Think again before asking family to donate blood

On Call

July 16, 1996|By Dr. Simeon Margolis | Dr. Simeon Margolis,Special to The Sun

My surgeon has told me that blood transfusions may be needed for an operation on my back that is scheduled for next month.

Since I am terrified at the thought of contracting AIDS from infected blood, would it be sensible for me to arrange for blood donations from my family?

That's probably not a good idea.

It seems reasonable to assume that blood given by your family and friends would be especially safe.

However, studies have shown that blood obtained from such directed donations is actually more likely to contain disease viruses than blood obtained from general donations, probably because relatives and friends are embarrassed to admit habits, such as intravenous drug abuse, that greatly increase their risk of getting one of these viral infections.

The two other possible sources for your blood transfusions are the general supply of blood obtained from volunteers and blood that you donate before your surgery.

Self-supply (called autologous donation) is the safest blood for transfusions.

If you are healthy enough, you can make multiple donations of your own blood and the blood can be stored for 35 to 42 days

before use.

Generally, no more than four units of blood are obtained, one unit at a time, preferably with a week between donations and the last donation at least three days before the operation.

Recent publications suggest that blood available from general jTC volunteers is safe enough to call into question the need for the extra expense and inconvenience of autologous donations.

The major threat from transfusions is that the blood is infected with one of four viruses: HIV, the virus that causes AIDS; HTLV, a virus that causes a specific type of leukemia in adults; and hepatitis B and C viruses.

All donated blood is tested for evidence of infections; and the blood is discarded when these tests show the presence of a viral infection.

However, because it takes several months after the onset of a viral infection before infection can be detected by these tests, tests may not always reveal infection.

If transfused blood carries a disease virus, there is about a 90% chance that an infection will develop.

A recent report in the New England Journal of Medicine reports that the overall risk that blood from the general donor supply is contaminated with the virus that causes AIDS -- the most dangerous of the infections -- is only about one in 500,000. The risk of contamination is much greater with hepatitis C (1/100,000) and especially hepatitis B (1/63,000). Fortunately, in adults, most infections with hepatitis B are transient and do not even cause symptoms.

Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

Pub Date: 7/16/96

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