USMLE Step 2 CK Surgery Topics: Perioperative Care
Preoperative Risk Assessment and Optimization
Success in preoperative assessment Step 2 questions hinges on identifying risk factors that increase perioperative morbidity and mortality. The most critical tool is the Revised Cardiac Risk Index (RCRI), which evaluates factors such as history of ischemic heart disease, congestive heart failure, cerebrovascular disease, and preoperative creatinine levels. For patients undergoing non-cardiac surgery, the exam often tests the threshold for further cardiac testing. If a patient can achieve more than 4 Metabolic Equivalents (METs)—such as climbing two flights of stairs—without symptoms, they generally do not require further stress testing, even with known risk factors. Conversely, those with poor functional capacity and significant risk factors may require a pharmacological stress test before proceeding to the operating room.
Beyond cardiac risk, pulmonary optimization is frequently tested. Smoking cessation is recommended at least eight weeks prior to surgery to significantly reduce the risk of postoperative pneumonia and atelectasis. For patients with diabetes, the goal is not perfect euglycemia but rather the prevention of ketoacidosis and severe hyperglycemia; clinicians typically target a blood glucose range of 140–180 mg/dL. Medication management is another high-yield area: while beta-blockers and statins are usually continued, ACE inhibitors and ARBs are often held the morning of surgery to prevent refractory intraoperative hypotension. Aspirin is frequently continued in high-risk cardiac patients, but anticoagulants like warfarin must be bridged with heparin or low-molecular-weight heparin depending on the patient's thromboembolic risk profile.
Managing Postoperative Fever and Complications
Effective postoperative complications management requires a chronological approach to the patient who develops a fever after surgery. The classic "5 Ws" framework—Wind, Water, Walking, Wound, and Wonder drugs—remains the gold standard for clinical reasoning. In the first 24 to 48 hours, atelectasis is a common cause of low-grade fever, though it is often a non-infectious inflammatory response to tissue injury. Between days 3 and 5, urinary tract infections (UTIs) become more likely, especially in patients with indwelling catheters. By day 5 to 7, deep vein thrombosis (DVT) and surgical site infections (SSIs) should be at the top of the differential. Finally, drug-induced fevers or deep abscesses typically manifest after the first week.
Exam questions often focus on the distinction between a superficial SSI and a deep-seated fascial dehiscence. An evisceration, where abdominal contents protrude through the surgical incision, is a surgical emergency requiring immediate coverage with sterile saline-soaked gauze and a return to the operating room. In contrast, a serosanguinous discharge without fascial separation (seroma) may only require observation or bedside drainage. Another critical complication is postoperative ileus, which must be differentiated from a mechanical small bowel obstruction. Ileus presents with diffuse bowel dilation and absent bowel sounds, whereas obstruction shows a transition point on imaging and hyperactive "tinkling" sounds early in the course. Management of ileus is primarily supportive, involving electrolyte correction and minimizing opioid use.
Venous Thromboembolism Prophylaxis Guidelines
Venous thromboembolism (VTE) prophylaxis is a cornerstone of surgical safety and a frequent target for Step 2 CK questions. The choice of prophylaxis—mechanical versus pharmacological—is determined by the patient's Caprini score or similar risk stratification tools. For low-risk patients undergoing minor procedures, early ambulation may suffice. However, most hospitalized surgical patients require either intermittent pneumatic compression (IPC) devices or pharmacologic anticoagulation with low-molecular-weight heparin (LMWH) or unfractionated heparin. LMWH is generally preferred due to its superior bioavailability and lower incidence of Heparin-Induced Thrombocytopenia (HIT), though unfractionated heparin remains the choice for patients with significant renal impairment (CrCl < 30 mL/min).
In the context of the exam, you must recognize contraindications to pharmacologic prophylaxis, such as active bleeding, recent intracranial hemorrhage, or a low platelet count. In these scenarios, mechanical prophylaxis is the only option. If a patient develops a pulmonary embolism (PE) despite prophylaxis, the immediate next step is often the initiation of a therapeutic heparin drip, provided there are no absolute contraindications to anticoagulation. For patients who cannot be anticoagulated and have a proven proximal DVT, the placement of an Inferior Vena Cava (IVC) filter is the indicated management. Understanding the timing of prophylaxis is also vital; most guidelines suggest starting pharmacologic measures within 2 to 12 hours postoperatively, once hemostasis is confirmed.
