RT Journal A1 Tsapatsaris NP T1 SIte for subcutaneous heparin injection-reply JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1993 FD January 25 VO 153 IS 2 SP 263 OP 263 DO 10.1001/archinte.1993.00410020105015 UL http://dx.doi.org/10.1001/archinte.1993.00410020105015 AB Inwood suggests that the use of insulin needles and highconcentration heparin may reduce hematoma formation. The incidence of severe hematoma formation from prophylactic low-dose heparin is sufficiently low that a reduction in frequency with this technique may be difficult to substantiate. A 13-mm (0.5-in) 25-gauge needle is recommended usually for injection of heparin. I would not expect that this minor difference in length or caliber would affect the rate of hematoma formation. I do not know whether injection with the 13-mm 25-gauge needle is less well tolerated by patients than injection with insulin needles.In most studies of low-dose heparin, a concentration of 25 000 IU/mL has been used. The injected volume is 0.2 mL. In other studies,1 concentrations from 1000 to 10000 IU/mL have been used. Currently, many institutions use 5000-IU/mL single-dose vials for low-dose heparin prophylaxis. Lower volume injections may be less painful to patients, but it