Background: Determining surgical assessment in infants with necrotizing enterocolitis (NEC) without radiographic pneumoperitoneum remains challenging. This study aimed to describe clinical factors associated with surgical intervention and to retrospectively assess an eight-parameter indicator in this setting. Methods: A retrospective study was conducted on infants with Bell stage II–III NEC treated between July 2014 and June 2023. Patients without radiographic pneumoperitoneum were classified into the conservative management group (CON) and surgical intervention group (SUR). Variables considered clinically relevant and suitable for bedside assessment were evaluated for the construction of an exploratory composite indicator. For selected parameters, each item was coded as present or absent, and the total number of positive parameters was calculated for each infant. Clinical characteristics, parameter frequencies, and the distribution of the composite indicator were compared between groups. Receiver operating characteristic (ROC) curve analysis was used descriptively to summarize the apparent discrimination of the composite indicator for observed surgical intervention. Results: A total of 115 infants were included; 70 received conservative management and 45 underwent surgical intervention. Eight bedside parameters were selected: endotracheal intubation history, hypotension, peritonitis, radiographic abnormalities, leukopenia, thrombocytopenia, acidosis, and hyponatremia. The SUR group had a higher frequency of several bedside abnormalities and a higher composite indicator score than the CON group. The exploratory composite indicator showed an area under the ROC curve of 0.842 for distinguishing infants who underwent surgical intervention from those managed conservatively. Conclusions: Infants with NEC who underwent surgical intervention showed a higher burden of bedside clinical, radiographic, and laboratory abnormalities. This exploratory eight-parameter indicator may provide a practical descriptive summary of disease severity and surgical concern in this challenging clinical setting.