Write a short note on Abscess.

What It Is

An abscess is a localised collection of pus walled off within a cavity. It represents the body's attempt to contain an infection it cannot clear: when bacteria (most often Staphylococcus aureus) establish themselves in tissue, the acute inflammatory response floods the area with neutrophils. These neutrophils kill bacteria but die in the process, and the mixture of dead neutrophils, digested tissue, bacteria and fluid is pus. The surrounding tissue lays down a wall of granulation tissue — the pyogenic membrane — which limits spread but also seals the pus off from the bloodstream.

How It Presents — and WHY

An abscess shows the classic signs of acute inflammation — pain, redness, swelling, warmth and loss of function — from the intense local inflammatory response. Two additional signs are characteristic and worth understanding:

• Fluctuation — because the cavity is filled with fluid, pressing on one side transmits the pressure equally in all directions, so a bulge is felt on the opposite side. This confirms a fluid-filled collection rather than a solid swelling.
• Pointing — pus tracks along the path of least resistance, usually towards the skin, where the overlying tissue becomes thin and shiny, about to burst. A pointing abscess is ready to drain.
• Throbbing pain — the rigid pyogenic membrane cannot expand, so as pus accumulates the pressure rises with each arterial pulse.

A deep abscess (e.g. Subphrenic, pelvic, psoas) may show none of these surface signs — only deep tenderness and a swinging (spiking) fever as pus intermittently releases pyrogens into the blood. This is why an unexplained swinging fever after abdominal surgery should always raise suspicion of a hidden collection.

Management — Drain the Pus

The definitive treatment is incision and drainage (I&D), captured in the adage 'never let the sun set on undrained pus' — drainage should not be delayed, because contained pus will otherwise enlarge, erode tissue, or discharge into the blood and cause sepsis. The surgeon incises at the point of maximum fluctuation, breaks down all the loculi so no pocket is left, washes out the cavity, sends pus for culture, and leaves the cavity open to heal by secondary intention. Antibiotics are an adjunct — added for surrounding cellulitis, sepsis or immunocompromise — but they cannot penetrate the avascular cavity, so alone they only suppress the infection while it recurs. A recurrent abscess signals an underlying cause — foreign body, fistula, tuberculosis ('cold abscess'), or diabetes — that must be found and treated.

Antibiotics alone cannot cure an abscess — it must be drained.

• Pus walled off by an avascular pyogenic membrane — so antibiotics can't reach it.
• Fluctuation (fluid transmits pressure) and pointing (tracks to skin); deep abscess → swinging fever only.
• Incision and drainage is definitive: 'never let the sun set on undrained pus'; break all loculi, culture the pus.
• Antibiotics adjunctive; recurrent abscess → seek a cause (foreign body, fistula, TB, diabetes).