CRN common mistakes
CRN · Understand the traps and how to avoid them.
When contrast extravasates, the candidate stops the injection but then applies a warm compress, leaves the extremity dependent, and does not escalate or document the event until the patient complains of pain.
Study habits focus on recognizing extravasation as a 'complication' rather than rehearsing a stepwise response; warm compresses are also the correct answer for some vesicant chemotherapy extravasations, so the two protocols get blended.
What to do instead
Memorize the iodinated-contrast sequence as a fixed chain: stop injection, disconnect and aspirate residual contrast through the cannula if possible, remove the cannula, elevate the extremity, apply cold compresses for 15-20 minutes several times daily for the first 24 hours, notify the radiologist and the patient's provider, document volume/agent/site/appearance, and arrange follow-up. Drill it as a sequence, not a list of options.
The candidate accepts a requisition for an iodinated contrast study and proceeds without checking a current eGFR/creatinine, pregnancy status, prior contrast reaction history, or metformin use in a patient with diabetes.
Screening feels like clerical work that 'someone else already did,' and candidates memorize contrast reactions in detail while treating pre-procedure risk screening as background noise.
What to do instead
Build a single pre-contrast checklist you can recite: indication, allergies and prior reaction (including premedication status), renal function within the institution's time window, pregnancy/lactation status, metformin or other nephrotoxic agents per policy, asthma/atopy, and hydration status. Practice applying it to vignettes where one element is abnormal so you learn the escalation step, not just the list.
The candidate holds or supports a patient's arm or chest during a portable or fluoroscopic procedure with no lead shielding and stands close to the beam, explaining that 'it was only for a few seconds.'
Candidates confuse patient safety with occupational safety, and 'time-distance-shielding' is memorized as a slogan rather than as three levers with specific numbers attached.
What to do instead
Anchor each principle to a concrete action and number: increase distance because exposure falls with the square of distance; use immobilization devices or family/colleague assistance instead of your own hands; if holding is unavoidable, wear apron and thyroid shield, keep hands out of the primary beam, and collimate. Separately memorize the units (Gy absorbed dose, Sv effective dose) and the limits (about 50 mSv/year occupational, 1 mSv/year public, 0.5 mSv/month to a declared pregnant worker) so they cannot be swapped.
Faced with a patient who becomes hypotensive, wheezing, and urticarial minutes after contrast, the candidate gives IV diphenhydramine first and waits to see if the hives improve before calling for epinephrine.
Urticaria is the most visually dramatic finding, so antihistamines get over-weighted; candidates under-practice the distinction between a mild reaction and anaphylaxis and are uncomfortable with epinephrine dosing.
What to do instead
Use a severity-driven algorithm: isolated mild urticaria or pruritus warrants observation and antihistamine; bronchospasm, hypotension, laryngeal edema, or rapidly progressing symptoms are anaphylaxis and epinephrine is first-line, given IM 0.3-0.5 mg of 1 mg/mL into the anterolateral thigh and repeated every 5-15 minutes as needed, with oxygen, IV access, fluids, and calling for help in parallel. Rehearse the dose, concentration, route, and site until automatic.
Post-procedure instructions are delivered rapidly in clinical language ('keep the site dry, watch for a hematoma, call if you have any problems') and the candidate accepts a nod as evidence the patient understood.
Time pressure plus familiarity with the content makes it hard to hear how jargon sounds; candidates also equate 'told' with 'taught.'
What to do instead
Convert every discharge instruction into plain language paired with a teach-back: 'Tell me in your own words when you would call us and what you would do.' Write down the specific red flags (bleeding, expanding swelling, cool or numb extremity, fever, pain unrelieved by your prescribed analgesic) and confirm the patient or caregiver can restate them and has a working phone number and transportation.
The candidate tells the patient that the nurse will obtain the informed consent, or has the patient sign the form without confirming that the proceduralist has already explained the risks, benefits, and alternatives in a language the patient understands.
The signature on the form looks like the consent itself, and busy units often route the paperwork through the nurse, so the legal distinction never gets corrected.
What to do instead
State the role precisely: the provider performs the disclosure and obtains consent; the RN may witness the signature and verify that consent is voluntary, the patient is competent and of age, the correct procedure and site are on the form, questions were answered, and an interpreter was used when needed. If those conditions fail, the nurse stops the process and returns it to the provider.
During moderate sedation for a procedure, the candidate documents vital signs and sedation scores at irregular intervals, and discharges the patient based on 'looking awake' rather than a scored readiness-for-discharge assessment.
Sedation cases reward vigilance but the exam tests intervals and criteria, which candidates skip as documentation trivia.
What to do instead
Fix the mechanics in memory: pre-sedation airway and ASA-risk assessment, fasting status per policy, continuous pulse oximetry and cardiac monitoring, vital signs and sedation depth documented at defined intervals, and discharge only after scoring meets the institution's threshold (commonly an Aldrete score of 9 or higher) with stable vitals, patent airway, and controlled pain and nausea. Know the reversal agents and their routes.
The candidate escorts a patient with an oxygen cylinder or a pacemaker into the scanner room after 'eyeballing' the patient as safe, without a formal implant and device screen or a zone-by-zone check at the doorway.
MRI safety knowledge is often reduced to 'no metal,' which does not capture the four-zone structure or the fact that many implants are conditional rather than automatically safe.
What to do instead
Learn the zones as physical gates: Zone I public, Zone II screening transition, Zone III restricted with physically controlled access, Zone IV the magnet room where the field is always on. Apply a written screen for implants, devices, foreign bodies, tattoos, and loose ferromagnetic items before Zone III, verify conditional devices against the manufacturer's field strength and conditions, and keep ferromagnetic equipment anchored outside Zone IV.
After an arterial catheterization, the candidate checks the groin once for a small bruise, attributes hypotension and back pain to anxiety or to lying flat too long, and continues simply observing.
Retroperitoneal bleeding is invisible at the puncture site, so candidates rely on inspection of the skin and on the assumption that bleeding must be visible.
What to do instead
Assess the site plus the whole patient: puncture site and surrounding tissue for expansion or bruit, distal pulses, color, warmth, sensation and movement, vital signs, and new back, flank, or abdominal pain. New hypotension, tachycardia, diaphoresis, or flank/back pain after femoral access is a bleeding emergency, not a vasovagal reaction - call the provider, prepare for fluid resuscitation and possible transfusion, and know that vasovagal responses typically present with bradycardia rather than tachycardia.
After a wrong-site near miss is caught before the procedure, the candidate handles it informally with the technologist and does not file an event report because 'nothing actually happened to the patient.'
Candidates reserve reporting for harm events and worry that a report implies personal fault, so near misses leave no trace.
What to do instead
Treat near misses as the highest-value data in the system: file the report the same day using objective facts and a non-punitive framing, participate in the root-cause or failure-mode review, and connect findings to the universal protocol checks (patient identification, procedure and site verification, allergy review, time-out participation). Understand that reporting protects patients and is a professional obligation, not an admission of incompetence.