Ten days after undergoing emergent colectomy for a ruptured bowel that she sustained in a motor vehicle accident, a 59-year-old woman has abdominal pain. During the procedure, she was transfused 3 units of packed red blood cells. She is currently receiving total parenteral nutrition. Her temperature is 38.9°C (102.0°F), pulse is 115/min, and blood pressure is 100/60 mm Hg. Examination shows tenderness to palpation in the right upper quadrant of the abdomen. Bowel sounds are hypoactive. Serum studies show: Aspartate aminotransferase 142 U/L Alanine aminotransferase 86 U/L Alkaline phosphatase 153 U/L Total bilirubin 1.5 mg/dL Direct bilirubin 1.0 mg/dL Amylase 20 U/L Which of the following is the most likely diagnosis?

Acute cholecystitis (calculous)

A 34-year-old man is admitted to the emergency department after a motor vehicle accident in which he sustained blunt abdominal trauma. On admission, he is conscious, has a GCS score of 15, and has normal ventilation with no signs of airway obstruction. Vitals initially are blood pressure 95/65 mmHg, heart rate 87/min, respiratory rate 14/min, and oxygen saturation of 95% on room air. The physical exam is significant only for tenderness to palpation over the left flank. Noncontrast CT of the abdomen shows fractures of the 9th and 10th left ribs. Intravenous fluids are administered and the patient's blood pressure increases to 110/80 mm Hg. Three days later after admission, the patient suddenly complains of weakness and left upper quadrant (LUQ) pain. Vitals are blood pressure 80/50 mm Hg, heart rate 97/min, respiratory rate 18/min, temperature 36.2℃ (97.2℉) and oxygen saturation of 99% on room air. Prompt administration of 2L of IV fluids increases the blood pressure to 100/70 mm Hg. On physical exam, there is dullness to percussion and rebound tenderness with guarding in the LUQ. Bowel sounds are present. Raising the patient's left leg results in pain in his left shoulder. Stat hemoglobin level is 9.8 g/dL. Which of the following findings would be most likely seen if a CT scan were performed now?

Low-density areas within the splenic parenchyma

Subdiaphragmatic air collection

Heterogeneous parenchymal enhancement of the pancreatic tail

Herniation of the stomach into the thoracic cavity

Irregular linear areas of hypoattenuation in the liver parenchyma

A 38-year-old man comes to the emergency department because of epigastric pain and multiple episodes of vomiting for 4 hours. Initially, the vomit was yellowish in color, but after the first couple of episodes it was streaked with blood. He had 2 episodes of vomiting that contained streaks of frank blood on the way to the hospital. He has been hospitalized twice in the past year for acute pancreatitis. He drinks 2 pints of vodka daily but had over 4 pints during the past 12 hours. He takes naproxen for his 'hangovers.' He appears uncomfortable. His temperature is 37°C (99.1°F), pulse is 105/min, and blood pressure is 110/68 mm Hg. Examination shows dry mucous membranes and a tremor of his hands. The abdomen is soft and shows tenderness to palpation in the epigastric region; there is no organomegaly. Cardiopulmonary examination shows no abnormalities. Rectal examination is unremarkable. His hemoglobin concentration is 11.3 g/dL and hematocrit concentration is 40%. Which of the following is the most likely cause of this patient's findings?

Mucosal tear at the gastroesophageal junction

Inflammation of the esophageal wall

Transmural tear of the lower esophagus

Pseudoaneurysm of the gastroduodenal artery

Neoplastic growth at the gastroesophageal junction

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

"Can you tell me more about the symptoms you have been experiencing?"

"Does the diarrhea typically precede the constipation, or vice-versa?"

"Is the diarrhea foul-smelling?"

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

"Are the symptoms worse in the morning or at night?"

