Peritonitis

Inflammation of the lining of the abdomen. A rigid, board-like abdomen with severe pain is a 999 call.

What it is

Inflammation of the peritoneum, the membrane lining the abdomen. It is a surgical emergency in most cases and it kills quickly if untreated.

Usually it follows something perforating or leaking into the abdominal cavity: a burst appendix, a perforated peptic ulcer, diverticular perforation, a ruptured bowel, or an infected gallbladder. Occasionally it arises without perforation, notably in people with liver cirrhosis and fluid in the abdomen, and in people on peritoneal dialysis.

The classic sign is an abdomen that is rigid, held completely still, and exquisitely painful to any movement. People lie absolutely still with their knees drawn up, because moving hurts. That stillness is the opposite of the restlessness seen in colicky pain such as kidney stones, and it is a useful distinction.

It progresses to sepsis rapidly. Time to antibiotics and to surgery determines survival.

Two groups get diagnosed late because the signs are muted: older people, and anyone on steroids or immunosuppressed, who may have serious peritonitis with surprisingly little to find.

Signs you might notice

Severe, constant abdominal pain, worse with any movement, coughing or being jolted.

An abdomen that is rigid and tender all over, and a person who lies very still.

Fever, chills, fast heart rate, feeling extremely unwell.

Nausea and vomiting, not passing wind or opening the bowels, a swollen abdomen.

Reduced urine output, confusion, and rapid deterioration.

999 immediately. Do not give anything to eat or drink, and do not give painkillers that might mask it before assessment.

For anybody on peritoneal dialysis: cloudy dialysis fluid, abdominal pain or fever means contacting the renal unit the same hour.

For anybody with cirrhosis and abdominal fluid: fever, abdominal pain or new confusion needs same-day assessment.

How it can affect day-to-day life

The main risk is delay, and delay usually comes from attributing severe abdominal pain to indigestion, constipation or a bug.

In older people, and in people with dementia or a learning disability, the presentation is often just being unwell, off food, or newly confused. A person who is suddenly much less well with a tender abdomen needs assessing regardless of what they can describe.

Recovery from surgery is prolonged, often with a temporary stoma, and nutrition and rehabilitation both matter afterwards.

For people on peritoneal dialysis, repeated peritonitis is the commonest reason the treatment has to be abandoned for haemodialysis, which is why technique training and prompt reporting matter so much.

Supporting someone well

Call 999 for severe abdominal pain with rigidity, fever or rapid deterioration. Do not wait.

Nothing by mouth once it is suspected.

Say what has changed and when, and mention any recent abdominal surgery, dialysis, cirrhosis, steroids or immunosuppression.

Take a low threshold in older people and in anybody who cannot describe pain; being off food and newly confused may be all there is.

For peritoneal dialysis, learn what cloudy fluid means and ring the unit immediately.

Afterwards, expect a long recovery and ask for dietetic and physiotherapy input.

Where to get help

999 or A and E immediately.

The renal unit directly for anyone on peritoneal dialysis.

UK Sepsis Trust for the sepsis warning signs.

Guts UK for information on abdominal conditions.