Surgery USMLE Practice Questions
Surgical principles and common procedures.
5 free surgery practice questions
Pick an answer and check it. After each question you get the same explanation StepGenie students see: the stem decoded clue by clue, the reasoning chain with its infographic, why every wrong option is wrong, and the trap the question was built around. Step 1 questions test mechanism; Step 2 CK questions ask for the next step.
A 43-year-old woman develops fever and chills 2 hours after an elective cholecystectomy. She received cephalexin for perioperative antibiotic prophylaxis and 1 unit of packed red blood cells during the procedure. Her medical history includes a hysterectomy 9 years ago for uterine leiomyomas and a 5-year history of hypertension treated with lisinopril. Her temperature is 39.5°C (102.3°F), pulse is 90/min, respirations are 18/min, and blood pressure is 125/90 mm Hg. Physical examination reveals a mildly tender abdominal incision without erythema. Lung auscultation is clear, and cardiac examination is normal. A Foley catheter and peripheral intravenous line were placed intraoperatively. Which of the following is the most likely cause of this patient’s symptoms?
Correct answer · F
Transfusion reaction
Decoding the stem
Step-by-step reasoning
- 1
Fever and chills starting 2 hours post-op is too early for most infectious causes, pushing us toward noninfectious perioperative complications.
- 2
She received packed RBCs intraoperatively, which immediately raises concern for acute transfusion reactions as a cause of sudden fever/chills.
- 3
Exam is largely benign: stable BP, clear lungs, normal heart, clean incision, no localizing signs → argues against PE, pneumonia, or wound infection.
- 4
Acute febrile nonhemolytic transfusion reactions are due to cytokines or anti-leukocyte antibodies in transfused blood, causing isolated fever/chills shortly after transfusion.
- 5
Given the timing, transfusion exposure, and lack of other findings, the most likely cause is an acute febrile transfusion reaction.
Why not the others?
A. Adverse effect of medication
This option implies a drug fever (e.g., from cephalexin or anesthetics), which typically develops after longer exposure and often lacks chills or has eosinophilia/rash, BUT here the acute onset right after transfusion with a completely normal exam strongly points to the transfusion itself.
B. Malignant hyperthermia
This option implies a hypermetabolic state triggered by inhaled anesthetics/succinylcholine, causing muscle rigidity, hypercarbia, tachycardia, acidosis, and very high fever, BUT this patient is hemodynamically stable, has a normal exam (no rigidity), and symptoms started post-op without those systemic signs.
C. Surgical site infection
This option implies postoperative wound infection presenting with erythema, warmth, purulent drainage, and pain, typically after >48–72 hours, BUT her fever began only 2 hours after surgery and the incision is only mildly tender without erythema or drainage.
D. Pulmonary embolism
This option implies sudden dyspnea, pleuritic chest pain, tachycardia, hypoxia, and possibly mild fever, BUT her lungs are clear, there is no respiratory distress, and vitals are stable aside from fever, making PE unlikely as the primary cause.
E. Urinary tract infection
This option implies dysuria, frequency, suprapubic pain, and often appears after a Foley is in place for longer; early postop fever from UTI is uncommon, and we are not given urinary symptoms or abnormal urinalysis, BUT we do have a very clear, immediate trigger: the blood transfusion.
Exam trap
Very early postoperative fever tempts students to pick infectious causes (surgical site infection, UTI, PE). Recognize that infections usually take >24–48 hours; within hours, think transfusion reaction, drugs, or malignant hyperthermia. The clean exam and normal vitals point away from infection and toward transfusion reaction.
The bottom line
Acute febrile transfusion reaction: cytokine-mediated fever and chills within hours of transfusion; normal exam and vitals, no focal infectious source.
A 67-year-old man presents 3 days after undergoing laparoscopic colectomy for colon cancer with swelling and pain in his right leg. His temperature is 38.5°C (101.3°F). Physical examination reveals nonerythematous swelling of the right lower extremity from the ankle to the thigh without rash. Which of the following is likely to be most helpful in establishing the diagnosis?
