GLASS Anatomic Stage (Chronic Limb-Threatening Ischemia)
The Global Limb Anatomic Staging System (GLASS) for chronic limb-threatening ischemia, from the Global Vascular Guidelines (Conte and colleagues, J Vasc Surg 2019).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Femoropopliteal segment grade
- 3
- Infrapopliteal segment grade
- 2
- Severe calcification within the femoropopliteal segment of the target arterial…
- No
- Severe calcification within the infrapopliteal segment of the target arterial…
- No
- Inframalleolar (pedal) modifier
- The target artery crosses the ankle into the foot, with an absent or…
Result: GLASS stage II, P1.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Grades
- Femoropopliteal and infrapopliteal segments of the target arterial path, each 0 to 4.
- Stage I
- Estimated technical failure under 10 percent, one-year limb-based patency over 70 percent.
- Stage II
- Estimated technical failure under 20 percent, one-year limb-based patency 50 to 70 percent.
- Stage III
- Estimated technical failure over 20 percent, one-year limb-based patency under 50 percent.
- Not applicable
- Grade 0 in BOTH segments is not stage I: with no significant disease there is no target path to stage.
- Calcification
- Severe calcification raises that SEGMENT grade by one, before the matrix lookup. Capped at 4.
- Modifier
- P0, P1, P2 describe the pedal circulation and are appended to the stage, never an input to the matrix.
- Scope
- Anatomic pattern only. Companion to wifi and rutherford-fontaine, not a decision to revascularize.
What you enter
- Femoropopliteal segment grade
- Severe calcification within the femoropopliteal segment of the target arterial path.
- Infrapopliteal segment grade
- Severe calcification within the infrapopliteal segment of the target arterial path.
- Inframalleolar (pedal) modifier.
Full field descriptions
- Femoropopliteal segment grade [0 = Mild or no significant disease (under 50 percent). 1 = Superficial femoral artery disease under one third of its length (under 10 cm). May include a single focal chronic total occlusion under 5 cm if not flush. Popliteal artery mild or normal. 2 = Superficial femoral artery disease one third to two thirds of its length (10 to 20 cm). May include chronic total occlusion totaling under one third (10 cm) but not flush. Focal popliteal stenosis under 2 cm, not involving the trifurcation. 3 = Superficial femoral artery disease over two thirds of its length (over 20 cm). May include any flush occlusion under 20 cm, or a non-flush chronic total occlusion of 10 to 20 cm. Short popliteal stenosis of 2 to 5 cm, not involving the trifurcation. 4 = Superficial femoral artery occlusion over 20 cm. Popliteal disease over 5 cm or extending into the trifurcation. Any popliteal chronic total occlusion.]
- Severe calcification within the femoropopliteal segment of the target arterial path. Raises the femoropopliteal grade by one before the matrix lookup, capped at 4.
- Infrapopliteal segment grade [0 = Mild or no significant disease in the primary target artery path. 1 = Focal stenosis of the tibial artery under 3 cm. 2 = Stenosis involving one third of the total vessel length. May include a focal chronic total occlusion under 3 cm. Does not include the tibioperoneal trunk or the tibial vessel origin. 3 = Disease up to two thirds of the vessel length. Chronic total occlusion up to one third of the length, which may include the tibial vessel origin but not the tibioperoneal trunk. 4 = Diffuse stenosis over two thirds of the total vessel length. Chronic total occlusion over one third of the length, which may include the vessel origin. Any chronic total occlusion of the tibioperoneal trunk if the anterior tibial artery is not the target artery.]
- Severe calcification within the infrapopliteal segment of the target arterial path. Raises the infrapopliteal grade by one before the matrix lookup, capped at 4.
- Inframalleolar (pedal) modifier. Reported ALONGSIDE the stage and never inside it: the guideline states it is not considered in the primary stage assignment [P0 = The target artery crosses the ankle into the foot, with an intact pedal arch. P1 = The target artery crosses the ankle into the foot, with an absent or severely diseased pedal arch. P2 = No target artery crosses the ankle into the foot.]
How this is calculated
Conte MS, Bradbury AW, Kolh P, et al. Global Vascular Guidelines on the Management of Chronic Limb-Threatening Ischemia. J Vasc Surg. 2019;69(6S):3S-125S. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.