Cost-effective test ordering US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Cost-effective test ordering. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Cost-effective test ordering US Medical PG Question 1: A mother presents to the family physician with her 16-year-old son. She explains, "There's something wrong with him doc. His grades are getting worse, he's cutting class, he's gaining weight, and his eyes are often bloodshot." Upon interviewing the patient apart from his mother, he seems withdrawn and angry at times when probed about his social history. The patient denies abuse and sexual history. What initial test should be sent to rule out the most likely culprit of this patient's behavior?
- A. Complete blood count
- B. Sexually transmitted infection (STI) testing
- C. Blood culture
- D. Urine toxicology screen (Correct Answer)
- E. Slit lamp examination
Cost-effective test ordering Explanation: ***Urine toxicology screen***
- The patient's presentation with **declining grades**, **cutting class**, **weight gain**, **bloodshot eyes**, and **irritability** are classic signs of **substance abuse** in an adolescent.
- A **urine toxicology screen** is the most appropriate initial test to detect common illicit substances, especially given the clear signs pointing towards drug use.
*Slit lamp examination*
- This test is used to examine the **anterior segment of the eye**, including the conjunctiva, cornea, iris, and lens.
- While the patient has **bloodshot eyes**, this specific test would be more relevant for ruling out ocular infections or injuries, not for diagnosing the underlying cause of systemic behavioral changes.
*Complete blood count*
- A **complete blood count (CBC)** measures different components of the blood, such as red blood cells, white blood cells, and platelets.
- A CBC is a general health indicator and while it can detect infections or anemia, it is not specific or sensitive enough to identify the cause of the behavioral changes described.
*Sexually transmitted infection (STI) testing*
- Although the patient denies sexual history, all adolescents presenting with certain risk factors or symptoms may warrant STI testing in a broader health assessment.
- However, in this scenario, the primary cluster of symptoms (poor grades, cutting class, bloodshot eyes, irritability) points more directly to substance abuse than to an STI.
*Blood culture*
- A **blood culture** is used to detect the presence of bacteria or other microorganisms in the bloodstream, indicating a systemic infection (sepsis).
- The patient's symptoms are not indicative of an acute bacterial bloodstream infection, and a blood culture would not be the initial test for the presented behavioral changes.
Cost-effective test ordering US Medical PG Question 2: A 50-year-old woman presents with esophageal varices, alcoholic cirrhosis, hepatic encephalopathy, portal hypertension, and recent onset confusion. The patient’s husband does not recall her past medical history but knows her current medications and states that she is quite disciplined about taking them. Current medications are spironolactone, labetalol, lactulose, and furosemide. Her temperature is 38.3°C (100.9°F), heart rate is 115/min, blood pressure is 105/62 mm Hg, respiratory rate is 12/min, and oxygen saturation is 96% on room air. On physical examination, the patient is disoriented, lethargic, and poorly responsive to commands. A cardiac examination is unremarkable. Lungs are clear to auscultation. The abdomen is distended, tense, and mildly tender. Mild asterixis is present. Neurologic examination is normal. The digital rectal examination reveals guaiac negative stool. Laboratory findings are significant for the following:
Basic metabolic panel Unremarkable
Platelet count 95,500/µL
Leukocyte count 14,790/µL
Hematocrit 33% (baseline is 30%)
Which of the following would most likely be of diagnostic value in this patient?
- A. Therapeutic trial of lactulose
- B. Abdominal paracentesis (Correct Answer)
- C. Noncontrast CT of the head
- D. Serum ammonia level
- E. Esophagogastroduodenoscopy
Cost-effective test ordering Explanation: ***Abdominal paracentesis***
- The patient presents with **fever, abdominal tenderness, distension, and new-onset confusion** in the setting of **cirrhosis and ascites**, which are highly suggestive of **spontaneous bacterial peritonitis (SBP)**.
