Preoperative laboratory testing US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Preoperative laboratory testing. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Preoperative laboratory testing US Medical PG Question 1: A 60-year-old rock musician presents to the office because he has been feeling increasingly tired for the past 6 months. He has a history of intravenous drug use and alcohol abuse. He states that he feels quite tired, but he otherwise has no complaints. Physical examination is noncontributory. His laboratory values are normal other than moderately elevated liver enzymes. Which of the following additional tests should you order first?
- A. Hepatitis C virus antibodies (Correct Answer)
- B. Hepatitis B surface antigen
- C. Hepatitis E virus-specific IgM antibodies
- D. Hepatitis D virus-specific IgG antibody
- E. Hepatitis A virus-specific IgM antibodies
Preoperative laboratory testing Explanation: ***Hepatitis C virus antibodies***
- The patient's history of **intravenous drug use** and **chronic fatigue** with **elevated liver enzymes** strongly suggests chronic viral hepatitis, with hepatitis C being the most common blood-borne infection in persons with IVDU history.
- **Hepatitis C** is the **most prevalent chronic viral hepatitis** in the United States among persons with history of injection drug use, with transmission efficiency via needle sharing being very high.
- Hepatitis C often has a **long asymptomatic phase** (decades) before symptoms like fatigue and liver damage become apparent, making antibody testing the appropriate initial screen.
- While both HBV and HCV should ultimately be screened in this patient, **HCV prevalence is significantly higher** in the IVDU population, making it the priority initial test.
*Hepatitis B surface antigen*
- While **hepatitis B** can also be transmitted via intravenous drug use and cause chronic liver disease, **hepatitis C is more prevalent** in persons with IVDU history in the United States.
- **HBsAg** is used to detect active hepatitis B infection and should also be ordered, but given resource constraints and the clinical context, **anti-HCV is the higher-yield initial test**.
- Many IVDU patients have been vaccinated against HBV, further reducing its likelihood compared to HCV (for which no vaccine exists).
*Hepatitis E virus-specific IgM antibodies*
- **Hepatitis E** is typically transmitted via the **fecal-oral route** (contaminated water) and usually causes **acute, self-limiting hepatitis**, not chronic insidious fatigue and liver enzyme elevation in a Western patient.
- **IgM antibodies** would indicate an acute infection, which is less likely given the 6-month duration of symptoms.
- HEV rarely causes chronic infection except in immunocompromised patients.
*Hepatitis D virus-specific IgG antibody*
- **Hepatitis D** requires an existing **hepatitis B infection** to replicate (it's a satellite virus), meaning you would first need to confirm chronic hepatitis B before testing for HDV.
- While HDV can cause severe liver disease and is transmitted via blood exposure, it's not the initial test to pursue without evidence of HBV co-infection.
*Hepatitis A virus-specific IgM antibodies*
- **Hepatitis A** is transmitted via the **fecal-oral route** and causes an **acute, self-limiting infection** with complete resolution, rarely leading to chronic liver disease or persistent fatigue over 6 months.
- **IgM antibodies** are indicative of acute infection, which contradicts the chronic nature of the patient's symptoms.
- HAV does not cause chronic hepatitis.
Preoperative laboratory testing US Medical PG Question 2: A 65-year-old man presents to his primary care physician for a pre-operative evaluation. He is scheduled for cataract surgery in 3 weeks. His past medical history is notable for diabetes, hypertension, and severe osteoarthritis of the right knee. His medications include metformin, hydrochlorothiazide, lisinopril, and aspirin. His surgeon ordered blood work 1 month ago, which showed a hemoglobin of 14.2 g/dL, INR of 1.2, and a hemoglobin A1c of 6.9%. His vital signs at the time of the visit show BP: 130/70 mmHg, Pulse: 80, RR: 12, and T: 37.2 C. He has no current complaints and is eager for his surgery. Which of the following is the most appropriate course of action for this patient at this time?
