If you have not been able to identify precipitating delirium factors on the initial evaluation, an additional search is needed.

Below are further considerations

A comprehensive evaluation is outlined here

Predisposing factors

• Consider reevaluating premorbid functional and cognitive baseline
  
• In some rare cases of unexplained (despite thorough investigation) or prolonged delirium, the culprit may be Lewy Body Dementia (LBD).
  Both delirium and LBD share alterations in cognition, attention, and arousal along with visual hallucinations making diagnosis difficult.

Precipitating

*Note on UTI: Frail older adults have rates of asymptomatic bacteriuria approaching 50%.  In the presence of delirium, but in absence of clear localizing symptoms, fever/leukocytosis, and sepsis, bacteriuria may be a red herring so continue to evaluate other potential precipitants.  UTIs should be a diagnosis of exclusion (in the absence of sepsis or localizing signs/symptoms) in delirium.