Hexosaminidase: A Marker for Intestinal Gangrene in Necrotizing Enterocolitis By Them E. Lobe, Marshall Z. Schwartz, C Joan Richardson, David K. Rassin, William K. Gourley, Satish K. Srivastava, and Rostyk B. Storozuk Galveston, Texas 9 Detection of intestinal ischemia, prior to necro- sis, is a major clinical problem. The lysosomal acid hydrolase, hexosaminidase (HEX), is known to be elevated in intestinal infarction. To determine if this enzyme could differentiate between partial intestinal ischemia and full-thickness intestinal gangrene, the following rat study was designed. Partial segmental intestinal ischemia was created by ligating alternate vascular bundles over a short (6 vessel) segment of the small-bowel mesentery, and complete segmental intestinal vascular occlusion was achieved by ligating the blood supply to the ileocecal segment. Preopera- tive serum HEX values were obtained from 15 ani- mals. The rats were separated into one sham- operated and two intestinal ischemia groups. At four hours after surgery HEX values were determined. Total HEX activity was significantly elevated four hours after insult in both partial and complete intes- tinal ischemia, (P < 0.005 and P < 0.001 respec- tively). Total HEX activity was greater in complete intestinal ischemia than in partial ischemia, (P < o.o5l. Three neonates with intestinal perforation, sec- ondary to necrotizing enterocolitis, were evaluated. The mean preoperative HEX activity was 1421 nmol/ hr/mL serum and the mean post-resection FlEX activity was 808 nmol/hr/mL serum. These data suggest that serum HEX activity may be a good marker for intestinal gangrene in neonates with necrotizing enterocolitis. INDEX WORDS: Hexosaminidase; necrotizing ente- rocolitis; intestinal gangrene; mesenteric infarction. D ETECTION of intestinal ischemia, prior to necrosis and perforation, remains a prob- lem in infants with necrotizing enterocolitis (NEC). Many investigators have searched for reliable techniques for detecting intestinal gan- grene in infants. These have included: abdominal paracentesis; 1radionuclide scanning;2'3and serial observations using radiography, physical exami- nation, and nonspecific laboratory data. Several authors have discussed the value of measuring acid-base balance,4 levels of organic phosphates: and serum levels of lysosomal enzyme activity, in order to detect intestinal infarction in adults with mesenteric ischemia.6 Recently Poison, et al 7 described experimental and clinical evidence that measurements of the lysosomal acid hydrolase, N-acetyl-hexosamini- dase (HEX), may be useful in the detection of intestinal necrosis. Their data suggested that the beta fraction of this enzyme (HEX B) is elevated in patients with mesenteric infarction. This study was designed to determine whether total HEX activity or the percent of HEX B activity could differentiate between partial intes- tinal ischemia and full-thickness intestinal gan- grene, and to assess the value of this enzyme assay in infants with NEC. MATERIALS AND METHODS Experimental Study Fifteen male Fisher rats, weighing between 150 to 200 g were anesthetized using ketamine sulfate, and blood was collected from each animal for preoperative control values. The rats were then divided into one sham-operated, and two intestinal ischemia groups. Group 1, sham-operated animals were subjected to lapa- rotomy. The small and large intestines were exteriorized, manipulated, and then returned to the peritoneal cavity. Group 2, partial intestinal ischemia rats were subjected to laparotomy. After exteriorization of the small and large intestine, partial segmental intestinal ischemia was created by ligating alternate vascular bundles over a short (six vessel) segment of the small bowel mesentery (see Fig. 1A). Group 3, Complete intestinal ischemia rats underwent intestinal exteriorization, and complete intestinal vascular occlusion was achieved by ligating the vascular supply to the ileocecal segment (see Fig. 1B). Four hours following operation, blood was drawn from each rat and the animals were then killed. Ischemic segments of intestine were resected, opened along the antimesenteric border, washed to remove intestinal contents, and placed in 10% formalin for fixation. All blood samples were centri- From the Pediatric Surgical Service, the Department of Surgery and the Departments of Pediatrics, Pathology, and Human Genetics, The University of Texas Medical Branch, Galveston, Texas. Presented before the 31st Annual Meeting of the Surgical Section of the American Academy of Pediatrics, New York, New York, October 23-24, 1982. Address reprint requests to Them E. Lobe, MD, Pediatric Surgical Service, Child Health Center g:C3-65, The Univer- sity of Texas Medical Branch, Galveston, TX 77550. 0022-3468/83/I 804~022/$01.00/0 Journal of Pediatric Surgery, Vol. 18, No. 4 (August), 1983 449