Heterogeneity of necrotizing enterocolitis associated with congenital heart disease: a comparative study of preoperative and postoperative clinical phenotypes.

PURPOSE: To characterize the clinical differences between pre- and postoperative congenital heart disease (CHD)-associated necrotizing enterocolitis (CHD-NEC) and to explore whether these entities represent distinct clinical phenotypes. METHODS: Patients with NEC episodes at our institution were retrospectively reviewed, and the NEC episodes were classified as classical NEC, preoperative CHD-NEC, or postoperative CHD-NEC. Clinical characteristics, clinical severity, laboratory data, detection triggers, and hemodynamic background at NEC onset were compared among groups. An exploratory subgroup analysis of postoperative CHD-NEC was performed. RESULTS: This analysis included 55 NEC episodes in 47 infants, comprising 7 classical NEC, 15 preoperative CHD-NEC, and 33 postoperative CHD-NEC. Preoperative CHD-NEC was associated with a higher perforation rate (26.7% vs. 3.0%), a lower pH (7.35 vs. 7.44), higher lactate levels (26.5 vs. 11.5 mg/dL), and lower antithrombin III levels (51.0% vs. 81.0%) compared with postoperative CHD-NEC. Postoperative CHD-NEC was more often detected on imaging findings, including portal venous gas on ultrasonography (24.2% vs. 0.0%). Meanwhile, preoperative CHD-NEC was more often identified after the onset of a bloody stool (80.0% vs. 42.4%). CONCLUSION: CHD-NEC may not be a uniform entity. However, preoperative CHD-NEC and postoperative CHD-NEC differ in terms of clinical severity, detection patterns, and hemodynamic background.