Acute Abdominal Surgical Emergencies
Differentiating Surgical vs. Medical Abdominal Pain
One of the most common challenges in surgical emergencies clinical knowledge is determining which patients with abdominal pain require a surgeon and which require a medical workup. The presence of peritonitis—marked by rebound tenderness, involuntary guarding, and rigidity—is the most significant clinical indicator of a surgical abdomen. If these signs are present, the next step is often an upright chest X-ray to look for free air under the diaphragm (pneumoperitoneum), which indicates a perforated viscus and necessitates immediate exploratory laparotomy. In the absence of peritonitis, the clinician has more time to utilize diagnostic imaging such as CT with IV contrast.
Medical causes of abdominal pain that mimic surgical emergencies include acute myocardial infarction (especially inferior wall), basal pneumonia, and diabetic ketoacidosis (DKA). Step 2 CK questions often present a patient with vague abdominal pain and metabolic derangements; if the patient has a high anion gap metabolic acidosis and ketonuria, the diagnosis is likely DKA rather than an acute abdomen. Conversely, certain conditions like acute mesenteric ischemia present with "pain out of proportion to exam" and require a high index of suspicion, as early CT angiography is necessary to prevent bowel necrosis. Distinguishing between these requires a careful synthesis of the patient’s history, such as a history of atrial fibrillation or recent vascular procedures.
Management of Acute Appendicitis and Cholecystitis
Acute appendicitis and cholecystitis are quintessential surgical topics. For appendicitis, the diagnosis in adults is often clinical, but CT scan is the preferred imaging modality if the presentation is equivocal. In children and pregnant women, ultrasound is the first-line imaging to avoid ionizing radiation. The management is typically an appendectomy, but the timing depends on the presence of perforation or abscess. If a patient presents with a walled-off abscess and stable vitals, the exam-correct answer is often interval appendectomy—initial treatment with IV antibiotics and percutaneous drainage, followed by surgery 6–8 weeks later.
Biliary disease follows a strict diagnostic hierarchy. For suspected cholecystitis, the initial test is a right upper quadrant ultrasound showing gallbladder wall thickening (>4mm), pericholecystic fluid, or a positive sonographic Murphy sign. If the ultrasound is inconclusive but clinical suspicion remains high, a HIDA scan (choleoscintigraphy) is the most sensitive secondary test; failure to visualize the gallbladder confirms cystic duct obstruction. Management involves NPO status, IV fluids, antibiotics, and cholecystectomy, usually within 24 to 48 hours. If the patient also has an elevated bilirubin or alkaline phosphatase, you must suspect choledocholithiasis and consider an ERCP (Endoscopic Retrograde Cholangiopancreatography) before cholecystectomy to clear the common bile duct.
Recognizing and Treating Bowel Obstruction and Perforation
Small bowel obstruction (SBO) is a frequent postoperative complication, often caused by adhesions from previous surgeries. The classic presentation includes colicky abdominal pain, distension, vomiting, and obstipation. On physical exam, high-pitched "tinkling" bowel sounds are a hallmark. Diagnosis is usually confirmed with an abdominal X-ray series showing dilated loops of small bowel with air-fluid levels and a lack of gas in the colon. Management begins with "drip and suck"—aggressive IV fluid resuscitation and nasogastric (NG) tube decompression. Surgery is indicated only if there are signs of strangulation or ischemia, such as fever, leukocytosis, or localized tenderness.
Perforation, whether from a peptic ulcer, diverticulitis, or ischemia, represents a higher level of urgency. A perforated peptic ulcer often presents with sudden-onset, severe epigastric pain that quickly becomes generalized. The diagnostic finding of pneumoperitoneum on imaging is an absolute indication for surgery. In the case of perforated diverticulitis, the Hinchey Classification helps guide management. Stage I and II (localized abscess) are often managed with CT-guided drainage and antibiotics, whereas Stage III and IV (generalized peritonitis) require a Hartmann’s procedure—resection of the affected colon with a temporary end-colostomy.
Trauma Surgery and Emergency Management
Primary Survey and ATLS Principles
In trauma surgery USMLE scenarios, the Advanced Trauma Life Support (ATLS) sequence is the only acceptable framework for management. The primary survey—Airway, Breathing, Circulation, Disability, and Exposure (ABCDE)—must be performed in order. A common trap on the exam is a patient with a clear airway but massive bleeding; the correct answer is to secure the airway first, unless the question specifically specifies a massive "Exsanguinating" hemorrhage where "C" might take precedence in some modern protocols (C-ABC). However, for Step 2 CK, always ensure the airway is patent and the cervical spine is stabilized before moving to breathing assessment.
