effect of injection duration on bruise size associated with subcutaneous heparin

background and objective: bruising is the most common complications that resulting from subcutaneous heparin injection. it causes the limitation of injection area, anxiety, disruption of body image, refusing treatment in patients and the reduction in patients trust in nurse. although different methods were suggested to lessen these unwanted complications, unfortunately none of them could decrease these complications effectively. the aim of this study was to compare the effect of injection duration on the bruising size of subcutaneous heparin injection.methods: this quasi-experimental study was performed on 50 patients who were administered by subcutaneous heparin. they were hospitalized in the internal-surgical ward of shahid beheshti hospital in babol, iran. for each patient two methods of subcutaneous injection, 10 second injection (control method) and 30 second injection (experimental method) were tried on right and left deltoid muscle accidentally. the interval between two injections was 12 hours. dimension of hands bruising and indurations were measured and compared using flexible, plastic ruler, 48and 60 hours after each injection.findings: the size of bruising caused by 30 second injection, was significantly less than 10 second injection (p=0.00). mean of bruising size in 10 second injection at 48 and 60 hours after injection was14±19.7 and 12.26±14.38, respectively and in 30 second injection at 48 and 60 hours after injection was 9.78±17.55 and 8.02±12.98, respectively. also, 48 and 60 hours after 30 second injection, absence of bruising, were significantly less than 10 second injection (p=0.03 and p=0.001, respectively). comparison of bruising size based on sex, females significantly had more bruising than males (p=0.001). furthermore, patients in internal wards compared to surgical wards had significantly bigger size of bruising (p=0.001). there wasn any significant relationship between age and bruising size.conclusion: the results of this study showed that the increase in injection duration significantly reduced the bruising size. so in order to improve the quality of care and lessen the uncomfortable and stressful experiences of patients it is suggested to increase the duration of subcutaneous heparin injection to 30 seconds.