To explore the value of abdominal ultrasound combined with serum activin A and triggering receptors expressed on myeloid cells 1 (TREM1) in the diagnosis of neonatal necrotizing enterocolitis (NEC).

This study was a retrospective cohort study. From November 2022 to December 2025, 261 children who visited Northwest Women's and Children's Hospital and were preliminarily suspected of having NEC were included as the research subjects. After clinical diagnosis, 102 children were finally diagnosed with NEC (NEC group), and 159 children were diagnosed as non-NEC (non-NEC group). The clinical data of the patients were recorded and abdominal ultrasound examination was conducted. The levels of serum activin A and TREM1 were measured by enzyme-linked immunosorbent assay (ELISA). The value of serum activin A and TREM1 in diagnosing NEC was evaluated using the receiver operating characteristic (ROC) curve. Moreover, Kappa consistency test was used to evaluate the consistency of abdominal ultrasound alone and in combination with serum activin A and TREM1 in diagnosing NEC compared with the clinical diagnosis results.

After propensity score matching, there were no statistically significant differences in pregnancy age, preterm birth, and non-breastfeeding between the non-NEC group and the NEC group (P>0.05). Both the non-NEC group and the NEC group consisted of 102 children. The consistency between abdominal ultrasound diagnosis of NEC and clinical diagnosis results was good, with a Kappa value of 0.745 (P<0.05). The levels of serum activin A and TREM1 in the NEC group were obviously higher than those in the non-NEC group (P<0.05). The area under the curve (AUC) for diagnosing NEC using serum activin A and TREM1 levels was 0.814 and 0.824 respectively, with the cutoff values being 687.60 and 476.88 pg/mL. The combined use of abdominal ultrasound and serum activin A and TREM1 in diagnosing NEC showed a high consistency with the clinical diagnosis results, with a Kappa value of 0.912 (P<0.05). The specificity, accuracy and positive predictive value of the combined diagnosis were obviously higher than those of abdominal ultrasound, serum activin A and TREM1 alone. The sensitivity and negative predictive value were also obviously higher than those of serum activin A and TREM1 alone (P<0.05).

Abdominal ultrasound combined with serum activin A and TREM1 can be a promising diagnostic method for neonatal NEC, and is expected to improve the accuracy of NEC diagnosis.