Omental reinforcement of intestinal anastomoses. An experimental study in the rabbit

Evidence according to Cochrane Systematic Reviews on Alterable Risk Factors for Anastomotic Leakage in Colorectal Surgery

Anastomotic leakage reflects a major problem in visceral surgery, leading to increased morbidity, mortality, and costs. This review is aimed at evaluating and summarizing risk factors for colorectal anastomotic leakage. A generalized discussion first introduces risk factors beginning with nonalterable factors. Focus is then brought to alterable impact factors on colorectal anastomoses, utilizing Cochrane systematic reviews assessed via systemic literature search of the Cochrane Central Register of Controlled Trials and Medline until May 2019. Seventeen meta-anaylses covering 20 factors were identified. Thereof, 7 factors were preoperative, 10 intraoperative, and 3 postoperative. Three factors significantly reduced the incidence of anastomotic leaks: high (versus low) surgeon's operative volume (RR = 0.68), stapled (versus handsewn) ileocolic anastomosis (RR = 0.41), and a diverting ostomy in anterior resection for rectal carcinoma (RR = 0.32). Discussion of all alterable factors is made in the setting of the pre-, intra-, and postoperative influencers, with the only significant preoperative risk modifier being a high colorectal volume surgeon and the only significant intraoperative factors being utilizing staples in ileocolic anastomoses and a diverting ostomy in rectal anastomoses. There were no measured postoperative alterable factors affecting anastomotic integrity.

Omentum a powerful biological source in regenerative surgery

The Omentum is a large flat adipose tissue layer nestling on the surface of the intra-peritoneal organs. Besides fat storage, omentum has key biological functions in immune-regulation and tissue regeneration.

Omentum biological properties include neovascularization, haemostasis, tissue healing and regeneration and as an in vivo incubator for cells and tissue cultivation. Some of these properties have long been noted in surgical practice and used empirically in several procedures.

In this review article, the author tries to highlight the omentum biological properties and their application in regenerative surgery procedures. Further, he has started a process of standardisation of basic biological principles to pave the way for future surgical practice.

A primer on wound healing in colorectal surgery in the age of bioprosthetic materials

Wound healing is a complex, dynamic process that is vital for closure of cutaneous injuries, restoration of abdominal wall integrity after laparotomy closure, and to prevent anastomotic dehiscence after bowel surgery. Derangements in healing have been described in multiple processes including diabetes mellitus, corticosteroid use, irradiation for malignancy, and inflammatory bowel disease. A thorough understanding of the process of healing is necessary for clinical decision making and knowledge of the current state of the science may lead future researchers in developing methods to enable our ability to modulate healing, ultimately improving outcomes. An exciting example of this ability is the use of bioprosthetic materials used for abdominal wall surgery (hernia repair/reconstruction). These bioprosthetic meshes are able to regenerate and remodel from an allograft or xenograft collagen matrix into site-specific tissue; ultimately being degraded and minimizing the risk of long-term complications seen with synthetic materials. The purpose of this article is to review healing as it relates to cutaneous and intestinal trauma and surgery, factors that impact wound healing, and wound healing as it pertains to bioprosthetic materials.

Omentoplasty in the prevention of anastomotic leakage after colorectal resection: a meta-analysis

PURPOSE

Whether omentoplasty after colorectal anastomosis can reduce anastomotic leakage is controversial. Our aim was to do a meta-analysis of randomized controlled trials to compare anastomotic leakage rates between an omentoplasty group and a no omentoplasty group after colorectal anastomosis.

MATERIALS AND METHODS

We searched the Cochrane Center Register of Controlled Trials, PubMed, EMBASE, and Chinese Biomedical Literature Database up to June 2008 in any language. Reference lists from all selected articles were also examined. Randomized controlled trials of omentoplasty in the prevention of anastomotic leakage after colorectal resection were selected and evaluated by two investigators. Analyses were performed using Review Manager 4.2.

RESULTS

Three randomized controlled trials totaling 943 participants were included. Meta-analysis results showed that no statistically significant difference was found between the omentoplasty group and the no omentoplasty group in radiological anastomotic leakage (RR 0.76, 95% CI 0.41 to 1.40), death (RR 1.01, 95% CI 0.55 to 1.86), and repeat operation (RR 0.60, 95% CI 0.35 to 1.05), except for clinical anastomotic leakage (RR 0.36, 95% CI 0.16 to 0.78).

