Association between haematoma after inguinal hernia repair and site of heparin injection

To see if subcutaneous heparin prophylaxis against deep vein thrombosis and pulmonary embolism given into the abdominal wall caused more haematomas after repair of inguinal hernia than the same dose given into the shoulder. Random control trial. District hospital. 101 consecutive patients admitted for elective inguinal hernia repair. Four injections of sodium heparin 5,000 IU given either into the abdominal wall or the shoulder, the first two hours, before, and the last 24 hours after operation. Incidence of haematoma after operation. There was no significant difference in the incidence of haematoma between the groups. Haematoma formation was associated with a fall in systolic blood pressure of more than 25% (p = 0.055), which in turn was significantly associated with age over 60 years (p less than 0.0003). Injection of heparin subcutaneously into the abdominal wall does not lead to more wound haematomas than injection into the shoulder. Haematoma formation seems to be associated with a drop in systolic blood pressure of 25% or more, and thus requires further investigation