Is it possible for sepsis to go undetected?

Doubtful: Sepsis is a severe, life-threatening illness that almost universally ends a person up in the hospital. Typically they are very ill, with high fevers, confusion, low blood pressure, etc.

Not for long: Sepsis may be misidentified at first, but it quickly becomes apparent after the first couple hours. There are no silent septic episodes - they all cause significant symptoms.