- An **abdominal paracentesis** with analysis of ascitic fluid (cell count with differential, culture) is necessary to diagnose SBP and guide appropriate antibiotic treatment.
*Therapeutic trial of lactulose*
- While the patient has **hepatic encephalopathy** and is on lactulose, her current presentation with **fever and abdominal tenderness** suggests an acute infectious process rather than worsening encephalopathy unresponsive to current therapy.
- A therapeutic trial of lactulose alone would delay the diagnosis of a potentially life-threatening infection like SBP.
*Noncontrast CT of the head*
- Although the patient has new-onset confusion, her presentation also includes **fever, abdominal tenderness, and signs of infection** in a patient with cirrhosis.
- A CT head would be more appropriate if there were focal neurological deficits, acute head trauma, or if SBP was ruled out and other causes of altered mental status were suspected.
*Serum ammonia level*
- The patient has known **hepatic encephalopathy**, and her current confusion is likely multifactorial.
- While an elevated ammonia level supports the diagnosis of hepatic encephalopathy, it is not diagnostic for the *cause* of her acute deterioration and would not rule out SBP, which requires urgent diagnosis and treatment.
*Esophagogastroduodenoscopy*
- The patient has a history of esophageal varices, but there is no evidence of active gastrointestinal bleeding (e.g., melena, hematemesis, guaiac positive stool).
- An **EGD** would be indicated for acute variceal bleeding, but it is not the most immediate or relevant diagnostic step for her current acute presentation of fever, abdominal pain, and confusion.
Cost-effective test ordering US Medical PG Question 3: You are developing a new diagnostic test to identify patients with disease X. Of 100 patients tested with the gold standard test, 10% tested positive. Of those that tested positive, the experimental test was positive for 90% of those patients. The specificity of the experimental test is 20%. What is the positive predictive value of this new test?
- A. 10%
- B. 90%
- C. 95%
- D. 11% (Correct Answer)
- E. 20%
Cost-effective test ordering Explanation: ***11%***
- The positive predictive value (PPV) is calculated as **true positives / (true positives + false positives)**.
- From 100 patients, 10 have disease (prevalence 10%). With 90% sensitivity, the test correctly identifies **9 true positives** (90% of 10).
- Of 90 patients without disease, specificity of 20% means 20% are correctly identified as negative (18 true negatives), so **72 false positives** = 90 × (1 - 0.20).
- Therefore, PPV = 9 / (9 + 72) = 9/81 = **11.1% ≈ 11%**.
*10%*
- This value represents the **prevalence** of the disease in the population, not the positive predictive value of the test.
- Prevalence is the proportion of individuals who have the disease (10 out of 100 patients).
*90%*
- This figure represents the **sensitivity** of the test, which is the percentage of true positives correctly identified by the experimental test.
- Sensitivity = true positives / (true positives + false negatives) = 9/10 = 90%.
*95%*
- This value is not directly derivable from the given data and does not represent any standard test characteristic in this context.
- It would imply a much higher PPV than what can be calculated given the low specificity of 20%.
*20%*
- This is the stated **specificity** of the test, which measures the proportion of true negatives correctly identified.
- Specificity = true negatives / (true negatives + false positives) = 18/90 = 20%.
Cost-effective test ordering US Medical PG Question 4: A family doctor in a rural area is treating a patient for dyspepsia. The patient had chronic heartburn and abdominal pain for the last 2 months and peptic ulcer disease due to a suspected H. pylori infection. For reasons relating to affordability and accessibility, the doctor decides to perform a diagnostic test in the office that is less invasive and more convenient. Which of the following is the most likely test used?
- A. Steiner's stain
- B. Culture of organisms from gastric specimen
- C. Stool antigen test (Correct Answer)
- D. Detection of the breakdown products of urea in biopsy
- E. Serology (ELISA testing)
Cost-effective test ordering Explanation: ***Stool antigen test***
- This **non-invasive** and **cost-effective** test detects *H. pylori* antigens in stool, making it suitable for a rural setting with limited resources.
