www.elsevier.com/locate/jpedsurg

Journal of Pediatric Surgery (2008) 43, 484–488

A population-based study of the outcome after small bowelatresia/stenosis in New South Wales and the AustralianCapital Territory, Australia, 1992-2003☆

Karen Walkera,⁎, Nadia Badawia, Celine H. Hamidb, Amish Vorac, Robert Hallidayc,Claire Taylord, Edward Shid, G.T. Roye, Edward Simpsonf, Andrew J.A. Holland,g

for the Neonatal Intensive Care Units’ (NICUS) Group, NSW Pregnancy and NewbornServices Network

aDepartment of Paediatrics and Child Health, Grace Centre for Newborn Care, The Children's Hospital at Westmead,The University of Sydney, Westmead, NSW 2145, AustraliabDepartment of Surgery, The Children's Hospital at Westmead, Westmead, NSW 2145, AustraliacGrace Centre for Newborn Care, The Children's Hospital at Westmead, Westmead, NSW 2145, AustraliadDepartment of Surgery, The Sydney Children's Hospital at Randwick, Randwick, NSW 2031, AustraliaeDepartment of Surgery, John Hunter Children's Hospital, Newcastle, NSW 2305, AustraliafDepartment of Surgery, The Canberra Hospital, Canberra City, ACT 2601, AustraliagDepartment of Academic Surgery, The Children's Hospital at Westmead, The University of Sydney,Westmead, NSW 2145, Australia

N

0d

Key words:Small bowelatresia/stenosis;

Neonate;Outcome;Population-based;Survival

AbstractPurpose: The purpose of the study was to describe the incidence, epidemiology, and survival of infantswith small bowel atresia/stenosis in New South Wales (NSW) and the Australian Capital Territory(ACT), Australia.Methods: A population-based cohort study was conducted of infants diagnosed with small bowelatresia/stenosis in NSW and the ACT from 1992 to 2003. Data were obtained from the prospectivelycollated NSW and ACT Neonatal Intensive Care Units' data collection. Individual risk factors formortality were assessed using the χ2 test.Results: The incidence of small bowel atresia/stenosis in NSW and the ACT was 2.9 per 10,000 births.Of 299 infants identified with small bowel atresia, 13 were stillborn. Of the 286 live born infants, most(52%) were delivered preterm (b37 weeks' gestation) with an 87% survival, whereas 48% were termwith a 98% survival. More than half the infants (54%) had an associated birth defect. The overallmortality was 8%. Prematurity and low birth weight were identified as independent risk factors formortality (P b .001).

☆ Funded by March of Dimes.⁎ Corresponding author. Corresponding author. Research Officer, Department of Neonatology, The Children's Hospital at Westmead, Westmead,

SW 2145, Australia. Tel.: 02 9515 2715; fax: 02 9515 2251.E-mail address: karenw4@chw.edu.au (K. Walker).

022-3468/$ – see front matter © 2008 Elsevier Inc. All rights reserved.oi:10.1016/j.jpedsurg.2007.10.028

485Congenital small bowel atresia/stenosis outcome

Conclusions: This study of small bowel atresia/stenosis provides population-based outcomes forclinicians and families. It is important to investigate infants with small bowel atresia for associated birthdefects. Although the mortality rate has decreased over the last 50 years, it remains substantial at 8% andis higher in premature and low birth weight infants.© 2008 Elsevier Inc. All rights reserved.

Intestinal atresia, the congenital absence of a patentlumen, and stenosis, the narrowing of the lumen, areuncommon causes of neonatal intestinal obstruction. Theincidence of small bowel atresia/stenosis lies between 2.5and 3.0 per 10,000 live births [1]. An Australian studydescribed the mortality rate of this condition to be as high as56% in the 1960s, decreasing to 22% in the 1980s [2]. Smallbowel atresia/stenosis can affect the duodenum, jejunum, andileum, with duodenal atresia/stenosis being the mostcommon. Duodenal atresia is frequently associated withother anomalies, in particular, chromosomal anomalies [3],whereas the incidence of associated anomalies is reported tobe less with jejunal and ileal atresia [1].

