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Question 841Question →

Match each of the following clinical presentations with the most likely underlying vascular pathology.

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Items

A 60-year-old man presenting with buttock claudication, erectile dysfunction, and absent bilateral femoral pulses.
A 68-year-old man developing painful, cyanotic toes with intact pedal pulses two days after undergoing coronary angiography.
A 45-year-old male heavy smoker presenting with recurrent migratory superficial thrombophlebitis and distal digital ulcerations.
A 72-year-old woman with a history of weight loss and 'food fear' who now presents with sudden-onset, severe abdominal pain that is out of proportion to physical exam findings.
A 55-year-old woman experiencing episodes of vertigo, diplopia, and syncope primarily when vigorously exercising her left upper extremity.

Matches

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Answer

The correct matches align the man with buttock claudication to Aortoiliac occlusive disease, the post-angiography man to Cholesterol atheroembolism, the young smoker to Thromboangiitis obliterans, the woman with abdominal pain to Acute-on-chronic mesenteric ischemia, and the woman with arm-exercise-induced vertigo to Subclavian steal syndrome.
Each pairing relies on identifying pathognomonic clinical features for major vascular pathologies. Aortoiliac occlusive disease (Leriche syndrome) is recognized by the triad of claudication, impotence, and absent femoral pulses. Cholesterol atheroembolism presents with blue toes but intact pulses after endovascular procedures. Thromboangiitis obliterans targets distal vessels and veins in young smokers. Acute-on-chronic mesenteric ischemia presents with a history of intestinal angina followed by sudden severe abdominal pain out of proportion to exam. Subclavian steal syndrome presents with vertebrobasilar insufficiency triggered by ipsilateral arm exercise.

Step-by-Step Solution

1
Analyze the first clinical presentation detailing buttock claudication, erectile dysfunction, and absent femoral pulses.
This specific symptom triad identifies Leriche syndrome.
Recognizing this classic triad points to severe narrowing of the distal aorta and iliac arteries, known as Aortoiliac occlusive disease.
2
Evaluate the second presentation of cyanotic toes with intact pedal pulses following coronary angiography.
This presentation identifies blue toe syndrome caused by an iatrogenic event.
Endovascular procedures can dislodge aortic atherosclerotic plaques, leading to Cholesterol atheroembolism in small distal vessels.
3
Examine the third case of a young male heavy smoker with migratory superficial thrombophlebitis and distal ulcerations.
This patient demographic and symptom profile is highly specific for Buerger disease.
These findings characterize Thromboangiitis obliterans, an inflammatory vasculopathy strongly associated with tobacco use.
4
Assess the fourth case of chronic 'food fear' transitioning to acute, severe, out-of-proportion abdominal pain.
The chronic symptoms suggest intestinal angina, while the acute severe pain suggests acute bowel ischemia.
This progression matches Acute-on-chronic mesenteric ischemia, often due to thrombosis of a severely atherosclerotic mesenteric artery.
5
Analyze the fifth presentation of vertigo and diplopia triggered by left arm exercise.
These vertebrobasilar symptoms triggered by upper extremity exertion identify a 'steal' phenomenon.
Stenosis of the proximal subclavian artery causes reverse flow in the vertebral artery during arm exercise, known as Subclavian steal syndrome.

Key Concept

Clinical recognition of hallmark vascular surgery syndromes based on patient demographics, specific symptom triggers, and distinct physical exam findings.
Question 842Question →

A busy metropolitan emergency department evaluates four patients presenting with varying signs of acute substance intoxication or withdrawal. Match each patient's clinical presentation with the most likely corresponding toxidrome or substance-related state.

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Items

Patient A: A 22-year-old presenting with a respiratory rate of 6/min, marked miosis, and absent bowel sounds.
Patient B: A 35-year-old brought in by police, demonstrating prominent horizontal and vertical nystagmus, aggressive behavior, and ataxia.
Patient C: A 42-year-old experiencing severe agitation, diaphoresis, tachycardia, mydriasis, and acute chest pain.
Patient D: A 50-year-old developing profound confusion, visual hallucinations, resting tremor, and autonomic hyperactivity on hospital day 3 following an elective surgery.

Matches

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Answer

Patient A matches Opioid intoxication; Patient B matches Phencyclidine (PCP) intoxication; Patient C matches Cocaine intoxication; Patient D matches Alcohol withdrawal (Delirium tremens).
Each patient's clinical vignette uniquely aligns with a specific substance toxidrome or withdrawal syndrome. Opioid overdose causes respiratory depression and miosis. PCP toxicity features aggressive behavior and prominent nystagmus. Cocaine causes profound sympathetic stimulation and coronary vasospasm. Delirium tremens occurs several days into abstinence and features hallucinations and autonomic instability.

Step-by-Step Solution

1
Analyze the clinical presentation of Patient A.
Identified marked respiratory depression and miosis.
These findings represent the classic triad of opioid toxicity.
2
Analyze the clinical presentation of Patient B.
Identified multidirectional nystagmus and aggressive behavior.
Rotary or multidirectional nystagmus combined with aggression is the hallmark presentation of PCP intoxication.
3
Analyze the clinical presentation of Patient C.
Identified a sympathomimetic toxidrome with chest pain.
Cocaine blocks catecholamine reuptake, causing sympathetic hyperactivity and potentially triggering coronary vasospasm.
4
Analyze the clinical presentation of Patient D.
Identified late-onset delirium, hallucinations, and autonomic hyperactivity after hospital admission.
The timeline (day 3) and severe autonomic symptoms strongly indicate delirium tremens due to abrupt cessation of alcohol upon admission.

Key Concept

Recognition of specific toxidromes and withdrawal syndromes based on unique physical examination findings and clinical timelines.
Question 843Question →

Match each clinical presentation of an adrenal mass with the most appropriate specific perioperative or surgical management step.