Correct answer · E
Compression ultrasonography
Decoding the stem
Step-by-step reasoning
- 1
Recent major abdominal surgery + colon cancer create strong risk for venous thrombosis (endothelial injury, stasis, hypercoagulability).
- 2
New unilateral leg swelling and pain extending from ankle to thigh indicates likely proximal lower extremity DVT (e.g., femoral/iliac veins).
- 3
Absence of erythema or rash argues against cellulitis or superficial thrombophlebitis, supporting a deep venous process.
- 4
For suspected lower-extremity DVT in a high‑probability, postoperative patient, the best initial imaging test is compression ultrasonography of the affected limb.
- 5
Compression ultrasound assesses vein compressibility and flow; a noncompressible, echogenic vein confirms DVT, directly establishing the diagnosis.
Why not the others?
A. D-dimer level
This option implies using D-dimer to rule out VTE in low–intermediate risk patients, BUT this patient is high risk (cancer, major surgery), and postoperative D-dimer is often elevated and nonspecific; imaging (compression ultrasonography) is needed.
B. Transthoracic echocardiography
This option implies evaluating cardiac function or right-heart strain from PE, BUT the patient’s primary problem is isolated unilateral leg swelling without cardiopulmonary symptoms; echo does not diagnose a leg DVT.
C. CT pulmonary angiography
This option implies diagnosing pulmonary embolism, which presents with dyspnea, pleuritic chest pain, or hypoxia, BUT the vignette gives no respiratory symptoms; you first confirm DVT in the leg with compression ultrasonography.
D. Blood cultures
This option implies bacteremia/sepsis (e.g., infectious thrombophlebitis or cellulitis), which causes systemic toxicity and local erythema, BUT the leg is nonerythematous with a presentation typical of sterile venous thrombosis, not infection.
Exam trap
Postoperative fever can push students toward infectious workups (blood cultures), but the key association is recent surgery + cancer + unilateral leg swelling, which should trigger DVT and the need for compression ultrasonography.
The bottom line
Acute postoperative DVT presents with unilateral leg swelling and pain; compression ultrasonography is the best initial diagnostic test in this setting.
Four days after hospital admission for a pulmonary contusion and whiplash injury sustained in a motor vehicle collision, a 66-year-old woman develops severe right flank pain associated with muscle spasms, nausea, vomiting, and abdominal bloating. Her pain had previously been well controlled with scheduled acetaminophen. Medical history is notable for an umbilical hernia repair 2 years ago and depression treated with sertraline. Vital signs show a temperature of 36.5°C (97.7°F), pulse of 99/min, respirations of 17/min, and blood pressure of 102/72 mm Hg, which improves to 118/79 mm Hg after administration of 0.5 L of crystalloid fluids. Physical examination reveals multiple ecchymoses over the anterior abdominal wall in a pattern consistent with a seatbelt injury and bilateral flank ecchymoses. Bowel sounds are absent. The abdomen is diffusely tender to palpation in all four quadrants with voluntary guarding. Laboratory studies show hemoglobin of 7.9 g/dL, leukocyte count of 8,500/mm3, platelet count of 350,000/mm3, prothrombin time of 11 seconds, and activated partial thromboplastin time of 33 seconds. An abdominal x-ray demonstrates obliteration of the right psoas shadow and uniform gas distribution throughout the small bowel, colon, and rectum without air-fluid levels. Lab Values: - Hemoglobin: 7.9 g/dL - Leukocyte count: 8,500/mm3 - Platelet count: 350,000/mm3 - Prothrombin time: 11 seconds - Activated partial thromboplastin time: 33 seconds Which of the following is the most likely explanation for this patient's symptoms?
Correct answer · F
Retroperitoneal hemorrhage
Decoding the stem
Step-by-step reasoning
- 1
This older patient had significant blunt trauma (MVC with seatbelt sign), so delayed intraabdominal or retroperitoneal complications must be considered days later.
- 2
She now has new severe right flank pain plus flank ecchymoses, which localize the pathology to the retroperitoneum rather than intraperitoneal hollow viscera.
