All practice questions

A 67-year-old male with severe chronic obstructive pulmonary disease requiring continuous home oxygen is evaluated for acute-onset, generalized abdominal cramping and bilious emesis over the past 24 hours. His surgical history is notable for an appendectomy and a partial colectomy for diverticulitis. Vital signs are temperature $37.8^\circ\text{C}$ ($100.0^\circ\text{F}$), pulse $102/\text{min}$, respirations $22/\text{min}$, and blood pressure $118/76 \text{ mmHg}$. Physical examination reveals a distended abdomen with focal, severe tenderness and involuntary guarding in the right lower quadrant. Laboratory testing shows a leukocyte count of $14,500/\text{mm}^3$ and a serum lactate level of $3.4 \text{ mmol/L}$. Cross-sectional imaging with intravenous contrast demonstrates a transition point in the distal ileum, a twisting of the mesenteric vessels, and a focal segment of small intestine exhibiting reduced wall enhancement. Which of the following is the most appropriate next step in management?

A cohort study is conducted to evaluate the safety profile of a novel calcitonin gene-related peptide (CGRP) inhibitor for migraine prophylaxis. The researchers investigate the association between the use of the new CGRP inhibitor and the incidence of severe constipation requiring medical intervention. In the initial unadjusted analysis, patients taking the CGRP inhibitor had a significantly higher risk of severe constipation compared to those taking standard prophylactic medications, with a relative risk (RR) of 3.2 (p < 0.01).

Suspecting that concurrent medication use might be influencing the results, the researchers perform a stratified analysis based on the concurrent use of tricyclic antidepressants (TCAs), which are also known to decrease gastrointestinal motility. The results of the stratified analysis are as follows:

Based on these findings, which of the following best describes the role of concurrent TCA use in the observed relationship between the CGRP inhibitor and severe constipation?

A $48$-year-old woman is evaluated in the surgical step-down unit $4$ hours after undergoing an uncomplicated total thyroidectomy for a large, symptomatic multinodular goiter. The nurse urgently requests an evaluation because the patient has developed sudden-onset difficulty breathing.

Upon arrival, the patient is agitated, diaphoretic, and exhibiting high-pitched inspiratory stridor. Her temperature is $38.0^\circ\text{C}$ ($100.4^\circ\text{F}$), blood pressure is $165/95\text{ mm Hg}$, pulse is $118\text{/min}$, and oxygen saturation is $90\%$ on room air. Physical examination reveals a tense, rapidly expanding swelling deep to the cervical incision. The skin edges are intact and approximated with sutures, and no active superficial bleeding is visible.

Laboratory studies drawn $30$ minutes prior to this acute event show:
- Serum total calcium: $8.2\text{ mg/dL}$ (Reference: $8.4-10.2\text{ mg/dL}$)
- Serum albumin: $4.0\text{ g/dL}$
- TSH: $2.5\text{ }\mu\text{U/mL}$

The patient's husband, who is her designated healthcare proxy, stepped out of the hospital $10$ minutes ago and is currently unreachable by phone.

Which of the following is the most appropriate next step in the management of this patient?

A 48-year-old man is evaluated in the surgical ward on postoperative day 2 following an open reduction and internal fixation of a closed, highly comminuted midshaft tibial fracture. Over the past 4 hours, he has complained of rapidly escalating pain in his right leg that is entirely unresponsive to intravenous morphine. His temperature is $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$), heart rate is $128$/min, blood pressure is $90/55$ mmHg, and respiratory rate is $24$/min. Physical examination reveals a markedly swollen right lower extremity. The skin surrounding the surgical incision is tense, erythematous, and notably discolored with scattered bullae containing dark fluid. Exquisite tenderness is present well beyond the margins of the erythema. Subcutaneous crepitus is palpable along the medial aspect of the tibia. Dorsalis pedis and posterior tibial pulses are faint but palpable. Laboratory studies show:

Leukocyte count: $28,000$/mm $^3$
Serum sodium: $129$ mEq/L
Blood urea nitrogen: $34$ mg/dL
Serum creatinine: $1.8$ mg/dL

What is the most appropriate next step in the management of this patient?

