Indocyanine green (ICG) lymphography is becoming popular in evaluation of lymphedema. However, indication of ICG lymphography is yet to be cleared. To solve this problem, Latency-Edema-Compression (LEC) score, which could be calculated solely from history taking, was developed based on a linear disease progression model. In 62 limbs of 31 patients with secondary lower extremity lymphedema, LEC scores were calculated and compared with corresponding dermal backflow (DB) stage of ICG lymphography. The LEC scores statistically correlated well with the DB stages (r = 0.713, P < 0.001). The DB stages in limbs with LEC scores smaller than 3.7 (n = 32) were significantly lower than those in limbs with LEC scores of ≥3.7 (n = 30) (1.3 ± 0.5 vs. 2.8 ± 0.7, P < 0.001). The LEC score can be used to determine whether further examination is necessary in outpatient assessment of new secondary lymphedema cases.