- A. Tell the patient he will have to delay his surgery for at least 1 year
- B. Medically clear the patient for surgery (Correct Answer)
- C. Repeat the patient's CBC and coagulation studies
- D. Schedule the patient for a stress test and ask him to delay surgery for at least 6 months
- E. Perform an EKG
Preoperative laboratory testing Explanation: **Medically clear the patient for surgery**
- The patient's **blood pressure is well-controlled** (130/70 mmHg), and his **hemoglobin A1c of 6.9%** indicates good glycemic control, both of which are favorable for elective surgery.
- He is currently on **aspirin**, which, for cataract surgery (a low-risk bleeding procedure), can generally be continued, and his **INR of 1.2 is within a safe range** for surgery.
*Tell the patient he will have to delay his surgery for at least 1 year*
- There are **no indications for such a prolonged delay** based on the provided clinical information.
- His chronic conditions (diabetes, hypertension) are **adequately managed**, and his lab values are acceptable.
*Repeat the patient's CBC and coagulation studies*
- The **existing blood work from 1 month ago is recent enough** for a pre-operative evaluation for cataract surgery, especially with no new symptoms.
- Repeating these tests without a clinical indication would be **unnecessary and inefficient**.
*Schedule the patient for a stress test and ask him to delay surgery for at least 6 months*
- The patient has **no active cardiac symptoms** (e.g., chest pain, shortness of breath), and his well-controlled hypertension does not automatically warrant a stress test for low-risk surgery.
- A stress test and a **6-month delay are not indicated** for a low-risk procedure like cataract surgery in an asymptomatic patient.
*Perform an EKG*
- While an EKG might be considered in some pre-operative evaluations for patients with cardiac risk factors, there are **no specific symptoms or significant new risk factors** presented that necessitate an EKG for this low-risk cataract surgery.
- Given his stable condition and controlled hypertension, an EKG is **not a mandatory part of medical clearance** for this procedure.
Preoperative laboratory testing US Medical PG Question 3: A student health coordinator plans on leading a campus-wide HIV screening program that will be free for the entire undergraduate student body. The goal is to capture as many correct HIV diagnoses as possible with the fewest false positives. The coordinator consults with the hospital to see which tests are available to use for this program. Test A has a sensitivity of 0.92 and a specificity of 0.99. Test B has a sensitivity of 0.95 and a specificity of 0.96. Test C has a sensitivity of 0.98 and a specificity of 0.93. Which of the following testing schemes should the coordinator pursue?
- A. Test A on the entire student body followed by Test B on those who are positive
- B. Test A on the entire student body followed by Test C on those who are positive
- C. Test C on the entire student body followed by Test B on those who are positive
- D. Test C on the entire student body followed by Test A on those who are positive (Correct Answer)
- E. Test B on the entire student body followed by Test A on those who are positive
Preoperative laboratory testing Explanation: ***Test C on the entire student body followed by Test A on those who are positive***
- To "capture as many correct HIV diagnoses as possible" (maximize true positives), the initial screening test should have the **highest sensitivity**. Test C has the highest sensitivity (0.98).
- To "capture as few false positives as possible" (maximize true negatives and confirm diagnoses), the confirmatory test should have the **highest specificity**. Test A has the highest specificity (0.99).
*Test A on the entire student body followed by Test B on those who are positive*
- Starting with Test A (sensitivity 0.92) would miss more true positive cases than starting with Test C (sensitivity 0.98), failing the goal of **capturing as many cases as possible**.
- Following with Test B (specificity 0.96) would result in more false positives than following with Test A (specificity 0.99).
*Test A on the entire student body followed by Test C on those who are positive*
- This scheme would miss many true positive cases initially due to Test A's lower sensitivity compared to Test C.
- Following with Test C would introduce more false positives than necessary, as it has a lower specificity (0.93) than Test A (0.99).
*Test C on the entire student body followed by Test B on those who are positive*
- While Test C is a good initial screen for its high sensitivity, following it with Test B (specificity 0.96) is less optimal than Test A (specificity 0.99) for minimizing false positives in the confirmation step.
- This combination would therefore yield more false positives in the confirmatory stage than using Test A.