CONCLUSION

Based on available data from a small number of trials, there is not enough evidence to say whether or not omentoplasty should be used to reduce anastomotic leakage after colorectal resection. The decision as to whether we should continue to use this technique might remain a matter of surgical judgment. Therefore, the results still need to be confirmed by future multicenter, well-designed trials.

Adhesions in patients with chronic pelvic pain: A role for adhesiolysis?

OBJECTIVE

To review the relation between adhesions and pelvic pain and the effectiveness of adhesiolysis in pain control.

DESIGN

Selective review of the literature.

PATIENT(S)

Patients with pelvic pain and/or undergoing adhesiolysis for pain control.

RESULT(S)

Intraabdominal adhesions are accepted as etiologic factors for infertility and small bowel obstruction; however, the contribution of adhesions to pelvic pain is less clear. The most common laparoscopic findings in patients with and without pelvic pain were endometriosis and adhesions. Immunohistologic studies also have shown evidence of nerve fibers in adhesions that had been removed from patients with and without pelvic pain. Multiple adhesiolysis techniques have been employed, with outcome of surgical procedures ranging from no pain relief to pain relief in 90% of patients. However, randomized trials have shown that adhesiolysis is ineffective in improving the outcome of the treatment of pelvic pain, possibly because of adhesion reformation. Interestingly, adhesions are usually not described as an etiologic factor for pelvic pain in men; this might be related to a gender difference in pain perception or the possibility that adhesions per se do not cause pain.

CONCLUSION(S)

The correlation between pelvic pain and adhesions is uncertain. Adhesiolysis has not been shown to be effective in achieving pain control in randomized clinical studies.

Human peritoneal adhesions are highly cellular, innervated, and vascularized

Peritoneal adhesions are a major complication of healing following surgery or infection and can lead to conditions such as intestinal obstruction, infertility, and chronic pain. Mature adhesions are the result of aberrant peritoneal healing and historically have been thought to consist of non-functional scar tissue. The aim of the present study was to analyse the cellular composition, vascularity, and extracellular matrix distribution of human peritoneal adhesions, to determine whether adhesions represent redundant scar tissue or are dynamic regenerating structures. Furthermore, the histological appearance of each adhesion was correlated with the clinical history of the patient, to determine whether maturity or intraperitoneal pathology influences adhesion structure. Human peritoneal adhesions were collected from 29 patients undergoing laparotomy for various conditions and were prepared for histology, immunocytochemistry, and transmission electron microscopy. All adhesions were highly vascularized, containing well-developed arterioles, venules, and capillaries. Nerve fibres, with both myelinated and non-myelinated axons, were present in adhesions from nearly two-thirds of the patients, with increased incidence in those with a malignancy. Approximately one-third of the adhesions contained conspicuous smooth muscle cell clusters lined by collagen fibres of heterogeneous size. Adipose tissue was a consistent feature of all the adhesions, with some areas displaying fibrosis. There appeared to be no correlation between the estimated maturity or site of each adhesion and its histological appearance. However, intraperitoneal pathology at the time of surgery did influence the incidence of some histological features, such as the presence of nerve fibres, clusters of smooth muscle cells, and inflammation. This study challenges previous concepts that adhesions represent non-functional scar tissue and clearly demonstrates that established adhesions are highly cellular, vascularized, and innervated, features more consistent with dynamic, regenerating structures.

Microvascular transplantation of a free omental graft to the distal extremity in dogs

OBJECTIVE

To assess the survival of a free omental graft applied to an experimentally created wound on the distal extremity in dogs.

STUDY DESIGN

A free omental graft was evaluated as a primary method of treatment for dogs with distal extremity wounds in an experimental model.

ANIMALS OR SAMPLE POPULATION

Five adult intact female mixed breed dogs weighing 21.8 kg to 25.0 kg.

