A 15-year-old boy is brought to the emergency department one hour after sustaining an injury during football practice. He collided head-on into another player while wearing a mouthguard and helmet. Immediately after the collision he was confused but able to use appropriate words. He opened his eyes spontaneously and followed commands. There was no loss of consciousness. He also had a headache with dizziness and nausea. He is no longer confused upon arrival. He feels well. Vital signs are within normal limits. He is fully alert and oriented. His speech is organized and he is able to perform tasks demonstrating full attention, memory, and balance. Neurological examination shows no abnormalities. There is mild tenderness to palpation over the crown of his head but no signs of skin break or fracture. Which of the following is the most appropriate next step?

Observe for 6 hours in the ED and refrain from contact sports for one week

Discharge without activity restrictions

Discharge and refrain from all physical activity for one week

Administer prophylactic levetiracetam and observe for 24 hours

Administer prophylactic phenytoin and observe for 24 hours

A 71-year-old man develops worsening chest pressure while shoveling snow in the morning. He tells his wife that he has a squeezing pain that is radiating to his jaw and left arm. His wife calls for an ambulance. On the way, he received chewable aspirin and 3 doses of sublingual nitroglycerin with little relief of pain. He has borderline diabetes and essential hypertension. He has smoked 15–20 cigarettes daily for the past 37 years. His blood pressure is 172/91 mm Hg, the heart rate is 111/min and the temperature is 36.7°C (98.0°F). On physical examination in the emergency department, he looks pale, very anxious and diaphoretic. His ECG is shown in the image. Troponin levels are elevated. Which of the following is the best next step in the management of this patient condition?

Clopidogrel, atenolol, anticoagulation and monitoring

CT scan of the chest with contrast

A 25-year-old woman presents with slightly yellow discoloration of her skin and eyes. She says she has had multiple episodes with similar symptoms before. She denies any recent history of nausea, fatigue, fever, or change in bowel/bladder habits. No significant past medical history. The patient is afebrile and vital signs are within normal limits. On physical examination, she is jaundiced, and her sclera is icteric. Laboratory findings are significant only for a mild unconjugated hyperbilirubinemia. The remainder of laboratory results is unremarkable. Which of the following is the most likely diagnosis in this patient?

Crigler-Najjar syndrome type II

A 31-year-old man presents with jaundice, scleral icterus, dark urine, and pruritus. He also says that he has been experiencing abdominal pain shortly after eating. He says that symptoms started a week ago and have not improved. The patient denies any associated fever or recent weight-loss. He is afebrile and vital signs are within normal limits. On physical examination, the patient’s skin appears yellowish. Scleral icterus is present. Remainder of physical examination is unremarkable. Laboratory findings are significant for: Conjugated bilirubin 5.1 mg/dL Total bilirubin 6.0 mg/dL AST 24 U/L ALT 22 U/L Alkaline phosphatase 662 U/L A contrast CT of the abdomen is unremarkable. An ultrasound of the right upper quadrant reveals a normal gallbladder, but the common bile duct is not visible. Which of the following is the next best step in the management of this patient?

Endoscopic retrograde cholangiopancreatography (ERCP)

Serologies for antimitochondrial antibodies

Antibiotics and admit to observation

Diagnostic algorithms by presentation — USMLE Lesson

Chest Pain Algorithm - Heartache Head-scratchers

Initial Assessment: ABCs, vitals, focused history & physical. Secure IV access.
Immediate Interventions (within 10 mins):
- ECG: Look for ST elevation/depression, T wave inversions, new LBBB.
- Aspirin 325 mg chewed.
- Nitroglycerin (if SBP >90), Oxygen (if SpO₂ <94%).

⭐ Exam Favourite: Dressler's syndrome is a post-myocardial infarction fibrinous pericarditis, typically occurring 2-8 weeks after the event. Presents with pleuritic chest pain, fever, and a pericardial friction rub.

Jaundice Approach - Going Yellow

Initial step: Fractionate bilirubin. The pattern guides the entire workup.

Unconjugated: Check for hemolysis (↑LDH, ↓haptoglobin, ↑retic count). If negative, consider genetic causes like Gilbert's syndrome.
Conjugated: Differentiate hepatocellular injury (viral, toxins) from cholestasis (stones, malignancy) using liver enzymes.
Imaging: Ultrasound is the first-line investigation for cholestatic jaundice to look for biliary obstruction.

⭐ In Gilbert's Syndrome, total bilirubin is typically < 3 mg/dL and rises with fasting or stress. It's a benign condition due to reduced UGT1A1 enzyme activity.

Diagnostic Algorithm for Jaundice

Fever of Unknown Origin (FUO) - The Heat Is On

Classic Definition: Fever > 38.3°C for ≥ 3 weeks with no diagnosis after 1 week of inpatient workup.
Core Causes: Infections (abscess, TB, endocarditis), Neoplasms (lymphoma, RCC), and Collagen Vascular Diseases (Still's disease, vasculitis).

FDG-PET/CT in Fever of Unknown Origin

⭐ In modern practice, FDG-PET/CT is a key investigation, often used earlier, to localize metabolic activity and guide targeted biopsies, significantly improving diagnostic yield.

Altered Sensorium Workup - Brain Fog Breakdown

Immediate Steps: Secure Airway, Breathing, Circulation. Check vitals & random blood sugar (RBS).
📌 Mnemonic (DON'T): Dextrose, Oxygen, Naloxone, Thiamine.

Investigations:
- Baseline: CBC, KFT, LFT, Serum electrolytes, ABG, Ammonia.
- Toxicology: Urine/Serum screen.
- Infectious: Lumbar Puncture (if safe), cultures.

⭐ In a patient with altered sensorium of unclear etiology, always consider Non-Convulsive Status Epilepticus (NCSE) and obtain an EEG.

High‑Yield Points - ⚡ Biggest Takeaways

In acute chest pain, the first test is always an ECG, followed by cardiac markers.

For suspected pulmonary embolism, CT pulmonary angiography is the gold standard diagnostic test.

In any acute stroke, the initial investigation is a non-contrast CT head to exclude hemorrhage.

For acute pancreatitis, serum lipase is the most specific initial test.

Ultrasound is the primary imaging modality for most causes of acute abdominal pain, especially in the RUQ.

For head trauma, always start with a non-contrast CT head.

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