Previous studies of surgical outcome have tended to beinstitution based and to focus on particular conditions such asduodenal atresia. In contrast, we aimed to describe thecontemporary survival of infants with small bowel atresia ina population-based study in New South Wales (NSW) andthe Australian Capital Territory (ACT), Australia. These 2regions lie on the eastern coast of Australia and have a totalpopulation of 6.6 million people, which is approximately onethird of the population of Australia. We also planned toassess the changing referral patterns associated withimproving antenatal diagnosis and the co-location of theChildren's Hospitals with maternity hospitals.

Fig. 1 Antenatal transfers and NETS transfers.

1. Patients and methods

Data were obtained from the Neonatal Intensive CareUnits' (NICUS) data collection for a population-based studyfrom 1992 to 2003 inclusive. The NICUS is a validatedregional audit that prospectively collects data from the 10neonatal intensive care units in NSW and the ACT [4,5].Four of these units also perform major neonatal surgery,defined as the opening of a body cavity [6]. Criteria forinclusion in the NICUS database are admission to a neonatalintensive care unit and any of the following: gestation of lessthan 32 weeks at birth, birth weight not exceeding 1500 g,assisted ventilation for 4 hours or more, and major surgeryduring the first 28 completed days of life. During the studyperiod, there were 21,994 babies registered with NICUS.Infants with small bowel atresia/stenosis were identifiedusing the International Classification of Diseases, Austra-lian Version (ICD-9-CM and ICD-10) [7,8]. Population datawere obtained from the NSWMidwives Data Collection [5].Statistical analysis was performed using SPSS statistical

software version 13.0.1 (SPSS, Chicago, IL) [9]. Individualrisk factors for mortality were assessed using the χ2 test(with continuity correction), and P b .05 was consideredstatistically significant.

2. Results

There were 1,046,607 births in NSW and the ACTbetween 1992 and 2003 inclusive [5], of whom 299 wereknown to have small bowel atresia. Of these, 13were stillbornand 286 were live born and admitted to a neonatal intensivecare unit, giving an incidence of 2.9 per 10,000 births.

2.1. Transfer

The NSW newborn and paediatric Emergency TransportService (NETS), a statewide transport service, transferred 38infants from a nonsurgical to a surgical unit during the studyperiod. Most NETS transfers were from nontertiary hospitalsto the surgical units. A fetal anomaly was detected in 103(36.1%) infants. Over the study period, there was anincreasing trend for antenatal diagnosis of a fetal anomalythat resulted in the babies being delivered at a tertiarymaternity unit co-located with a surgical neonatal unit.Consequent to this, there was a corresponding trend for fewerbabies to require postnatal transport by NETS (Fig. 1).

2.2. Maternal factors, antenatal history, andobstetric care

The median maternal age of infants with duodenal atresiawas 30 years (17-53 years), and this was similar to mothers

486 K. Walker et al.

of infants with jejunoileal atresia (29 years; range, 15-42years) (Table 1). There was a slightly higher incidence ofprimigravid pregnancies in mothers whose infants hadduodenal atresia (34% vs 28%); however, both groups hadsimilar ethnicity (88% white vs 89%). In both the duodenaland jejunoileal groups, 60% and 62% were born by normalvaginal delivery, whereas 26.9% and 28.8% were born bycesarean delivery, with the remainder in both groups born byinstrumental delivery. These characteristics were similar tothe background population rates during the study period [5].

Of the 152 infants with duodenal atresia, 51% were bornat term or at least 37 weeks' gestation (n = 78), in comparisonto 33% (n = 39) with jejunoileal atresia. In both groups, mostpreterm infants were born at 32 to 36 weeks' gestation(91.5% and 94%). The sex differences were similar betweenthe two groups, 53%, compared with 46% in the jejunoilealgroup. Infants with jejunoileal atresia tended to be slightlyheavier (2742 g; range, 684-4770 g) than infants withduodenal atresia (2487 g; range, 1000-4440 g). A signifi-cantly greater number of infants with duodenal atresia had alow birth weight (b2500 g) (50.7% vs 32%, P ≤ .001). Teninfants had a low 5-minute Apgar score (≤5) (3 withduodenal atresia, 4 with jejunoileal, and 3 unspecified), 7(70%) of whom were preterm.

