EMG Quality Assurance & Compliance 3 — Questions and Answers
Question 1: An EMG report is sent to the referring physician but contains a transcription error in the patient's MRN. What should occur?
- Issue an addendum correcting the error and notify the referring physician (Correct answer)
- Delete the original report and reissue without documentation
- Leave the error because clinical content is unchanged
- Verbally notify only; no written correction is necessary
Correct answer: Issue an addendum correcting the error and notify the referring physician
Errors in medical records must be corrected through a formal addendum that is dated, timed, signed, and communicated to all parties who received the erroneous document.
Question 2: What does 'common mode rejection ratio' (CMRR) measure in EMG equipment quality assessment?
- The ratio of signal amplitude to noise floor in decibels
- The amplifier's ability to reject electrical signals common to both input leads (Correct answer)
- The electrode impedance balance between active and reference
- The frequency at which the amplifier gain drops by 3 dB
Correct answer: The amplifier's ability to reject electrical signals common to both input leads
CMRR quantifies how well the differential amplifier rejects noise or interference signals that appear equally on both input leads, with higher CMRR indicating less artifact contamination.
Question 3: A patient with a pacemaker is referred for nerve conduction studies. What is the safest initial action?
- Proceed normally since NCS currents are too low to affect pacemakers
- Consult cardiology and review pacemaker manufacturer guidelines before proceeding (Correct answer)
- Perform only needle EMG, skipping all electrical stimulation
- Postpone the study indefinitely
Correct answer: Consult cardiology and review pacemaker manufacturer guidelines before proceeding
Although NCS stimulation currents are typically low, consulting cardiology and pacemaker manufacturer guidelines is required to determine whether stimulation near the device is safe.
Question 4: According to standard infection control practice, how long must high-level disinfection (HLD) be maintained for reusable EMG surface electrodes?
- Contact time specified by the disinfectant manufacturer's label for HLD (Correct answer)
- A minimum of 5 minutes in any disinfectant solution
- 30 seconds of wiping with 70% isopropyl alcohol
- Autoclaving at 121°C for 15 minutes only
Correct answer: Contact time specified by the disinfectant manufacturer's label for HLD
The disinfectant manufacturer's label specifies the minimum contact time required to achieve high-level disinfection, and this time must be strictly followed to ensure efficacy.
Question 5: Which filtering parameter most affects the appearance of the CMAP onset latency in nerve conduction studies?
- High-frequency filter (high-pass) setting (Correct answer)
- Low-frequency filter (low-pass) setting
- Notch filter at 60 Hz
- Sampling rate of the analog-to-digital converter
Correct answer: High-frequency filter (high-pass) setting
The high-frequency filter (high-pass) setting shapes the early rising phase of the CMAP; raising it excessively can cause the onset to appear later, artificially prolonging latency measurements.
Question 6: In a QA review of needle EMG reports, it is found that the resting activity section is consistently left blank. What is the most likely implication?
- The studies were performed on pediatric patients only
- Critical findings such as fibrillation potentials or positive sharp waves may be unreported (Correct answer)
- The reporting physicians prefer concise documentation styles
- Resting activity is optional per AANEM reporting guidelines
Correct answer: Critical findings such as fibrillation potentials or positive sharp waves may be unreported
Resting activity, including fibrillation potentials and positive sharp waves, is a mandatory component of needle EMG reporting because its absence or presence directly informs the diagnosis.
Question 7: What is the recommended maximum storage temperature for single-use EMG needle electrodes to maintain sterility and packaging integrity?
- Below 60°C (140°F) as per most manufacturer guidelines (Correct answer)
- Above 4°C (39°F) only; no upper limit is specified
- Exactly 25°C (77°F) at all times
- Temperature is irrelevant if the package seal is intact
Correct answer: Below 60°C (140°F) as per most manufacturer guidelines
Most manufacturers specify storage below 60°C (140°F) to prevent degradation of packaging materials and maintenance of sterility assurance level; exceeding this risks seal failure.
EMG Quality Assurance & Compliance 3
An EMG report is sent to the referring physician but contains a transcription error in the patient's MRN.
What should occur?