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Items

A 45-year-old patient with episodic palpitations, diaphoresis, elevated plasma fractionated metanephrines, and a 4.5-cm adrenal mass.
A 38-year-old patient with resistant hypertension, muscle cramps, low serum potassium, high aldosterone-to-renin ratio, and a 2-cm unilateral adrenal mass.
A 50-year-old patient with central adiposity, proximal muscle weakness, elevated 24-hour urine free cortisol, suppressed ACTH, and a 3.5-cm adrenal mass.
A 55-year-old patient with abdominal pain, a rapidly enlarging 9-cm heterogeneous adrenal mass with irregular margins on CT, and elevated serum DHEA-S.

Matches

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Answer

Pheochromocytoma pairs with alpha/beta blockade; Conn syndrome pairs with aldosterone antagonists; Adrenal Cushing syndrome pairs with postoperative glucocorticoids; Adrenocortical carcinoma pairs with open en bloc resection.
Each adrenal pathology requires distinct surgical planning. Pheochromocytoma requires sequential alpha then beta blockade to prevent intraoperative hypertensive crisis. Primary hyperaldosteronism requires potassium repletion and mineralocorticoid receptor blockade. Adrenal Cushing syndrome causes contralateral gland atrophy, necessitating perioperative stress-dose glucocorticoids to prevent acute adrenal insufficiency after tumor removal. Large, suspicious masses (adrenocortical carcinoma) require open en bloc resection to avoid capsular rupture and tumor seeding, which are risks with laparoscopic approaches and percutaneous biopsies.

Step-by-Step Solution

1
Analyze the clinical, laboratory, and imaging findings for each adrenal mass presentation to establish the underlying diagnosis.
Identified diagnoses are pheochromocytoma, primary hyperaldosteronism, adrenal Cushing syndrome, and adrenocortical carcinoma.
Each type of functional or malignant adrenal tumor has distinct physiologic consequences that dictate perioperative management.
2
Determine the specific pathophysiologic risks associated with the surgical removal of each tumor type.
Pheochromocytoma risks hypertensive crisis; Conn syndrome involves potassium wasting and hypertension; Cushing syndrome risks postoperative adrenal crisis due to HPA axis suppression; Adrenocortical carcinoma risks tumor spillage and local invasion.
Surgical and perioperative strategies are tailored to mitigate these life-threatening complications.
3
Match the diagnosis with the standard-of-care surgical and perioperative intervention.
Correct pairings are made based on surgical guidelines for endocrine pathology.
Ensures adherence to best practices in endocrine surgery and patient safety.

Key Concept

Perioperative and surgical management of functioning and malignant adrenal tumors
Question 844Question →

Match each clinical research scenario or epidemiologic calculation to the most appropriate measure of disease frequency or association.

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Items

A prospective study compares the development of lung cancer between a group of smokers and a group of non-smokers.
A retrospective study compares the history of smoking between a group of patients with lung cancer and a group of healthy controls.
A public health survey determines the proportion of residents in a city who currently have asthma on a specific date.
A surveillance program tracks the number of newly diagnosed asthma cases in a population over a one-year period.

Matches

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Answer

The prospective study pairs with relative risk, the retrospective case-control study pairs with odds ratio, the survey of current cases pairs with point prevalence, and the tracking of new cases pairs with incidence rate.
Cohort studies follow subjects forward in time to determine disease incidence, allowing the calculation of relative risk. Case-control studies start with diseased patients and look backward at exposures, necessitating the odds ratio. Point prevalence is a snapshot of all current cases at one moment, while incidence rate measures only newly diagnosed cases over a specified duration.

Step-by-Step Solution

1
Analyze the study design or measurement described in each clinical scenario.
The scenarios describe a cohort study (left 1), a case-control study (left 2), a measurement of existing cases (left 3), and a measurement of new cases (left 4).
Identifying the fundamental study design or calculation type is required to select the correct statistical measure.
2
Match the identified study design or calculation to its corresponding epidemiologic measure.
Cohort studies use relative risk. Case-control studies use odds ratios. Existing cases at a specific time is point prevalence. New cases over a period is incidence rate.
Different study designs and temporal relationships necessitate specific mathematical measures of frequency and association.

Key Concept

Measures of Disease Frequency and Association
Question 845Question →

Match each clinical presentation of an endocrine lesion with its most appropriate diagnostic or surgical management step.

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Items

A 45-year-old woman with a 2-cm thyroid nodule, decreased TSH, elevated free T4, and increased uptake on a radionuclide scan.
A 55-year-old man with a 1.5-cm thyroid nodule, normal TSH, and fine-needle aspiration demonstrating intranuclear inclusions and grooved nuclei.
A 60-year-old woman with asymptomatic hypercalcemia of 11.2 mg/dL, elevated intact parathyroid hormone, and a 24-hour urine calcium of 350 mg.
A 40-year-old man with an incidentally discovered 5-cm adrenal mass and significantly elevated 24-hour urine fractionated metanephrines.

Matches

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Answer

The correct matches align each specific endocrine pathology (toxic adenoma, papillary thyroid carcinoma, primary hyperparathyroidism, and pheochromocytoma) with its standard diagnostic and perioperative surgical management.
Each matching pair appropriately links the clinical endocrine pathology with the standard of care. Toxic adenomas do not require FNA and are managed definitively. Papillary thyroid carcinomas require surgical excision. Primary hyperparathyroidism is treated with parathyroidectomy after localization. Pheochromocytomas require mandatory alpha-blockade to prevent life-threatening intraoperative hemodynamic instability.

