RVS common mistakes
RVS · Understand the traps and how to avoid them.
Calculating the resistance index as (peak systolic − end diastolic) ÷ peak systolic but substituting mean velocity or mixing systole and diastole inconsistently between patients, so values are not comparable across a study.
The RI formula is memorized loosely and applied under time pressure; candidates confuse it with the pulsatility index (peak-to-peak ÷ mean) and then cannot interpret a value like 0.55 versus 0.75 consistently.
What to do instead
Write the two formulas side by side before every practice set: RI = (PSV − EDV)/PSV, PI = (PSV − EDV)/TAMAX. Drill 20 waveform problems where you compute both from the same spectral trace, and state aloud which vessel and which formula you are using before calculating.
Reporting a stenosis grade from peak systolic velocity alone without applying the correct diagnostic threshold for the specific vessel being examined.
Candidates memorize a single 'high velocity means stenosis' rule and apply carotid thresholds (e.g., PSV ≥125 cm/s for ≥50%) to renal, mesenteric, or peripheral arteries, where the validated criteria and velocity cutoffs differ substantially.
What to do instead
Build a one-page threshold table per vascular bed (carotid, vertebral, renal, mesenteric, iliac, femoral, graft) and practice classifying the same velocity value under each bed's criteria until the bed-specific numbers are automatic.
Confusing the direction of flow in the vertebral artery with the side of the lesion, or mislabeling the vertebral as the basilar during a transcranial or neck study.
Anatomy is studied as a list rather than as a connected circuit, so candidates lose track of which vessel is proximal versus distal and which side supplies which territory when a subclavian stenosis reverses vertebral flow.
What to do instead
Redraw the aortic arch and its branches from memory daily, labeling origin, course, and the territory each supplies. Then work through subclavian steal scenarios step by step: where the stenosis sits, which way vertebral flow goes, and what the spectral waveform shows.
Treating the venous system with arterial assumptions, such as expecting pulsatile flow in a normal peripheral vein or calling continuous flow abnormal in every vein.
Most study time goes to arterial physiology, so candidates do not internalize venous phasicity, augmentation, valsalva response, and the effect of respiration and compression on venous waveforms.
What to do instead
Practice a structured venous protocol on every practice case: assess spontaneity, phasicity with respiration, augmentation with distal compression, and compressibility. Explain each finding in one sentence linking it to the physiology (right heart pressure, valve competence, obstruction).
Describing a plaque or lesion in vague terms ('moderate plaque', 'some narrowing') instead of reporting measurable features such as location, length, echogenicity, surface, and residual lumen.
Candidates focus on the final percentage and skip the descriptive findings that drive clinical decisions, or they lack a standard vocabulary for plaque characterization.
What to do instead
Use a fixed reporting template for every practice case: vessel and segment, plaque presence and type (calcified, fibrous, soft), surface (smooth, irregular, ulcerated), residual lumen, and velocity data. Fill every field before writing any conclusion.
Confusing indirect physiologic tests with direct imaging when choosing the appropriate test for a clinical question, such as ordering a segmental pressure study to characterize a carotid plaque.
The indications for ABI, segmental pressures, pulse volume recording, duplex, and plethysmography are learned as isolated facts rather than matched to the question being asked (screening versus localization versus characterization).
What to do instead
For each clinical scenario, write the question first ('is there hemodynamically significant PAD?', 'where is the occlusion?', 'what is the plaque morphology?') and then select the test that answers that specific question. Practice 15 scenarios this way.
Skipping or rushing the pre-procedure history and risk assessment, such as failing to identify anticoagulant use, contrast allergy, or a limb at risk before a venous or arterial study.
Candidates treat patient care as background material and concentrate on instrumentation and interpretation, so safety questions feel like filler and get minimal attention.
What to do instead
Create a pre-study checklist (indication, anticoagulation, allergies, prior surgery or grafts, limb status, ability to cooperate) and apply it verbally in every practice case before touching the machine settings.
Ignoring ergonomic and machine-safety practices, including transducer grip, patient positioning, and acoustic output limits, treating them as unimportant compared with diagnostic findings.
These topics appear briefly in training materials and candidates assume they will not be tested or that common sense suffices, so they cannot recall specific principles such as ALARA or the reason for limiting thermal and mechanical indices.
What to do instead
Study the safety principles as named concepts (ALARA, thermal index, mechanical index, dwell time) and connect each to a concrete action you would take during a scan. Rehearse a short explanation of why each action protects the patient or the sonographer.
Misinterpreting spectral broadening, wall filter settings, or gain artifacts as true pathology, then reporting stenosis that is not present.
Candidates adjust machine settings by habit rather than understanding how sample volume size, wall filter, scale, and gain change the displayed waveform, so artifacts are read as disease.
What to do instead
Deliberately create artifacts on a normal volunteer or phantom: widen the sample volume, raise the wall filter, lower the scale until aliasing appears. Observe each change and record what true versus artifactual spectral broadening looks like.
Providing a final impression that repeats measurements without a clinical conclusion, or gives a conclusion unsupported by the reported data.
Candidates separate data collection from interpretation and either stop at the numbers or jump to a diagnosis without linking it to the findings, which is exactly what the exam tests in case-based items.
What to do instead
For every practice case, write a two-part report: findings (measurements and descriptions) and impression (a single sentence answering the original clinical question and stating its basis). Check that every claim in the impression traces to a specific finding above it.