*Test B on the entire student body followed by Test A on those who are positive*
- Test B has a sensitivity of 0.95, which is lower than Test C's sensitivity of 0.98, meaning it would miss more true positive cases at the initial screening stage.
- While Test A provides excellent specificity for confirmation, the initial screening step is suboptimal for the goal of capturing as many diagnoses as possible.
Preoperative laboratory testing US Medical PG Question 4: A 17-year-old woman presents to the emergency department with dysuria. She denies any hematuria or dyspareunia. Her last menstrual period was 3 weeks ago, and she denies any recent sexual activity. Her temperature is 99.7°F (37.6°C), blood pressure is 127/67 mmHg, pulse is 90/min, and respirations are 17/min. An unusual odor is detected on inspection of the vagina and some gray discharge is noted. Speculum exam reveals a normal cervix and a bimanual exam is unremarkable for adnexal masses or tenderness. What is the next best step in management?
- A. Urinalysis and Pap smear
- B. Urinalysis, urine culture, KOH prep, and urine pregnancy test (Correct Answer)
- C. Urinalysis, KOH prep, and nucleic acid amplification tests for N. gonorrhea and C. trachomatis
- D. Urinalysis, urine culture, and potassium hydroxide prep (KOH)
- E. Complete blood count (CBC)
Preoperative laboratory testing Explanation: ***Urinalysis, urine culture, KOH prep, and urine pregnancy test***
- The patient's primary complaint of **dysuria** warrants a **urinalysis** and **urine culture** to rule out **urinary tract infection (UTI)**. The presence of unusual odor and gray discharge suggests a vaginal infection, making a **KOH prep** essential to check for **bacterial vaginosis** or **Candida**.
- Although she denies recent sexual activity, her age and symptoms make an **excluded pregnancy** important, especially before prescribing certain medications.
*Urinalysis and Pap smear*
- While a **urinalysis** is appropriate for dysuria, a **Pap smear** is a screening tool for cervical cancer and is not indicated for the acute management of these symptoms.
- A Pap smear would not help diagnose the immediate cause of the odorous gray discharge.
*Urinalysis, KOH prep, and nucleic acid amplification tests for N. gonorrhea and C. trachomatis*
- **NAAT testing** for STIs (gonorrhea and chlamydia) would be considered if there were risk factors or other symptoms, however the presence of **dysuria** necessitates a **urine culture** for infection.
- The patient denies recent sexual activity and initial presentation is more consistent with a UTI or more common vaginal infection.
*Urinalysis, urine culture, and potassium hydroxide prep (KOH)*
- This option correctly includes tests for **UTI** and **vaginal infection**.
- However, it **omits a pregnancy test**, which is a crucial step for a female of reproductive age, especially when considering treatment options for potential infections.
*Complete blood count (CBC)*
- A **CBC** would generally be ordered if there were signs of **systemic infection** or other more serious underlying conditions, which are not suggested by the patient's current symptoms and vital signs.
- While it may provide some information, it is not the most direct or immediate diagnostic test for dysuria or vaginal discharge.
Preoperative laboratory testing US Medical PG Question 5: A 69-year-old man is scheduled to undergo radical retropubic prostatectomy for prostate cancer in 2 weeks. He had a myocardial infarction at the age of 54 years. He has a history of GERD, unstable angina, hyperlipidemia, and severe osteoarthritis in the left hip. He is unable to climb up stairs or walk fast because of pain in his left hip. He had smoked one pack of cigarettes daily for 30 years but quit 25 years ago. He drinks one glass of wine daily. Current medications include aspirin, metoprolol, lisinopril, rosuvastatin, omeprazole, and ibuprofen as needed. His temperature is 36.4°C (97.5°F), pulse is 90/min, and blood pressure is 136/88 mm Hg. Physical examination shows no abnormalities. A 12-lead ECG shows Q waves and inverted T waves in leads II, III, and aVF. His B-type natriuretic protein is 84 pg/mL (N < 125). Which of the following is the most appropriate next step in management to assess this patient's perioperative cardiac risk?
