ABIM Internal Medicine common mistakes
ABIM Internal Medicine · Understand the traps and how to avoid them.
Selects the diagnostic label that fits the vignette when the lead-in actually asks 'which of the following is the most appropriate next step in management' - e.g., choosing 'acute cholecystitis' when the answer options call for a hepatobiliary iminodiacetic acid (HIDA) scan or surgery.
The lead-in is the last line of a long paragraph and is reached under time pressure, while the diagnostic gestalt is the most salient feature of the stem; the verb in the question is never explicitly checked against the chosen option.
What to do instead
Read the final sentence of the stem first and label the task out loud (diagnosis / next test / best initial therapy / mechanism / most likely organism). Then read the vignette with that task in mind, and before submitting, re-read the lead-in and confirm the selected option answers that specific verb.
Assigns 'GERD' or 'anxiety' to a 68-year-old with diabetes whose only symptoms are nausea, diaphoresis, and exertional dyspnea, reasoning from a single normal ECG and the absence of chest pain.
Pattern templates are built on 'crushing substernal chest pain with ST elevation'; the vignette deliberately withholds both, and one normal ECG is treated as exclusionary rather than as a single point in time.
What to do instead
In women, adults over 65, and patients with diabetes or chronic kidney disease, treat new exertional dyspnea, nausea, epigastric discomfort, or unexplained weakness as possible acute coronary syndrome: obtain serial troponins and repeat ECGs. State explicitly that a single normal ECG does not exclude acute coronary syndrome before choosing a non-cardiac answer.
Gives hypertonic saline, fluid restriction, or tolvaptan on the basis of the serum sodium value alone, without first obtaining serum osmolality, urine osmolality, and urine sodium, and without committing to a volume category.
The abnormal number drives the response, and the classification algorithm is recalled as a fragmented diagram rather than a fixed sequence, so candidates skip the early steps under time pressure.
What to do instead
Run the sequence every time: serum osmolality first (exclude pseudohyponatremia, hyperglycemia, hyperproteinemia), then urine osmolality (is ADH acting?), then urine sodium plus volume assessment to separate hypovolemic, euvolemic (SIADH), and hypervolemic causes. Write the category down before selecting therapy; the therapy is determined by the category, not the number.
Calls a single blood culture bottle growing coagulase-negative Staphylococcus a bloodstream infection, keeps broad-spectrum antibiotics running, and never addresses the line or repeats the culture.
'Positive culture equals infection' is a heavily conditioned reflex, and the stem usually supplies a plausible source (a catheter, a recent procedure) that reinforces the error.
What to do instead
Before committing, ask three questions: how many bottles grew, what organism, and what host? Skin flora in one of several bottles in a patient without a prosthesis, line, or signs of sepsis is a contaminant - repeat cultures from separate sites and do not treat. Conversely, the same organism in multiple bottles with a line or valve warrants therapy and device evaluation.
Labels a rising creatinine 'prerenal' and gives intravenous fluids without calculating fractional excretion of sodium or urine sodium and without deliberately reading the medication list for an ACE inhibitor or ARB plus an NSAID plus a diuretic.
Prerenal is the most common and most comfortable answer, and the offending drug combination is buried in a long medication list that candidates skim rather than read.
What to do instead
For every acute kidney injury, do three things before answering: urinalysis with microscopy, urine sodium and fractional excretion of sodium (plus urine urea when the patient is on diuretics), and a line-by-line medication review. If fractional excretion of sodium is above 2% with muddy brown casts, the diagnosis is acute tubular necrosis and fluids will not reverse it - the answer becomes stopping nephrotoxins and supportive care.
Starts oral ferrous sulfate for an older man with microcytic anemia and schedules a repeat complete blood count, never ordering upper and lower endoscopy.
The item is filed as a treatment question rather than a 'find the cause' question; iron is the obvious, memorable answer and the age and sex clues that mandate a search for a gastrointestinal source are easy to pass over.
What to do instead
In men and postmenopausal women, iron deficiency is a gastrointestinal bleed until proven otherwise: order colonoscopy plus esophagogastroduodenoscopy, and add celiac serology if both are negative. Iron replacement is adjunctive; any answer that stops at iron without addressing the source is incomplete.
Chooses zoledronic acid as the immediate next step for a patient with squamous cell lung cancer, calcium 14.2 mg/dL, creatinine 1.9 mg/dL, and blood pressure 88/54 mmHg.
Bisphosphonates are the memorable 'cancer hypercalcemia drug,' and the volume-depleted, prerenal patient is read simply as 'needs the specific therapy' rather than as a patient in whom the antiresorptive will be ineffective and potentially nephrotoxic.
What to do instead
Sequence the treatment: isotonic saline resuscitation first (restores glomerular filtration and calciuresis), then calcitonin for rapid effect plus a bisphosphonate for durability once volume and renal function are addressed. Also identify the mechanism - PTHrP-mediated humoral hypercalcemia in squamous cell carcinoma - because it determines the durable therapy.
Orders CT pulmonary angiography on a young patient with pleuritic chest pain, heart rate 78, no risk factors, and a negative PERC, instead of pursuing the evident alternative diagnosis in the stem.
Pulmonary embolism is a high-yield 'cannot miss' diagnosis, so candidates over-apply imaging to feel safe, and the alternative diagnosis embedded in the vignette (costochondritis, pneumonia, pericarditis) is discounted.
What to do instead
Apply a structured score (Wells or Geneva) explicitly. If pretest probability is low and PERC is negative, stop - no D-dimer, no imaging. If D-dimer is negative in a low or intermediate probability patient, embolism is excluded; the correct answer is then the alternative diagnosis, and the task becomes naming and treating it.
Diagnoses 'dementia' in a 78-year-old brought in with two days of fluctuating confusion and inattention after a new urinary catheter was placed, and plans outpatient follow-up without a workup for a cause.
The word 'confusion' triggers the chronic neurodegenerative template, while the acute onset, fluctuating course, and inattention that define delirium are skimmed past; delirium is also under-recognized in patients who appear cooperative.
What to do instead
Establish onset and course first: hours-to-days with fluctuating attention is delirium, a medical emergency, not dementia. Then search for the cause with a focused examination, urinalysis and culture, basic metabolic panel, glucose, oxygen saturation, medication review, and assessment for urinary retention, constipation, and pain. Dementia is a diagnosis of chronicity and is never made in the emergency department.
For a cirrhotic patient with hematemesis and hypotension, selects 'urgent esophagogastroduodenoscopy' as the single best next step and omits starting a vasoactive agent and prophylactic antibiotics.
Endoscopy is the definitive procedure and therefore looks like the correct answer, while the pre-endoscopic pharmacologic bundle is stored as a separate fact that is recalled only in isolation.
What to do instead
For suspected variceal hemorrhage, answer with the bundle: resuscitate with blood products (restrictive transfusion), start octreotide or terlipressin plus ceftriaxone, then endoscopy within 12 hours with band ligation. If the options force a single choice, prefer the one that includes pharmacologic therapy; the option that offers endoscopy alone is the trap.