ABO blood type as a risk factor for secondary post-tonsillectomy haemorrhage

Introduction: Blood type-O is associated with decreased expression of von Willebrand factor. Type-O patients suffer fewer thrombotic problems and may be more prone to haemorrhage. Secondary post-tonsillectomy haemorrhage is the most common severe complication of tonsillectomy. We propose that type-O blood may be over-represented in patients presenting with secondary bleeds. Methods: We reviewed patients treated in the Royal Victoria Eye and Ear Hospital and the Midwestern Regional Hospital for secondary post-tonsillectomy haemorrhages from 2001 to 2006. Results: Three-hundred and three patients suffered secondary post-tonsillectomy haemorrhages over the study period. Blood group data was available in 206 cases (68%). Sixty-three percent of patients studied were blood group O, compared with 55% of the general population (. p=. 0.01). Conclusions: Blood group O is disproportionately represented in secondary post-tonsillectomy haemorrhage patients. Although we cannot demonstrate causality, this association suggests that patients with type-O blood are more likely to suffer from secondary bleeds following tonsillectomy.