[5] This reaction has been shown not to be specific to ozone: it also detects superoxide, an important distinction in cell physiology.

Indigotindisulfonate sodium, sold under the brand name Bludigo, is used as a contrast agent during surgical procedures.

In urologic surgery, intravenous indigo carmine can be used to highlight portions of the urinary tract.

[8] Indigo carmine stain is not absorbed into cells, so it is applied to tissues to enhance the visibility of mucosa.

This leads to its use for examination and diagnosis of benign and malignant lesions and growths on mucosal surfaces of the body.