Diarrhea is common in infants (children less than 2 years of age), usually acute, and, if chronic, commonly caused by allergies and occasionally by infectious agents. Congenital diarrheas and enteropathies (CODEs) are rare causes of devastating chronic diarrhea in infants. Evaluation of CODEs is a lengthy process and infrequently leads to a clear diagnosis. However, genomic analyses and the development of model systems have increased our understanding of CODE pathogenesis. With these advances, a new diagnostic approach is needed. We propose a revised approach to determine causes of diarrhea in infants, including CODEs, based on stool analysis, histologic features, responses to dietary modifications, and genetic tests. After exclusion of common causes of diarrhea in infants, the evaluation proceeds through analyses of stool characteristics (watery, fatty, or bloody) and histologic features, such as the villus to crypt ratio in intestinal biopsies. Infants with CODEs resulting from defects in digestion, absorption, transport of nutrients and electrolytes, or enteroendocrine cell development or function have normal villi to crypt ratios; defects in enterocyte structure or immune-mediated conditions result in an abnormal villus to crypt ratios and morphology. Whole-exome and genome sequencing in the early stages of evaluation can reduce the time required for a definitive diagnosis of CODEs, or lead to identification of new variants associated with these enteropathies. The functional effects of gene mutations can be analyzed in model systems such as enteroids or induced pluripotent stem cells and are facilitated by recent advances in gene editing procedures. Characterization and investigation of new CODE disorders will improve management of patients and advance our understanding of epithelial cells and other cells in the intestinal mucosa.

Short bowel syndrome (SBS) is a malabsorptive state occuring as a result of surgical resection or congenital disease of a significant portion of the small intestine . The amount of resection or remaining bowel generally dictates the degree of malabsorption and consequentely the need for specialized enteral nutrition or parenteral nutrition (PN). Intestinal failure in the context of SBS is defined as a dependence on PN to maintain minimal energy and fluid requirement for growth in children. Common causes of SBS in infants and children include necrotizing enterocolitis, midgut volvulus, intestinal atresia, and gastroschisis. Early identification of patients at risk for long-term PN dependency is the first step toward avoiding severe complications. Close monitoring of nutritional status, steady and early introduction of enteral nutrition, and aggressive prevention, diagnosis, and treatment of infections such as central venous catheter sepsis and bacterial overgrowth can significantly improve the prognosis. Intestinal transplantation is an emerging treatment that may be considered when intestinal failure is irreversible and children are experiencing serious complications related to TPN administration.

BACKGROUND-Serial transverse enteroplasty (STEP) is a novel surgical therapy for short bowel syndrome and is being used with increasing frequency worldwide. Because no single center is likely to obtain sufficient experience for meaningful analysis, we created the International STEP Data Registry to allow for larger, multicenter patient accrual and followup. This report describes patient characteristics, operative parameters, and early results of STEP in the first 38 patients enrolled in the International STEP Data Registry.