Subcutaneous low molecular weight heparins are widely used in hospitalised patients for the treatment of DVT, pulmonary embolism and acute coronary syndromes, as well as for thromboprophylaxis. Rectus sheath hematoma is a recognised, but sometimes misdiagnosed, complication of treatment with anticoagulant therapy,1 including full and prophylactic doses of low molecular weight heparin.2 Studies have shown that the most frequent location of a haematoma is in the lower part of the abdomen. The explanation for this lies in the anatomy of the abdominal wall.3 The rectus abdominis muscle lies between the aponeuroses of the transverse and oblique muscles, which form the so-called rectus sheath. In this lower aspect of the muscle the perforating branches of the inferior epigastric artery running in the preperitoneal fat may rupture causing a large haematoma widely spreading in this loose space. Care should be taken to avoid this area for injection of heparin, particularly in thin patients where inadvertent intramuscular [download-attachments container="div" style="list" dipslay_icon="1" display_count="1" display__size="0"]