13.6 Other Diagnostic Tests, Endoscopy, and Preventive Screening
Key Takeaways
An ECG records the heart's electrical activity for arrhythmias and heart attacks; an echocardiogram uses ultrasound to show valves and pumping strength (ejection fraction).
EMG and nerve conduction studies distinguish nerve-root, peripheral nerve, and muscle disorders such as carpal tunnel syndrome and radiculopathy.
Spirometry shows obstruction when the FEV1/FVC ratio is below 0.70; an ankle-brachial index of 0.90 or less indicates peripheral artery disease.
USPSTF recommends mammography every two years for women 40-74 and colorectal cancer screening for adults 45-75.
Cervical screening starts at 21; lung cancer screening with low-dose CT is yearly for adults 50-80 with a 20 pack-year history who smoke or quit within 15 years.
13.6 Other Diagnostic Tests, Endoscopy, and Preventive Screening
Quick Answer: The 2026 BIOM outline asks you to identify indications for "other diagnostic tests (e.g., EMG, EKG, biopsy)," recognize the significance of their findings, and recognize the need for preventive screening. You do not order or interpret these tests independently in most states, but you must understand what a patient's results mean, recognize when a test is overdue, and refer appropriately. Imaging (X-ray, CT, MRI, ultrasound, DEXA) is covered in Section 13.4 and blood and urine tests in Section 13.5.
Cardiac Tests
| Test | What it shows | Common indications |
|---|---|---|
| ECG (EKG) | Electrical activity of the heart: rate, rhythm, conduction, ischemia, and infarction (such as ST elevation) | Chest pain, palpitations, fainting, atrial fibrillation, pre-operative assessment |
| Holter or event monitor | Continuous ECG over 24-48 hours (Holter) or weeks (event monitor) | Intermittent palpitations or unexplained fainting |
| Echocardiogram | Ultrasound of the heart: valve function, wall motion, and ejection fraction (normal about 50-70%; 40% or less indicates heart failure with reduced ejection fraction) | Murmurs, heart failure, after a heart attack |
| Stress test | ECG or imaging during exercise or medication-induced stress | Suspected coronary artery disease, exercise-related chest pain |
| Ankle-brachial index (ABI) | Ratio of ankle to arm systolic pressure; 0.90 or less indicates peripheral artery disease; above 1.40 suggests stiff, non-compressible arteries | Leg pain on walking (claudication), diabetes, non-healing foot wounds |
Nerve, Muscle, and Brain Tests
- Nerve conduction studies (NCS) measure how fast and how strongly nerves carry signals. Electromyography (EMG) uses a fine needle electrode to record electrical activity in muscles. Together they localize problems to the nerve root (radiculopathy), a peripheral nerve (carpal tunnel syndrome), multiple nerves (peripheral neuropathy), the neuromuscular junction (myasthenia gravis), or the muscle itself (myopathy).
- Electroencephalography (EEG) records brain electrical activity through scalp electrodes. It is used to diagnose and classify seizures and epilepsy and is part of sleep studies.
Lung and Sleep Tests
- Spirometry (pulmonary function testing): an FEV1/FVC ratio below 0.70 after a bronchodilator confirms airflow obstruction (COPD). An improvement in FEV1 of at least 12% and 200 mL after a bronchodilator supports asthma. A low total lung capacity with a normal or high ratio suggests restrictive disease, such as pulmonary fibrosis.
- Pulse oximetry: normal oxygen saturation is about 95-100% at sea level.
- Polysomnography (sleep study): diagnoses obstructive sleep apnea by the apnea-hypopnea index (AHI): 5-14 events per hour is mild, 15-29 moderate, and 30 or more severe. It also helps diagnose narcolepsy and other sleep disorders.
Biopsy and PET
- Biopsy removes tissue for microscopic examination and is the definitive test for most cancers. Types include fine-needle aspiration, core needle biopsy, and excisional biopsy; skin lesions are often sampled with a punch or shave biopsy.
- PET scan uses a radioactive glucose tracer (FDG) to show metabolically active tissue. It is used to stage cancer and detect recurrence, and in some heart and brain (dementia) evaluations. It is usually combined with CT (PET-CT). Blood sugar must be controlled before the scan.
