Diagnostic testing NCLEX-RN Practice Questions

Diagnostic testing NCLEX-RN Practice Questions strengthen your ability to interpret results, prepare clients safely, and anticipate complications—core priorities under the Reduction of Risk Potential domain. This topic-wise collection is tailored for M. Pharma students aiming to master nursing diagnostics at a real NCLEX-RN level. You’ll practice pre-/post-procedure care, specimen handling, contraindications, and critical value interpretations that drive immediate nursing actions. From ABGs, coagulation studies, and troponins to invasive procedures like lumbar puncture, thoracentesis, paracentesis, and cardiac catheterization, these questions integrate safety, evidence-based prep, and complication recognition. Use these curated MCQs to refine decision-making, reduce preventable harm, and understand how accurate diagnostic stewardship impacts outcomes across acute and ambulatory settings.

Q1. A client is scheduled for a contrast-enhanced CT scan. Which pre-procedure assessment requires immediate action by the nurse to reduce risk?

• Current metformin therapy with last dose taken this morning
• History of anaphylaxis to iodinated contrast media
• Blood urea nitrogen (BUN) 18 mg/dL
• Fasting state for 6 hours prior

Correct Answer: History of anaphylaxis to iodinated contrast media

Q2. The nurse prepares to obtain an arterial blood gas (ABG). Which action is essential to reduce complications?

• Apply a warm compress to the site for 20 minutes after the draw
• Use a tourniquet above the puncture site to improve flow
• Perform an Allen test prior to radial artery puncture
• Ask the client to fast for 8 hours before sampling

Correct Answer: Perform an Allen test prior to radial artery puncture

Q3. A client on heparin infusion has aPTT of 120 seconds (control 30 sec). What is the priority nursing action?

• Continue infusion; value is therapeutic
• Stop infusion and prepare protamine sulfate
• Notify provider to increase heparin dose
• Switch to warfarin immediately

Correct Answer: Stop infusion and prepare protamine sulfate

Q4. Post-lumbar puncture care for a client includes which key intervention to reduce risk of complications?

• Encourage early ambulation after the procedure
• Position prone for 12–24 hours
• Maintain flat or slight head elevation and encourage oral fluids
• Apply heat to puncture site for vasodilation

Correct Answer: Maintain flat or slight head elevation and encourage oral fluids

Q5. Which finding contraindicates a lumbar puncture?

• Platelet count 80,000/µL
• Serum sodium 130 mEq/L
• Hemoglobin 10 g/dL
• Glucose 140 mg/dL

Correct Answer: Platelet count 80,000/µL

Q6. A client is scheduled for an MRI with contrast. Which assessment is most important for the nurse to identify first?

• Presence of a pacemaker
• History of GERD
• Mild claustrophobia
• Peripheral IV in the left forearm

Correct Answer: Presence of a pacemaker

Q7. The nurse prepares a client for paracentesis. Which action reduces risk of bladder injury?

• Keep the client NPO for 12 hours beforehand
• Administer prophylactic antibiotics before the procedure
• Have the client void immediately before the procedure
• Place the client flat in left lateral position

Correct Answer: Have the client void immediately before the procedure

Q8. After thoracentesis, which finding requires immediate provider notification?

• Mild pleuritic discomfort on deep breath
• Diminished breath sounds on the puncture side
• Respiratory rate 18/min
• Oxygen saturation 96% on room air

Correct Answer: Diminished breath sounds on the puncture side

Q9. For a client undergoing cardiac catheterization via femoral approach, which post-procedure intervention is most important?

• Encourage oral fluids only after 12 hours
• Keep the affected leg straight and monitor distal pulses
• Ambulate after 1 hour to prevent DVT
• Place warm compresses over the groin site

Correct Answer: Keep the affected leg straight and monitor distal pulses

Q10. A clean-catch midstream urine specimen is needed. Which instruction is correct?

• Begin voiding into the cup, stop, then continue into the toilet
• Cleanse perineum, void into toilet, then collect midstream in sterile cup
• Collect the first urine of the day without cleansing
• Use the same container for 24 hours

Correct Answer: Cleanse perineum, void into toilet, then collect midstream in sterile cup

Q11. A 24-hour urine collection is ordered. Which action by the nurse ensures accuracy?

• Discard the first void and then start timing the collection
• Start timing with the first void included
• Keep the sample at room temperature
• If a void is missed, estimate the volume

Correct Answer: Discard the first void and then start timing the collection

Q12. A client’s troponin I is 0.28 ng/mL (normal <0.04). What is the priority nursing action?

• Administer sublingual nitrates and notify the provider
• Repeat the test in 72 hours without intervention
• Administer IM morphine and discharge home
• Schedule an outpatient stress test

Correct Answer: Administer sublingual nitrates and notify the provider

Q13. Which instruction is correct for sputum culture collection?

• Collect saliva after toothbrushing
• Collect early morning deep cough sputum before antibiotics
• Rinse mouth with antiseptic mouthwash before collection
• Collect after breakfast to mobilize secretions

Correct Answer: Collect early morning deep cough sputum before antibiotics

Q14. Which ECG-related assignment reduces risk of a misleading tracing?

• Place electrodes over areas with heavy hair to improve conduction
• Cleanse skin with alcohol and dry before lead placement
• Place limb leads on the torso to speed setup in all circumstances
• Ask the client to talk during the tracing to reduce anxiety

Correct Answer: Cleanse skin with alcohol and dry before lead placement

Q15. The nurse prepares for an EGD (upper endoscopy). Which post-procedure assessment is most critical?

