Portal venous gas and surgical outcome of neonatal necrotizing enterocolitis

Presented at the 51st Annual Congress of the British Association of Paediatric Surgeons, Oxford, England, July 27-30, 2004.
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Abstract

Purpose

The prognostic significance of portal venous gas (PVG) in neonatal necrotizing enterocolitis (NEC) for operative intervention (OP), neonatal complications, and mortality remains uncertain. The authors designed a long-term prospective study to describe the natural history of PVG related to these outcomes and to test the hypothesis that PVG does not mandate OP.

Methods

All infants admitted to a single center between October 1991 and February 2003 were evaluated weekly to identify all cases of NEC (defined as Bell stage II or higher). Demographic, radiological, surgical, and outcome data were abstracted prospectively. Radiographic studies were performed at the onset of illness and at subsequent 6- to 8-hour intervals or as clinically indicated. A single pediatric radiologist reviewed all radiographs. Values are expressed as mean ± SD. Odds ratios and relative risk ratios are reported with 95% CIs. The level of significance was P ≤ .05.

Results

After the exclusion of 24 infants with lethal diseases, major congenital or chromosomal anomalies, or recurrent episodes of NEC, 194 of 5891 infants developed NEC. The overall incidence of NEC was 3.7%. In 194 infants with NEC, the incidence of PVG was 33% (n = 64). Gestational age (30.8 ± 4 vs 29.3 ± 4.2 weeks; P = .02) but not birth weight (1609 ± 761 vs 1434 ± 810 g; P = NS) was greater in infants with PVG compared with infants without PVG (n = 130). Sixty-six (34%) infants with NEC underwent OP. Operative intervention occurred more frequently in infants with PVG compared with infants without PVG (OR, 2.5; CI, 1.37-4.76; P = .003)—only 48% of infants with PVG underwent OP. Among the variables, gestational age, severe NEC (Bell stage III), severe intramural gas (in all 4 abdominal quadrants), and the presence of PVG, severe NEC was most highly associated with OP (OR, 77.47; CI, 10.36-580.16; P < .0001). Bell stage III NEC was present in 98% of infants who underwent OP compared with 40% of infants without OP (P < .0001). Of all infants with NEC, 37 (19%) died. Mortality was higher among infants who underwent OP (33% vs 12%; P < .0003). A multivariate regression model identified Bell stage III (OR, 3.74; CI, 1.20-11.62; P = .02), but neither PVG nor OP, to be significantly associated with mortality. Of interest is that survival in infants with PVG was greater (but not significantly so) than in infants without PVG in both OP (74% vs 59%) and non-OP (91% vs 87%) groups. Furthermore, 30 of 64 (47%) infants with PVG survived without OP, and of all 33 infants with PVG who did not undergo OP, 30 (91%) infants survived.

Conclusions

Decision for OP should be based on the severity of NEC and not on the presence of PVG alone because nearly half of infants with PVG survive without OP. Overall, the presence of PVG does not increase the risk of mortality among infants with NEC. Severe NEC, but not OP, is associated with higher mortality.

Section snippets

Materials and methods

From October 1991 to February 2003, we prospectively identified all infants with NEC (Bell stage II or higher) [5]. We excluded infants with birth weights (BWs) 400 g or less, infants with major congenital or chromosomal abnormalities, and infants with recurrent episodes of NEC. Evaluations performed at the onset of illness included abdominal radiographs, complete blood cell count, blood culture, arterial blood gas, and serum electrolytes. Fecal specimens were tested for bacteria, Clostridium

Results

A total of 194 infants met the diagnostic criteria for NEC and was included in the study (Fig. 1). The overall incidence of NEC was 3.7%. Portal venous gas was identified in 64 (33%) of the 194 infants with NEC. Sixty-two (97%) of the infants with PVG had been receiving partial or total enteral feeds. Two infants manifested PVG within the first few hours of life without having received enteral nutrition. Both infants had been born prematurely (at 24 and at 34 weeks) to mothers with

Discussion

Portal venous gas in neonatal NEC was first described by Wolfe and Evans [9] in 1955. The preponderance of PVG in infants with severe IMG in our study population supports the contention that PVG is an extension of IMG in neonatal NEC [1], [3]. The origin of IMG and PVG is the fermentation of substrates in milk feedings by bacteria present in the gastrointestinal lumen [10]. Hydrogen and methane are the predominant components of IMG [10]. The presence of PVG in an unfed infant has not been

Acknowledgments

The authors thank Carmela B. Monteiro, MD, Associate Professor, Department of Pathology, for examination of specimens. The authors thank Savithri Raja, BSc (student), King's College, University of London, for data entry; Pam Pieper, ARNP, Pediatric Surgery, Department of Surgery, and Patricia A. Williams, ARNP, Division of Neonatology, for data collection; and the nursing staff with all neonatal nurse practitioners of Shands Jacksonville for their cooperation with this project.

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