['Nonoperative management (NOM) of blunt splenic injuries has become standard of care for its high success rate. We observe that many blunt assault (BA) patients fail NOM despite lower overall injury severity. We performed this study to determine whether BA is independently associated with failed initial NOM (FiNOM) of splenic injuries.', 'Using the Trauma Registry at our level I center, we reviewed data of all patients with blunt splenic injuries, who did not undergo immediate operative management of the spleen, admitted from January 1, 1992 to December 31, 2007. Initial NOM was defined as any patient who did not undergo immediate (< or =12 hours after admission) operative intervention for the spleen or did not undergo operation for the spleen at any time during the admission. FiNOM was defined as any patient who underwent operative management of the spleen greater than 12 hours after admission. Logistic regression was performed to determine whether BA was independently associated with FiNOM.', 'FiNOM occurred in 57 of the 419 (13.6%) patients initially managed nonoperatively. FiNOM decreased significantly in non-BA patients from 15.8% (1992-1999) to 6.2% (2005-2007) (p = 0.05) over time. This was not true for BA patients (33.3% vs. 30%) (p = 0.78). FiNOM for BA patients was 36.1% (13 of 36) versus 11.5% (44 of 383) for all other mechanisms combined. FiNOM was increased across all Organ Injury Scale scores for the spleen in BA patients. BA was independently associated with FiNOM.'] Is blunt assault associated with failure of nonoperative management of the spleen independent of organ injury grade and despite lower overall injury severity?