- It is highly sensitive and specific, useful for both initial diagnosis and confirming eradication after treatment.
*Steiner's stain*
- **Steiner's stain** (Steiner silver stain) is primarily used for histological visualization of *Legionella* species, and **not for** *H. pylori* detection in routine clinical practice.
- It requires an **endoscopic biopsy**, making it more invasive and costly than the stool antigen test.
*Culture of organisms from gastric specimen*
- This method requires an **endoscopic biopsy** and specialized culture facilities, which may not be available in a rural doctor's office.
- It is more expensive and time-consuming, and primarily used when **antibiotic resistance** is suspected.
*Detection of the breakdown products of urea in biopsy*
- This refers to the **rapid urease test** (e.g., CLOtest), which is performed on a **gastric biopsy** obtained during endoscopy.
- While quick, it is an **invasive procedure** requiring endoscopy, which contradicts the patient's and doctor's preferences for a less invasive test.
*Serology (ELISA testing)*
- **Serology** detects antibodies to *H. pylori* but cannot differentiate between **active infection** and **past exposure**.
- Its utility in monitoring eradication is limited, and it's generally not recommended as the primary diagnostic test due to its inability to confirm active infection.
Cost-effective test ordering US Medical PG Question 5: A 55-year-old woman presents with fatigue and flu-like symptoms. She says her symptoms started 5 days ago with a low-grade fever and myalgia, which have not improved. For the past 4 days, she has also had chills, sore throat, and rhinorrhea. She works as a kindergarten teacher and says several children in her class have had similar symptoms. Her past medical history is significant for depression managed with escitalopram, and dysmenorrhea. A review of systems is significant for general fatigue for the past 5 months. Her vital signs include: temperature 38.5°C (101.3°F), pulse 99/min, blood pressure 115/75 mm Hg, and respiratory rate 22/min. Physical examination reveals pallor of the mucous membranes. Initial laboratory findings are significant for the following:
Hematocrit 24.5%
Hemoglobin 11.0 g/dL
Platelet Count 215,000/mm3
Mean corpuscular volume (MCV) 82 fL
Red cell distribution width (RDW) 10.5%
Which of the following is the best next diagnostic test in this patient?
- A. Serum iron level
- B. Serum ferritin level
- C. Reticulocyte count (Correct Answer)
- D. Hemoglobin electrophoresis
- E. Serum folate level
Cost-effective test ordering Explanation: ***Reticulocyte count***
- The patient presents with **fatigue, pallor, and anemia (Hb 11.0 g/dL)**. Given the acute illness (flu-like symptoms) and underlying chronic fatigue, a **reticulocyte count** helps determine if the bone marrow is adequately responding to the anemia.
- A low or inappropriately normal reticulocyte count in the setting of anemia suggests a problem with **red blood cell production** (e.g., marrow suppression, nutritional deficiency), while a high count would suggest hemolysis or acute blood loss.
*Serum iron level*
- While iron-deficiency anemia is common, the patient's **MCV of 82 fL** is within the normal range, suggesting a **normocytic anemia**, which makes iron deficiency less likely as a primary cause without further investigation.
- Furthermore, **serum iron levels** can be acutely affected by inflammation or infection, making them unreliable in the presence of acute flu-like symptoms.
*Serum ferritin level*
- **Ferritin** is an acute-phase reactant; therefore, in the context of an acute infection or inflammation (flu-like symptoms, fever), a **serum ferritin level** can be falsely elevated, masking true iron deficiency, which makes it less reliable as the *best first* diagnostic test in this scenario.
- While low ferritin is diagnostic of iron deficiency, a normal or even elevated ferritin does not rule it out in the presence of inflammation, thus complicating interpretation.
*Hemoglobin electrophoresis*
- **Hemoglobin electrophoresis** is used to diagnose **hemoglobinopathies** like **sickle cell disease** or **thalassemia**. There are no clinical or laboratory findings (e.g., microcytosis, prior family history of hemoglobinopathies) to suggest this as the most appropriate initial investigation for this patient's acute presentation.
