Although most people with acute pancreatitis recover without experiencing further problems, severe cases can have serious complications.

Pseudocysts

Pseudocysts are sacs of fluid that can develop on the surface of the pancreas. They are a common complication of acute pancreatitis, thought to affect around 1 in 20 people with the condition.

Pseudocysts usually develop four weeks after the symptoms of acute pancreatitis started. In many cases, they do not cause any symptoms and are only detected during a computerised tomography (CT) scan.

However, in some people, pseudocysts can cause bloating, indigestion and a dull abdominal (tummy) pain.

If the pseudocysts are small and not causing any symptoms, there may be no need for further treatment as they usually go away on their own.

Treatment will usually be recommended if you are experiencing symptoms, or the pseudocysts are large. Larger pseudocysts are at risk of bursting, which could cause internal bleeding or trigger an infection.

Pseudocysts can be treated by draining the fluid out of the cyst by inserting a needle into the cyst through your skin or carrying out an endoscopy.  A thin, flexible tube called an endoscope is passed down your throat and tiny tools are used to drain away the fluid.

Infected pancreatic necrosis

In around 1 in every 3 severe cases of acute pancreatitis, a common and serious complication called infected pancreatic necrosis occurs.

In infected pancreatic necrosis, high levels of inflammation cause an interruption to the blood supply of your pancreas. Without a consistent supply of blood, some of the tissue of your pancreas will die. Necrosis is the medical term for the death of tissue.

The dead tissue is extremely vulnerable to infection from bacteria. Once an infection has occurred, it can quickly spread into the blood (blood poisoning) and cause multiple organ failure. If left untreated, infected pancreatic necrosis will almost certainly result in death.

Infected pancreatic necrosis usually develops 2 to 6 weeks after symptoms of acute pancreatitis started, and is marked by increased abdominal pain and a high temperature. The infection will need to be treated with injections of antibiotics. The dead tissue will need to be removed to prevent the infection returning.

In some cases it may be possible to drain away the dead tissue using a thin tube known as a catheter, which is placed through the skin.

Alternatively, laparoscopic surgery (keyhole surgery) can be used. A small incision is made in your back and a small, flexible tube called an endoscope is inserted and used to wash away any dead tissue.

It isn't always possible to use a laparoscopic approach, for example, if you are obese or the area of dead tissue is not easily accessible. In such circumstances an incision is made in your abdomen to allow the dead tissue to be removed.

Infected pancreatic necrosis is a very serious complication and even with the highest standards of medical care the risk of dying from organ failure is estimated to be around 1 in 5.

Systemic inflammatory response syndrome (SIRS)

Another common complication of severe acute pancreatitis is systemic inflammatory response syndrome (SIRS). SIRS develops in an estimated 1 in every 10 severe cases of acute pancreatitis.

In SIRS, the inflammation that affects the pancreas spreads throughout the body, which can cause one or more organs to fail. It usually develops during the first week after symptoms of acute pancreatitis started, with most cases developing on the same day.

Symptoms of SIRS include:

• a rise in body temperature to more than 38°C (100.4°F), or a fall in body temperature to below 36°C (96.8°F)
• a rapid heartbeat of more than 90 beats a minute
• an unusually fast breathing rate (more than 20 breaths a minute)

There is currently no cure for SIRS, so treatment involves trying to support the body’s functions until the inflammation has passed. The outcome depends on how many organs fail. The higher the number of organs affected, the greater the risk of death.