Step-by-Step Solution

1
Evaluate the patient with a low TSH, high T4, and a 'hot' nodule on radionuclide scan.
Identify the lesion as a toxic adenoma.
Hyperfunctioning nodules have a very low risk of malignancy, so fine-needle aspiration is bypassed in favor of definitive therapy (surgery or radioactive iodine).
2
Analyze the cytology findings of intranuclear inclusions and grooved nuclei in a euthyroid patient with a nodule.
Diagnose papillary thyroid carcinoma.
These are classic histologic features requiring surgical resection via lobectomy or total thyroidectomy.
3
Interpret the laboratory panel showing hypercalcemia, elevated PTH, and high 24-hour urine calcium.
Confirm the diagnosis of primary hyperparathyroidism.
Elevated urine calcium distinguishes this from familial hypocalciuric hypercalcemia, indicating that surgical removal of the hyperfunctioning gland is appropriate.
4
Assess the adrenal mass presenting with elevated fractionated metanephrines.
Identify the tumor as a pheochromocytoma.
Medical preparation with alpha-blockade (e.g., phenoxybenzamine) is mandatory prior to surgical resection to control blood pressure during tumor manipulation.

Key Concept

Diagnostic workup and perioperative surgical management of thyroid, parathyroid, and adrenal lesions.
Question 846Question →

Match each patient's clinical presentation to the most appropriate initial diagnostic step or definitive procedural intervention.

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Items

32-year-old man with a firm, painless testicular nodule and retroperitoneal lymphadenopathy on imaging
41-year-old man with a pelvic fracture, inability to void, and blood at the urethral meatus following a high-speed collision
68-year-old man with painless gross hematuria and a 2-cm exophytic mucosal bladder lesion seen on office cystoscopy
27-year-old pregnant patient at 24 weeks gestation with acute pyelonephritis secondary to an obstructing 8-mm ureteral calculus

Matches

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Answer

The painless testicular mass pairs with radical inguinal orchiectomy. The pelvic fracture with urethral blood pairs with retrograde urethrography. The exophytic bladder lesion pairs with TURBT. The pregnant patient with infected obstructing stone pairs with ureteral stent placement.
Each right-side item represents the definitive standard of care for the corresponding left-side presentation. Urethral injury requires retrograde urethrography, testicular cancer requires inguinal orchiectomy, bladder tumors require TURBT, and infected obstructing stones require urgent stent placement or nephrostomy.

Step-by-Step Solution

1
Analyze each clinical presentation to identify the underlying urologic pathology.
Identified suspected testicular cancer, posterior urethral injury, bladder cancer, and complicated nephrolithiasis in pregnancy.
Accurate recognition of the clinical syndrome is prerequisite to determining the correct standard of care intervention.
2
Select the definitive diagnostic test or surgical management for each identified condition.
Matched each condition to its respective gold-standard urologic procedure.
USMLE guidelines emphasize knowing the absolute contraindications (e.g., blind catheterization in urethral injury) and emergent indications (e.g., immediate decompression of an infected obstructed kidney).

Key Concept

Diagnosis and procedural management of core urologic emergencies and genitourinary malignancies.
Question 847Question →

Match each clinical presentation to its most appropriate definitive surgical procedure.

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Items

A 68-year-old man with benign prostatic hyperplasia, suffering from recurrent acute urinary retention despite maximal medical therapy.
A 14-year-old boy presenting with sudden, severe unilateral scrotal pain and an absent cremasteric reflex, highly suspicious for testicular torsion.
A 62-year-old man diagnosed with localized, muscle-invasive urothelial carcinoma of the bladder.
A 28-year-old man with a newly identified, firm, solid testicular mass and elevated serum tumor markers.

Matches

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Answer

BPH refractory to medical therapy is treated with TURP. Testicular torsion requires immediate surgical exploration and bilateral orchiopexy. Muscle-invasive bladder cancer is treated with radical cystectomy and urinary diversion. A solid testicular mass requires a radical inguinal orchiectomy.
Each clinical scenario requires a highly specific, standard-of-care surgical intervention. BPH refractory to medical therapy necessitates procedures like TURP. Testicular torsion is a surgical emergency requiring exploration and bilateral orchiopexy. Muscle-invasive bladder cancer requires radical cystectomy. Finally, a suspicious testicular mass is managed with a radical inguinal orchiectomy to prevent tumor seeding.

Step-by-Step Solution

1
Analyze each clinical presentation to determine the underlying urologic diagnosis.
The diagnoses are: medically refractory BPH, testicular torsion, muscle-invasive bladder cancer, and suspected testicular cancer.
Accurate diagnosis is required to select the correct definitive surgical management.
2
Select the standard-of-care surgical procedure for each diagnosis.
BPH is matched to TURP; Torsion is matched to Exploration & Orchiopexy; Bladder Cancer is matched to Radical Cystectomy; Testicular Mass is matched to Radical Inguinal Orchiectomy.
These represent the fundamental surgical treatments for these core urologic conditions.

Key Concept

Indications for core urologic surgical procedures
Question 848Question →

Match the following common breast pathologies with their classic clinical presentations.

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Items

Fibroadenoma
Fibrocystic changes
Intraductal papilloma
Inflammatory breast cancer

Matches

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Answer

Fibroadenoma pairs with the painless, mobile mass in a young woman. Fibrocystic changes pair with cyclic, bilateral tender masses. Intraductal papilloma pairs with unilateral bloody nipple discharge. Inflammatory breast cancer pairs with rapid erythema and peau d'orange.
Proper diagnosis of breast complaints relies on the direct pattern recognition of key clinical features. Age, pain, mobility, relationship to the menstrual cycle, and overlying skin changes are critical distinguishing factors between common benign entities (like fibroadenomas and fibrocystic changes) and specific malignancies (like inflammatory breast cancer).

Step-by-Step Solution

1
Identify the characteristic presentation of a fibroadenoma.
It matches the painless, firm, mobile mass in a woman under 30.
Fibroadenomas are the most common benign breast tumors in this age group, known for their distinct mobility on physical exam.
2
Identify the characteristic presentation of fibrocystic changes.
It matches the bilateral, tender masses that fluctuate with the menstrual cycle.
These benign breast changes are hormonally driven, causing cyclical pain and nodularity in the breast tissue.
3
Identify the characteristic presentation of an intraductal papilloma.
It matches the unilateral bloody nipple discharge without a palpable mass.
A benign papilloma located within a lactiferous duct is prone to bleeding, causing the distinct unilateral discharge.
4
Identify the characteristic presentation of inflammatory breast cancer.
It matches the rapidly progressive erythema, swelling, and peau d'orange.
Dermal lymphatic invasion by tumor cells causes marked edema of the skin, resulting in the classic 'orange peel' appearance and rapid onset of symptoms.

