Summary

A 17-year-old woman, with a history of three operations on the upper gut in early life and intermittent diarrhoea, presented with a history of epistaxis and leg ecchymosis for the previous 3 months. Initial investigation revealed mild anaemia, low serum albumin, moderately elevated aminotransferases and an exceedingly prolonged prothrombin time (PT) which was promptly shortened to normal by intravenous vitamin K. Additional investigations revealed a grossly abnormal glucose hydrogen breath test, a dilated duodenum and deficiencies of vitamins A, D and E. Repeated courses of antimicrobial agents caused prompt but transient shortening of PT and eventually a duodenal–jejunal anastomosis was performed. Since then, up to 36 months later, the patient has been in good general health and PT has been consistently normal with no vitamin K supplementation. Small intestinal bacterial overgrowth has previously been associated with several conditions but this is the first description of its association with vitamin K-responsive coagulopathy.