- 3
Her hemoglobin is 7.9 g/dL with otherwise normal coagulation, indicating blood loss rather than a coagulopathy or pure inflammatory process.
- 4
Abdominal x-ray shows obliteration of the right psoas shadow, a classic radiographic clue to retroperitoneal hematoma or inflammation along the psoas muscle.
- 5
The same x-ray shows uniform gas throughout the bowel without air-fluid levels, indicating a functional ileus, typically due to irritation (eg, retroperitoneal bleeding) rather than mechanical obstruction or perforation.
- 6
Combining flank ecchymosis, low Hb, psoas shadow loss, and ileus in a post-trauma patient points to retroperitoneal hemorrhage as the unifying diagnosis.
Why not the others?
A. Small bowel perforation
This option implies pneumoperitoneum and peritonitis with free air under the diaphragm and possibly focal air-fluid levels, BUT this patient’s x-ray shows no free air and uniform gas distribution without air-fluid levels, favoring ileus over perforation.
B. Intraabdominal adhesions
This option implies mechanical small bowel obstruction, usually with prior surgery history and x-ray showing dilated loops with multiple air-fluid levels, BUT her x-ray shows uniform gas throughout small and large bowel without air-fluid levels and her only prior surgery (umbilical hernia repair) is remote and not strongly suggestive of new adhesive obstruction right after trauma.
C. Effect of pain medication
This option implies opioid-induced ileus or constipation causing mild distension, BUT her pain had been controlled with acetaminophen (non-opioid), and this does not explain the falling hemoglobin, flank ecchymosis, or loss of psoas shadow.
D. Sigmoid volvulus
This option implies a large-bowel obstruction with x-ray showing massively dilated loop in a coffee-bean shape and little distal gas, BUT her imaging shows uniform gas in small bowel, colon, and rectum without a focal transition point, arguing against volvulus.
E. Spinal cord injury
This option implies neurogenic bowel and possible ileus, BUT it does not explain the acute right flank pain, flank ecchymoses, low hemoglobin, or psoas shadow obliteration; her neurologic status is not described as impaired.
G. Acute mesenteric ischemia
This option implies severe, classically disproportionate abdominal pain, metabolic acidosis, and often risk factors like atrial fibrillation, BUT she has normal labs aside from anemia, no lactic acidosis mentioned, and x-ray findings consistent with ileus rather than ischemic bowel changes; it also doesn’t explain the flank ecchymoses or psoas shadow loss.
Exam trap
The presence of severe abdominal pain and absent bowel sounds tempts a choice like perforation or obstruction, but the key is the psoas shadow obliteration + flank ecchymosis + anemia, which specifically point to retroperitoneal hemorrhage rather than a primary intraperitoneal bowel pathology.
The bottom line
Retroperitoneal hemorrhage after blunt trauma causes flank ecchymoses, falling hemoglobin, psoas shadow obliteration, and ileus with diffuse uniform bowel gas.
A 32-year-old man is brought to the emergency department after colliding with another skier while skiing downhill. He is alert and reports chest and abdominal pain. Medical history is significant for intravenous drug use, peptic ulcer disease, and current tobacco use. On arrival, temperature is 97.4°F (36.3°C), blood pressure is 77/53 mm Hg, pulse is 127/min, and respirations are 13/min. He has a Glasgow Coma Scale score of 15 and bilateral shallow breath sounds. Abdominal examination reveals a soft but distended abdomen with ecchymosis over the epigastrium. The patient has scattered facial lacerations, is moving all extremities, and has cool skin with delayed capillary refill. Focused Assessment with Sonography for Trauma (FAST) reveals free fluid in Morison’s pouch. Two large-bore IV catheters are placed, and he receives 2 L of normal saline. After fluid resuscitation, temperature is 97.5°F (36.4°C), blood pressure is 97/62 mm Hg, pulse is 115/min, and respirations are 12/min. Which of the following is the best next step in management?
Correct answer · E
Emergency laparotomy
Decoding the stem
Step-by-step reasoning
- 1
Blunt trauma + hypotension + tachycardia + cool skin and delayed capillary refill → class IV hemorrhagic shock is likely from internal bleeding.