Key Concept

Clinical presentation of benign and malignant breast pathologies
Question 849Question →

Match the following types of intracranial hemorrhage with their classic presentation on a noncontrast head computed tomography (CT) scan.

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Items

Epidural hematoma
Subdural hematoma
Subarachnoid hemorrhage
Intraparenchymal hemorrhage

Matches

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Answer

Epidural hematoma matches with the biconvex (lens-shaped) hyperdensity; Subdural hematoma matches with the crescent-shaped hyperdensity; Subarachnoid hemorrhage matches with hyperdensity in the cisterns/sulci; Intraparenchymal hemorrhage matches with localized deep hyperdensity in the basal ganglia.
Each type of intracranial hemorrhage has a distinct anatomic space that dictates its appearance on noncontrast CT. The firm attachment of the dura to the skull sutures causes arterial epidural bleeds to form a biconvex shape. Venous subdural bleeds spread over the hemisphere as a crescent. Subarachnoid blood fills the pre-existing CSF spaces (cisterns and sulci), and intraparenchymal blood pools directly within brain tissue, typically in deep structures like the basal ganglia due to hypertension.

Step-by-Step Solution

1
Evaluate the anatomy and bleeding source of an epidural hematoma.
Identify that arterial bleeding between the skull and dura creates a localized, high-pressure biconvex (lens) shape limited by cranial sutures.
This structural limitation dictates its distinct radiographic appearance on CT.
2
Evaluate the anatomy and bleeding source of a subdural hematoma.
Identify that venous bleeding between the dura and arachnoid spreads out, forming a crescent shape that can cross sutures but is stopped by dural folds.
Venous pressure is lower, allowing blood to diffuse over a larger hemispheric area.
3
Evaluate the distribution of subarachnoid hemorrhage.
Identify that blood mixes with CSF in the subarachnoid space, appearing as hyperdensity outlining the sulci and basal cisterns.
Bleeding is occurring on the surface of the brain inside the fluid-filled spaces.
4
Evaluate the location of intraparenchymal hemorrhage.
Identify that this type of bleeding occurs inside the brain parenchyma, classically in deep structures like the basal ganglia.
It is often caused by hypertensive vasculopathy affecting deep penetrating arteries.

Key Concept

Radiographic appearance and anatomic boundaries of intracranial hemorrhages
Question 850Question →

Match each of the following clinical presentations with the most appropriate definitive surgical or interventional next step in management.

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Items

An 18-year-old male is rushed to the emergency department reporting excruciating, sudden-onset right-sided scrotal pain. Physical evaluation reveals an elevated, transversely oriented testicle with a negative cremasteric reflex. Sonography demonstrates absent testicular arterial flow.
A 45-year-old male presents in a state of shock with a blood pressure of 85/50 mmHg, rigors, and a temperature of 39.4°C (102.9°F). Non-contrast CT identifies an 8-mm calculus lodged in the left proximal ureter, causing moderate hydronephrosis.
During a routine workup for vague dyspepsia, a 60-year-old male is incidentally found to have a 3.5-cm, heavily enhancing, exophytic solid lesion isolated to the cortical surface of the right kidney.
Following an episode of painless macroscopic hematuria, a 71-year-old male undergoes a transurethral resection. Pathology confirms a high-grade urothelial malignancy penetrating into the detrusor muscle. Staging scans are entirely negative for spread.
A 29-year-old male notices a firm, non-tender nodule in his left hemiscrotum. Subsequent ultrasonography highlights a 2.8-cm solid, hypoechoic, highly vascularized mass contained within the testicular parenchyma.

Matches

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Answer

Each urologic emergency or oncology scenario must be paired with its standard-of-care surgical intervention, prioritizing organ preservation where safe, and aggressive extirpation where oncologically necessary.
The correct matches align distinct urologic pathologies with their gold-standard surgical interventions. Testicular torsion requires immediate restoration of blood flow and bilateral orchiopexy to prevent future occurrences. An infected, obstructing ureteral stone leading to sepsis is a surgical emergency demanding urgent decompression of the collecting system, rather than definitive stone fragmentation. For a small, localized renal mass, a partial nephrectomy is indicated to preserve renal function while ensuring oncologic efficacy. Muscle-invasive bladder cancer necessitates definitive extirpation via radical cystectomy and urinary diversion. Finally, a highly suspicious solid testicular mass requires a radical inguinal orchiectomy.

Step-by-Step Solution

1
Evaluate the patient with an acute scrotum lacking arterial flow.
Diagnose testicular torsion.
Requires emergent surgical unwinding and bilateral orchiopexy to prevent necrosis.
2
Analyze the case of an obstructing ureteral stone accompanied by fever and hypotension.
Identify a urologic emergency (obstructive pyelonephritis/sepsis).
Demands immediate percutaneous or internal stent decompression prior to definitive stone treatment.
3
Assess the 3.5-cm isolated, exophytic renal mass.
Diagnose a Stage T1a renal cell carcinoma.
Indicates partial nephrectomy to maximize preserved functional renal parenchyma.
4
Evaluate the pathology showing detrusor muscle invasion in bladder cancer.
Confirm muscle-invasive disease.
Requires radical cystectomy rather than repeat transurethral resection.
5
Identify the solid intratesticular mass in a young adult.
Diagnose primary testicular cancer.
Necessitates a radical inguinal orchiectomy to prevent altering lymphatic drainage.

