CB is a medical abbreviation with several different meanings depending on the specialty and context. The most common uses include chronic bronchitis, cannabinoid receptors (CB1 and CB2), carotid bruit, cerebral blood flow (CBF), and cone biopsy. If you’ve seen “CB” on a medical document, the surrounding context usually makes the intended meaning clear.
Chronic Bronchitis
In pulmonology and primary care, CB most often stands for chronic bronchitis. This is a long-term inflammation of the airways that causes persistent coughing and mucus production. The classic definition used in medical literature is a cough that produces mucus for at least three months per year, occurring two years in a row. Chronic bronchitis falls under the umbrella of chronic obstructive pulmonary disease (COPD) and is strongly associated with smoking, though long-term exposure to air pollution and occupational dust can also cause it.
When you see CB in a pulmonologist’s notes, a discharge summary, or a research paper about lung disease, chronic bronchitis is almost always what’s meant.
Cannabinoid Receptors (CB1 and CB2)
In pharmacology and neuroscience, CB refers to cannabinoid receptors, specifically CB1 and CB2. These are proteins found throughout the body that respond to both the body’s own signaling molecules and compounds found in cannabis. You’ll encounter this abbreviation in discussions about pain management, medical marijuana, and the endocannabinoid system.
CB1 receptors are among the most abundant receptors in the brain. They’re concentrated in areas that control movement, memory, cognition, and pain perception. On nerve endings, they work by dialing down the release of chemical signals between cells. CB1 receptors also exist at lower levels in organs throughout the body, including the heart, lungs, liver, and reproductive organs.
CB2 receptors play a different role. They’re found primarily in immune tissues like the spleen, tonsils, and white blood cells, where they help regulate immune responses and inflammation. For a long time, researchers believed CB2 receptors were absent from the brain entirely. More recent work has found them in brain tissue affected by diseases like Alzheimer’s and multiple sclerosis, where they appear to ramp up in response to inflammation. Whether they’re meaningfully present in a healthy brain is still debated.
The distinction matters because drugs targeting CB1 tend to affect brain function (and can produce psychoactive effects), while those targeting CB2 are being studied primarily for their potential to modulate inflammation and immune activity without altering mood or cognition.
Carotid Bruit
In cardiovascular and general medicine, CB can stand for carotid bruit. A bruit is an abnormal whooshing sound a doctor hears through a stethoscope when listening to a blood vessel. When that sound comes from the carotid arteries in the neck, it suggests turbulent blood flow, often caused by narrowing from plaque buildup. A carotid bruit doesn’t always mean a person is at immediate risk of stroke, but it typically prompts further testing with ultrasound to evaluate how much the artery has narrowed.
Cerebral Blood Flow
You may also see CBF (cerebral blood flow) in neurology and emergency medicine contexts, sometimes shortened informally to CB. Normal cerebral blood flow in an awake adult is roughly 50 milliliters per 100 grams of brain tissue per minute. When flow drops below about 22 mL/100g/min, brain function starts to fail. The brain has a built-in mechanism called autoregulation that keeps blood flow relatively steady even when blood pressure fluctuates. In studies of patients whose blood pressure was lowered from dangerously high levels, cerebral blood flow typically held stable as long as the pressure reduction was gradual and moderate.
Cone Biopsy
In gynecology and pathology, CB can refer to cone biopsy, also called conization. This is a surgical procedure where a cone-shaped piece of tissue is removed from the cervix, usually after an abnormal Pap smear. The procedure serves a dual purpose: it provides a tissue sample for lab analysis and can also remove precancerous or early-stage cancerous cells entirely. Doctors typically recommend it when less invasive tests like colposcopy haven’t explained abnormal cell changes, or when early-stage cervical cancer needs to be treated.
How to Tell Which Meaning Applies
Medical abbreviations are notoriously context-dependent, and CB is no exception. A few clues can help you figure out the intended meaning. If the abbreviation appears in a pulmonology or respiratory note, it almost certainly means chronic bronchitis. In a pharmacology or cannabis-related context, it refers to cannabinoid receptors. On a cardiovascular exam note, carotid bruit is the likely meaning. In a gynecology report, think cone biopsy. And in neurology or stroke-related documentation, cerebral blood flow is the most probable interpretation.
If you’re reading your own medical records and aren’t sure what CB means, the diagnosis codes, specialty of the provider, and surrounding terminology will usually resolve the ambiguity. Most hospitals maintain approved abbreviation lists to reduce confusion, and some institutions restrict the use of certain abbreviations altogether to prevent misinterpretation.