate next step?