1. Initial Cause – Obstruction of the Appendix

The appendix is a small, tube-like structure attached to the large intestine. It’s narrow and can easily become blocked at its opening (called the appendiceal lumen). The most common causes of blockage are:

Fecaliths – hard masses of stool

Lymphoid hyperplasia – swelling of lymph tissue inside the appendix, often due to viral infections (common in children and teens)

Parasites – like pinworms (less common)

Tumors – rare, but can also block the lumen

🔹 2. Inflammation and Bacterial Overgrowth

Once blocked, the trapped mucus creates a perfect environment for bacteria (like E. coli and Bacteroides) to multiply. This leads to:

Inflammation of the appendix wall

Production of pus

Swelling and pressure build-up inside the appendix

This pressure starts to cut off the appendix’s blood supply, leading to ischemia (lack of oxygen and nutrients to the tissues). Without oxygen, the tissue begins to die.

🔹 3. Necrosis and Rupture

As tissue death (necrosis) progresses:

The wall of the appendix weakens

Eventually, it can perforate (tear open), allowing the infectious material to spill into the abdominal cavity

This rupture usually occurs around 48–72 hours after symptoms begin if not treated.

🔹 4. Aftermath – Peritonitis or Abscess Formation

Once the appendix bursts:

The infection spreads in the abdomen, leading to peritonitis – a dangerous, widespread infection of the peritoneum (the lining of the abdominal cavity)

Alternatively, the body may try to contain the infection by forming a localized abscess – a pocket of pus around the appendix