FDA to warn hospitals about capillary tubes

Safety alert: Devices cause HCW injuries

The Food and Drug Administration (FDA) will issue a safety alert warning hospitals and health care workers of the risk of injury and infection from breakage of glass capillary tubes frequently used for hematocrit determination, Hospital Employee Health has learned.

The safety alert, due to be released nationally by this spring, is only the second sharps-related warning from the FDA, although additional safety alerts are being considered for syringes and needles, says Tim Ulatowski, MS, director of the agency’s division of dental, infection control, and general hospital devices. The FDA, along with other federal agencies, is more aggressively seeking ways to reduce sharps injuries among U.S. HCWs in response to a congressional directive. (See cover story.)

The first FDA safety alert, issued in 1992, warned against the practice of using needles to access intravenous lines and generally was considered effective in reducing that type of percutaneous injury among HCWs.

Both alerts were requested by Janine Jagger, PhD, MPH, director of the International Health Care Worker Safety Research and Resource Center at the University of Virginia Medical Center in Charlottesville. Jagger requested a safety alert warning against glass capillary tubes in 1993.

Despite the time lag, Jagger, who operates the Exposure Prevention Information Network (EPINet) surveillance system for gathering data on HCW blood exposures, applauds the FDA initiative.

"We have very good means of tracking the transition to safer technologies and tracking injury reductions, so we look forward to documenting the benefits of the safety alert," she says.

In 1993, the FDA published a small article in one of its publications recommending that HCWs use safer alternatives to glass capillary tubes,1 but the warning went largely unnoticed.

The alert will warn users of "frequent fractures of tubes during use or when poked into putty to seal them," Ulatowski notes. He says the FDA will provide a list of "alternative devices or procedures," but he declined to reveal them before the list is reviewed to determine if the alternatives are "legally marketed."

However, Jagger notes that three safer alternatives presently are on the market: plastic capillary tubes, Mylar-wrapped glass capillary tubes, and a hemoglobin reader using a flat plastic microcuvette to hold the blood sample.2

While the exact number of glass capillary tube injuries occurring annually is unknown, about 108 million are sold annually in the United States, according to William Kendrick, president of Safe-Tec Clinical Products in Ivyland, PA, manufacturer of a Mylar-wrapped tube with a safety seal designed to eliminate breakage and potential bloodborne pathogen transmission.

At one hospital that has eliminated glass capillary tubes reported 2.6 injuries per 100,000 tubes purchased prior to elimination. Extrapolating those figures nationally suggests that about 2,800 capillary tube injuries occur annually in health care settings.2

Glass capillary tubes filled with blood are prone to break when HCWs push one end into sealing clay and during centrifugation. In one case, a physician acquired HIV when a tube broke as he attempted to seal it with putty. He has since died of AIDS.3

EPINet data from 77 hospitals reveal that from 1993 through 1996, 38 injuries from glass capillary tubes were reported. Of those, 20 (53%) occurred in clinical labs, six (16%) in intensive or critical care units, three (8%) in outpatient clinics, and nine (24%) in emergency departments, dialysis units, blood banks, labor and delivery units, procedure rooms, or utility areas.4


1. Food and Drug Administration. Glass capillary tubes pose risk to health-care workers. FDA Medical Bulletin 1993; 23:6.

2. Jagger J, Deitchman S. Hazards of glass capillary tubes to health care workers (letter). JAMA 1998; 280:31.

3. Aoun H. When a house officer gets AIDS. N Engl J Med 1989; 321:693-696.

4. Exposure Prevention Information Network (Database). Charlottesville, VA; 1996. Updated March 1998.