Background Non-freezing cold injury (NFCI) occurs when peripheral tissue is damaged by cold exposure but not to the extent of freezing. Historically, the phenotype of NFCIs sustained was severe, whereas today the spectrum of injury represented in the UK military predominantly comprises subtler injuries. The diagnostic challenge of recognising these injuries, both in the acute and chronic settings, can lead to mismanagement and subsequent morbidity.

Methods We characterised a recent case series of 100 UK Service Personnel referred with suspected NFCI to a Military UK NFCI clinic. We characterised the acute and chronic phenotype of those diagnosed with NFCI (n=76) and made comparison to those who received alternate diagnoses (n=24), to find discriminatory symptoms and signs.

Results The most common acute symptoms of NFCI were the extremities becoming cold to the point of loss of feeling for more than 30 min (sensitivity 96%, specificity 90%, p<0.001), followed by a period of painful rewarming (sensitivity 81%, specificity 67%, p<0.001). In-field foot/hand inspections took place in half of the NFCI cases. Importantly, remaining in the field and undergoing multiple cycles of cooling and rewarming after an initial NFCI was associated with having double the risk of the NFCI persisting for more than a week. The most common and discriminant chronic symptoms and signs of NFCI were having extremities that behave differently during cold exposures (sensitivity 81%, specificity 75%, p<0.001) and having abnormal pinprick sensation in the affected extremity (sensitivity 88%, specificity 88%, p<0.001).

Conclusions A small collection of symptoms and signs characterise acute and chronic NFCIs and distinguish this vasoneuropathy from NFCI mimics.