A study published in Breastfeeding Medicine was conducted to describe the changes occurring to nipple skin and to classify signs of nipple trauma in breastfeeding women during postpartum week 1. The study was conducted in two phases. Phase 1 was an observational prospective study of breastfeeding mothers wherein data were collected from photographs and digital images of nipple skin and were analyzed to classify the signs of nipple trauma anatomically. Phase 2 of the study confirmed the reliability of the signs identified in Phase 1 with the help of eight clinical midwives.

Overall, 776 images of 50 breastfeeding mothers were obtained daily. The signs of nipple trauma included erythema, swelling, blistering, fissure, and scabbing. Purpura and peeling were identified only with photographic image analysis. Scabbing and blistering were classified as damage to the dermis, while erythema and swelling were categorized as damage to the epidermis, on the basis of anatomical evidence and the mothers subjective experiences of pain intensity. Erythema and swelling were observed from day 0, with erythema being observed most frequently. For inter-rater reliability of the five signs of nipple trauma, Kendalls coefficient of concordance ranged from 0.46 (moderate) to 0.85 (almost perfect). Reliability was found to be high for fissure, substantial for blistering and scabbing, and moderate for erythema and swelling. Image analysis thus revealed five signs of nipple trauma; erythema and swelling were the most frequently observed signs during postpartum week 1. The agreement rate was lower than that for other signs, pointing towards the possibility of conflicting interpretations in clinical evaluation.