Endoscopy
| Procedure | What is examined | Common indications |
|---|---|---|
| Colonoscopy | Rectum and entire colon | Colorectal cancer screening, polyps, rectal bleeding, change in bowel habits, iron deficiency anemia, inflammatory bowel disease |
| Upper endoscopy (EGD) | Esophagus, stomach, and duodenum | Difficulty swallowing, persistent reflux, ulcers, upper GI bleeding, Barrett's esophagus, H. pylori biopsies |
| Cystoscopy | Urethra and bladder | Blood in the urine, recurrent urinary infections, suspected bladder cancer |
| Bronchoscopy | Airways and lungs | Coughing blood, a lung mass, persistent infiltrates, airway foreign body |
Colonoscopy requires bowel preparation, and patients may be advised to pause anticoagulants and some supplements beforehand under medical direction.
Thyroid Panel
| Pattern | Interpretation |
|---|---|
| High TSH, low free T4 | Primary hypothyroidism (most often Hashimoto's thyroiditis; TPO antibodies positive) |
| Low TSH, high free T4 or T3 | Hyperthyroidism (Graves' disease with TSH receptor antibodies, toxic nodules, thyroiditis) |
| High TSH, normal free T4 | Subclinical hypothyroidism |
| Low TSH, normal free T4 and T3 | Subclinical hyperthyroidism |
TSH is the usual first test. Biotin supplements can interfere with some thyroid assays, so patients may be told to stop biotin before testing. Clinical features of thyroid disease are covered in Section 12.4.
Preventive Screening (USPSTF)
The U.S. Preventive Services Task Force (USPSTF) grades screening recommendations. Key adult recommendations include:
| Screening | Who and how often |
|---|---|
| Blood pressure | All adults 18 and older |
| Cervical cancer | Ages 21-29: Pap test every 3 years. Ages 30-65: Pap every 3 years, HPV testing every 5 years, or both together every 5 years |
| Breast cancer | Mammography every 2 years for women 40-74 |
| Colorectal cancer | Adults 45-75 (colonoscopy every 10 years or other approved tests); selective at 76-85 |
| Lung cancer | Yearly low-dose CT for adults 50-80 with a 20 pack-year smoking history who smoke now or quit within the past 15 years |
| Abdominal aortic aneurysm | One-time ultrasound for men 65-75 who have ever smoked |
| Osteoporosis | Women 65 and older, and younger postmenopausal women at increased risk |
| Prediabetes and type 2 diabetes | Adults 35-70 with overweight or obesity |
| Hepatitis C | One-time test for adults 18-79 |
| HIV | Ages 15-65, and others at increased risk |
| Chlamydia and gonorrhea | Sexually active women 24 and younger, and older women at increased risk |
| Depression and anxiety | Adults (anxiety screening for adults 64 and younger) |
| Prostate cancer | Men 55-69: individual decision after discussing benefits and harms |
| Unhealthy alcohol use and intimate partner violence | Adults (alcohol) and women of reproductive age (intimate partner violence) |
When the history shows that a screening test is overdue, encourage the patient to discuss it with their primary care provider and document the recommendation.
A patient with numbness and weakness in the thumb, index, and middle fingers is referred for testing to confirm carpal tunnel syndrome. Which test is most appropriate?
Electroencephalography (EEG) of the scalp
Nerve conduction studies and EMG
Overnight polysomnography
Colonoscopy
A 62-year-old patient who smokes reports calf pain when walking that is relieved by rest. Which test result would confirm peripheral artery disease?
An ankle-brachial index of 0.75
An FEV1/FVC ratio of 0.82
An ejection fraction of 60%
A TSH of 2.0 mIU/L
According to current USPSTF recommendations, which patient is due for lung cancer screening?
A 67-year-old with a 30 pack-year history who quit smoking 8 years ago
A 45-year-old who has never smoked
A 72-year-old with a 10 pack-year history who quit 30 years ago
An 85-year-old with a 40 pack-year history who quit 20 years ago
A patient's lab report shows a high TSH and a low free T4. Which condition does this pattern indicate?
Primary hyperthyroidism
Subclinical hyperthyroidism
Primary hypothyroidism
Normal thyroid function
Sections you finish are checked off in the contents.