Massive bloody stools in two neonates caused by cow's milk allergy.

Two neonatal cases of cow's milk allergy showing bilous vomiting and massive bloody stool are presented. In both cases, laboratory data on admission showed no eosinophilia. The immediate upper gastrointestinal series of both cases demonstrated no evidence of intestinal malrotation, but revealed a narrowing of the duodenum and upper jejunal loops and marked stasis of barium in one case, suggesting an edema with inflammation. Rectal mucosal punch biopsy of the other case showed eosinophilic infiltration in the lamina propria. These findings suggested an allergic origin, useful information for avoiding confusion with some diseases requiring emergency surgery. In both cases, bleeding resolved soon after elimination of cow's milk from the diet. Thereafter both cases showed a moderate to marked increase in peripheral eosinophilia, while serum radioallergosorbent tests for cow's milk protein were negative. Definitive diagnosis of allergic enterocolitis is difficult because there is neither specific laboratory data nor tests. Allergic enterocolitis can occur in the early neonatal period and should be considered in differential diagnosis of any newborn developing gastrointestinal bleeding.