- 2
Abdominal distension and epigastric ecchymosis localize the source to the abdomen rather than extremities or chest alone.
- 3
FAST showing free fluid in Morison’s pouch confirms intra-abdominal hemorrhage.
- 4
Despite 2 L crystalloid, patient remains hypotensive (SBP <100) and tachycardic → hemodynamically unstable or only transient responder.
- 5
In unstable patients with positive FAST, ATLS algorithm: go directly to emergency laparotomy to control bleeding, not more diagnostic tests.
Why not the others?
A. Close observation
This option implies hemodynamic stability and no clear source of bleeding, BUT this patient is hypotensive with positive FAST → requires operative intervention, not observation.
B. Upper gastrointestinal endoscopy
This option implies peptic ulcer bleeding, which causes hematemesis/melena, BUT the patient has traumatic blunt abdominal injury and positive FAST, not GI bleed symptoms.
C. Diagnostic peritoneal lavage
This option implies uncertain intra-abdominal bleeding, BUT FAST is already positive in an unstable patient; DPL is redundant and delays definitive surgery.
D. Diagnostic laparoscopy
This option implies a stable patient needing evaluation for possible injury, BUT in an unstable patient with positive FAST, you skip laparoscopy and perform open laparotomy for rapid hemorrhage control.
Exam trap
Students may overthink due to the patient’s partial response to fluids and history of peptic ulcer disease, but ATLS prioritizes: unstable + positive FAST → emergency laparotomy without additional tests.
The bottom line
Hemodynamically unstable blunt abdominal trauma with positive FAST (free fluid in Morison’s pouch) requires immediate emergency laparotomy, not further diagnostics.
A 72-year-old man is evaluated 3 days after coronary artery bypass graft surgery for acute right upper quadrant abdominal pain, fever, nausea, and vomiting. His medical history includes type 2 diabetes mellitus, benign prostatic hyperplasia, peripheral vascular disease, and chronic mesenteric ischemia. He has a 30–pack-year smoking history but quit 10 years ago and drinks 8 cans of beer per week. Home medications are metformin, aspirin, simvastatin, and finasteride. Temperature is 38.9°C (102°F), pulse is 102/min, respirations are 18/min, and blood pressure is 110/60 mm Hg. Lung auscultation reveals bilateral inspiratory crackles. Cardiac examination is normal. Abdominal examination shows a soft abdomen with marked right upper quadrant tenderness and a positive Murphy sign; there is no rebound tenderness or guarding. Abdominal ultrasonography demonstrates a distended gallbladder with wall thickening and pericholecystic fluid but no gallstones. Lab Values: - Hemoglobin: 13.1 g/dL - Hematocrit: 42% - Leukocyte count: 15,700/mm³ - Segmented neutrophils: 65% - Bands: 10% - Lymphocytes: 20% - Monocytes: 3% - Eosinophils: 1% - Basophils: 0.5% - AST: 40 U/L - ALT: 100 U/L - Alkaline phosphatase: 85 U/L - Total bilirubin: 1.5 mg/dL - Direct bilirubin: 0.9 mg/dL - Amylase: 90 U/L Which of the following is the most appropriate next step in management?
Correct answer · D
Intravenous piperacillin-tazobactam therapy and percutaneous cholecystostomy
Decoding the stem
Step-by-step reasoning
- 1
RUQ pain, fever, leukocytosis, positive Murphy sign, and ultrasound showing wall thickening + pericholecystic fluid indicate acute cholecystitis.
- 2
Absence of gallstones on ultrasound in a critically ill/postoperative patient points to acute acalculous cholecystitis rather than calculous disease.
- 3
Acalculous cholecystitis is due to gallbladder ischemia and stasis in severely ill or postoperative patients → often more severe and higher risk of complications (gangrene, perforation).
- 4
Recent CABG, bilateral crackles, age, and comorbidities make him a poor candidate for immediate general anesthesia and surgery.
- 5
Standard management in high-risk, unstable, or postoperative patients with acute acalculous cholecystitis is broad-spectrum IV antibiotics plus percutaneous cholecystostomy for drainage.
