Minimally Invasive Surgery US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Minimally Invasive Surgery. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Minimally Invasive Surgery US Medical PG Question 1: A 36-year-old woman is brought to the emergency department 20 minutes after being involved in a high-speed motor vehicle collision. On arrival, she is unconscious. Her pulse is 140/min, respirations are 12/min and shallow, and blood pressure is 76/55 mm Hg. 0.9% saline infusion is begun. A focused assessment with sonography shows blood in the left upper quadrant of the abdomen. Her hemoglobin concentration is 7.6 g/dL and hematocrit is 22%. The surgeon decided to move the patient to the operating room for an emergent explorative laparotomy. Packed red blood cell transfusion is ordered prior to surgery. However, a friend of the patient asks for the transfusion to be held as the patient is a Jehovah's Witness. The patient has no advance directive and there is no documentation showing her refusal of blood transfusions. The patient's husband and children cannot be contacted. Which of the following is the most appropriate next best step in management?
- A. Administer hydroxyethyl starch
- B. Transfusion of packed red blood cells (Correct Answer)
- C. Consult hospital ethics committee
- D. Administer high-dose iron dextran
Minimally Invasive Surgery Explanation: ***Transfusion of packed red blood cells***
- This patient is in **hemorrhagic shock** (tachycardia, hypotension, low hemoglobin, and hematocrit with evidence of active bleeding), requiring emergent blood transfusion to prevent irreversible organ damage and death.
- In an **emergency setting** with an **unconscious patient** and **no documented refusal** of blood products, the principle of **presumed consent** for life-saving treatment takes precedence, especially when next of kin cannot be reached.
*Administer hydroxyethyl starch*
- **Colloids** like hydroxyethyl starch can temporarily increase intravascular volume but do not provide oxygen-carrying capacity, which is critically needed for a patient with severe anemia and hemorrhagic shock.
- While useful for volume expansion, it is **not a substitute for blood products** in severe bleeding and can have adverse effects such as kidney injury.
*Consult hospital ethics committee*
- Consulting an ethics committee is appropriate for **complex ethical dilemmas** when there is time for deliberation and the patient's life is not in immediate danger.
- In this acute, life-threatening emergency, **delaying treatment** to consult an ethics committee would jeopardize the patient's life and is not appropriate.
*Administer high-dose iron dextran*
- **Iron dextran** is used to treat iron-deficiency anemia and works by supporting red blood cell production over several days to weeks.
- It is **ineffective in acute hemorrhagic shock** where immediate restoration of oxygen-carrying capacity is required.
Minimally Invasive Surgery US Medical PG Question 2: During a surgical procedure to repair an abdominal aortic aneurysm, the surgeon must be careful to avoid injury to which of the following arterial structures that originates near the level of the renal vessels?
- A. Left renal artery (Correct Answer)
- B. Celiac trunk
- C. Right renal artery
- D. Superior mesenteric artery
Minimally Invasive Surgery Explanation: ***Left renal artery***
- The **left renal artery** arises from the aorta usually just below the superior mesenteric artery, making it susceptible to injury during an **abdominal aortic aneurysm (AAA) repair** if the aneurysm extends proximally.
- Its proximity to the typical location of AAA, often near or involving the **infrarenal aorta**, necessitates careful identification and protection during clamping or graft placement.
*Celiac trunk*
- The **celiac trunk** originates higher up from the aorta, typically at the level of **T12-L1 vertebrae**, well above the common infrarenal AAA repair site.
- While important, it is generally less directly threatened during a typical infrarenal AAA repair compared to arteries immediately adjacent to or within the aneurysm sac.
*Right renal artery*
- The **right renal artery** also originates from the aorta near the level of the renal veins, but it is typically located more posteriorly and usually passes behind the inferior vena cava.
- Although it can be at risk, the left renal artery's course is often more anterior and directly in the field of dissection for the **aortic neck** during AAA repair.
*Superior mesenteric artery*
- The **superior mesenteric artery (SMA)** originates from the aorta proximal to the renal arteries, typically around the L1 vertebral level.
- While crucial, its origin is usually cephalad to the infrarenal aneurysm neck, making it generally less prone to direct injury during infrarenal AAA repair, though flow must be monitored.
Minimally Invasive Surgery US Medical PG Question 3: A research team develops a new monoclonal antibody checkpoint inhibitor for advanced melanoma that has shown promise in animal studies as well as high efficacy and low toxicity in early phase human clinical trials. The research team would now like to compare this drug to existing standard of care immunotherapy for advanced melanoma. The research team decides to conduct a non-randomized study where the novel drug will be offered to patients who are deemed to be at risk for toxicity with the current standard of care immunotherapy, while patients without such risk factors will receive the standard treatment. Which of the following best describes the level of evidence that this study can offer?
- A. Level 1
- B. Level 3 (Correct Answer)
- C. Level 5
- D. Level 4
- E. Level 2
Minimally Invasive Surgery Explanation: ***Level 3***
- A **non-randomized controlled trial** like the one described, where patient assignment to treatment groups is based on specific characteristics (risk of toxicity), falls into Level 3 evidence.
- This level typically includes **non-randomized controlled trials** and **well-designed cohort studies** with comparison groups, which are prone to selection bias and confounding.
- The study compares two treatments but lacks randomization, making it Level 3 evidence.
*Level 1*
- Level 1 evidence is the **highest level of evidence**, derived from **systematic reviews and meta-analyses** of multiple well-designed randomized controlled trials or large, high-quality randomized controlled trials.
- The described study is explicitly stated as non-randomized, ruling out Level 1.
*Level 2*
- Level 2 evidence involves at least one **well-designed randomized controlled trial** (RCT) or **systematic reviews** of randomized trials.
