Almost two-thirds of all blood used in transfusions goes to surgical patients. Those who receive it usually face lower risks from transfusion than from anesthesia and surgery. But, then, surgery sounds risky. Getting blood does not—at least it didn't until the discovery that the AIDS virus could be spread through blood transfusions. For the first time, many people realized that the nation's blood supply was vulnerable.

Yet blood can harbor a variety of infectious microbes besides the AIDS virus. And even perfectly acceptable blood can cause problems in some recipients.

By far the most crucial factor in a transfusion is the proper match of blood types. Human blood is classified into four major types: A, B, AB, and 0. Blood with red cells of one type will commonly contain antibodies against some or all of the other types. Transfusing the wrong type of blood can cause serious reactions—in extreme cases, shock, kidney failure, and even death.

Fortunately, the blood-banking system safeguards against such mix-ups. Blood banks type and label blood as soon as it's collected. Before hospitals use blood, they cross-match it with the recipient's blood to make sure the two are compatible. Minor incompatibilities sometimes escape the cross-matching process, but serious reactions from them are uncommon. A person who receives blood for the first time has only a one-in-10,000 chance of an adverse reaction. If it happens, that reaction is usually chills and fever.

A much greater risk arises from infected blood. Blood-borne parasites and viruses can cause malaria, hepatitis, and AIDS, as well as less familiar diseases. Cytomegalovirus, for example, gained brief but worldwide notoriety in 1981 for complicating Pope John Paul II's recovery after a transfusion he received for blood loss from a gunshot wound.

Blood banks can't test for all infectious organisms; there are just too many. Instead, banks rely partly on a series of questions to screen out potential carriers. One set of questions focuses on identifying people most likely to be carrying the AIDS virus. Among those are gay men, intravenous-drug users, hemophiliacs, recent immigrants from Haiti and certain parts of Africa, and people who have engaged in prostitution anytime since 1977, as well as their sexual partners.

After the initial screening, blood tests provide the second line of defense, especially against AIDS. The ELISA test, or "enzyme-linked immunosorbent assay," detects an antibody to the AIDS virus, indicating that the prospective donor has been exposed to infection. The test, which is now performed on all donated blood, is designed for maximum sensitivity, so that any questionable blood will test positive. While this results in many false-positive readings, it makes ELISA highly effective as a screening tool.

If the ELISA test is positive, repeat tests are done. Unless two repeat tests are negative—indicating that the first test was a false positive—the blood is withheld from the blood supply and ultimately destroyed. Blood that's positive on two ELISA tests is also subjected to a more sophisticated and expensive test, the Western blot. If that test is negative, the bank assumes the ELISA results were in error (but even so, the blood is destroyed). If the Western blot test is positive, the bank notifies the donor that he or she has been exposed to the AIDS virus, and typically offers to arrange counseling.

Despite its sensitivity, ELISA may not detect AIDS-tainted blood if a recently infected donor is just beginning to make antibodies to the virus. It usually takes from a few weeks to about three months after exposure to the virus for antibody levels to reach the point of detection. However, such "false negative" results are rare. As of mid-1988, federal health officials had identified only 16 cases of AIDS-virus infection that can be traced to transfusions received since April 1985, when ELISA tests were adopted for blood donors.

The Greater Threat: Hepatitis

While public fears about the blood supply have focused on AIDS, hepatitis poses a far more common threat—and one that can be just as deadly. The American Red Cross has estimated that the chances of receiving AIDS-contaminated blood in a transfusion are less than one in several hundred thousand. By contrast, the chances of receiving hepatitis-contaminated blood may be as high as one in fifty.

There are three forms of hepatitis, two of which present little, if any, threat to blood recipients. In hepatitis A (infectious hepatitis), the virus is blood-borne only during the acute phase, when the victim is already becoming sick, and most unlikely to be giving blood. Another form, hepatitis B (serum hepatitis), was virtually eliminated from the nation's blood supply by an accurate screening test developed in 1972. But a third form, designated non-A/non-B hepatitis, infects roughly 2 percent of all those who receive a blood transfusion.

There is as yet no treatment for non-A/non-B hepatitis. At its worst, the virus can cause severe liver disease, including cirrhosis and cancer. Of the people who develop acute hepatitis, one in three will progress to a form of chronic hepatitis. And one in 20, according to some estimates, will ultimately develop cirrhosis.