2.3. Medical care, associated anomalies,and outcome

Among the 286 infants with small bowel atresia/stenosis,53% were duodenal, 22% were jejunal, 19% were ileal, and16% were coded in the database as small bowel atresia/stenosis site unspecified. More than half (n = 153, 54%) of all

Table 1 Comparison between duodenal and jejunoileal atresia

Duodenal (152) Jejunoileal(118)

Significance

Maternalage (y)

30 (17-53) 29 (15-42) NS

Primigravid 34% 28% NSWhite 88% 89% NSNVD 60% 62% NSCD 26.9% 28.8% NS≥37 wk 51%

(n = 78)33%(n = 39)

P ≤ .01

32-36 wk n = 67 n = 74 P ≤ .01b32 wk n = 7 n = 5 NSFemale 81 (53%) 54 (46%) NSBirth

weight (g)2488(1000-4440)

2742(684-4770)

Low birthweight

77 (50.7%) 38 (32%) P ≤ .001

Apgar5 min b5

3 Infants 4 Infants NS

NVD indicates normal vaginal delivery; CD, cesarean delivery; NS,not significant.

infants had at least one associated birth defect. Ninety-twoinfants (61%) with duodenal atresia/stenosis had anassociated anomaly, compared with 54 (46%) infants withjejunoileal atresia/stenosis (P ≤ .025). Of those, 31 infants(48%) had jejunal atresia/stenosis and 23 infants (43%) hadileal atresia/stenosis. Seven infants (44%) with associatedanomalies had an unspecified site of small bowel atresia/stenosis (Table 2).

Most infants (87% duodenal and 88% jejunoileal)received total parenteral nutrition. The median durationranged from 10 days (1-86) for duodenal atresia to 15 daysfor jejunoileal atresia (2-290 days). Blood-culture–provensepsis was documented in 20% (4 of 16) of infants (19%duodenal, 19.5% jejunoileal, and 25% unspecified), and themedian length of stay was 21 days (0-550 days) (duodenal19 days, jejunoileal 26 days, and unspecified 23 days).

All but 3 of the 286 infants (99%) underwent surgicalrepair. Thirty-one (11%) infants had a stoma and theremainder had a primary anastomosis. Eight of these infantshad duodenal atresia with associated anomalies requiring astoma. Three infants had lethal anomalies and did notundergo surgery.

Overall, 23 infants died (8%): 20 (87%) were bornpreterm and 15 (65%) had an associated birth defect. Thepostoperative mortality was low (7%), with 263 (92%)infants surviving to discharge. The median age at deathwas 18 days (1-290). Prematurity and low birth weightwere statistically significant predictors of increasedmortality (P b .001).

Mortality was because of sepsis in 7 (30%), other birthdefects in 6 (26%), necrotizing enterocolitis in 3 (13%),hepatic failure and malabsorption in 3 (13%), and othercauses in 4 (17%).

3. Discussion

This population-based study from more than 1 millionbirths has identified a small bowel atresia/stenosisincidence of 2.9:10,000 births using validated databasesthat collect prospective regional information. This inci-dence is in keeping with previously published estimates[1], although there have been very few population-basedstudies of this condition.

The increasing trend of antenatal diagnosis of fetalanomalies and the subsequent delivery of the babies at aco-located maternity unit is in keeping with recent NSWDepartment of Health guidelines [10]. The fall in thenumber of babies with small bowel atresia requiringemergency transport by NETS to a surgical unit wouldseem beneficial to both the baby and parents: it decreasesseparation, obviates the need to transport a sick neonate,expedites surgical treatment, and represents optimal use oflimited health resources.