Key Concept

Definitive surgical management of core urologic pathologies
Estimated Time:2m 0s
Question 851Question →

Match each clinical study scenario with the most appropriate epidemiological measure of disease frequency or association.

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Items

A prospective cohort study follows 1,000 initially healthy adults for 5 years to determine the proportion that develops incident hypertension.
A case-control study identifies adults with hepatocellular carcinoma and age-matched healthy volunteers, then surveys them regarding previous hepatitis C infection.
A trial compares a new antihypertensive to placebo; the rate of stroke is 3% in the intervention arm and 5% in the placebo arm, with the researchers reporting the 2% difference.
A randomized controlled trial reports that 15 patients must be treated with a novel lipid-lowering medication to prevent one major adverse cardiac event.

Matches

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Answer

Prospective tracking measures Cumulative Incidence; Case-control studies use Odds Ratio; The simple difference in event rates is the Absolute Risk Reduction; The number of patients treated to prevent one event is the Number Needed to Treat.
Each study design conceptually maps to a specific metric. Cohort studies follow at-risk populations to determine incidence. Case-control studies require the odds ratio due to an inability to measure true incidence. Simple subtraction of adverse event rates between trial arms produces the absolute risk reduction, and identifying how many patients must be treated to prevent one event is the number needed to treat.

Step-by-Step Solution

1
Analyze the first scenario tracking healthy adults over 5 years.
Identifies the measurement of new disease cases in an at-risk population.
This fundamentally describes Cumulative Incidence (or incidence proportion).
2
Evaluate the second scenario involving patients with a known disease (hepatocellular carcinoma) and healthy controls.
Identifies a case-control study design.
Because case-control studies start with the outcome rather than the population at risk, Relative Risk cannot be calculated. The appropriate measure of association is the Odds Ratio.
3
Assess the third scenario where researchers calculate the difference between 5% and 3%.
Identifies a simple subtraction of two risk proportions (5% - 3% = 2%).
Subtracting the intervention risk from the baseline/control risk directly yields the Absolute Risk Reduction (ARR).
4
Review the fourth scenario quantifying the population required to receive treatment to prevent a single event.
Identifies a value representing 1 / ARR.
This is the precise definition of the Number Needed to Treat (NNT).

Key Concept

Epidemiological study designs dictate which measures of disease frequency and association can be mathematically and logically applied.
Question 852Question →

Match each vascular condition with its most characteristic clinical presentation.

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Items

Ruptured abdominal aortic aneurysm
Acute aortic dissection
Acute limb ischemia
Peripheral arterial disease

Matches

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Answer

Ruptured abdominal aortic aneurysm matches with sudden back pain, hypotension, and a pulsatile mass. Acute aortic dissection matches with tearing chest pain and asymmetric blood pressures. Acute limb ischemia matches with the 6 Ps (pain, pallor, pulselessness, etc.). Peripheral arterial disease matches with reproducible exertional calf pain relieved by rest.
Each major vascular condition has a highly distinct, pathognomonic clinical presentation that guides immediate diagnosis and management. Recognizing the triad of a ruptured AAA, the tearing pain and asymmetric pulses of an aortic dissection, the 6 Ps of acute limb ischemia, and the claudicatory pain of chronic PAD is essential foundational clinical knowledge.

Step-by-Step Solution

1
Analyze the presentation of sudden back pain, hypotension, and a pulsatile mass.
This triad is the classic manifestation of a ruptured abdominal aortic aneurysm (AAA).
Rupture leads to rapid retroperitoneal or intraperitoneal blood loss (hypotension) from the dilated aorta (pulsatile mass), causing severe pain.
2
Analyze the presentation of tearing chest pain and asymmetric blood pressures.
This describes an acute aortic dissection.
The intimal tear causes ripping pain, and involvement of the aortic arch branches can lead to disparate pulse and blood pressure measurements between the arms.
3
Analyze the presentation of sudden unilateral pain, pallor, and pulselessness.
These are the hallmark signs of acute limb ischemia.
Acute arterial occlusion completely cuts off blood supply, leading to immediate ischemic symptoms described as the 6 Ps.
4
Analyze the presentation of reproducible exertional calf pain relieved by rest.
This represents intermittent claudication, characteristic of chronic peripheral arterial disease (PAD).
Chronic atherosclerotic narrowing limits blood flow during exercise, causing ischemic pain that resolves when metabolic demand decreases during rest.

Key Concept

Classic clinical presentations of major vascular emergencies and conditions
Question 853Question →

Match the following classic clinical presentations and neuroanatomical findings with their corresponding brain herniation syndrome.

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Items

Ipsilateral fixed and dilated pupil followed by contralateral hemiparesis
Contralateral lower extremity weakness secondary to anterior cerebral artery compression
Progressive bilateral rostrocaudal neurologic deterioration with Cheyne-Stokes respirations
Sudden onset of respiratory arrest and flaccid paralysis due to medullary compression

Matches

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Answer

The correct matches are: Ipsilateral blown pupil with Uncal herniation; Contralateral leg weakness with Subfalcine herniation; Progressive bilateral deterioration with Central herniation; and Respiratory arrest with Tonsillar herniation.
Each specific herniation syndrome compresses distinct neurovascular structures. Uncal herniation compresses CN III and the cerebral peduncle. Subfalcine herniation compresses the anterior cerebral artery. Central herniation causes downward displacement of the brainstem resulting in symmetric progression of signs. Tonsillar herniation directly impacts the medulla, disrupting vital autonomic functions.

Step-by-Step Solution

1
Analyze the finding of 'ipsilateral fixed and dilated pupil with contralateral hemiparesis'.
Matches Uncal herniation.
Compression of the ipsilateral CN III and cerebral peduncle is the classic hallmark of uncal (transtentorial) herniation.
2
Analyze the finding of 'contralateral lower extremity weakness'.
Matches Subfalcine herniation.
The cingulate gyrus herniates under the falx cerebri, trapping the anterior cerebral artery which supplies the motor cortex for the lower extremities.
3
Analyze the finding of 'progressive bilateral rostrocaudal deterioration'.
Matches Central transtentorial herniation.
Downward pressure on the diencephalon and midbrain causes a gradual, symmetric progression of brainstem dysfunction, notably affecting respiratory patterns early on.
4
Analyze the finding of 'sudden onset of respiratory arrest'.
Matches Tonsillar herniation.
Displacement of the cerebellar tonsils through the foramen magnum directly compresses the medullary respiratory centers.