METHODS

A free omental graft was harvested from the abdomen and transferred to a wound bed overlying the medial aspect of the tibia. A microvascular anastomosis was performed between the graft vessels and vessels at the recipient site. Daily clinical assessment of graft viability was performed. Angiography and 99mTechnetium labeled macroaggregated albumin (99mTc MAA) scintigraphic perfusion scans were performed on either day 4, 5, or 7. Postmortem collection of tissues for histopathologic analysis was performed immediately after imaging. Total operative time and graft ischemia time were evaluated for effects on graft survival.

RESULTS

Two of seven grafts survived to the end of the study, three of seven grafts failed because of ischemia, and two of seven grafts failed because of self-trauma. There was no clinically significant morbidity associated with the abdominal portion of the procedure. Because of the small number of surviving grafts, the effects of operative time and graft ischemia time could not be statistically evaluated.

CONCLUSIONS

Microvascular transplantation of a free omental graft can result in a viable tissue covering of a distal extremity wound, however, the failure rate is unacceptably high.

CLINICAL RELEVANCE

A free omental graft may not have sufficient durability to be an acceptable wound covering by itself. Further studies combining omentum with a skin graft or other tissues may result in a clinically useful technique.

Avaliação da resistência de suturas duodenais com ou sem omentoplastia pediculada: estudo experimental em ratas

Estudamos os efeitos da omentoplastia pediculada como método de reforço de suturas sobre o duodeno. Foram utilizadas 135 ratas HOLTZMAN, divididas em nove subgrupos de quinze ratas cada (n=15). Após a realização de uma lesão padronizada na segunda porção do duodeno, os animais, exceto os do grupo controle, foram submetidos, dependendo do subgrupo, a dois tipos diferentes de reparos: n sutura da lesão e omentoplastia pediculada de reforço. n sutura da lesão sem omentoplastia de reforço. A avaliação da resistência do reparo da lesão duodenal, foi realizada através da insuflação de ar até a ruptura do segmento testado. Esta avaliação foi feita em três períodos pós-operatórios diferentes: dois, sete e 14 dias em todos os subgrupos. O coeficiente de variação (CV) foi utilizado como forma de avaliar a variabilidade interna das variáveis centrais do estudo. Nos casos em que a análise indicou a existência de influência de algum fator ou de interações entre os fatores estudados, realizamos as comparações múltiplas de médias segundo o teste "Least Significant Difference" (LSD). Os achados mostraram que a realização de uma omentoplastia pediculada como reforço de um reparo sobre uma lesão padronizada do duodeno, quando comparado a uma simples sutura, não aumentou a resistência do reparo. Não importando o dia de pós-operatório em que o teste de resistência foi realizado. Os achados histológicos demonstraram que a omentoplastia pediculada proporcionou reação inflamatória intensa no nível do reparo.

Use of the greater omentum in colorectal surgery

INTRODUCTION

Complications related to impaired healing remain a major challenge in colorectal surgery. This review examines the potentially protective role of the greater omentum in colorectal operations.

METHODS

Review of all reports concerning applications of the greater omentum in colorectal surgery identified through MEDLINE (1966-1997) and other sources.

RESULTS

Clinical case studies indicate that an interposition flap of omentum is beneficial in the management of complex rectal fistulas. Pelvic omentoplasty or an omental hammock appears to reduce the incidence of radiation enteropathy in patients receiving pelvic radiotherapy after rectal resection. However, recent research demonstrates that omental wrapping does not "protect" colonic or rectal anastomoses. Nor is there convincing evidence that pelvic omentoplasty promotes primary perineal healing after abdominoperineal resection for cancer, although it may reduce the incidence of perineal wound breakdown.

CONCLUSIONS

Previous assumptions concerning the omentum are now being rigorously investigated with the aim of defining its true value in colorectal applications. This must be encouraged, especially where use of the omentum increases the magnitude or duration of operations significantly.

