The Non accidental injury page has been updated with information about the rarity of bruising in children < 6 months of age presenting to the ED with presentations not related to NAI (1.3% overall, 0.2% in children presenting without trauma).
Pierce MC et al. The prevalence of bruising among infants in pediatric emergency departments. Ann Emerg Med 2015 Jul 29; [e-pub]. (http://dx.doi.org/10.1016/j.annemergmed.2015.06.021)