Key Concept

Clinical presentations of brain herniation syndromes
Question 854Question →

Match each clinical presentation of a large bowel emergency with its most appropriate next step in management.

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Items

A 32-year-old man with fulminant ulcerative colitis and toxic megacolon becomes hypotensive; imaging shows impending perforation.
A 71-year-old woman presents with acute abdominal pain; imaging reveals a massively dilated cecum. She is hemodynamically stable without peritonitis, and laparotomy shows viable bowel.
A 78-year-old man presents with progressive abdominal distension; abdominal radiograph shows a 'coffee bean' sign. He is hemodynamically stable with no signs of peritonitis.
A 64-year-old man presents with sudden-onset diffuse abdominal pain; emergency laparotomy reveals generalized fecal peritonitis from a ruptured sigmoid diverticulum.

Matches

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Answer

The correct matches align each specific anatomical and pathological emergency with its standard-of-care intervention: unstable toxic megacolon requires subtotal colectomy with end ileostomy; stable cecal volvulus requires right hemicolectomy; uncomplicated sigmoid volvulus requires endoscopic detorsion; and Hinchey IV diverticulitis requires a Hartmann procedure.
Each correct pairing directly reflects the surgical standard of care. Large bowel emergencies dictate treatment based on anatomical location, physiological stability, and peritoneal contamination. Stable, uncontaminated patients often tolerate primary anastomoses or non-operative interventions (like endoscopy), whereas unstable or contaminated patients require rapid resection with ostomy diversion.

Step-by-Step Solution

1
Identify the underlying pathology and anatomical location based on the vignette.
Recognize fulminant ulcerative colitis, cecal volvulus, sigmoid volvulus, and perforated diverticulitis.
Surgical management of the large bowel is heavily dependent on the specific disease process and the specific anatomical segment involved.
2
Assess the patient's hemodynamic stability and the presence of generalized peritonitis or bowel ischemia.
The toxic megacolon and perforated diverticulitis patients are unstable or have gross contamination; the volvulus patients are stable and without peritonitis.
Hemodynamic instability or gross fecal contamination typically precludes a safe primary anastomosis, necessitating an ostomy (e.g., end ileostomy or colostomy).
3
Select the optimal intervention based on established surgical guidelines.
Assign subtotal colectomy for emergency IBD, right hemicolectomy for cecal volvulus, endoscopy for uncomplicated sigmoid volvulus, and a Hartmann procedure for fecal peritonitis.
These represent algorithmic standards designed to minimize perioperative mortality and disease recurrence.

Key Concept

Emergency Surgical Management of Large Bowel Pathologies
Question 855Question →

Match each clinical presentation of an acute surgical abdomen to the most appropriate next step in management.

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Items

A 35-year-old man presents with 5 days of right lower quadrant pain, fever, and leukocytosis. Computed tomography (CT) reveals a 6.5-cm periappendiceal abscess without generalized peritonitis.
A 71-year-old woman is admitted with sudden-onset, severe generalized abdominal pain, confusion, and a systolic blood pressure of 85 mm Hg. CT imaging demonstrates sigmoid diverticulitis with diffuse pneumoperitoneum.
A 52-year-old man presents with left lower quadrant pain and low-grade fever. CT reveals sigmoid diverticulitis complicated by a localized 1.5-cm pericolic fluid collection.
A 58-year-old man with a history of open appendectomy presents with obstipation, abdominal distension, and bilious vomiting. CT reveals a small bowel transition point with normal wall enhancement.

Matches

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Answer

The 6.5-cm abscess matches with percutaneous drainage; the perforated diverticulitis with shock matches with emergent laparotomy; the 1.5-cm microabscess matches with IV antibiotics alone; and the uncomplicated small bowel obstruction matches with nasogastric tube decompression.
Appropriate triage relies on established surgical indications. Uncomplicated small bowel obstruction and small (<3 cm) abscesses are managed conservatively. Large abscesses (>4 cm) require percutaneous drainage to allow inflammation to subside prior to any definitive operation. Free perforation with hemodynamic instability requires emergent operative source control.

Step-by-Step Solution

1
Evaluate the 6.5-cm periappendiceal abscess.
Determine that the abscess is large enough to warrant drainage rather than immediate surgery.
Operating on a large, acute abscess risks iatrogenic bowel injury and necessitates more extensive resection.
2
Assess the hemodynamically unstable patient with diffuse pneumoperitoneum.
Identify Hinchey IV diverticulitis requiring emergent laparotomy.
Free fecal or purulent peritonitis with shock is life-threatening and demands immediate operative source control (Hartmann procedure).
3
Analyze the 1.5-cm pericolic fluid collection.
Classify as a microabscess suitable for medical management.
Collections smaller than 3-4 cm have excellent resolution rates with antibiotics alone and are technically difficult to drain percutaneously.
4
Review the small bowel obstruction presentation.
Recognize an uncomplicated obstruction due to normal bowel wall enhancement.
Without signs of ischemia or closed-loop physiology, conservative management is the standard first-line approach.

Key Concept

Surgical triage of the acute abdomen based on complication severity, imaging findings, and hemodynamic stability
Question 856Question →

Match the following clinical presentations of patients with adrenal masses or adrenal dysfunction to the most appropriate next step in management or surgical intervention.