AÇÃO DO OMENTO NA CICATRIZAÇÃO DE ANASTOMOSES COLÔNICAS. ESTUDO EXPERIMENTAL EM RATOS

Desde o século XIX o omento maior vem sendo utilizado em diferentes procedimentos cirúrgicos. O objetivo desse estudo foi avaliar os efeitos da omentoplastia na cicatrização de anastomoses colônicas em ratos. Utilizaram-se 64 ratos machos, que foram divididos em 4 grupos (A,AN,B,C). Realizou-se uma anastomose colônica situada há 5 cm da borda anal, de três maneiras diferentes: para os grupos A e AN , anastomose padrão com 8 pontos seromusculares; para o grupo B, anastomose isquêmica e, para o grupo C uma anastomose deficiente com apenas 4 pontos. Na metade dos animais de cada grupo a anastomose foi recoberta com o omento e desta forma obteve-se os subgrupos AO, ANO, BO, CO. No grupo AN e ANO utilizou-se tinta nanquim para avaliar a neovascularizção. Todos os animais foram submetidos a eutanásia no 7o dia de pós-operatório. Concluiu-se que a utilização da omentoplastia promoveu, uma neovascularização na área de anastomose, aumentou a presença de colágeno e levou a uma diminuição da presença de aderências próximo da linha de sutura.

Omentoplasty in the prevention of anastomotic leakage after colonic or rectal resection: a prospective randomized study in 712 patients. French Associations for Surgical Research

OBJECTIVE

To investigate the role of omentoplasty (OP) in the prevention of anastomotic leakage after colonic or rectal resection.

SUMMARY BACKGROUND DATA

It has been proposed that OP--wrapping the omentum around the colonic or rectal anastomosis--reinforces intestinal sutures with the expectation of lowering the rate of anastomotic leakage. However, there are no prospective, randomized trials to date to prove this.

METHODS

Between September 1989 and March 1994, a total of 705 patients (347 males and 358 females) with a mean age of 66 +/- 15 years (range, 15-101) originating from 20 centers were randomized to undergo either OP (n = 341) or not (NO, n = 364) to reinforce the colonic anastomosis after colectomy. Patients had carcinoma, benign tumor, colonic Crohn's disease, diverticular disease of the sigmoid colon, or another affliction located anywhere from the right colon to and including the midrectum. Patients undergoing emergency surgery were not included. Random allotment took place once the resection and anastomosis had been performed, the surgeon had tested the anastomosis for airtightness, and the omental flap was deemed feasible. Patients were divided into four strata: ileo- or colocolonic anastomosis, supraperitoneal ileo- or colorectal anastomosis, infraperitoneal ileo- or colorectal anastomosis, and ileo- or coloanal anastomosis. The primary end point was anastomotic leakage. Secondary end points included intra- and extraabdominal related morbidity and mortality. Severity of anastomotic leakage was based on the rate of repeat operations and related deaths.

RESULTS

Both groups were comparable in terms of preoperative characteristics. Intraoperative findings were similar, except that there were significantly more septic operations and abdominal drainage performed in the NO group (p < 0.05 and p < 0.01, respectively). Thirty-five patients (4.9%) had postoperative anastomotic leakage, 16 in the OP group (4.7%) and 19 in the NO group (5.2%). There were 32 deaths (4.5%), 17 (4.9%) in the OP group and 15 (4.2%) in the NO group. Five patients with anastomotic leakage died (0.8%), 2 of whom had OP. There were 37 repeat operations (30%), 12 (6 in each group) for anastomotic leakage. Repeat operation was associated with fatal outcome in 14% of cases. The rate of these and the other intra- and extraabdominal complications did not differ significantly between the two groups.

CONCLUSION

OP to reinforce colorectal anastomosis decreases neither the rate nor the severity of anastomotic failure.

Healing in the gastrointestinal tract

Healing in the GI tract is rapid when free of complications: Unlike cutaneous healing, in which progress can be observed on a daily basis and intervention instituted early if necessary, healing of the intestinal anastomosis is anatomically obscured from inspection, allowing the surgeon only the patient's parameters of general well-being to judge the success of the operation. For the same reason, complications usually require re-operation, with the associated morbidity of a laparotomy and additional general anesthetic. This places a great responsibility on the surgeon to be cognizant of all the preoperative, intraoperative, and postoperative factors relating to anastomotic healing that might compromise the healing process. Bearing these in mind, along with attention to technical detail, should limit complications to an acceptable level. Patients most at risk are (1) those who perioperatively develop physiologic problems that lead to shock, hypoxia, and resultant anastomotic ischemia, (2) those with radiation-induced tissue injury, (3) those with sepsis, and (4) those with preoperative bowel obstruction. Malnourishment, malignancy, diabetes, steroids, and age also influence outcome to varying degrees. Future advancement in the field of GI healing lies in our ability to manipulate the early struggle between collagen synthesis and collagen breakdown. A profound understanding of the molecular and biochemical pathways and the factors that control them will bring us closer to this goal. Clinically, this may be accomplished by the introduction of wound healing enhancers into the anastomotic site, possibly by incorporating them into suture materials, biofragmentable anastomotic rings, or staple materials. Already much is known about the influence of different cytokines and growth factors on collagen regulation, knowledge that will help resolve many of the long-standing problems associated with GI surgery.