- The patient's **normocytic anemia** (MCV 82 fL) further argues against typical thalassemia presentations, which are usually microcytic.
*Serum folate level*
- **Folate deficiency** typically causes a **macrocytic anemia** (elevated MCV), which is not observed in this patient (MCV 82 fL being normocytic).
- There are no specific risk factors or clinical signs presented that would clearly point towards folate deficiency as the primary cause for her anemia.
Cost-effective test ordering US Medical PG Question 6: A research study is comparing 2 novel tests for the diagnosis of Alzheimer’s disease (AD). The first is a serum blood test, and the second is a novel PET radiotracer that binds to beta-amyloid plaques. The researchers intend to have one group of patients with AD assessed via the novel blood test, and the other group assessed via the novel PET examination. In comparing these 2 trial subsets, the authors of the study may encounter which type of bias?
- A. Selection bias (Correct Answer)
- B. Confounding bias
- C. Recall bias
- D. Measurement bias
- E. Lead-time bias
Cost-effective test ordering Explanation: ***Selection bias***
- This occurs when different patient groups are assigned to different interventions or measurements in a way that creates **systematic differences** between comparison groups.
- In this study, having **separate patient groups** assessed with different diagnostic methods (blood test vs. PET scan) means any differences observed could be due to **differences in the patient populations** rather than differences in test performance.
- To validly compare two diagnostic tests, both tests should ideally be performed on the **same patients** (paired design) or patients should be **randomly assigned** to receive one test or the other, ensuring comparable groups.
- This is a fundamental **study design flaw** that prevents valid comparison of the two diagnostic methods.
*Measurement bias*
- Also called information bias, this occurs when there are systematic errors in how outcomes or exposures are measured.
- While using different measurement tools could introduce measurement variability, the primary issue here is that **different patient populations** are being compared, not just different measurement methods on the same population.
- Measurement bias would be more relevant if the same patients were assessed with both methods but one method was systematically misapplied or measured incorrectly.
*Confounding bias*
- This occurs when an extraneous variable is associated with both the exposure and outcome, distorting the observed relationship.
- While patient characteristics could confound results, the fundamental problem is the **study design itself** (separate groups for separate tests), which is selection bias.
*Recall bias*
- This involves systematic differences in how participants remember or report past events, common in **retrospective case-control studies**.
- Not relevant here, as this involves prospective diagnostic testing, not recollection of past exposures.
*Lead-time bias*
- Occurs in screening studies when earlier detection makes survival appear longer without changing disease outcomes.
- Not applicable to this scenario, which focuses on comparing two diagnostic methods in separate patient groups, not on survival or disease progression timing.
Cost-effective test ordering US Medical PG Question 7: Two studies are reviewed for submission to an oncology journal. In Study A, a novel MRI technology is evaluated as a screening tool for ovarian cancer. The authors find that the mean survival time is 4 years in the control group and 10 years in the MRI-screened group. In Study B, cognitive behavioral therapy (CBT) and a novel antidepressant are used to treat patients with comorbid pancreatic cancer and major depression. Patients receiving the new drug are told that they are expected to have quick resolution of their depression, while those who do not receive the drug are not told anything about their prognosis. Which of the following describes the likely type of bias in Study A and Study B?
- A. Latency Bias; Golem effect
- B. Confounding; Golem effect
- C. Lead time bias; Golem effect
- D. Lead time bias; Pygmalion effect (Correct Answer)
- E. Latency bias; Pygmalion effect
Cost-effective test ordering Explanation: ***Lead time bias; Pygmalion effect***
- In Study A, the MRI technology detects ovarian cancer earlier, artificially making the survival time appear longer simply due to earlier diagnosis, not necessarily improved outcomes, which is characteristic of **lead time bias**.
