Double-knotting Blood Storage Bag Tubing Reduces Contamination

To prevent bacterial contamination during storage, blood storage bags must be airtight and secure. In high-income settings, blood bags use tubing that is heat-sealed after donation. However, heat-sealing is not feasible in many low-income settings due to lack of electricity and cost.  Many parts of Africa use a single knot in the tubing of blood bags as recommended by military handbooks. To see if a double knot in the tubing would reduce the risk of bacterial contamination, researchers filled 180 blood bags with sterile culture medium and closed half of the bags with one knot and the other half with two knots. Bacterial cultures were then introduced into the tubing and positioned to be in direct contact with the knots in each bag. After 35 days of storage at 20 to 22°C, the culture medium in the bags was tested for bacterial contamination, and 8 of 90 bags sealed with a single knot were contaminated compared to zero bags sealed with double knots. Double-knotting tubing for blood storage bags may be a low-tech method to reduce microbial contamination in low-resource settings and is even less expensive than metal clamps.

Reference:

Selleng K, Ismail H, Kohler C, Wesche J, et al. Reducing Bacterial Contamination of Blood Bags with a Double Knot. N Engl J Med. 2026 May 7;394(18):1865-1866. d PMID: 42090799.