During the "Circulation" phase, the Focused Assessment with Sonography for Trauma (FAST) exam is the critical decision point for hemodynamically unstable patients. A positive FAST (showing intraperitoneal fluid) in an unstable patient is a direct ticket to the operating room for an exploratory laparotomy. If the patient is hemodynamically stable, even with a positive FAST, the next step is usually a CT scan of the abdomen and pelvis to better characterize the injuries. Understanding this branch point in the trauma algorithm—stability vs. instability—is essential for answering management questions correctly.
Diagnosis of Life-Threatening Thoracic Injuries
Thoracic trauma questions often require the differentiation of tension pneumothorax, massive hemothorax, and cardiac tamponade. A tension pneumothorax is a clinical diagnosis characterized by respiratory distress, decreased breath sounds, and tracheal deviation away from the affected side. The exam will test your knowledge that needle decompression (in the 2nd intercostal space at the midclavicular line or 5th at the anterior axillary line) must precede a chest X-ray. A massive hemothorax presents similarly with shock but will have dullness to percussion rather than hyperresonance.
Cardiac tamponade is suggested by Beck’s Triad: hypotension, jugular venous distension, and muffled heart sounds. It is often associated with penetrating trauma to the "box" (the area between the clavicles and the costal margins). The diagnostic test of choice is an echocardiogram (often part of the FAST exam), and the definitive treatment in an acute trauma setting is a pericardial window or thoracotomy. Another high-yield thoracic injury is flail chest, defined by three or more ribs fractured in two or more places, resulting in paradoxical chest wall movement. The primary management for flail chest is pain control and pulmonary toilet, but intubation with positive pressure ventilation may be necessary if oxygenation fails.
Management of Hemorrhagic Shock and Fluid Resuscitation
Hemorrhagic shock is the most common form of shock in the trauma patient. The exam tests the classification of shock based on blood loss, heart rate, and blood pressure. Class I and II shock may respond to crystalloid resuscitation, but Class III and IV shock (characterized by hypotension and altered mental status) require blood products. The modern approach emphasizes balanced resuscitation, using a 1:1:1 ratio of packed red blood cells (pRBCs), fresh frozen plasma (FFP), and platelets to avoid the coagulopathy associated with massive crystalloid infusion.
The "lethal triad" of trauma—acidosis, hypothermia, and coagulopathy—is a concept frequently tested indirectly. To prevent this, surgeons may employ damage control surgery, which focuses on stopping hemorrhage and limiting contamination rather than definitive repair of all injuries. In these scenarios, the patient is stabilized in the ICU and returned to the OR 24–48 hours later. Additionally, the exam may ask about the use of tranexamic acid (TXA), which should be administered within three hours of injury in patients with significant hemorrhage to improve survival outcomes.
Breast Surgery and Endocrine Disorders
Breast Cancer Screening and Diagnostic Workup
Breast surgery questions on Step 2 CK focus on the diagnostic pathway for a palpable mass or an abnormal screening mammogram. For a woman over 30 with a palpable mass, the first step is a diagnostic mammogram and ultrasound. If the patient is under 30, the initial test is an ultrasound because dense breast tissue limits the utility of mammography. Any suspicious lesion (BI-RADS 4 or 5) requires a core needle biopsy for tissue diagnosis. Fine-needle aspiration is generally insufficient for a primary breast cancer diagnosis because it cannot distinguish between in situ and invasive disease.
Management of breast cancer involves a choice between breast-conserving surgery (lumpectomy) with radiation or a total mastectomy; both have equivalent long-term survival rates. A critical component of the surgical workup is the Sentinel Lymph Node Biopsy (SLNB). If the sentinel node is negative, a full axillary lymph node dissection (ALND) is avoided, significantly reducing the risk of lymphedema. You should also be familiar with the indications for systemic therapy, such as tamoxifen or aromatase inhibitors for ER/PR-positive tumors and trastuzumab for HER2-positive cancers.