- In Study B, the patients receiving the new drug are told to expect quick resolution of their depression, leading to increased expectation of improvement, which describes the **Pygmalion effect** (a form of observer-expectancy effect where higher expectations lead to increased performance).
*Latency Bias; Golem effect*
- **Latency bias** refers to a delay in the manifestation of an outcome, which is not the primary issue in Study A's screening context.
- The **Golem effect** is a form of negative self-fulfilling prophecy where lower expectations placed upon individuals by superiors/researchers lead to poorer performance, which is opposite to what is described in Study B.
*Confounding; Golem effect*
- **Confounding** occurs when an unmeasured third variable is associated with both the exposure and the outcome, distorting the observed relationship; while confounding is common, the scenario in Study A specifically points to a screening effect on survival time.
- As mentioned, the **Golem effect** refers to negative expectations leading to poorer outcomes, which is not present in Study B.
*Lead time bias; Golem effect*
- **Lead time bias** correctly identifies the issue in Study A, as explaining the apparently longer survival as a result of earlier detection.
- However, the **Golem effect** incorrectly describes the scenario in Study B, where positive expectations are given, not negative ones.
*Latency bias; Pygmalion effect*
- **Latency bias** is not the primary bias described in Study A; the immediate impact of early detection on survival statistics points to lead time bias.
- The **Pygmalion effect** correctly describes the bias in Study B, where positive expectations from the researchers influence patient outcomes.
Cost-effective test ordering US Medical PG Question 8: A pharmaceutical corporation is developing a research study to evaluate a novel blood test to screen for breast cancer. They enrolled 800 patients in the study, half of which have breast cancer. The remaining enrolled patients are age-matched controls who do not have the disease. Of those in the diseased arm, 330 are found positive for the test. Of the patients in the control arm, only 30 are found positive. What is this test’s sensitivity?
- A. 330 / (330 + 30)
- B. 330 / (330 + 70) (Correct Answer)
- C. 370 / (30 + 370)
- D. 370 / (70 + 370)
- E. 330 / (400 + 400)
Cost-effective test ordering Explanation: ***330 / (330 + 70)***
- **Sensitivity** measures the proportion of actual **positives** that are correctly identified as such.
- In this study, there are **400 diseased patients** (half of 800). Of these, 330 tested positive (true positives), meaning 70 tested negative (false negatives). So sensitivity is **330 / (330 + 70)**.
*330 / (330 + 30)*
- This calculation represents the **positive predictive value**, which is the probability that subjects with a positive screening test truly have the disease. It uses **true positives / (true positives + false positives)**.
- It does not correctly calculate **sensitivity**, which requires knowing the total number of diseased individuals.
*370 / (30 + 370)*
- This expression is attempting to calculate **specificity**, which is the proportion of actual negatives that are correctly identified. It would be **true negatives / (true negatives + false positives)**.
- However, the numbers used are incorrect for specificity in this context given the data provided.
*370 / (70 + 370)*
- This formula is an incorrect combination of values and does not represent any standard epidemiological measure like **sensitivity** or **specificity**.
- It is attempting to combine false negatives (70) and true negatives (370 from control arm) in a non-standard way.
*330 / (400 + 400)*
- This calculation attempts to divide true positives by the total study population (800 patients).
- This metric represents the **prevalence of true positives within the entire study cohort**, not the test's **sensitivity**.
Cost-effective test ordering US Medical PG Question 9: A 65-year-old man is admitted to the hospital because of a 1-month history of fatigue, intermittent fever, and weakness. Results from a peripheral blood smear taken during his evaluation are indicative of possible acute myeloid leukemia. Bone marrow aspiration and subsequent cytogenetic studies confirm the diagnosis. The physician sets aside an appointed time-slot and arranges a meeting in a quiet office to inform him about the diagnosis and discuss his options. He has been encouraged to bring someone along to the appointment if he wanted. He comes to your office at the appointed time with his daughter. He appears relaxed, with a full range of affect. Which of the following is the most appropriate opening statement in this situation?