Screening tests for carriers of non-A/non-B hepatitis have been nonspecific—they haven't been able to detect the presence of the virus itself, only signs that it might be there. In 1986, faced with an unacceptably high hepatitis rate among transfusion recipients, blood banks reluctantly began using two marginal tests for non-A/non-B hepatitis. They hoped each would compensate for the deficiencies of the other, together picking up 40 to 60 percent of the contaminated blood. In short, the tests have been wrong as often as right, allowing some hepatitis-contaminated blood through and causing good blood to be thrown out.

In 1988, one group of researchers reported that the virus responsible for non-A/non-B hepatitis had been isolated for the first time. A specific antibody test to detect carriers of the disease may soon become available.

Donating Your Own Blood to Yourself

The only blood that's virtually risk-free in a transfusion is your own. In emergencies, of course, medical personnel have to depend on blood from the public supply, since the risks associated with blood transfusions pale before the immediate need to save someone's life. But less than 20 percent of transfusions are required for emergencies, reports the American Association of Blood Banks (AABB). In cases of elective surgery, physicians often can help patients arrange for an autologous transfusion—one that uses the patient's own blood.

Patients who want to use their own blood have two options. They can donate and store a few pints of their blood before surgery. Or, in special cases, the surgeon can use a procedure called "intraoperative salvage" to recycle the blood lost during surgery. (Intraoperative salvage is used mainly in large medical centers for heart and chest surgery, which often involve heavy blood loss. The procedure requires special equipment and people trained to use it.)

Using your own blood virtually eliminates the risks associated with blood transfusions. Infectious diseases are no longer a threat: You can't give yourself something you don't have. Nor need you worry about allergic or immunologic reactions. Your immune system will gladly accept your own blood. The American Medical Association, major blood-banking institutions, the U.S. Food and Drug Administration, and the National Institutes of Health all recommend that you donate your own blood before elective surgery. That recommendation does not extend, however, to speculative blood banking—paying a blood-storage company to freeze some of your blood "just in case."

The Wrong Way ...

Several blood-storage companies have cropped up around the country in recent years. One of them, Idant Laboratories in New York City, which has run a frozen-sperm bank for years, initiated a new type of "employee benefit" by signing agreements with Warner Communications and IMS International to provide blood-storage services for all of their employees.

It's expensive to store your blood on the chance that you might someday need it. Between charges for typing, testing, freezing, and storing your blood, you can easily pay over $500 a year. There's another charge for withdrawing your blood from the bank (plus transportation costs)—but don't worry, it's highly unlikely that you'll ever need it.

The chance that any one person will need blood in the next year, or even the next three years (the longest that red blood cells can be stored frozen), is slim; and in emergencies, people who have paid to store their blood may still have to depend on the public supply. Frozen red cells must first be thawed, then washed by hand to remove dead cells. That takes at least 90 minutes. Then there's the problem of getting the blood to you—no small feat if, say, you've been in a car accident hundreds of miles from the blood center.

S. Gerald Sandler, M.D., of the American Red Cross says that blood-storage companies are capitalizing on the fact that blood banks can't guarantee that someone receiving blood won't contract a disease such as hepatitis or AIDS. But, says Sandler, "the alternative doesn't guarantee that people who need blood will be able to use the blood they have stored."

An unpublished study by the Red Cross reveals how seldom frozen blood is used—or needed. The Red Cross maintains a supply of frozen red cells for people with rare blood types, the largest supply of frozen blood in the nation. They surveyed 3000 people in their rare-donor registry to gauge how the blood was being used. Only 20 people had used any of the stored blood; and in every case, the Red Cross concluded, an aware donor could have donated his or her own blood in the weeks before surgery. In no instance were the frozen cells used in a traumatic bleeding incident to save anyone's life.

... and the Right Way

With a bit of foresight, physicians can usually schedule elective surgery to allow their patients enough time to donate a few pints, or units, of blood beforehand. Studies published in the journal Transfusion and in The New England Journal of Medicine report that two-thirds of patients who pre-donated their blood needed no additional blood from the public supply. Those who couldn't donate all they needed still reduced their risks by limiting their exposure to the blood of others. Another study, published in The Journal of the American Medical Association, examined an autologous blood program used for orthopedic patients at a Florida hospital since 1976. Over a 10-year period, 95 percent of the blood used was autologous. Even though a few patients needed additional units from the public supply, the hospital had encountered no instance of hepatitis symptoms among patients who took part in the program.

