SPLENECTOMY

by Dr Dick Mayon-White, Consultant for Communicable Disease Control, Oxfordshire Health Authority

The spleen

The spleen plays a part in the resistance to infection (immunity). It is situated in the upper left-hand side of the abdomen, partly protected by the bottom of the rib cage. The spleen may be removed, or cease to function normally, for a number of reasons. If it is injured in an accident, it may have to be removed (splenectomy) to control the bleeding. In a range of diseases of blood cells, from some forms of leukaemia to sickle cell disease, the spleen may cease to function properly. If it becomes uncomfortably large as a consequence of such a disease, removal may be the best option.

There was a time when the spleen was thought to be inessential to health (like the appendix), but it is now known that people without spleens have a greater risk of severe infection than people with normal spleens. Therefore, doctors try not to remove the spleen unless a splenectomy is either life-saving after injury, or very important in the treatment of a disease that involves the spleen.

What if the spleen has been removed or ceases to function?

The main problem is the risk of severe infection. The risk depends on age (children have a higher risk than adults if their spleens are removed) and on whether there is another disease present or not. The commonest type of infection is by a bacterium, Streptococcus pneumoniae or the "pneumococcus", which is, as its name suggests, a cause of pneumonia amongst other diseases. In people without spleens, these bacteria are not filtered out of the bloodstream as effectively as they should be, so the infection can progress to septicaemia, a severe and sometimes fatal infection of the blood by a pneumococcus, or other micro-organisms. The lack of a spleen also makes people more susceptible to attacks of malaria.

How great is the risk of infection after splenectomy?

The risk of severe infection in healthy people with spleens is very low; the chances of dying from severe infection are about the same as the chances of dying from a home accident - 1 in 30,000 per year. The risk to a person without a functioning spleen varies from eight times higher (an adult who has the spleen removed because of injury), to fifty times higher (children without spleens), than the general population. This is still a low risk, being of the same order as being killed in a road accident. Another way of expressing this risk is that if 100 people without spleens were followed up for 10 years, between one and five of them would have severe infection within that period of time.

How long does the risk of infection last after splenectomy?

It used to be thought that the infection risk occurred in childhood and the first year or two after splenectomy. While this is true, it is 'not the complete story. Medical journals have repeatedly published accounts of severe infection in adults up to ten years after splenectomy. It is likely that there is some small increased risk life-long.

What can be done to reduce the risk?

Stopping a minor treatable infection becoming a fatal septicaemia
If you are without a functioning spleen, you should consult a doctor if signs of infection appear. The main sign of infection is fever. A severe sore throat, unexpected cough, severe abdominal pain, a headache with drowsiness, or a rash, are other indications to seek medical advice. Doctors may need to be told if you have had a splenectomy.

Other ways of alerting doctors and nurses are to carry a card saying that the bearer does not have a functioning spleen, or to wear a Medic-Alert bracelet or necklet. Information about the Medic-Alert system can be obtained from - The Medic-Alert Foundation, 12 Bridge Wharf, 156 Caledonian Road, LONDON N1 9UU, Freephone: 0800-220386. The system backs up the simple notice on the bracelet or necklet with more medical data from an emergency bureau, contactable by telephone 24 hours a day.

Vaccination against pneumococcal infection
Fortunately there is an effective vaccine against the important pneumococcal infection. The vaccine is a single injection of purified bacterial substances derived from the 23 most common types of the pneumococcus. It gives 60-70% protection in children over the age of two, and in adults. The vaccine has been used in America for 14 years and has an excellent record of safety. It is now officially recommended by the Department of Health for patients without functioning spleens ("Immunisation against Infectious Disease", HMSO, 1992, pages 100-103). When possible, the vaccine should be given before the spleen is removed. This will not be possible in an emergency operation after an accident. A booster dose of vaccine 5 to 10 years after the first dose may be advised for people without spleens.

Regular antibiotics (prophylactic antibiotics)
In children, the risk of infection after splenectomy is high enough to justify a tablet of penicillin once or twice a day, at least until their 16th birthday. The dose is a 125mg tablet up to the age of 6 years, 250mg tablet from 6 years onwards. There is no standard medical opinion on whether twice a day is better than once a day, nor on the exact age at which to stop. For simplicity, one tablet a day until the age of 16 has advantages.

In adulthood, the risks of infection two years or more after splenectomy have reduced to the point that regular antibiotics may not be advisable. A person's own views about taking regular antibiotics should be taken into account, because there are varying opinions on whether these antibiotics are necessary. It is advisable to ask your own doctor, who can get and give advice to suit your particular case.

For people who are allergic to penicillin, there are other antibiotics which can be used instead. Once again, individual advice from your own doctor is best.

Precautions against malaria
People without spleens must avoid risks of malaria when travelling in tropical countries. Avoid mosquito bites (e.g. use insect-repellent creams, mosquito nets or screens, wear long sleeves and trousers in the evening) and take anti-malarial tablets as prescribed by your doctor.

What is being done to reduce risks even further?
Surgeons who treat accident victims and other doctors who treat patients with diseases that affect the spleen are now aware of the infection risk. If possible, the spleen is not removed, or not completely removed. There are vaccines being developed against other bacteria, like Haemophilus influenzae type b (Hib) and the meningococcus, which could be used to protect people without spleens in the future. Some of the new antibiotics may prove to be useful as regular treatment to prevent infection, but penicillin is still the first choice.

In conclusion
If you don't have a spleen, there is a good chance that you may never miss it. But there is a small risk of severe infection, which can be reduced by being aware of the risk, by being vaccinated against pneumococcal infection, by taking penicillin if you are under 16 years of age, and by avoiding malaria.