A physician at a university health clinic is designing an observational study to examine if regular consumption of energy drinks increases the risk of new-onset hypertension in college students. A major concern is that students who consume energy drinks may also have poorer sleep habits, and poor sleep is independently associated with higher blood pressure. To properly address this specific issue, which of the following methodological approaches should be considered? (Select all that apply)

A 45-year-old woman is brought to the trauma center following a high-speed motor vehicle collision where she was the unrestrained driver and struck the steering wheel. On arrival, she is alert but in severe respiratory distress, using accessory muscles to breathe. Her temperature is 36.8°C (98.2°F), blood pressure is 112/68 mm Hg, pulse is 122/min, and respirations are 38/min. Pulse oximetry demonstrates an oxygen saturation of 84% despite receiving 15 L/min of oxygen via a non-rebreather mask. Physical examination of the chest wall demonstrates a large contusion over the right anterior thorax with an adjacent segment of the rib cage that moves inward during inspiration. Auscultation reveals crackles over the right middle and lower lung fields. An emergent portable chest radiograph displays multiple segmental fractures of ribs 4 through 8 on the right, along with patchy airspace opacities in the underlying lung parenchyma. There is no visible pleural line or significant blunting of the costophrenic angles. Which of the following is the most appropriate next step in the management of this patient?

A team of epidemiologists conducts a case-control study to evaluate the association between the use of a novel agricultural herbicide and the development of a rare form of non-Hodgkin lymphoma. They recruit 100 patients recently diagnosed with this specific lymphoma (cases) and 400 healthy age- and sex-matched individuals from the same region (controls).

The exposure histories of both groups are summarized in the table below:

The annual incidence of this specific non-Hodgkin lymphoma in the general population is approximately 3 per 100,000.

Based on these findings, what percentage of the lymphoma cases among the exposed workers can be attributed to this herbicide exposure?

A team of epidemiologists is conducting a retrospective cohort study to investigate the association between chronic exposure to aerosolized industrial solvents and the subsequent development of idiopathic pulmonary fibrosis. During a preliminary review of the literature, the researchers identify a history of tobacco smoking as a major potential confounder in this relationship. The research protocol utilized a large pre-existing national healthcare database, and all patient data has already been fully extracted and compiled into the final dataset for evaluation. Which of the following statistical or epidemiological methods can the researchers employ at this current stage of the study to adjust for the confounding effect of tobacco smoking? (Select all that apply)

A 65-year-old man is evaluated in the cardiovascular intensive care unit due to a sudden onset of shortness of breath and confusion. He underwent a four-vessel coronary artery bypass grafting procedure three days ago. His medical history includes hypertension, hyperlipidemia, and chronic obstructive pulmonary disease. Vital signs are temperature $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure $82/50\text{ mmHg}$, pulse $122\text{ /min}$, and respirations $24\text{ /min}$. Physical examination demonstrates distended jugular veins, muffled heart sounds, and clear lung fields bilaterally. His systolic blood pressure decreases by $18\text{ mmHg}$ during inspiration. Which of the following is the most appropriate next step in management?

A group of investigators is conducting a case-control study to evaluate the association between maternal use of a new over-the-counter anti-nausea medication during pregnancy and the incidence of congenital heart defects in newborns. The researchers interview mothers of infants born with congenital heart defects (cases) and mothers of healthy infants (controls) to gather information about their medication use during the first trimester. The interview data reveals a strong, statistically significant positive association between the medication and congenital heart defects. However, a subsequent review of objective electronic pharmacy dispensing records reveals no significant difference in medication purchases between the two groups. Which of the following is the most likely explanation for the initial study findings?