The benefits of autologous transfusions extend beyond the patient. Safe blood is also reassuring to surgeons. Because of the risks associated with ordinary transfusions—especially from several different donors—surgeons tend to be stingy with blood that comes from the public supply. For example, blood plasma (the fluid part of the blood) is ideal for certain types of plastic surgery because it both replaces fluids and aids in blood clotting. But the surgeon often winds up substituting a saline solution because the benefits of the plasma don't justify the risks. If the plasma is the patient's own, however, the surgeon will gladly use that rather than salt water.

Using your own blood also helps ease the burden on the public supply. Red Cross officials estimate that they lose about 10 percent of their potential donations because either the donor or the donor's blood doesn't pass their screening tests. But such tests are waived for autologous blood. Every unit you predonate represents a unit saved for the public supply.

Autologous transfusions are dramatically underused. Joseph Bove, M.D., as chairman of the AABB's committee on transfusion-transmitted disease, estimated that less than one percent of the transfusions in the United States before 1987 used a patient's own blood. The study published in The New England Journal of Medicine reported that out of 20,640 units of blood used in transfusions at 18 hospitals, only 193 were autologous units. The authors concluded that fully two-thirds of the patients in the study could have avoided blood from the public supply by predonating their own.

Autologous transfusions are probably underutilized because they are more work for everyone involved. The vast machinery it takes to get the public blood supply's 12 million units of blood annually from donor to hospital to patient runs surprisingly smoothly. But a John or Jane Doe who wants to donate and get back the same units of blood adds an extra cog to the system. Enough Does and the system has to be reworked or it may grind to a halt.

In recent years, almost every major medical organization in the United States has endorsed the use of autologous transfusions. As the practice becomes more common, hospitals and blood banks will have little choice but to adjust.

How Autologous Transfusion Works

To gain the advantage of presurgical donation, you should ask your physician as soon as elective surgery is scheduled whether you'll need a transfusion. If you can use your own blood, you'll need time to make donations. Your surgeon should make the necessary arrangements with the community or hospital blood bank.

The main requirement for predonating blood is that you be in reasonably good health. Many people who are ineligible to donate to the public supply—because of age, weight, or medical history, for example—can store blood for themselves. The only thing that absolutely precludes storing blood for your own later use is an active infection, such as the flu.

Blood-donor guidelines normally recommend that people give blood no more than once every eight weeks, which allows a wide margin of protection against anemia. But that limit is waived for autologous donations. You can usually store up to one pint per week for four to six weeks (depending on hospital policy), with the last unit being taken as late as 72 hours before surgery. (Blood counts should be checked along the way to make sure that nothing worse than mild anemia develops.)

The six-week maximum arises because that's the limit on how long blood can be stored fresh. Although red cells can be kept frozen for up to three years and plasma for a year, many hospitals do not use frozen blood in their autologous programs because it's more expensive.

Your body restores the lost fluid volume within a few hours of donating blood, but red cells are replenished more slowly. Not everyone can donate blood weekly without becoming anemic. Not everyone has to: The average amount of blood required in a transfusion is only 2 or 3 units. Even patients who donate only part of what they need still reduce their risk.

Most hospitals charge the same for your own blood as for blood from the public supply. A few charge less. The Red Cross reports that some of their banks in urban areas tack on a surcharge of about $25 for the cost of special handling. As long as you are storing blood for upcoming surgery at your physician's request, most insurance companies will cover any extra costs, including those of getting to and from the blood bank. Note, however, that insurance coverage applies only to blood that's actually transfused, not to units beyond what you need.

Some patients who can't donate their own blood turn to friends or family members rather than to the public supply. Although some banks will take such "directed" donations with a physician's consent, most discourage the practice. There's no evidence that directed donations are any safer than blood from the public supply. Indeed, many experts suspect such donations could be less safe.

Directed donations bypass one of the safeguards in blood banking—anonymity. Someone who donates blood anonymously has no incentive to disguise the fact that he or she may be in a high-risk group for transmitting disease. Some friends and relatives, on the other hand, might find it preferable to donate than to explain how they happen to fall into one of the high-risk groups. If the hepatitis or ELISA test is positive, moreover, only the donor is notified. The patient may not learn that the blood has been rejected until he or she arrives for surgery.

Another common misconception—especially since the emergence of AIDS—is that giving blood might somehow expose the donor to infection. Impossible. The equipment used is sterile and disposable. There is absolutely no risk of contracting AIDS or any other disease when you donate blood.

Luis Treacy

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