- A. No further testing
- B. 24-hour ambulatory ECG monitoring
- C. Radionuclide myocardial perfusion imaging (Correct Answer)
- D. Treadmill stress test
- E. Resting echocardiography
Preoperative laboratory testing Explanation: ***Radionuclide myocardial perfusion imaging***
- This patient requires **perioperative cardiac risk assessment** before intermediate-risk surgery (radical prostatectomy).
- Key factors include: history of **myocardial infarction**, current cardiac risk factors, and **inability to exercise** due to severe osteoarthritis.
- Since he cannot perform exercise stress testing, **pharmacologic stress testing** with radionuclide myocardial perfusion imaging (using agents like adenosine, dipyridamole, or regadenoson) is the most appropriate test to assess for **inducible myocardial ischemia**.
- This provides functional assessment of coronary perfusion under pharmacologic stress, helping guide perioperative risk stratification and management.
- *Note: The presence of unstable angina would typically require cardiac stabilization first; this question focuses on selecting the appropriate stress test modality for a patient unable to exercise.*
*No further testing*
- This patient has significant cardiac risk factors including **prior MI**, ongoing cardiac medications, and ECG changes suggesting old infarction.
- Proceeding directly to surgery without functional cardiac assessment would be **inappropriate** given his risk profile and the intermediate-risk nature of the planned surgery.
*24-hour ambulatory ECG monitoring*
- Holter monitoring detects arrhythmias and silent ischemic episodes but does not provide **functional capacity assessment** or evaluation of inducible ischemia under stress conditions.
- It is not the primary tool for **perioperative cardiac risk stratification** before major surgery.
*Treadmill stress test*
- The patient's **severe osteoarthritis** prevents him from climbing stairs or walking fast, making him unable to achieve adequate exercise workload for a treadmill stress test.
- This functional limitation makes **exercise stress testing contraindicated**; pharmacologic stress testing is required instead.
*Resting echocardiography*
- Resting echocardiography assesses **baseline left ventricular function**, wall motion abnormalities from prior infarction, and valvular disease.
- While useful for structural assessment, it does **not evaluate for exercise-induced or stress-induced ischemia**, which is critical for perioperative risk assessment in patients with coronary artery disease.
- His normal BNP (84 pg/mL) suggests adequate baseline ventricular function, making functional ischemia assessment more relevant than structural evaluation alone.
Preoperative laboratory testing US Medical PG Question 6: A 48-year-old Caucasian woman presents to her physician for an initial visit. She has no chronic diseases. The past medical history is significant for myomectomy performed 10 years ago for a large uterine fibroid. She had 2 uncomplicated pregnancies and 2 spontaneous vaginal deliveries. Currently, she only takes oral contraceptives. She is a former smoker with a 3-pack-year history. Her last Pap test performed 2 years ago was negative. She had a normal blood glucose measurement 3 years ago. The family history is remarkable for systolic hypertension in her mother and older brother. The blood pressure is 110/80 mm Hg, heart rate is 76/min, respirations are 16/min, and oxygen saturation is 99% on room air. The patient is afebrile. The BMI is 32 kg/m2. Her physical examination is unremarkable. Which of the following preventative tests is indicated for this patient at this time?
- A. Abdominal ultrasound
- B. Colonoscopy
- C. Pap smear
- D. Chest CT
- E. Fasting blood glucose (Correct Answer)
Preoperative laboratory testing Explanation: ***Fasting blood glucose***
- This patient has a **BMI of 32 kg/m² (obesity)** and is 48 years old, which are significant risk factors for **type 2 diabetes mellitus**.
- The American Diabetes Association (ADA) recommends screening for type 2 diabetes with a **fasting plasma glucose**, 2-hour 75-g oral glucose tolerance test, or HbA1c in asymptomatic adults who are overweight or obese (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) and have one or more additional risk factors, or starting at age 35 for all individuals.
- Her **last glucose measurement was 3 years ago**, making rescreening appropriate at this visit.
- Given her obesity and the time interval, **diabetes screening is the highest priority preventative test** at this time.