• Presence of bowel sounds
• Return of gag reflex before oral intake
• Urine output within 2 hours
• Pain at IV insertion site

Correct Answer: Return of gag reflex before oral intake

Q16. A client on warfarin has an INR of 5.2. No active bleeding is present. What is the best initial nursing action?

• Administer vitamin K as ordered and hold warfarin
• Administer protamine sulfate immediately
• Continue warfarin and recheck INR in 24 hours
• Start heparin infusion to bridge therapy

Correct Answer: Administer vitamin K as ordered and hold warfarin

Q17. Preparing a client for colonoscopy, which instruction reduces procedural risk?

• Eat a low-residue breakfast on the morning of the procedure
• Maintain clear liquid diet day before and complete bowel prep as prescribed
• Take iron supplements the night before for anemia
• Continue anticoagulants the morning of the test

Correct Answer: Maintain clear liquid diet day before and complete bowel prep as prescribed

Q18. A blood culture is ordered for a febrile client. Which step is most critical to reduce contamination?

• Draw from a peripheral site after chlorhexidine prep
• Draw from an existing peripheral IV line
• Collect after first antibiotic dose
• Warm the site for vasodilation

Correct Answer: Draw from a peripheral site after chlorhexidine prep

Q19. Which lab result requires immediate action for a client scheduled for liver biopsy?

• INR 1.1
• Platelets 58,000/µL
• ALT 98 U/L
• AST 75 U/L

Correct Answer: Platelets 58,000/µL

Q20. Post–liver biopsy, which position reduces risk of hemorrhage?

• Supine with knees flexed
• High Fowler’s
• Right lateral decubitus with pillow under site
• Prone with head turned to side

Correct Answer: Right lateral decubitus with pillow under site

Q21. The nurse is caring for a client undergoing a D-dimer test. A markedly elevated D-dimer suggests which condition?

• Severe hypoglycemia
• Acute thrombus formation such as PE or DVT
• Viral hepatitis
• Iron-deficiency anemia

Correct Answer: Acute thrombus formation such as PE or DVT

Q22. A stool sample for fecal occult blood testing is collected. Which instruction reduces false results?

• Eat red meat 24 hours before testing
• Avoid vitamin C supplements for 3 days prior
• Use NSAIDs for pain the day before testing
• Collect from formed stool only if constipated

Correct Answer: Avoid vitamin C supplements for 3 days prior

Q23. A client is receiving metformin and is scheduled for contrast-enhanced imaging. Which plan reduces risk of lactic acidosis?

• Continue metformin and increase fluids
• Hold metformin on the day of study and 48 hours after; reassess renal function
• Switch to insulin 7 days before the study
• Double the metformin dose after the procedure

Correct Answer: Hold metformin on the day of study and 48 hours after; reassess renal function

Q24. For a suspected C. difficile infection, which stool collection principle is correct?

• Collect formed stool to reduce contamination
• Collect unformed (liquid) stool promptly in a sterile container
• Place stool on ice for 24 hours before sending
• Add preservative to the sample at bedside

Correct Answer: Collect unformed (liquid) stool promptly in a sterile container

Q25. Which client is at highest risk for bleeding after bone marrow biopsy, requiring close monitoring?

• Client with WBC 18,000/µL
• Client with platelet count 65,000/µL
• Client with hemoglobin 16 g/dL
• Client with serum potassium 5.1 mEq/L

Correct Answer: Client with platelet count 65,000/µL

Q26. When obtaining an ammonia level, the nurse should prioritize which specimen handling step?

• Allow specimen to clot at room temperature
• Place the sample on ice and send to the lab immediately
• Protect the sample from light
• Draw the specimen from a tourniqueted limb for 2 minutes

Correct Answer: Place the sample on ice and send to the lab immediately

Q27. Which ABG result requires the most immediate nursing response?

• pH 7.48, PaCO2 30 mm Hg, HCO3- 23 mEq/L
• pH 7.30, PaCO2 50 mm Hg, HCO3- 24 mEq/L
• pH 7.36, PaCO2 40 mm Hg, HCO3- 22 mEq/L
• pH 7.45, PaCO2 35 mm Hg, HCO3- 18 mEq/L

Correct Answer: pH 7.30, PaCO2 50 mm Hg, HCO3- 24 mEq/L

Q28. A client with suspected pulmonary embolism is scheduled for CT pulmonary angiography. Which pre-test step is essential?

• Verify creatinine and assess for contrast media reactions
• Ensure the client is NPO for 24 hours
• Administer diuretics to reduce contrast load
• Hold all inhaled bronchodilators

Correct Answer: Verify creatinine and assess for contrast media reactions

Q29. The Mantoux test (PPD) is placed. When should the nurse instruct the client to return for reading?

• 12–24 hours after placement
• 24–36 hours after placement
• 48–72 hours after placement
• 5–7 days after placement

Correct Answer: 48–72 hours after placement

Q30. Before administering a contrast radiology exam to a client with a transdermal patch, what should the nurse do?

• Leave the patch on to maintain therapeutic levels
• Remove patches with metallic backing to prevent burns during imaging
• Cover the patch with aluminum foil
• Place a warm compress over the patch to improve absorption

Correct Answer: Remove patches with metallic backing to prevent burns during imaging

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com