Increased risk of small intestinal atresia among twins in the United States.

OBJECTIVE

To compare the prevalence of small intestinal atresia among twins and singletons in the United States.

DESIGN

Descriptive analysis.

MEASUREMENTS: The McDonnell Douglas Health Information System (MDHIS), a national registry of newborn diagnoses, 1982 through 1988; and the Metropolitan Atlanta Congenital Defects Program (MACDP), a registry of defects among infants in Atlanta, 1968 through 1989.

PATIENTS: Live-born infants with small intestinal atresia.

INTERVENTIONS: None.

MAIN

RESULTS

In both systems, the rate of small intestinal atresia was higher among twins than singletons (MDHIS: 5.5 per 10,000 vs 2.0, relative risk [RR] = 2.8, 95% confidence interval [CI] = 1.9 to 4.0; MACDP: 7.3 vs 2.5, RR = 2.9, 95% CI = 1.5 to 5.7). The increase was more notable among same-sex twins than opposite-sex twins, suggesting an increase among monozygotic twins. It was also more notable among twins with jejunoileal atresia than those with duodenal atresia, suggesting a vascular cause in many cases.

CONCLUSION

Twins have a higher rate of small intestinal atresia than singletons, possibly due to vascular disruption in monozygotic twins.