PANRE common mistakes
PANRE · Understand the traps and how to avoid them.
In a patient with acute chest pain, the candidate's first-order selection is a diagnostic study (stress ECG, echocardiogram, CT angiography, chest radiograph) rather than a 12-lead ECG obtained and interpreted within minutes of presentation.
The exam stem reads like a classic angina vignette and the candidate jumps to 'which test shows ischemia' instead of applying the acuity-first rule; candidates also fuse outpatient stable angina workup (exercise ECG, stress imaging) with the emergency department pathway.
What to do instead
Before choosing any option, classify the stem as acute versus chronic. For acute chest pain, the answer set is ordered: ECG within 10 minutes, cardiac troponin, monitor and IV access, then risk stratification. Any option that delays the ECG is wrong regardless of its sensitivity. Drill the distinction between 'next best step' (ECG) and 'most definitive diagnosis' (catheterization).
The candidate reads a spirometry report and labels obstruction or restriction without checking whether the values are pre- or post-bronchodilator, and without comparing the post-bronchodilator FEV1/FVC to the fixed 0.70 threshold.
PFT interpretation is taught once and rarely revisited; candidates pattern-match 'low FEV1' to obstruction and 'low FVC' to restriction, and they conflate the diagnosis of obstruction with the assessment of reversibility for asthma.
What to do instead
Use a fixed sequence on every PFT item: (1) is there obstruction - post-bronchodilator FEV1/FVC below 0.70; (2) if obstructed, what is the severity by FEV1 percent predicted; (3) if not obstructed but FVC is low, get lung volumes (total lung capacity) to confirm restriction. Reversibility (12% and 200 mL improvement) supports asthma but does not define obstruction.
For a patient with epigastric pain radiating to the back and vomiting, the candidate orders abdominal CT as the initial diagnostic test instead of serum lipase, and treats a single normal lipase as excluding pancreatitis.
Candidates equate 'imaging the organ' with 'best diagnosis' and forget that pancreatitis is a clinical-plus-laboratory diagnosis; they also do not recall that lipase need only exceed three times the upper limit of normal and that enzyme levels do not track severity.
What to do instead
Apply the two-of-three rule: characteristic pain, lipase (or amylase) greater than three times the upper limit of normal, and imaging findings. Two of three establishes the diagnosis. Reserve CT for unclear cases, failure to improve, or suspected complications after 48 to 72 hours, and use right-upper-quadrant ultrasound to look for gallstones as the etiology.
A febrile patient with a single hot, swollen knee is empirically labeled as a gout flare and started on colchicine or a corticosteroid without arthrocentesis, with no synovial fluid cell count, Gram stain, or crystal analysis ordered.
The classic vignette features (older man, podagra, hyperuricemia) anchor the candidate, and candidates are uncomfortable selecting an invasive option on a multiple-choice test, so they treat the more familiar diagnosis.
What to do instead
Set a hard rule: a first-time acutely inflamed joint, or any inflamed joint with fever or systemic illness, requires arthrocentesis before treatment. Order cell count with differential, Gram stain and culture, and crystal analysis. Synovial white count above 50,000 with neutrophil predominance points to septic arthritis and mandates empiric IV antibiotics after aspiration; gout can coexist with infection.
The candidate prescribes a topical corticosteroid for a red, painful eye with a dendritic corneal lesion, or prescribes antibiotics for 3 days of nasal congestion and facial pressure and labels it bacterial sinusitis.
Candidates prioritize symptom relief and reach for the familiar therapeutic class; they under-weight the corneal examination findings (dendrites, fluorescein uptake) and the duration criteria that separate viral rhinosinusitis from bacterial.
What to do instead
For red eye, always ask whether vision is affected and whether fluorescein staining was done; a dendritic pattern means herpes simplex keratitis, so no steroids and urgent ophthalmology referral for topical antiviral therapy. For rhinosinusitis, require symptoms longer than 10 days, or severe onset with fever above 39 C for 3 to 4 days, or initial improvement followed by worsening, before antibiotics.