*Abdominal ultrasound*
- An abdominal ultrasound is generally not indicated as a routine screening test in an asymptomatic 48-year-old woman without specific risk factors for abdominal pathology.
- While it's used to diagnose conditions like **gallstones** or **hepatic steatosis**, it is not a recommended preventative screening measure in this context.
*Colonoscopy*
- Routine screening colonoscopy is recommended starting at **age 45** for individuals of average risk.
- While this patient is 48 and colonoscopy screening would be appropriate if not previously done, the question provides no information about prior colonoscopy screening.
- More importantly, given her **obesity and 3-year interval since last glucose check**, diabetes screening takes priority as the most indicated test "at this time."
*Pap smear*
- The patient had a normal Pap test 2 years ago, and recommended screening intervals are typically every **3 years for cytology alone** or every 5 years for co-testing (cytology plus HPV) in women aged 30-65.
- Thus, a Pap smear is not indicated for another year based on current guidelines.
*Chest CT*
- Chest CT for lung cancer screening is indicated only for individuals with a significant **smoking history (≥20 pack-years)** and who are current smokers or have quit within the last 15 years, aged 50-80.
- This patient has a 3-pack-year history and is a former smoker, placing her well below the threshold for lung cancer screening with chest CT.
Preoperative laboratory testing US Medical PG Question 7: A 35-year-old man arrives at the emergency department within minutes after a head-on motor vehicle accident. He suffered from blunt abdominal trauma, several lacerations to his face as well as lacerations to his upper and lower extremities. The patient is afebrile, blood pressure is 45/25 mmHg and pulse is 160/minute. A CBC is obtained and is most likely to demonstrate which of the following?
- A. Hb 17 g/dL, Hct 20%
- B. Hb 15 g/dL, Hct 45% (Correct Answer)
- C. Hb 5 g/dL, Hct 30%
- D. Hb 20 g/dL, Hct 60%
- E. Hb 5 g/dL, Hct 20%
Preoperative laboratory testing Explanation: ***Hb 15 g/dL, Hct 45%***
- This option represents **normal hemoglobin and hematocrit values**, which are expected in the **initial minutes following acute hemorrhage**.
- In acute blood loss, **whole blood is lost** (both RBCs and plasma together), so the **concentration of RBCs remains unchanged** initially.
- **Hemodilution has not yet occurred**, as there hasn't been enough time for fluid shifts from the extravascular to the intravascular space to dilute the blood.
- This is a **critical teaching point**: early CBC values can be **falsely reassuring** and don't reflect the severity of hemorrhagic shock.
*Hb 17 g/dL, Hct 20%*
- This option shows a **medically implausible combination** - the normal Hb:Hct ratio is approximately **1:3**, so an Hb of 17 g/dL should correspond to an Hct of approximately 51%, not 20%.
- This combination cannot occur physiologically and does not represent any stage of acute blood loss.
*Hb 5 g/dL, Hct 30%*
- This shows an **incorrect Hb:Hct ratio** (6:1 instead of the expected 3:1) - if Hb is 5 g/dL, the Hct should be approximately 15%, not 30%.
- While severe anemia can occur with massive blood loss, this would only be apparent **hours after injury** once hemodilution from fluid shifts occurs, not within minutes.
- The implausible ratio makes this medically incorrect.
*Hb 20 g/dL, Hct 60%*
- These values represent **polycythemia** (abnormally high red blood cell counts), which is the opposite of what would be expected after acute traumatic blood loss.
- The Hb:Hct ratio is appropriate (1:3), but the elevated values suggest chronic hypoxemia, dehydration, or myeloproliferative disorders - not acute hemorrhage.
*Hb 5 g/dL, Hct 20%*
- This shows an **incorrect Hb:Hct ratio** (4:1 instead of the expected 3:1) - if Hb is 5 g/dL, the Hct should be approximately 15%, not 20%.
- Even if we accept these as severe anemia values, they would only be seen **several hours after injury** when sufficient time has passed for fluid shifts and hemodilution to occur, not within minutes of the trauma.
