All practice questions

A 61-year-old man in the intensive care unit develops a fever and hypotension on hospital day 8. Blood cultures grow methicillin-resistant *Staphylococcus aureus* (MRSA), and he is diagnosed with a central line-associated bloodstream infection (CLABSI). An initial incident review reveals that his central venous catheter was placed during an emergency resuscitation without maximum sterile barrier precautions. Furthermore, the catheter was not exchanged within 48 hours, violating established hospital policy. The unit director notes this is the fourth similar CLABSI event this quarter involving emergency line placements. The quality improvement committee is convened to address this trend. Which of the following is the most appropriate next step for the committee?

A 55-year-old woman is admitted to the intensive care unit after experiencing severe intraoperative anaphylaxis during an elective laparoscopic cholecystectomy. Review of the electronic health record reveals that she has a documented severe anaphylactic allergy to cephalosporins. However, the surgical team bypassed an automated warning and administered prophylactic cefazolin prior to the incision. The patient required epinephrine, corticosteroids, and prolonged mechanical ventilation but is now physiologically stable. The surgical department chair is coordinating the institutional response to this preventable adverse event.

Arrange the following actions in the most appropriate chronological sequence for managing and investigating this sentinel event according to established patient safety protocols.

During a journal club, medical residents evaluate several recently published epidemiological studies. Each study contains a potential methodological vulnerability. Match each specific study scenario to the epidemiological term that best describes the dominant bias or flaw.

A 22-year-old male is brought to the emergency department after a severe collision during a rugby match. On presentation, he is in severe pain. His vital signs are temperature 37.1°C (98.8°F), blood pressure 130/80 mmHg, heart rate 98/min, and respiratory rate 16/min. Physical examination reveals a grossly deformed left knee with a significant posterolateral prominence. The left foot is cool and pale, and both the dorsalis pedis and posterior tibial pulses are not palpable. Capillary refill is delayed. Assume that after initial interventions, the distal pulses return but remain asymmetric compared to the contralateral limb, and subsequent advanced imaging reveals a popliteal artery intimal flap. Arrange the following steps in the correct chronological order for the acute evaluation and management of this patient.

A 54-year-old woman comes to the primary care clinic for an annual health maintenance examination. She has a history of a heart transplant 3 years ago for nonischemic cardiomyopathy and is currently maintained on a regimen of tacrolimus, mycophenolate mofetil, and low-dose prednisone. Her last menstrual period occurred at age 50. During the review of systems, she mentions noticing a small amount of pinkish vaginal spotting on her toilet tissue yesterday, which she assumes is due to vaginal dryness. She has never smoked and consumes alcohol socially. Her last screening mammogram was at age 52, and her last colonoscopy was at age 48; both were normal. She has not received any vaccinations since prior to her transplant. Vital signs are within normal limits. Physical examination reveals a well-healed median sternotomy scar but is otherwise unremarkable. Which of the following combinations represents the most appropriate management plan for this patient today?

A $32$-year-old woman, who is $34$ weeks pregnant (gravida 1, para 0), is brought to the emergency department by ambulance after a high-speed motor vehicle collision. She was the restrained driver and struck the steering wheel. On arrival, she is restless, confused, and diaphoretic. Her medical history is notable for mild persistent asthma. Temperature is $37.0^\circ\text{C}$, blood pressure is $76/42$ mmHg, heart rate is $138/\text{min}$, and respiratory rate is $28/\text{min}$. Pulse oximetry is $91\%$ on room air. Primary survey reveals a patent airway. The jugular veins are markedly distended. Auscultation of the lungs reveals diffuse expiratory wheezing. Heart sounds are distant and muffled. The gravid uterus is non-tender. A bedside Focused Assessment with Sonography for Trauma (FAST) reveals an anechoic fluid stripe surrounding the heart with inward collapse of the right ventricular free wall during diastole; there is no free intra-abdominal fluid. Continuous fetal monitoring shows a baseline heart rate of $155/\text{min}$ with minimal variability and recurrent late decelerations. Which of the following is the most appropriate next step in management?