During a weekend snowboarding trip, a 24-year-old man falls forward onto his outstretched right hand. He presents to an urgent care clinic three hours later reporting pain in his right wrist. On physical examination, there is mild swelling and focal tenderness over the dorsal radial aspect of the wrist, specifically in the depression bounded by the extensor pollicis longus and extensor pollicis brevis tendons. Range of motion is limited by pain, but there is no gross deformity. Sensation and radial pulses are intact. Initial anterior-posterior, lateral, and scaphoid views of the right wrist on radiography show no abnormalities. Which of the following is the most appropriate next step in management?

A primary care physician refers a $65$-year-old retired chemical worker to the urology service due to alarming urinary changes. Over the preceding four weeks, the patient noted three distinct episodes where his entire urinary stream was bright red. He reports no associated pain during urination, flank discomfort, fever, or weight loss. He has a history of essential hypertension and smoked one pack of cigarettes daily for $40$ years before quitting recently. In the clinic, his vital signs are stable. Examination of the abdomen and external genitalia shows no abnormalities, and digital rectal examination reveals a smooth, non-enlarged prostate. A catheter-free urinalysis demonstrates $>50$ red blood cells per high-power field, with absent leukocyte esterase. A multiphasic computed tomography urogram is subsequently performed, which outlines normally functioning kidneys and pristine ureters without any solid masses or nephrolithiasis. Which of the following is the most appropriate next step in management?

A 74-year-old individual with a history of persistent atrial fibrillation and nonadherence to systemic anticoagulation is rushed to the operating room with sudden-onset, severe abdominal pain that is entirely out of proportion to physical examination findings. Laboratory studies reveal a profound lactic acidosis. A clinical diagnosis of acute superior mesenteric artery (SMA) embolism is made. Arrange the following intraoperative steps in the correct sequential order required to optimize the patient's surgical outcome and minimize the long-term risk of short bowel syndrome.

Researchers conduct a randomized controlled trial to evaluate the efficacy of a novel recombinant vaccine against respiratory syncytial virus (RSV) in older adults. A total of 16,000 healthy volunteers aged 65 years and older are enrolled and randomly assigned in a 1:1 ratio to receive either the vaccine or a placebo. Over a 24-month follow-up period, the investigators record the incidence of severe lower respiratory tract disease (LRTD) confirmed by laboratory testing. The results are summarized in the following table:

Based on these study results, what is the number needed to treat (NNT) to prevent one case of severe LRTD?

A 10-year prospective cohort study is conducted to evaluate the association between chronic shift work (defined as working primarily night shifts) and the incidence of type 2 diabetes mellitus. The study enrolls a total of $20,000$ adult participants who do not have diabetes at baseline. Among these participants, $5,000$ are classified as chronic shift workers, and $15,000$ are classified as regular day-shift workers. Over the 10-year follow-up period, $600$ of the chronic shift workers and $600$ of the day-shift workers develop type 2 diabetes mellitus. Assuming that this association is causal, which of the following is the percentage of type 2 diabetes cases among the chronic shift workers that can be attributed to their shift work?

A $52$-year-old man comes to the urology clinic to discuss the results of recent imaging. Two weeks ago, he presented to the emergency department with mild left lower quadrant abdominal discomfort. A CT scan of the abdomen and pelvis with contrast was performed to evaluate for diverticulitis; the colon appeared normal, but an incidental $3.4$-cm solid, heterogeneously enhancing, exophytic mass was discovered in the lower pole of the left kidney. He has a history of well-controlled hypertension and hyperlipidemia. His BMI is $28$ kg/m $^2$. Vital signs are within normal limits. Physical examination reveals a soft, non-tender abdomen without palpable masses. Serum creatinine is $0.9$ mg/dL, and urinalysis shows no abnormalities. There is no evidence of lymphadenopathy or vascular involvement on the imaging. Which of the following is the most appropriate next step in management?

Match each lumbosacral nerve root compression or spinal syndrome with its classic neurological examination findings. This clinical localization is essential for determining the appropriate neurosurgical intervention.

Match each classic vascular clinical presentation to its most likely underlying diagnosis.

Match each epidemiological research scenario with the specific type of bias or confounding it best describes.

Match each patient's clinical presentation of an acute abdomen with the most appropriate next step in management.