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Items

A 55-year-old patient with a 6.5-cm right adrenal mass. Unenhanced CT Hounsfield units (HU) = 35. Biochemical evaluation for hypercortisolism, primary aldosteronism, and pheochromocytoma is normal.
A 45-year-old patient with resistant hypertension and hypokalemia. CT abdomen is normal. Adrenal vein sampling (AVS) Aldosterone/Cortisol ratios: Right = 15, Left = 12, Inferior Vena Cava (IVC) = 10.
A 45-year-old patient with resistant hypertension and hypokalemia. CT shows a 1.5-cm left adrenal nodule. AVS Aldosterone/Cortisol ratios: Left = 25, Right = 2, IVC = 5.
A 60-year-old patient with an incidentally discovered 3.5-cm left adrenal mass. Unenhanced CT HU = 5. Morning cortisol after 1-mg dexamethasone suppression is 1.1 µg/dL. Plasma metanephrines are normal.
A 40-year-old patient with episodic severe headaches and tachycardia. CT abdomen shows a 4.5-cm right adrenal mass with unenhanced HU = 35. Plasma free metanephrines are markedly elevated.

Matches

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Answer

The presentations map specifically to their optimal management paths: suspicious masses require open surgery, non-functioning adenomas require observation, bilateral aldosteronism is managed medically, unilateral aldosteronomas are removed laparoscopically, and pheochromocytomas require sequential medical blockade prior to laparoscopic removal.
Optimal management of adrenal lesions depends on differentiating benign adenomas from adrenocortical carcinoma (using size cutoffs and unenhanced HU < 10) and identifying hormone hypersecretion. Primary aldosteronism requires AVS to definitively differentiate unilateral from bilateral disease. Pheochromocytoma requires proper preoperative sequential medical blockade.

Step-by-Step Solution

1
Evaluate the 6.5-cm, HU=35 non-functioning mass.
Identify high risk for adrenocortical carcinoma.
Size > 4 cm and unenhanced HU > 10 indicate a suspicious lesion requiring open surgical resection.
2
Calculate the AVS lateralization index for the patient with normal CT.
Ratio = 1.25, indicating bilateral hyperplasia.
A lateralization index < 3 confirms bilateral disease, which is treated medically.
3
Calculate the AVS lateralization index for the patient with the 1.5-cm left nodule.
Ratio = 12.5, indicating a unilateral left aldosteronoma.
A lateralization index > 4 confirms unilateral disease, making the patient a candidate for laparoscopic adrenalectomy.
4
Evaluate the 3.5-cm, HU=5 non-functioning mass.
Identify a benign, non-functioning lipid-rich adenoma.
Size < 4 cm, HU < 10, and negative biochemical workup require only serial observation.
5
Determine the preoperative management for the patient with elevated metanephrines.
Identify pheochromocytoma requiring sequential blockade.
Alpha-blockade must be initiated before beta-blockade to prevent unopposed alpha-adrenergic stimulation.

Key Concept

Surgical management of adrenal masses requires integration of tumor size, unenhanced Hounsfield units, biochemical functionality, and adrenal vein sampling lateralization.
Estimated Time:3m 0s
Question 857Question →

In the management of severe traumatic brain injury and refractory intracranial hypertension, various interventions are utilized to lower intracranial pressure (ICP) while maintaining adequate cerebral perfusion. Match each advanced neurocritical care intervention with its precise physiological mechanism of action and primary clinical limitation.

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Items

Induced hypocapnia (target PaCO2 30-35 mmHg)
Intravenous hypertonic saline administration
High-dose barbiturate therapy
Decompressive craniectomy

Matches

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Answer

Induced hypocapnia matches with pH-mediated vasoconstriction. Hypertonic saline matches with osmotic gradient and hyperchloremic acidosis. High-dose barbiturate therapy matches with suppression of CMRO2 and myocardial depression. Decompressive craniectomy matches with expanding fixed volume and syndrome of the trephined.
Each neurocritical care intervention targets a specific component of the Monro-Kellie doctrine (brain parenchyma, cerebrospinal fluid, or blood). Hyperventilation rapidly constricts vessels to decrease blood volume. Hyperosmolar therapy shrinks the brain parenchyma. Barbiturates reduce metabolic demand and coupled blood flow. Craniectomy increases the total allowable volume in the intracranial vault.

Step-by-Step Solution

1
Analyze the mechanism of induced hypocapnia (hyperventilation).
Identified that lowering PaCO2 reduces perivascular hydrogen ion concentration, causing vasoconstriction and lowering cerebral blood volume.
This corresponds to the definition highlighting pH-mediated arteriolar vasoconstriction and buffer equilibration.
2
Evaluate the properties of hypertonic saline in neurotrauma.
Identified that it creates an osmotic gradient across the blood-brain barrier to extract tissue water.
This matches the mechanism of reducing parenchymal water, with hyperchloremic metabolic acidosis being its classic high-dose complication.
3
Determine the role of high-dose barbiturate therapy.
Identified that barbiturates lower ICP via metabolic suppression (reducing CMRO2) and coupled flow reduction.
This matches the description of CMRO2 suppression, with systemic hypotension as the primary dose-limiting toxicity.
4
Assess the physiological impact of decompressive craniectomy.
Identified that removing the skull alters the fundamental volume-pressure relationship (Monro-Kellie doctrine) by removing the rigid constraint.
This aligns with expanding intracranial volume and the characteristic late complication of syndrome of the trephined.

Key Concept

Management of Elevated Intracranial Pressure
Question 858Question →

Match each clinical presentation of a urologic injury or surgical complication to its most appropriate definitive management or immediate next step.

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Items

A 42-year-old man with a pelvic fracture has gross hematuria. CT cystography reveals contrast extravasation confined to the retropubic space. No other injuries are identified.
A 35-year-old man presents with acute abdominal pain following a seatbelt injury. CT cystography demonstrates contrast material outlining the loops of the small intestine.
A 28-year-old man with a crush pelvic fracture presents with blood at the urethral meatus. Retrograde urethrography shows contrast extravasation at the bulbomembranous junction.
A 45-year-old woman develops a continuous, clear vaginal discharge two weeks after a radical hysterectomy. CT urography shows right-sided hydronephrosis and contrast pooling in the vagina.
A 31-year-old woman presents with fever and flank pain 3 days after ureteroscopy. CT reveals a 4-cm retroperitoneal fluid collection and contrast extravasation from the distal ureter.