An emaciated 79-year-old woman is evaluated in the emergency department for intractable vomiting and generalized abdominal pain that has progressively worsened over the past 48 hours. She has a long-standing history of anorexia nervosa, and her current body mass index is $15.2\text{ kg/m}^2$. Temperature is 38.4°C (101.1°F), blood pressure is 86/52 mmHg, pulse is 124/min, and respirations are 22/min. Physical examination reveals a distended abdomen with diffuse guarding and rebound tenderness. No masses are palpable in the bilateral groins or abdominal wall. During the examination, passive extension and medial rotation of her right hip elicits sudden, excruciating pain radiating down the anteromedial aspect of her right thigh. Laboratory studies show a leukocyte count of $16,800/\text{mm}^3$ and a serum lactate of $4.9\text{ mmol/L}$. An upright abdominal radiograph demonstrates multiple dilated loops of small bowel with prominent air-fluid levels and a paucity of colonic gas. There is no free subdiaphragmatic air. Which of the following is the most appropriate next step in management?

A nursing home resident is brought to the surgical evaluation unit due to a sudden decline in his clinical status. The 76-year-old male has a history of severe dementia, atrial fibrillation, and a remote open appendectomy. According to the accompanying staff, he has not had a bowel movement in three days and began vomiting dark, foul-smelling fluid this morning. Over the last hour, he has become increasingly lethargic. Vital signs show a temperature of 38.6 °C (101.5 °F), pulse of 122/min, respirations of 24/min, and blood pressure of 85/55 mm Hg. Physical examination reveals a rigid, markedly distended abdomen with diffuse rebound tenderness. Laboratory studies demonstrate a leukocyte count of $18,500/\text{mm}^3$ and a serum lactate level of $4.2 \text{ mmol/L}$. An upright chest radiograph shows no free air under the diaphragm. A supine abdominal radiograph demonstrates significantly dilated loops of small bowel with prominent valvulae conniventes and an absence of colonic gas. Which of the following is the most appropriate next step in the management of this patient?

An 18-month-old girl is evaluated in the pediatric oncology clinic. She was recently diagnosed with acute lymphoblastic leukemia and has been on induction chemotherapy for the past month. She is currently afebrile, well-appearing, and her vital signs are within normal limits. Her parents report that she missed her 12-month and 15-month well-child visits due to her illness, and they want to catch up on her missing immunizations to protect her as much as possible. Which of the following vaccines is safe and appropriate to administer to this patient at this time?

A 32-year-old man comes to an outpatient community clinic in early autumn complaining of fever, cough, and myalgias. Epidemiological surveillance estimates that the prevalence of influenza A among symptomatic patients in this community is currently $20\%$. The physician decides to use a new rapid point-of-care antigen test for influenza A. During its initial validation study at a tertiary care center during peak flu season (prevalence of $50\%$), the test demonstrated a sensitivity of $80\%$ and a specificity of $90\%$. Assuming the test's sensitivity and specificity remain constant, if this patient's test yields a positive result, which of the following best estimates the probability that he actually has influenza A?

A team of dermatological researchers is investigating a novel topical gene therapy for severe atopic dermatitis in a randomized, double-blind, vehicle-controlled clinical trial. The study is appropriately powered at $80\%$ ($\beta = 0.20$) to evaluate the primary endpoint, which is the mean change in the Eczema Area and Severity Index (EASI) score at 12 weeks.

During the design phase, the investigators pre-specify the analysis of $20$ distinct and independent secondary outcomes, including various serological cytokine levels, epidermal barrier function metrics, and sleep disruption indices. The researchers aim to maintain the overall study-wide probability of committing a Type I error at exactly $5\%$ ($\alpha = 0.05$) across the analysis of these secondary outcomes. To counteract the problem of multiple comparisons, the biostatistician applies a Bonferroni correction to adjust the significance level.

Based on this statistical design, what specific $p$-value threshold must a single secondary outcome achieve to be considered statistically significant? (Express the answer as a precise decimal).

Match each clinical scenario describing a change in diagnostic testing strategy with its corresponding predictable effect on the test's statistical performance parameters. Assume that all other disease factors and test properties remain constant.

A 58-year-old woman comes to the office for a health maintenance examination. She recently moved to the area and has not seen a healthcare provider in 6 years. She states she feels well overall, but mentions that three weeks ago she noticed a faint pink stain on her underwear that lasted for one day and has not recurred. She attributes this to vaginal dryness. Her last menstrual period was at age 51. Medical history is significant for type 2 diabetes mellitus, hypertension, and obesity. She smoked 1 pack of cigarettes daily for 25 years but quit 4 years ago. Her father was diagnosed with colon cancer at age 62. Her last screening mammogram and Pap test were 6 years ago. Vital signs show a blood pressure of 138/86 mmHg and a BMI of 34 kg/m2. Physical examination is unremarkable. Which of the following is the most appropriate set of clinical interventions for this patient today?