Duodenal atresia was the most common type of atresia,with ileal atresia being the least common. This finding was

Table 2 Birth defects

Associated anomalies (153/286 infants, 54%)

Duodenal (92) Jejunal (31) Ileal (23) Unspecified (7)

35 Chromosomal 0 Chromosomal 1 Chromosomal 3 Chromosomal25 Multiple 5 Multiple 3 Multiple15 Cardiac 2 Cardiac 2 Cardiac4 Renal 1 Renal 1 Neuro4 Pancreatic 2 Musculoskeletal 1 AWD10 TEF/EA 1 ARM 1 ARM3 Malrotation 1 Urogenital 1 Malrotation3 ARM 2 Malrotation 1 Pancreatic1 AWD 1 AWD 1 Musculoskeletal1 IHPS 1 Neuro 1 Other GIT1 Spleen1 Mesenteric cyst5 Urogenital4 Neuro6 Musculoskeletal1 Other20 Gastrointestinal 19 Gastrointestinal 11 Gastrointestinal 2 Gastrointestinal6 Malrotation 10 Malrotation 1 Malrotation4 ARM 1 ARM 1 ARM1 TEF/EA 3 Volvulus 2 Volvulus5 Pancreatic 4 AWD 5 AWD2 Volvulus 2 Meconium plug 2 Other atresia1 Spleen 3 Other atresia 1 Other anomaly1 Stomach 2 Unspecified 1 Mesenteric cyst3 Unspecified 1 Meckel diverticulum5 Cardiac 3 Cardiac 2 Cardiac 1 Cardiac2 Metabolic 2 Cystic fibrosis (confirmed) 3 Cystic fibrosis (confirmed) 1 Metabolic2 Urogenital 1 Urogenital 2 Urogenital3 Other 1 Musculoskeletal 1 Syndrome

Multiple anomalies included anomalies affecting more than one organ system. Infants may have had more than one anomaly. TEF indicatestracheoesophageal fistula; EA, esophageal atresia; IHPS, infantile hypertrophic pyloric stenosis; AWD, abdominal wall defect; GIT, gastrointestinal tract.

487Congenital small bowel atresia/stenosis outcome

consistent with the literature, although unlike most otherpublished studies that report a preponderance of male infantswith small bowel atresia/stenosis, we found no sex difference[1,11]. In our study, trisomy 21 was found in 19.7% ofinfants with duodenal atresia, which is similar to thatreported by Forrester and Merz [1] but lower than thatreported by Dalla Vecchia et al [12].

We were surprised by the finding that more than half ofthe infants had at least one additional birth defect (Table 1),and this finding should prompt clinicians to investigate thesechildren carefully. Most associated anomalies in theduodenal atresia group were chromosomal (38%), althoughother gastrointestinal anomalies were also found in 20% ofthese infants. Other gastrointestinal anomalies made up 56%of the infants with associated anomalies and jejunoilealatresia. The increased incidence of cystic fibrosis injejunoileal atresia has previously been reported [13].

The mortality rate has continued to decrease over thelast few decades. In a previous Australian study, Smith andGlasson reported that survival rates had increased from44% to 88% over a 25-year period from 1961 to 1986 [2].

Outcome data from other large case series in the UnitedStates and China support this improvement in survival[12,14]. The decrease in mortality is undoubtedly multi-factorial in origin and may be related to place of birth,earlier diagnosis, improved surgical techniques, andneonatal intensive care practices. Our overall survival of92% is similar to that reported in the current literature, withsepsis remaining a leading cause of death [15]. In ourstudy, the strongest predictor for mortality was prematurityand low birth weight (P b .001), which is consistent withother studies.

4. Conclusions

This study examined small intestinal atresia/stenosis inNSW and the ACT, Australia, from 1992 to 2003 inclusive.We identified an incidence of 2.9 per 10,000 births, with 36%of infants being diagnosed antenatally. Our mortality ratewas low at 8%, with live born term infants having a 98%survival rate compared with 87% for preterm infants.

488 K. Walker et al.

Prematurity and low birth weight were significantlyassociated with mortality. The high incidence of associatedanomalies in both groups of infants ought to make thethreshold for further investigation low.

Although short-term mortality outcome data were avail-able on all infants, the long-term outcome specificallyexamining developmental outcome was not addressed andwill be the subject of future studies.

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