- The current study is *non-randomized*, which means it cannot be classified as Level 2 evidence, as randomization is a key criterion for this level.
*Level 4*
- Level 4 evidence includes **case series**, **case-control studies**, and **poorly designed cohort or case-control studies**.
- While the study is non-randomized, it is a controlled comparative trial rather than a case series or retrospective case-control study, placing it at Level 3.
*Level 5*
- Level 5 evidence is the **lowest level of evidence**, typically consisting of **expert opinion** without explicit critical appraisal, or based on physiology, bench research, or animal studies.
- While the drug was initially tested in animal studies, the current human comparative study offers a higher level of evidence than expert opinion or preclinical data.
Minimally Invasive Surgery US Medical PG Question 4: A pharmaceutical company conducts a randomized clinical trial to demonstrate that their new anticoagulant drug, Aclotsaban, prevents more thrombotic events following total knee arthroplasty than the current standard of care. A significant number of patients are lost to follow-up, and many fail to complete treatment according to the study arm to which they were assigned. Despite these protocol deviations, the results for the patients who completed the course of Aclotsaban are encouraging. Which of the following analytical approaches is most appropriate for the primary analysis to establish the efficacy of Aclotsaban?
- A. Intention-to-treat analysis (Correct Answer)
- B. Sub-group analysis
- C. Per-protocol analysis
- D. As-treated analysis
- E. Non-inferiority analysis
Minimally Invasive Surgery Explanation: ***Intention-to-treat analysis***
- **Intention-to-treat (ITT) analysis** is the gold standard for the **primary analysis in superiority trials** and includes all patients in the groups to which they were originally randomized, regardless of protocol deviations, loss to follow-up, or treatment discontinuation.
- ITT preserves **randomization balance**, prevents bias from selective dropout (patients may drop out due to adverse effects or lack of efficacy), and provides a **conservative, realistic estimate** of treatment effect in actual clinical practice.
- For **regulatory approval and establishing efficacy**, ITT is the most appropriate primary analysis method even when dropout rates are high, as it maintains the integrity of the randomized comparison.
*Per-protocol analysis*
- **Per-protocol analysis** includes only patients who completed the study exactly as planned without protocol deviations.
- While the encouraging results in completers are noted, per-protocol analysis can **introduce significant bias** by excluding patients who dropped out due to adverse events or lack of efficacy, potentially **overestimating treatment benefit**.
- Per-protocol is typically used as a **secondary/supportive analysis**, not the primary method for establishing superiority.
*As-treated analysis*
- **As-treated analysis** categorizes patients according to the treatment they actually received rather than their randomized assignment.
- This violates the principle of randomization and can introduce **confounding bias**, as actual treatment received may be influenced by prognostic factors.
*Sub-group analysis*
- **Sub-group analysis** evaluates treatment effects within specific patient subsets.
- This is **hypothesis-generating** rather than confirmatory and increases the risk of false-positive findings (multiple comparisons problem) unless pre-specified in the protocol.
*Non-inferiority analysis*
- **Non-inferiority analysis** tests whether a new treatment is not worse than control by more than a pre-specified margin.
- The goal here is to demonstrate **superiority** (better than standard care), not non-inferiority, making this approach inappropriate.
Minimally Invasive Surgery US Medical PG Question 5: A 27-year-old man presents to the emergency department after being stabbed. The patient was robbed at a local pizza parlor and was stabbed over 10 times with a large kitchen knife with an estimated 7 inch blade in the ventral abdomen. His temperature is 97.6°F (36.4°C), blood pressure is 74/54 mmHg, pulse is 180/min, respirations are 19/min, and oxygen saturation is 98% on room air. The patient is intubated and given blood products and vasopressors. Physical exam is notable for multiple stab wounds over the patient's abdomen inferior to the nipple line. Which of the following is the best next step in management?
- A. Exploratory laparotomy (Correct Answer)
- B. Diagnostic peritoneal lavage
- C. CT scan of the abdomen and pelvis
- D. Exploratory laparoscopy
- E. FAST exam
Minimally Invasive Surgery Explanation: ***Exploratory laparotomy***
- The patient presents with **multiple stab wounds** to the abdomen and signs of **hemorrhagic shock** (BP 74/54 mmHg, HR 180/min), which are clear indications for immediate surgical intervention.
- An exploratory laparotomy allows for direct visualization and repair of internal injuries, which is critical in this life-threatening situation.
*Diagnostic peritoneal lavage*
- While DPL can detect intra-abdominal bleeding, it is an **invasive procedure** and may delay definitive treatment in a hemodynamically unstable patient with obvious penetrating trauma.
- It is **less specific** than a laparotomy for identifying the exact location and nature of injuries, and it has largely been replaced by imaging studies or direct surgical exploration in unstable patients.
*CT scan of the abdomen and pelvis*
- A CT scan requires a **hemodynamically stable** patient and time for scanning and interpretation, which this patient does not have.
- Delaying definitive treatment for imaging in a patient with severe shock could lead to worse outcomes.
*Exploratory laparoscopy*
- Although less invasive, laparoscopy can be time-consuming and may not be feasible or safe in a patient with **profound hemorrhagic shock** and extensive injuries, especially if major vascular or visceral damage is suspected.
- Conversion to a **laparotomy** is often necessary in cases of significant injury, making immediate open exploration more efficient.
*FAST exam*
- A FAST exam can rapidly detect free fluid in the abdomen, suggesting internal bleeding, but it does **not provide specific information** about the source or extent of the injuries.
- While useful in the initial assessment, a positive FAST exam in a hemodynamically unstable patient with penetrating trauma directly points to the need for immediate surgical intervention, not further diagnostic delay.
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