Fatal dysnatraemia caused by elective colonoscopy

Editor—Respondents on bmj.com to the article by Ayus et al have already questioned the lesson that serum concentrations of sodium should always be checked after colonoscopy.¹,² Many millions of colonoscopies have been performed around the world without any other such report of fatal electrolyte imbalance.

Many millions more may be performed in the future. It may be ill advised to make an argument for an across the board increase in procedural costs—checking serum concentrations of sodium—to prevent a complication seemingly so rare that the cases reported by Ayus et al may be the first in the medical literature.

Let us be selective in the use of scarce medical resources. We should reserve serum sodium measurement in the context of colonoscopy for the few patients in whom notable electrolyte disturbance as a consequence of preparation for the procedure, or whose clinical condition afterwards, makes a potentially life threatening imbalance likely.