Secondary post-tonsillectomy haemorrhage: is there evidence of diurnal and monthly variation in haemorrhage rates?

Background: Anecdotally, secondary post-tonsillectomy haemorrhage tends to occur out-of-hours. This study sought to establish whether there is a link between haemorrhage and time of day, and examined correlations with month and with monthly temperature.

Methods: Data were obtained for patients in our hospital undergoing surgical arrest of secondary post-tonsillectomy haemorrhage between January 2002 and December 2020. Haemorrhage timing was categorised into daytime (07:00-18:00), evening (18:00-22:00) and overnight (22:00-07:00). The chi-square test was used to assess diurnal and monthly variation in haemorrhage rates ( < 0.05). Pearson's correlation test was used to analyse monthly haemorrhage rates and average monthly temperature.

Results: Fifty per cent of patients suffered post-tonsillectomy haemorrhage overnight and 28.1 per cent haemorrhaged in the evening, representing a significant difference ( = 0.018). The highest rate of haemorrhage was in July (2.96 per cent), which was statistically significant ( = 0.0024). There was a positive correlation between average monthly temperature and haemorrhage rate (Pearson's correlation = 0.478, = 0.116004), although this was not significant.

Conclusion: Most post-tonsillectomy haemorrhages occur out-of-hours (78.1 per cent), which could be conveyed during the consent process. The haemorrhage rate is lower in winter, which may influence planned operating theatre scheduling.