Abscess | |
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Other names | Latin: Abscessus |
Five-day-old inflamed epidermal inclusion cyst. The black spot is a keratin plug which connects with the underlying cyst. | |
Specialty | General surgery, infectious disease, dermatology |
Symptoms | Redness, pain, swelling[1] |
Usual onset | Rapid |
Causes | Bacterial infection (often MRSA)[1] |
Risk factors | Intravenous drug use[2] |
Diagnostic method | Ultrasound, CT scan[1][3] |
Differential diagnosis | Cellulitis, sebaceous cyst, necrotising fasciitis[3] |
Treatment | Incision and drainage, Antibiotics[4] |
Frequency | ~1% per year (United States)[5] |
An abscess is a collection of pus that has built up within the tissue of the body.[1] Signs and symptoms of abscesses include redness, pain, warmth, and swelling.[1] The swelling may feel fluid-filled when pressed.[1] The area of redness often extends beyond the swelling.[6] Carbuncles and boils are types of abscess that often involve hair follicles, with carbuncles being larger.[7] A cyst is related to an abscess, but it contains a material other than pus, and a cyst has a clearly defined wall. Abscesses can also form internally on internal organs and after surgery.
They are usually caused by a bacterial infection.[8] Often many different types of bacteria are involved in a single infection.[6] In many areas of the world, the most common bacteria present is methicillin-resistant Staphylococcus aureus.[1] Rarely, parasites can cause abscesses; this is more common in the developing world.[3] Diagnosis of a skin abscess is usually made based on what it looks like and is confirmed by cutting it open.[1] Ultrasound imaging may be useful in cases in which the diagnosis is not clear.[1] In abscesses around the anus, computer tomography (CT) may be important to look for deeper infection.[3]
Standard treatment for most skin or soft tissue abscesses is cutting it open and drainage.[4] There appears to be some benefit from also using antibiotics.[9] A small amount of evidence supports not packing the cavity that remains with gauze after drainage.[1] Closing this cavity right after draining it rather than leaving it open may speed healing without increasing the risk of the abscess returning.[10] Sucking out the pus with a needle is often not sufficient.[1]
Skin abscesses are common and have become more common in recent years.[1] Risk factors include intravenous drug use, with rates reported as high as 65% among users.[2] In 2005, 3.2 million people went to American emergency departments for abscesses.[5] In Australia, around 13,000 people were hospitalized in 2008 with the condition.[11]