What is the appropriate dose of indocyanine green (ICG) to administer for a segmental colectomy?

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Last updated: September 24, 2026 • View editorial policy

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ICG Dosing for Segmental Colectomy

For segmental colectomy, administer 0.027 mg/kg of indocyanine green (ICG) when using overlay fluorescence mode, or 0.0108 mg/kg when using monochromatic mode with an LED imaging system.

Recommended Dosing Protocol

The optimal weight-based dosing for left-sided colorectal resections has been specifically validated 1:

  • Overlay mode: 0.027 mg/kg IV
  • Monochromatic mode: 0.0108 mg/kg IV

These doses provide medium-to-maximum fluorescent signal intensity for both identifying the descending colon transection line and assessing colorectal anastomotic perfusion, while minimizing problematic background fluorescence if a second injection is needed 1.

Administration Technique

Preparation: Dissolve 25 mg ICG powder with exactly 5 mL of aqueous solvent provided, yielding 5 mg/mL solution. Use within 6 hours of preparation 2.

Injection method:

  • Inject rapidly as a bolus into an antecubital vein
  • Immediately follow with a 5 mL normal saline flush 2
  • Switch imaging system to near-infrared (NIR) mode
  • Fluorescence visualization occurs within seconds 3

Two-Injection Strategy

For segmental colectomy requiring both transection line identification and anastomotic perfusion assessment:

  1. First injection: Administer calculated dose to identify optimal bowel transection site
  2. Wait period: Background fluorescence clears at median 19 minutes (range 9-96 minutes depending on mode) 1
  3. Second injection: Repeat same dose to assess anastomotic perfusion after construction

The weight-based doses above specifically allow adequate clearance between injections, with overlay mode showing no recognizable background fluorescence and monochromatic mode showing only minimal residual fluorescence 1.

Alternative Dosing Considerations

While the FDA label describes doses up to 0.5 mg/kg for hepatic function studies 2, these higher doses are not recommended for colorectal perfusion assessment as they create excessive background fluorescence that impedes accurate visualization if repeat injection is needed 1.

Some studies report using fixed 5 mL volumes of ICG solution 3, but this approach lacks the precision of weight-based dosing and may result in suboptimal fluorescence intensity or excessive background signal.

Clinical Outcomes

ICG fluorescence angiography in colorectal surgery demonstrates:

  • Safe administration with no adverse reactions reported 3, 4
  • Successful anastomotic perfusion visualization in 100% of cases 5
  • Potential to change surgical strategy in 5-26% of cases based on perfusion findings 3
  • Enhanced lymph node identification when injected submucosally (2.5 mg/mL concentration) 6

Important Caveats

Perfusion interpretation: In 25% of cases, ICG may demonstrate fluorescence beyond areas with clinically pulsatile arterial flow, raising questions about whether ICG-positive perfusion always indicates adequate blood supply for anastomotic healing 5. Therefore, ICG should complement—not replace—clinical assessment of pulsatile bleeding at mesenteric margins.

Timing considerations: The fluorescence duration depends on administered dose. Lower doses (0.0108-0.027 mg/kg) provide adequate but shorter visualization windows compared to higher doses, making them ideal for procedures requiring repeat assessment 1.

Equipment dependency: These specific doses were validated using LED fluorescence systems; different imaging platforms may require dose adjustments 1.

References

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.