Evaluation of Thyroid Nodules and Cancer
The evaluation of a thyroid nodule begins with a TSH level and an ultrasound. If the TSH is low, the next step is a radioiodine uptake scan to look for a "hot" (functioning) nodule, which is rarely malignant. If the TSH is normal or high, or if the nodule is "cold" on the scan, a Fine Needle Aspiration (FNA) is indicated for nodules larger than 1 cm or those with suspicious ultrasound features (e.g., microcalcifications, irregular margins). The results of the FNA are reported using the Bethesda System for Reporting Thyroid Cytopathology.
Papillary thyroid cancer is the most common type and generally has an excellent prognosis. Surgical treatment ranges from hemithyroidectomy to total thyroidectomy depending on the size and presence of metastases. Medullary thyroid cancer is a high-yield topic because of its association with Multiple Endocrine Neoplasia (MEN) 2A and 2B. If a patient is diagnosed with medullary thyroid cancer, the exam will often expect you to screen for a coexisting pheochromocytoma by checking plasma metanephrines before performing thyroid surgery to avoid an intraoperative hypertensive crisis.
Management of Parathyroid Disease and Hypercalcemia
Primary hyperparathyroidism is most commonly caused by a single parathyroid adenoma. It presents with the classic "stones, bones, abdominal groans, and psychic overtones." The biochemical profile—elevated calcium, low phosphorus, and elevated or inappropriately normal Parathyroid Hormone (PTH)—is diagnostic. Before surgery, a Sestamibi scan is used to localize the adenoma. The definitive treatment is a parathyroidectomy, during which intraoperative PTH monitoring is used; a drop in PTH by more than 50% after excision of the gland confirms a successful procedure.
Acute severe hypercalcemia (calcium >14 mg/dL) is a medical emergency that must be managed before surgical intervention. The first step is aggressive volume expansion with normal saline to promote urinary calcium excretion. Bisphosphonates like zoledronic acid are used for long-term control, especially in malignancy-associated hypercalcemia, but they take 48–72 hours to work. Calcitonin may be used for a more rapid, albeit short-lived, reduction in calcium levels. Understanding the relationship between calcium and albumin is also vital; always calculate the corrected calcium if the albumin is low to determine if true hypercalcemia is present.
Vascular Surgery Essentials
Abdominal Aortic Aneurysm Screening and Repair Indications
Abdominal Aortic Aneurysm (AAA) management is heavily tested through screening and intervention thresholds. The current recommendation is a one-time screening ultrasound for men aged 65–75 who have ever smoked. An aneurysm is generally defined as a diameter greater than 3.0 cm. Management is based on size: 3.0–4.0 cm requires ultrasound every 12 months; 4.0–4.9 cm requires ultrasound every 6 months; and 5.0–5.4 cm requires ultrasound every 3 months.
Indications for surgical repair include a diameter ≥ 5.5 cm in men (≥ 5.0 cm in women), a growth rate of > 0.5 cm in 6 months, or any symptomatic aneurysm (e.g., back or abdominal pain). For a ruptured AAA, the presentation is a triad of hypotension, pulsatile abdominal mass, and back pain. If the patient is unstable, they go directly to surgery. If they are stable, a CT angiogram is performed to plan the repair, which can be done via traditional open laparotomy or Endovascular Aneurysm Repair (EVAR). EVAR is less invasive but requires lifelong imaging surveillance to monitor for endoleaks.
Peripheral Arterial Disease and Claudication Management
Peripheral Arterial Disease (PAD) is diagnosed clinically by intermittent claudication—pain in the legs brought on by exertion and relieved by rest. The first diagnostic step is the Ankle-Brachial Index (ABI). An ABI ≤ 0.90 is diagnostic of PAD, while an ABI > 1.40 suggests non-compressible, calcified vessels (common in diabetics) and requires further testing with Toe-Brachial Indices. Management begins with aggressive risk factor modification: smoking cessation, statin therapy, and antiplatelet agents (aspirin or clopidogrel).
For symptomatic claudication, the most effective initial treatment is a supervised exercise program. Pharmacological treatment with cilostazol can be added if exercise alone is insufficient. Revascularization (angioplasty, stenting, or bypass) is reserved for patients with "lifestyle-limiting" claudication that does not respond to medical therapy, or those with Chronic Limb-Threatening Ischemia (CLTI), characterized by rest pain, non-healing ulcers, or gangrene. The exam often tests the identification of these "red flags" as indications for urgent vascular consultation.
