Sodium Fluorescein

Sodium fluorescein is a fluorescent xanthene dye that emits a yellow-green color under blue (490 nm) or ultraviolet light, visible even at very low concentrations in urine. In GU practice it has a niche role as an IV ureteral-identification agent and as an intravesical leak-detection dye — filling the gap left by indigo carmine shortages and serving as a low-cost alternative to NIR fluorophores in centers without NIR imaging.^[1]

Pharmacology

Property	Value
Class	Xanthene fluorescent dye
Color	Yellow-green (visible), intensifies under blue/UV light
Route	IV or intravesical
Renal excretion	Rapid glomerular filtration → visible in urine within 5–15 minutes of IV dose
Duration	30–60 minutes of visible urinary fluorescence
FDA approval	FLUORESCITE: retinal/iris angiography or angioscopy; GU use is off-label, not approved “by extension”

GU Applications

1. IV ureteral identification during MIS / open pelvic surgery

25–50 mg IV (diluted) produces visible yellow-green urinary efflux within 5–15 minutes
Particularly useful when indigo carmine is unavailable and NIR imaging is not in place
Doyle et al. 2015 described 25–100 mg IV for ureteral efflux; the later Grimes randomized trial used 25 mg. These are off-label study regimens, not the labeled ophthalmic dose.^[1][2]

2. Intravesical applications

Intravesical use is off-label and lacks a standardized regimen established by the cited IV-efflux studies. Do not transfer an IV or ophthalmic preparation into the bladder without an appropriate local protocol and pharmacy review.

3. Perfusion / angiography (limited GU use)

Widely used in ophthalmology for retinal angiography
Occasional intraoperative use for flap perfusion assessment in plastic surgery
Rare in GU reconstruction (ICG preferred for perfusion)

Dosing

IV ureteral identification: 25–50 mg IV (dilute in 10 mL saline, give slowly)
Intravesical leak testing: use a locally reviewed protocol; the IV studies do not establish a bladder dose.
Verify the supplied concentration: FLUORESCITE 10% is 100 mg/mL. GU studies used much less than the labeled 500 mg adult ophthalmic dose.^[3]

Adverse Events

Skin yellowing — transient
Yellow urine — expected, resolves in 24 hours
Nausea, vomiting — occasional at higher doses
Hypersensitivity, including fatal anaphylaxis — known fluorescein/component hypersensitivity is a contraindication; low-dose GU use does not establish freedom from this risk. Have emergency treatment available.
Extravasation can cause severe tissue damage; confirm a functioning IV.^[3]
Fluorescent/colorimetric assays may be affected; notify the laboratory of recent dye administration