Local complications of acute pancreatitis for USMLE Step 3: High-Yield Internal Medicine Lessons

Classification - The Fluid & Debris Spectrum

Based on the 2012 Revised Atlanta Classification, local complications are stratified by pancreatitis type and time. Interstitial edematous pancreatitis leads to fluid collections, while necrotizing pancreatitis results in collections containing necrotic debris. These collections mature and encapsulate after 4 weeks.

⭐ A key distinction: Pancreatic pseudocysts contain sterile fluid and lack a true epithelial lining. Walled-off necrosis (WON) is encapsulated and contains a mixture of liquid and solid necrotic material, with a higher risk of infection.

Fluid Collections - Just Fluid, Folks!

Acute Peripancreatic Fluid Collection (APFC): Occurs <4 weeks post-pancreatitis. Homogenous fluid collection without a defined wall. Most resolve with expectant management.
Pancreatic Pseudocyst: Develops >4 weeks later, forming a well-defined, encapsulated fibrous wall around the collection.
- Drainage Indications: Reserved for symptomatic patients (pain, obstruction), cysts >6 cm, or those that are enlarging.

⭐ A pseudocyst's wall is fibrous granulation tissue, NOT a true epithelial lining-a key distinction from cystic neoplasms.

Necrotic Collections - Walled-Off Trouble

Develops from necrotizing pancreatitis. Initially an Acute Necrotic Collection (ANC) (<4 weeks), a heterogeneous mix of fluid and solid debris without a defined wall.
Matures into Walled-Off Necrosis (WON) (≥4 weeks), an encapsulated collection with a thick, inflammatory wall.
Imaging (CECT): Shows non-enhancing pancreatic parenchyma with heterogeneous fluid/debris. Gas bubbles imply infection.

Walled-off necrosis on CT and MRI

Management:
- Sterile: Often managed supportively.
- Infected (suspected): Confirm with CT-guided Fine-Needle Aspiration (FNA). Treat with broad-spectrum antibiotics and drainage.
- Intervention: Endoscopic necrosectomy is preferred.

⭐ High-Yield: Delaying intervention for WON until at least 4 weeks allows the wall to mature, making endoscopic drainage safer and more effective.

Vascular Issues - Bleeding & Clotting Chaos

Splenic Vein Thrombosis: Proximal inflammation can lead to thrombosis of the splenic vein, causing left-sided portal hypertension.
- Leads to isolated gastric varices (via short gastric veins) without esophageal varices.
Pseudoaneurysm Formation: Enzymatic digestion weakens adjacent arteries (splenic, gastroduodenal, pancreaticoduodenal).
- Rupture can cause life-threatening hemorrhage into a pseudocyst, the GI tract, or peritoneum.

⭐ Splenic vein thrombosis is a classic cause of isolated gastric varices; suspect it in a patient with pancreatitis and upper GI bleeding.

Management:
- Diagnosis: CT Angiography.
- Treatment: Angiographic embolization.

Organ Obstruction - Neighborhood Nuisances

Gastric Outlet Obstruction: Duodenal inflammation or compression by a pseudocyst leads to early satiety and vomiting.
Biliary Obstruction: Common bile duct compression from edema or a pseudocyst can cause jaundice.
Colonic Inflammation: Most commonly affects the transverse colon and splenic flexure, risking ischemia.
Pancreatic Ascites/Pleural Effusion: From a disrupted pancreatic duct leaking fluid.

⭐ A pleural effusion with markedly high amylase (>1000 IU/L) is pathognomonic for a pancreaticopleural fistula.

Acute peripancreatic fluid collections (APFC) are the most common complication, seen <4 weeks after onset.

Pancreatic pseudocysts are encapsulated fluid collections that mature at >4 weeks; they have high amylase content.

Pancreatic necrosis is the most severe complication; infected necrosis carries the highest mortality risk.

Walled-off necrosis (WON) is a mature, encapsulated area of necrosis, developing after >4 weeks.

Contrast-enhanced CT (CECT) is the imaging modality of choice to differentiate fluid from necrosis.

Vascular complications include splenic vein thrombosis and pseudoaneurysm formation.

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