Acute Limb Ischemia: Diagnosis and Urgent Intervention
Acute limb ischemia is a vascular emergency characterized by the "6 Ps": Pain, Pallor, Pulselessness, Paresthesia, Paralysis, and Poikilothermia (coldness). Unlike the gradual progression of PAD, acute ischemia is usually caused by an embolic event (often from the heart in a patient with atrial fibrillation) or acute thrombosis of a pre-existing bypass graft. The diagnosis is clinical, and the immediate next step is the initiation of an IV heparin bolus and infusion to prevent clot propagation.
The viability of the limb determines the next steps according to the Rutherford Classification. A viable limb has no sensory or motor loss and audible Doppler signals; these patients may undergo urgent imaging (CT angiography). A threatened limb has partial sensory loss and inaudible arterial signals, requiring immediate surgical embolectomy or catheter-directed thrombolysis. A non-viable limb is characterized by profound anesthesia, paralysis, and absent Doppler signals (both arterial and venous); in these cases, amputation is often the only remaining option to prevent systemic toxicity from reperfusion injury.
Key Subspecialty Presentations
Urological Emergencies: Testicular Torsion and Renal Colic
Urological emergencies on Step 2 CK often focus on the "acute scrotum." Testicular torsion is a surgical emergency caused by the twisting of the spermatic cord, leading to ischemia. It presents with sudden-onset pain, a high-riding testis, and a negative cremasteric reflex. While Doppler ultrasound can show decreased blood flow, if the clinical suspicion is high, the correct answer is immediate surgical exploration and bilateral orchiopexy (fixing the testes to the scrotum to prevent recurrence). Success rates for salvage drop significantly after 6 hours of ischemia.
Renal colic, caused by nephrolithiasis, presents with sudden, severe flank pain radiating to the groin and hematuria. The diagnostic test of choice is a non-contrast CT scan of the abdomen and pelvis. Management depends on the size of the stone: stones < 5 mm usually pass spontaneously with hydration and alpha-blockers (like tamsulosin); stones 5–10 mm may require lithotripsy; and stones > 10 mm or those causing infection (urosepsis) or renal failure require urgent decompression with a ureteral stent or percutaneous nephrostomy tube. The presence of fever and infection in a patient with an obstructing stone is a surgical emergency.
Common Orthopedic Injuries and Fracture Management
Orthopedic questions frequently focus on fracture management and the recognition of "must-miss" complications. For hip fractures in the elderly, the presentation is a shortened and externally rotated leg. Management is surgical (ORIF or arthroplasty), but the exam often asks about the timing; surgery should be performed within 24–48 hours once the patient's medical comorbidities are optimized. Another high-yield topic is Compartment Syndrome, characterized by pain out of proportion to the injury and pain with passive stretch. If suspected, the next step is measuring compartment pressures; a delta pressure (diastolic BP minus compartment pressure) ≤ 30 mmHg is an indication for emergent fasciotomy.
Pediatric orthopedics includes conditions like Slipped Capital Femoral Epiphysis (SCFE) and Developmental Dysplasia of the Hip (DDH). SCFE presents in obese adolescents with hip or knee pain and an externally rotated gait; the treatment is surgical pinning. In the emergency setting, you must also recognize Open Fractures, which require immediate IV antibiotics (usually a first-generation cephalosporin), tetanus prophylaxis, and urgent surgical debridement. For any joint dislocation or displaced fracture, the first step after ensuring neurovascular stability is typically closed reduction under sedation.
Pre- and Post-Transplant Care Principles
Transplant surgery topics on the USMLE center on the timing and management of graft rejection. Hyperacute rejection occurs within minutes of anastomosis due to pre-formed ABO or HLA antibodies; it is characterized by thrombosis and cyanosis of the graft and requires immediate removal. Acute rejection occurs within days to months and is T-cell mediated. It is diagnosed by biopsy showing inflammatory infiltrates and is treated with high-dose corticosteroids or antithymocyte globulin.
Chronic rejection occurs months to years later and is characterized by fibrosis and vascular occlusion (e.g., bronchiolitis obliterans in lung transplants or vanishing bile duct syndrome in liver transplants). Candidates should also be familiar with the common side effects of immunosuppressants: Cyclosporine and Tacrolimus are nephrotoxic and can cause gingival hyperplasia or tremors, while Mycophenolate Mofetil is associated with significant GI upset and bone marrow suppression. Prophylaxis against opportunistic infections, such as Trimethoprim-Sulfamethoxazole for Pneumocystis jirovecii and Valganciclovir for CMV, is a standard postoperative requirement for all transplant recipients.