Effect of an omental wrap on the healing and vascularity of compromised intestinal anastomoses

Adult Wistar rats were used to investigate the ability of an omental wrap to limit leakage from compromised intestinal anastomoses. Under ketamine anesthesia, a section of small bowel was divided and then reanastomosed using a "control" anastomosis, a "deficient" anastomosis, or an "ischemic" anastomosis, plus or minus the addition of a wrap of omentum. Initially 10 rats were randomly assigned to each group. Nineteen of the 20 rats with unwrapped compromised anastomoses died within six weeks, compared with five deaths in the rats protected by an omental wrap (Fisher's exact test; P less than 0.01). The experiment was then repeated with a sample of rats from each anastomotic group being sacrificed for histologic examination on days 2 to 7, 10, 14, and 42. At the time of sacrifice a dye was injected into the omental vasculature to determine its contribution to the healing anastomosis. An anastomosis could be demonstrated between omental and bowel wall vessels by the third postoperative day. At one week the infarcted bowel edges were being resorbed and the omentum formed a fibrotic cylinder aligning the separated ends of bowel wall. At six weeks the scar became more contracted and the bowel mucosa had started to grow onto its luminal surface. It is concluded from this study that the omental wrap is protective to a compromised anastomosis by providing a biologically viable plug to prevent early leakage and a source of granulation tissue and neovasculature for later wound repair.

[Securing colon anastomoses by surrounding it with a polyglycolic acid filament net. An animal experiment study]

Resorbable polyglycolic-acid (PGA)-nets are used successfully for the treatment of traumatic ruptures of parenchymous organs. This experimental study was carried out to investigate whether PGA-nets can also re-enforce jeopardized colon anastomoses. In 75 Wistar rats the transverse colon was transsected and reanastomosed. Animals were divided into 2 groups: in one group the anastomosis was applied sufficiently, in the other group the anastomosis was applied potentially insufficient. Out of each group a PGA-net was placed around the anastomosis in one half of the animals. The results demonstrated that delayed healing of the anastomoses as well as spontaneous suture line disruptions followed by peritonitis only occurred in those animals in which a PGA-net had been used. The evaluation of the bursting strength could confirm this finding of delayed consolidation. The bursting pressure therefore was significantly decreased in all animals in which a PGA-net had been applied, compared to the control group operated without PGA-net application. We therefore conclude that PGA-net application in colon anastomoses inhibits the consolidation of the suture line, probably because of a lack of contact to the peritoneal and omental tissue.

Management of the pelvic space following low anterior resection

Four cases of low anterior resection without pelvic drainage are described. The outcome was unsatisfactory in three of the four patients. The role of pelvic drains and omentum in the management of the pelvic space following low anterior resection for rectal cancer is reviewed and discussed. Pelvic drains are required to remove blood and omentum may be used to fill the pelvic space. Pelvic collections are related to anastomotic leakage and the optimal management of the pelvic space can reduce the incidence of this complication. A suggested regimen for management of the pelvic space after low anterior resection is outlined.

The omentum in malignant diseases

The technique and applications of omentoplasty are reviewed from the point of view of the surgical oncologist, with particular emphasis on the use of the omentum in gastrointestinal anastomoses, covering peritoneal defects or radical intra-abdominal operations for neoplastic disease, urological complications, breast cancer, abdominal and chest wall resections, the prevention of arterial graft erosions, and the treatment of lymphoedema and chemotherapeutic burns. Complications are discussed as well as future prospects.