A team of clinical epidemiologists is investigating a potential association between maternal use of a newly approved antiemetic medication during the first trimester of pregnancy and the development of ventricular septal defects (VSD) in offspring. The researchers utilize a comprehensive national electronic health record database containing data from 2015 to 2025. They begin by identifying $5,000$ women who were prescribed the antiemetic during their first trimester. To establish a comparison group, they identify $15,000$ women who did not receive this medication, matching three unexposed women to each exposed woman based on maternal age, body mass index, and smoking status. Finally, the researchers review the pediatric records of all the offspring to determine and compare the incidence of VSD between the two groups. Which of the following best describes this epidemiologic study design?

A $4$-year-old boy is brought to the pediatric clinic for a routine well-child visit. He has a history of severe persistent asthma. For the past $4$ weeks, he has been taking oral prednisone at a dose of $2 \text{ mg/kg/day}$ to manage a severe exacerbation. His immunizations were completely up to date at his $2$-year well-child visit. Which of the following vaccines can be safely administered at today's visit? (Select all that apply)

A frail $87$-year-old woman is brought to the emergency department from a nursing care facility due to a $48$-hour history of obstipation, intractable vomiting, and progressive abdominal distension. Over the past $12$ hours, she has also developed severe pain along the medial aspect of her right thigh that worsens when her hip is extended. Her medical history includes hypertension, osteoporosis, and significant unintentional weight loss over the past year. She has never had abdominal surgery. Her temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $96/60\text{ mmHg}$, pulse is $115/\text{min}$, and respirations are $22/\text{min}$. On examination, the abdomen is markedly distended, tympanitic, and diffusely tender with involuntary guarding. High-pitched bowel sounds are present. Movement of the right hip, particularly internal rotation and extension, exacerbates the medial thigh pain. Laboratory results are notable for a leukocyte count of $18,200/\text{mm}^3$ and a serum lactate of $4.1\text{ mmol/L}$. An upright abdominal radiograph reveals multiple dilated loops of small bowel with air-fluid levels and an absence of colonic gas. Which of the following is the most appropriate next step in the management of this patient?

A 42-year-old woman is admitted to an ambulatory surgery center for an elective outpatient procedure. During preoperative preparation, a nurse goes to the automated dispensing cabinet to retrieve intravenous cefazolin for surgical prophylaxis. The nurse almost withdraws a vial of intravenous tranexamic acid instead, as both medications are supplied in similar-looking vials with blue caps and are stored in adjacent bins. The nurse recognizes the near-miss error before administering the medication. The clinic's quality improvement committee decides to initiate a formal investigation to prevent future occurrences. Arrange the following steps of the Root Cause Analysis (RCA) process in the correct chronological order to address this near-miss event.

A 45-year-old female healthcare worker presents to the occupational health clinic for routine screening. A research consortium is currently analyzing the efficacy of a new serum assay for detecting latent tuberculosis infection at this facility. In a recent validation cohort, the assay was administered to $200$ individuals with confirmed latent tuberculosis and $800$ individuals who are definitively uninfected. The assay yielded a positive result in $170$ of the infected individuals and in $40$ of the uninfected individuals.

Based on these validation study results, what is the positive likelihood ratio of this new serum assay?

A 54-year-old man is currently hospitalized in the intensive care unit for severe acute gallstone pancreatitis. On day 21 of his admission, he develops new-onset fevers, a leukocyte count of 22,000/mm³, and worsening hypotension requiring vasopressor support. A contrast-enhanced CT scan of the abdomen reveals extensive walled-off pancreatic necrosis containing multiple pockets of gas. The surgical team is consulted for management. Arrange the following interventions in the correct sequential order according to the modern 'step-up' approach for infected necrotizing pancreatitis.

A 45-year-old man is brought to the emergency department after a high-speed motor vehicle collision. He has sustained severe blunt abdominal trauma and is actively bleeding. The trauma surgeon explains that an emergent exploratory laparotomy and blood transfusions are required to save his life. The patient is awake, alert, and oriented to person, place, and time. He demonstrates a clear understanding of his critical condition and acknowledges the certainty of death without a transfusion. He states, "I understand that I will likely die without a transfusion, but my religious beliefs strictly forbid receiving blood products. Under no circumstances should I be transfused." He signs a document reflecting these wishes and consents only to the surgery and non-blood volume expanders. Shortly after, his blood pressure drops precipitously, and he loses consciousness. His wife, who is not of the same faith, arrives at the bedside and demands that the medical team administer blood immediately to save his life. Which of the following is the most appropriate next step in management?