Controlling Peritoneal Adhesions

Comparative effectiveness of several agents for preventing postoperative adhesions

Postoperative adhesions (PAs) are usually clinically asymptomatic. Symptomatic cases, however, may present with chronic abdominal and pelvic pain, infertility, and intestinal obstruction; and they may require intensive, costly therapeutic modalities. Various agents have been used to prevent PAs, but the results indicate general suboptimal effectiveness. Our objective was to evaluate the comparative effectiveness of two pharmacologic agents for preventing PA: nadroparine calcium (low-molecular-weight heparin, or LMWH) and aprotinin, as well as a barrier agent, sodium hyaluronate/carboxymethycellulose (SCMC). Our subjects were 40 male Wistar-Albino rats divided into four groups, each consisting of 10 rats, which underwent standard cecal abrasion preceding midline laparotomy. In the control group (group 1) 1 ml of 0.9% NaCl was administered intraperitoneally before abdominal closure. In the three preventive groups, 100 U AXa (anti factor X activity) LMWH, 1800 IU aprotinin, and SCMC were administered intraperitoneally to groups 2, 3, and 4, respectively. Relaparotomy was performed on the 14th postoperative day. Visceral and abdominal wall adhesions were scored in a blinded fashion. The adhesion scores (mean +/- SD) for groups 1, 2, 3, and 4 were 2.00 +/- 0.67, 0.6.00 +/- 0.84, 1.10 +/- 0.74, and 0.20 +/- 0.42, respectively. The differences in the adhesion scores among all three preventive groups (groups 2, 3, 4) were statistically significant when compared with the control group ( p < 0.001, p = 0.017, p < 0.001, respectively). Intraperitoneal SCMC and administration of LMWH were more effective than giving aprotinin.

Induction of peritoneal adhesions with small intestinal ischaemia and distention in the foal

Twenty-two foals were divided into groups of intestinal distension and intestinal ischaemia as methods to induce peritoneal adhesions. In the first group, the lumen of a segment of distal small intestine was occluded without extramural vascular compromise and distended with lactated Ringer's solution to a constant pressure of 25 cm H2O for 2 h within the abdomen. The ischaemic group underwent 70 mins total vascular occlusion of identical segments of bowel. Serosal biopsies were obtained before and after each experimental procedure and following 60 mins of reperfusion. Similar biopsies were harvested from a control group of foals with no bowel occlusions. The foals were destroyed 10 days after surgery and tissues collected for histological and ultrastructural evaluation. Experimental and control mesothelial surfaces were denuded histologically immediately after experimental occlusions. Serosal oedema and cellular infiltration were observed following reperfusion of the ischaemic segments but were present immediately after 2 h of distension. All foals had developed bowel-to-bowel and bowel-to-mesentery adhesions of the experimental segments. Control foals under 30 days old exhibited mesenteric contraction and thickening of the isolated segment whereas those older than 30 days had little or no mesenteric thickening or contraction. Histologically, in the experimental segments, fibrous tissue had formed on the outer boundary of the original serosa, and new mesothelial-like cells were present on the surface of fibrous tissue in some areas. Some serosal fibrosis was also seen in most of the control segments.

Abdominal adhesions after small intestinal surgery in the horse

One hundred thirteen of 172 horses (66%) undergoing exploratory celiotomy for a small intestinal lesion survived 4 or more days after surgery. Intra-abdominal adhesions causing clinical problems requiring additional surgery or euthanasia were documented in 25 horses (22.1%). Problems developed in significantly more males than females. The most common initial small bowel lesion was ileal impaction (12 horses); 21 horses underwent small intestinal resection or bypass. However, there was no significant difference in the incidence of intra-abdominal adhesions between horses that underwent intestinal resection or bypass and those that did not. Only 4 of the 25 horses (16%) with problems associated with postoperative adhesions survived. The mean interval between surgical procedures or between the initial procedure and euthanasia for all horses was 84 days (range, 7-512 days; median, 25 days). However, 70% of the subsequent celiotomies were performed within 60 days of the previous surgery. The mean interval between celiotomies was 221 days (range, 9-512 days) for the survivors and 61 days (range, 7-358 days) for the nonsurvivors. These results indicated that most of the problems related to postoperative intra-abdominal adhesions occurred within 2 months of the initial small intestinal surgery. Furthermore, the earlier development of postoperative adhesions was associated with a poorer prognosis for survival.

Prevention of intraabdominal adhesions in ponies by low-dose heparin therapy

An ischemic bowel model was used to stimulate adhesion formation in eight ponies. Heparin (40 USP u/kg) or saline was administered intravenously at surgery and was continued subcutaneously every 12 hours for 48 hours to evaluate the efficacy of heparin in preventing intraabdominal adhesions. Ponies were euthanatized after 6 weeks, and postmortem examinations were performed. A statistically significant difference was found between the heparin-treated and the control groups. Adhesions developed in three of four control ponies, and adhesions did not develop in three of four heparin-treated ponies. None of the adhesions resulted in clinical disease. In this study, heparin decreased the formation of adhesions in ponies after experimentally induced intestinal ischemia.