- 6
Therefore, the most appropriate next step is intravenous piperacillin-tazobactam therapy and percutaneous cholecystostomy.
Why not the others?
A. Intravenous heparin therapy followed by embolectomy
This option implies acute arterial mesenteric ischemia (e.g., embolus causing sudden, severe diffuse abdominal pain out of proportion to exam), BUT this patient has localized RUQ tenderness, a positive Murphy sign, and ultrasound findings strongly supporting cholecystitis, not mesenteric ischemia.
B. Careful observation with serial abdominal examinations
This option implies a non-surgical, watchful waiting approach for mild/uncertain abdominal pathology, BUT this patient has clear clinical and ultrasound evidence of acute acalculous cholecystitis with systemic signs (fever, leukocytosis) requiring urgent intervention, not observation alone.
C. Immediate cholecystectomy
This option implies definitive surgical treatment for acute cholecystitis in a stable operative candidate, BUT the patient is only 3 days post-CABG with pulmonary findings and multiple comorbidities, making him high risk for general anesthesia; guidelines favor percutaneous cholecystostomy in such high-risk patients.
E. Endoscopic retrograde cholangiopancreatography with papillotomy
This option implies choledocholithiasis or ascending cholangitis (obstructive jaundice, markedly elevated bilirubin/alk phos, ductal dilation), BUT this patient has only mildly elevated bilirubin, normal alkaline phosphatase, and no stones or duct dilation on ultrasound, indicating gallbladder (not bile duct) pathology.
Exam trap
Postoperative abdominal pain after major surgery may push you toward ischemic bowel or expectant management; however, the key is the RUQ focus + Murphy sign + ultrasound without stones → think acute acalculous cholecystitis in critically ill/post-op patients, which is managed with percutaneous cholecystostomy, not immediate surgery or simple observation.
The bottom line
Acute acalculous cholecystitis in a critically ill/postoperative patient → treat with broad-spectrum IV antibiotics and percutaneous cholecystostomy (not immediate surgery).
Source: StepGenie question bank. Questions are written by StepGenie, not taken from NBME or USMLE materials, and are chosen for this page by how students actually performed on them (first-attempt accuracy on StepGenie). Selection last refreshed September 5, 2026.
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Surgical fundamentals including pre-operative assessment, wound healing, fluid management, trauma, and organ-specific surgical conditions. Master the surgical approach to acute abdomen and emergencies.
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Surgery — Frequently Asked Questions
How do you approach an acute abdomen question?
Localise the pain, then use its character and progression. Pain that begins periumbilically and migrates to the right lower quadrant suggests appendicitis. Right upper quadrant pain after fatty food suggests biliary disease. Sudden severe pain with rigidity and free air suggests perforation. Pain out of proportion to examination findings suggests mesenteric ischemia.
What are the phases of wound healing and their timing?
The inflammatory phase occupies roughly the first three days with neutrophils then macrophages. The proliferative phase runs from days three to weeks, with fibroblasts laying down type III collagen, angiogenesis and epithelialisation. The remodelling phase runs for months as type III collagen is replaced by type I, which is when tensile strength increases most.
What is the initial priority in a trauma patient?
Follow the primary survey in order: airway with cervical spine protection, breathing, circulation with hemorrhage control, disability, and exposure. The sequence matters because a compromised airway kills faster than a compromised circulation. An unstable patient with a positive focused abdominal ultrasound goes to the operating room rather than to CT.
Which postoperative complications map to specific days?
Fever in the first day is usually atelectasis or the inflammatory response to surgery. Days three to five suggest urinary tract or catheter-related infection. Days five to seven suggest wound infection. After a week, consider deep abscess or anastomotic leak. Deep vein thrombosis can occur throughout the postoperative period and rises with immobility.
Are the surgery practice questions on this page free?
Yes. The 5 questions above come from StepGenie's question bank and can be answered here without an account, with the full explanation shown after each one. From the link under the set you can try three more Surgery questions in the dashboard preview, also without an account; a free account is what lets you choose the system and keep going.