A patient with first-trimester cramping and bleeding is diagnosed with a threatened abortion and sent home after a positive urine hCG, with no quantitative beta-hCG, blood type and Rh, or transvaginal ultrasound to establish the location of the pregnancy.
Reassuring language in the stem ('mild cramps, small amount of spotting') pulls the candidate toward the benign label, and candidates default to the urine test they already have instead of the quantitative and imaging workup.
What to do instead
In early pregnancy bleeding, the mandatory bundle is quantitative beta-hCG, blood type and Rh with antibody screen, and transvaginal ultrasound. Use the discriminatory zone: an intrauterine gestational sac should be visible by transvaginal ultrasound when beta-hCG exceeds roughly 3,500 mIU/mL. If it is not, manage as a pregnancy of unknown location with serial hCG and repeat ultrasound. Give Rh immunoglobulin to Rh-negative patients with bleeding.
The candidate starts levothyroxine in a patient with hypothyroidism and known or suspected pituitary disease or adrenal insufficiency without first excluding or treating cortisol deficiency.
Candidates memorize the replacement drug and dose but not the ordering constraint; central hypothyroidism looks like primary hypothyroidism in the stem, and the adrenal crisis that follows thyroid replacement is not a salient association.
What to do instead
In any hypothyroid patient with a history of pituitary disease, recent postpartum hemorrhage, or concurrent hyponatremia and hypotension, check morning cortisol and ACTH first. Replace glucocorticoids before or simultaneously with levothyroxine, because thyroid hormone accelerates cortisol clearance and can precipitate an adrenal crisis. Also remember that TSH is unreliable in central hypothyroidism, so titrate against free T4.
The candidate attributes a sudden, severe, maximal-at-onset headache to migraine or tension headache and orders an analgesic or triptan instead of noncontrast head CT, with lumbar puncture if the CT is negative and the presentation is within the appropriate window.
Candidates match on the word 'headache' and on the patient's history of prior migraines, and they treat the photophobia and nausea in the stem as confirming migraine rather than as findings compatible with meningeal irritation.
What to do instead
Use a red-flag trigger list for any headache item: thunderclap onset, worst-ever, exertion-triggered, age over 50 with new headache, fever or neck stiffness, or focal deficit. Any of these forces imaging before analgesia. For suspected subarachnoid hemorrhage, noncontrast CT is highly sensitive within 6 hours; beyond that, proceed to lumbar puncture for xanthochromia and red cell count that does not diminish across tubes.
The candidate starts an SSRI for a depressed patient without screening for prior manic or hypomanic episodes, and does not ask about prior antidepressant-induced activation.
The stem emphasizes depressive symptoms and a PHQ-9 score, and candidates move directly from 'depression' to 'first-line SSRI' without running the bipolar screen that changes the treatment entirely.
What to do instead
Before any antidepressant is chosen, ask the two screening questions for bipolar disorder (prior distinct period of elevated or irritable mood with increased energy) and about family history and prior activation. If bipolar disorder is suspected, an SSRI is the wrong answer; start a mood stabilizer, and if the patient is severely depressed or suicidal, refer. Antidepressant monotherapy in bipolar disorder risks inducing mania and rapid cycling.
The candidate orders a urine culture and prescribes antibiotics for a bacteriuric, asymptomatic patient - typically an older adult with a mildly abnormal urinalysis - while labeling the presentation a urinary tract infection.
Pyuria and a positive culture are treated as synonymous with infection, and the stem's abnormal lab value creates pressure to act; candidates also confuse the criteria used in pregnancy and before urologic procedures with the general population.
What to do instead
Require attributable symptoms (dysuria, frequency, suprapubic or flank pain, fever with an appropriate source) before treating. Asymptomatic bacteriuria is treated only in pregnancy and before urologic instrumentation with mucosal trauma. Pyuria alone does not justify antibiotics. In an older adult with confusion, look for another cause of delirium before attributing it to the urinary tract.