Preoperative laboratory testing US Medical PG Question 8: A 66-year-old man with severe aortic stenosis (valve area 0.7 cm², mean gradient 55 mmHg) and Class III heart failure requires emergent hemicolectomy for perforated diverticulitis with peritonitis. He is hemodynamically stable on pressors. Cardiology states he is high-risk for valve replacement but could undergo TAVR in 2-3 weeks. The surgeon believes he needs surgery within 6-8 hours. Evaluate the management approach.
- A. Delay surgery, perform urgent TAVR, then colectomy in 2-3 weeks
- B. Proceed with colectomy under invasive monitoring with cardiology backup (Correct Answer)
- C. Perform colostomy only under local anesthesia, defer resection
- D. Medical management of perforation with antibiotics pending TAVR
- E. Simultaneous TAVR and emergency colectomy in hybrid OR
Preoperative laboratory testing Explanation: ***Proceed with colectomy under invasive monitoring with cardiology backup***
- Perforated diverticulitis with **peritonitis** is an immediate surgical emergency requiring intervention within hours to prevent **sepsis** and death.
- Management of **severe aortic stenosis** in non-cardiac emergencies involves **invasive hemodynamic monitoring** to maintain a fixed cardiac output, adequate **preload**, and stable **systemic vascular resistance**.
*Delay surgery, perform urgent TAVR, then colectomy in 2-3 weeks*
- Waiting 2-3 weeks for a **TAVR** is not feasible for a patient with **peritonitis**, as the risk of mortality from untreated perforation is nearly 100%.
- **TAVR** requires a recovery period and often **antiplatelet therapy**, which would further complicate and delay the necessary abdominal surgery.
*Perform colostomy only under local anesthesia, defer resection*
- **Local anesthesia** is insufficient for managing generalized **peritonitis** and would not allow for the necessary thorough abdominal washout and source control.
- A simple colostomy without **resection** of the perforated segment fails to eliminate the source of **fecal contamination**, leading to persistent sepsis.
*Medical management of perforation with antibiotics pending TAVR*
- Antibiotics alone are inadequate for **Hinchey III/IV peritonitis**; the lack of **source control** results in high mortality regardless of cardiac status.
- The patient is already on **pressors**, indicating that the septic process is advanced and requires mechanical/surgical correction rather than conservative medical therapy.
*Simultaneous TAVR and emergency colectomy in hybrid OR*
- Combining a **clean-contaminated** or dirty surgery (colectomy) with a sterile cardiac procedure (TAVR) carries an unacceptable risk of **prosthetic valve infection**.
- The physiological stress of both procedures simultaneously would likely exceed the patient's **hemodynamic compensatory** mechanisms in the setting of acute sepsis.
Preoperative laboratory testing US Medical PG Question 9: A 35-year-old woman scheduled for thyroidectomy for papillary thyroid cancer is found to have prolonged aPTT (52 seconds, normal 25-35) on routine preoperative labs. PT/INR is normal. She has history of two first-trimester miscarriages but denies personal bleeding history. Further testing reveals lupus anticoagulant positivity. Evaluate the perioperative hemostatic management.
- A. Cancel surgery and treat with anticoagulation indefinitely
- B. Proceed with surgery without additional precautions as bleeding risk is not increased (Correct Answer)
- C. Administer fresh frozen plasma preoperatively to correct aPTT
- D. Start therapeutic anticoagulation and bridge perioperatively
- E. Delay surgery, perform comprehensive thrombophilia workup, individualize management
Preoperative laboratory testing Explanation: ***Proceed with surgery without additional precautions as bleeding risk is not increased***
- **Lupus anticoagulant** is an in-vitro laboratory artifact that causes a **prolonged aPTT** but is actually associated with a **prothrombotic state** rather than a bleeding risk.
- Since the patient has no personal history of bleeding and the **PT/INR** is normal, she can safely proceed with thyroidectomy without correction of the laboratory values.