- A. Your lab reports show that you have an acute myeloid leukemia
- B. What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies? (Correct Answer)
- C. You must be curious and maybe even anxious about the results of your tests.
- D. I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.
- E. Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?
Cost-effective test ordering Explanation: ***"What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies?"***
- This **open-ended question** allows the patient to express their current knowledge and perceptions, which helps the physician tailor the discussion.
- It establishes a **patient-centered approach**, respecting the patient's existing understanding and preparing them for further information.
*"You must be curious and maybe even anxious about the results of your tests."*
- While empathic, this statement makes an **assumption about the patient's feelings** rather than inviting them to share their own.
- It is often better to ask directly or use more open-ended questions that allow the patient to express their true emotions, especially given their **relaxed demeanor**.
*"I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.”"*
- This statement immediately introduces **overwhelming and potentially alarming information** (referral, chemotherapy, radiotherapy) without first establishing the diagnosis or assessing the patient's readiness to receive it.
- It prematurely jumps to treatment and logistics, potentially causing **unnecessary distress** before the patient has processed the core diagnosis.
*"Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?""*
- While it attempts to assess the patient's preference for information, this question is a **closed-ended "either/or" choice** that might limit the patient's ability to express nuanced needs.
- It also prematurely introduces the idea of "options" without first explaining the diagnosis in an understandable context.
*"Your lab reports show that you have an acute myeloid leukemia"*
- This is a **direct and blunt delivery of a serious diagnosis** without any preparatory context or assessment of the patient's existing knowledge or emotional state.
- Delivering such news abruptly can be shocking and overwhelming, potentially **hindering effective communication** and rapport building.
Cost-effective test ordering US Medical PG Question 10: A 23-year-old female college basketball player presents in Sports Clinic after she felt a "pop" in her knee after coming down with a rebound. To examine the patient, you have her lie down on the table with her knees flexed 90 degrees. With your hand around her knee you are able to draw the tibia toward you from underneath the femur. The torn structure implicated by this physical exam maneuver has which of the following attachments?
- A. The posterior intercondylar area of tibia and the posteromedial aspect of the lateral femur
- B. The anterior intercondylar area of tibia and the posteromedial aspect of the lateral femur (Correct Answer)
- C. The patella and tibial tuberosity
- D. The lateral epicondyle of the femur and the head of fibula
- E. The medial condyle of the femur and the medial condyle of the tibia
Cost-effective test ordering Explanation: ***The anterior intercondylar area of tibia and the posteromedial aspect of the lateral femur***
- The patient's presentation with a "pop" in the knee after a basketball maneuver and a positive **anterior drawer test** (drawing the tibia forward) is classic for an **anterior cruciate ligament (ACL) tear**.
- The **ACL originates from the anterior intercondylar area of the tibia** and **inserts into the posteromedial aspect of the lateral femoral condyle**.
*The posterior intercondylar area of tibia and the posteromedial aspect of the lateral femur*
- This describes the attachments of the **posterior cruciate ligament (PCL)**.
- A PCL tear would typically be indicated by a **posterior drawer test** (pushing the tibia backward), which is not described.
*The patella and tibial tuberosity*
- These are the attachment points for the **patellar ligament** (or patellar tendon).
- Injury to the patellar ligament would cause pain and difficulty with knee extension, but not primarily instability evident with an anterior drawer test.
*The lateral epicondyle of the femur and the head of fibula*
- These are the attachment points for the **fibular collateral ligament (LCL)**.
- An LCL injury would present with pain on the lateral side of the knee and instability to **varus stress**, not an anterior drawer.
*The medial condyle of the femur and the medial condyle of the tibia*
- These are general areas involved with the **medial collateral ligament (MCL)**.
- An MCL injury would cause pain on the medial side of the knee and instability to **valgus stress**, not an anterior drawer.
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