Matches

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Answer

Extraperitoneal bladder rupture requires urethral Foley catheter drainage. Intraperitoneal bladder rupture requires exploratory laparotomy with primary closure. Posterior urethral injury requires suprapubic cystostomy placement. Ureterovaginal fistula requires urinary diversion via percutaneous nephrostomy. Ureteral injury with urinoma requires ureteral stent placement and percutaneous fluid drainage.
Each clinical presentation is uniquely matched to its guideline-directed surgical or conservative management based on the specific anatomical location of the injury and the timeline of the presentation.

Step-by-Step Solution

1
Analyze the imaging findings to classify the anatomical location of the bladder injury.
Contrast confined to the retropubic space indicates extraperitoneal rupture, whereas contrast outlining bowel loops indicates intraperitoneal rupture.
Management of bladder trauma strictly depends on the relationship of the rupture to the peritoneal reflection.
2
Determine the optimal initial intervention for suspected urethral injuries.
Avoid blind urethral catheterization and place a suprapubic cystostomy.
Catheterization can convert a partial urethral tear into a complete transection.
3
Evaluate the timeline and presentation of the iatrogenic ureteral injuries to guide surgical timing.
Recognize that a 2-week-old ureterovaginal fistula is highly inflamed, requiring diversion (nephrostomy) rather than immediate reconstruction. An infected urinoma needs active drainage alongside internal stenting.
Operating on acutely inflamed, friable tissue leads to high failure rates in reconstructive urologic surgery, and undrained collections lead to sepsis.

Key Concept

The management of urologic trauma and post-surgical complications relies on accurate anatomical diagnosis (intra- vs. extraperitoneal, anterior vs. posterior urethra) and avoiding interventions that exacerbate the injury or risk sepsis.
Question 859Question →

Match each clinical study scenario to the epidemiological measure of disease frequency or association it best describes.

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Items

A cross-sectional survey on July 1st identifies 500 people with asthma out of a town of 10,000 residents.
Over a 5-year period, 200 out of 5,000 previously healthy adults are newly diagnosed with type 2 diabetes.
A prospective cohort study determines that the incidence of lung cancer in smokers is 8 times higher than the incidence in non-smokers.
A case-control study determines that patients with food poisoning had 5 times higher odds of having eaten potato salad compared to healthy controls.

Matches

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Answer

The correct pairings match each distinct study scenario with its defining epidemiological measure.
Each scenario perfectly aligns with the fundamental definition of the respective epidemiological measure.

Step-by-Step Solution

1
Analyze the first scenario regarding existing asthma cases at a specific time (July 1st).
Identified as Point prevalence.
Prevalence measures the proportion of all existing cases in a population at a single point in time.
2
Analyze the second scenario regarding newly diagnosed diabetes cases over 5 years.
Identified as Cumulative incidence.
Incidence measures the proportion of new cases occurring in an at-risk population over a specified period.
3
Analyze the third scenario comparing disease incidence between exposed and unexposed groups.
Identified as Relative risk.
Relative risk is the ratio of incidence in the exposed group to the incidence in the unexposed group.
4
Analyze the fourth scenario comparing past exposures between cases and controls.
Identified as Odds ratio.
Odds ratio compares the odds of exposure among cases to the odds of exposure among controls.

Key Concept

Measures of Disease Frequency and Association
Question 860Question →

Match each clinical presentation to its most likely neurosurgical diagnosis.

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Items

A 22-year-old struck in the head with a baseball presents with brief loss of consciousness, a lucid interval, and subsequent rapid neurological decline.
An 81-year-old with a history of falls presents with insidious onset of confusion, headache, and a crescent-shaped hyperdensity on head CT.
A 45-year-old presents to the emergency department with the sudden onset of a 'thunderclap' headache, photophobia, and nuchal rigidity.
A 60-year-old man involved in a rear-end motor vehicle collision develops bilateral upper extremity weakness with relative sparing of the lower extremities.

Matches

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Answer

The lucid interval points to an epidural hematoma. The elderly patient with a crescent-shaped CT finding has a subdural hematoma. The 'thunderclap' headache represents a subarachnoid hemorrhage. The upper extremity-predominant weakness after a rear-end collision indicates central cord syndrome.
Each vignette represents a highly classic presentation of a distinct neurosurgical condition. Recognizing these 'textbook' patterns is essential for rapid diagnosis and management on the USMLE Step 2 exam.

Step-by-Step Solution

1
Analyze the first vignette regarding the 22-year-old with a lucid interval.
The classic 'lucid interval' after trauma suggests an epidural hematoma.
Tear of the middle meningeal artery leads to rapid arterial bleeding after initial recovery.
2
Analyze the second vignette regarding the 81-year-old with a crescent-shaped CT finding.
This presentation is characteristic of a subdural hematoma.
Tearing of bridging veins in an elderly patient causes slow venous bleeding that conforms to the shape of the skull.
3
Analyze the third vignette regarding the 45-year-old with a 'thunderclap' headache.
This is the pathognomonic presentation for a subarachnoid hemorrhage.
A ruptured aneurysm releases arterial blood directly into the subarachnoid space, causing sudden severe meningeal irritation.
4
Analyze the fourth vignette regarding the 60-year-old with upper extremity weakness.
This pattern of weakness following a hyperextension injury describes central cord syndrome.
The cervical spinal cord's central gray matter, which disproportionately innervates the upper extremities, is injured during hyperextension, especially with underlying spondylosis.

Key Concept

Diagnosis of common neurosurgical emergencies based on classic clinical presentations.
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