*Cancel surgery and treat with anticoagulation indefinitely*
- Primary **anticoagulation** is generally reserved for patients with a history of **venous or arterial thrombosis**, not just isolated laboratory findings or miscarriages without confirmed APS diagnosis.
- **Cancer surgery** should not be indefinitely delayed for an asymptomatic laboratory abnormality that does not increase operative mortality.
*Administer fresh frozen plasma preoperatively to correct aPTT*
- **Fresh frozen plasma (FFP)** is used to replace clotting factors, but the aPTT prolongation here is due to **antiphospholipid antibodies** interfering with the assay, not a factor deficiency.
- Administering FFP will not significantly correct the **aPTT** and exposes the patient to unnecessary risks like **TRALI** or volume overload.
*Start therapeutic anticoagulation and bridge perioperatively*
- **Therapeutic anticoagulation** is contraindicated immediately before surgery due to the high risk of **intraoperative hemorrhage**, especially in delicate areas like the neck.
- Bridging is only indicated for patients with a high-risk history of **thromboembolism** who are already on chronic anticoagulation.
*Delay surgery, perform comprehensive thrombophilia workup, individualize management*
- While the patient likely has **Antiphospholipid Syndrome (APS)** based on miscarriages and LA positivity, a full workup is not required to establish **hemostatic safety** for the procedure.
- **Lupus anticoagulant** is already identified; further testing will not change the fact that the patient does not have a clinical **bleeding diathesis**.
Preoperative laboratory testing US Medical PG Question 10: A 48-year-old woman with newly diagnosed pheochromocytoma (4 cm right adrenal mass) is scheduled for laparoscopic adrenalectomy. Initial blood pressure is 180/110 mmHg with episodes of hypertension to 220/120 mmHg, headaches, and palpitations. Plasma metanephrines are markedly elevated. Evaluate the optimal preoperative preparation timeline and management.
- A. Urgent surgery within 48 hours with IV phentolamine available
- B. Alpha-blockade for 7-14 days, then beta-blockade, volume expansion, then surgery (Correct Answer)
- C. Beta-blockade first to control heart rate, then surgery in one week
- D. Combined alpha-beta blocker (labetalol) for one week, then surgery
- E. Calcium channel blocker for blood pressure control and immediate surgery
Preoperative laboratory testing Explanation: ***Alpha-blockade for 7-14 days, then beta-blockade, volume expansion, then surgery***
- Optimal preoperative preparation requires **phenoxybenzamine** (a non-competitive alpha-blocker) for 7-14 days to stabilize blood pressure and restore **intravascular volume**.
- **Beta-blockers** are only added after adequate alpha-blockade to manage tachycardia; **volume expansion** via high-salt diet/IV fluids prevents post-resection hypotension.
*Urgent surgery within 48 hours with IV phentolamine available*
- Urgent surgery without proper preparation carries a high risk of **intraoperative hypertensive crisis** due to catecholamine release during tumor manipulation.
- **Phentolamine** is used for acute crisis management but does not replace the requirement for preoperative **long-acting alpha-blockade** to stabilize the patient.
*Beta-blockade first to control heart rate, then surgery in one week*
- Initiating beta-blockade first is contraindicated because it can lead to **unopposed alpha-adrenergic stimulation**, causing a severe hypertensive crisis.
- Beta-blockers must only be introduced after the patient has achieved **adequate alpha-receptor blockade** to prevent peripheral vasoconstriction.
*Combined alpha-beta blocker (labetalol) for one week, then surgery*
- Labetalol has a much higher **beta-to-alpha blockade ratio** (approx 7:1), which can still result in worsening hypertension through **unopposed alpha-stimulation**.
- Standard of care mandates selective or non-selective **alpha-blockers** as the primary agent rather than mixed agents for initial stabilization.
*Calcium channel blocker for blood pressure control and immediate surgery*
- While **Calcium Channel Blockers** (CCBs) can supplement blood pressure control, they are not the gold standard for blocking the systemic effects of massive **catecholamine surges**.
- Immediate surgery is globally avoided in elective cases to ensure the patient is not **volume depleted**, which would lead to vascular collapse after tumor removal.
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