Let sleeping dogs lie: role of the omentum in the ileal pouch-anal anastomosis procedure

What are the short- and long-term abdominal consequences of an omentectomy? A systematic review

This review provides an overview regarding the abdominal effects of an omentectomy, with or without extra-peritoneal reconstructions. In general, reported complication rates were low. Short-term complications involved ileus, bowel stenosis, abdominal abscess and sepsis (range 0.0%-23%). Donor-site hernia was mainly reported as long-term complication (up to 32%) and negligible gastrointestinal complications were observed. However, the level of evidence and methodological quality are quite low with a maximum of 8.5 years follow-up.

Revisiting the Use of Normal Saline for Peritoneal Washing in Ovarian Cancer

The omentum is the predominant site of ovarian cancer metastasis, but it is difficult to remove the omentum in its entirety. There is a critical need for effective approaches that minimize the risk of colonization of preserved omental tissues by occult cancer cells. Normal saline (0.9% sodium chloride) is commonly used to wash the peritoneal cavity during ovarian cancer surgery. The omentum has a prodigious ability to absorb fluid in the peritoneal cavity, but the impact of normal saline on the omentum is poorly understood. In this review article, we discuss why normal saline is not a biocompatible solution, drawing insights from clinical investigations of normal saline in fluid resuscitation and from the cytopathologic evaluation of peritoneal washings. We integrate these insights with the unique biology of the omentum and omental metastasis, highlighting the importance of considering the absorptive ability of the omentum when administering agents into the peritoneal cavity. Furthermore, we describe insights from preclinical studies regarding the mechanisms by which normal saline might render the omentum conducive for colonization by cancer cells. Importantly, we discuss the possibility that the risk of colonization of preserved omental tissues might be minimized by using balanced crystalloid solutions for peritoneal washing.

Exploring the Obesity Paradox in A Murine Model of Sepsis: Improved Survival Despite Increased Organ Injury in Obese Mice

ABSTRACT

Despite the known deleterious effects of obesity, clinical data indicate that overweight or obese patients experience higher rates of sepsis survival compared to normal and underweight patients; a phenomenon called the obesity paradox. Results from preclinical sepsis studies have not been able to replicate these findings. The objective of this study was to test the existence of the obesity paradox in a murine model of cecal slurry (CS)-induced sepsis with insulin-resistant diet-induced obese mice. Male C57BL/6 mice were provided high-fat (HFD) or low-fat (LFD) diets for 20 weeks. HFD-fed mice experienced higher rates of survival compared to LFD-fed mice after septic challenge induced by CS injection (66% vs. 25%, P = 0.01, survival assessed for 14 days). Despite the survival advantage, HFD-fed mice had higher rates of positive bacterial cultures and increased markers of kidney injury. Circulating levels of IL-6, IL-1β, TNFα, and IL-23 were equivalent 24 h after CS-injection; however, IL-17A was uniquely increased in HFD-fed mice. While LFD-fed mice maintained euglycemia, HFD-fed mice were hyperglycemic 6 and 12 h after CS-injection. Stable isotope resolved metabolomics analysis of liver tissue showed diverging pathways of glucose utilization during sepsis, with LFD-fed mice significantly upregulating glycolytic activity and HFD-fed mice decreasing glucose entry into the TCA cycle. This murine study corroborates clinical data that obesity confers a survival benefit in sepsis, albeit at the expense of more significant organ injury. The mechanisms promoting survival in the obese remain unknown; however, this model appears to be well-poised to begin answering this question. Differences in glucose utilization are a novel target to investigate this paradox.

Is omentectomy necessary in the treatment of benign or malignant abdominal pathologies? A systematic review

BACKGROUND

The omentum is an organ that is easily sacrificed during abdominal surgery. The scope of omentectomy and whether a routine omentectomy should be performed are still unknown.

AIM

To review the literature in order to determine the physiological functions of the omentum and the roles it plays in pathological events in order to reveal the necessity for removal and preservation of the omentum.

METHODS

A clinical review of the English language literature based on the MEDLINE (PubMed) database was conducted using the keywords: “abdomen”, “gastrointestinal”, “tumor”, “inflammation”, “omental flap”, “metastasis”, “omentum”, and “omentectomy”. In addition, reports were also identified by systematically reviewing all references in retrieved papers.

RESULTS

The omentum functions as a natural barrier in areas where pathological processes occur in the abdominal cavity. The omentum limits and controls inflammatory and infectious pathologies that occur in the abdomen. It also aids in treatment due to its cellular functions including lymphatic drainage and phagocytosis. It shows similar behavior in tumors, but it cannot cope with increasing tumor burden. The stage of the disease changes due to the tumor mass it tries to control. Therefore, it is considered an indicator of poor prognosis. Due to this feature, the omentum is one of the first organs to be sacrificed during surgical procedures. However, there are many unknowns regarding the role and efficacy of the omentum in cancer.

CONCLUSION

The omentum is a unique organ that limits and controls inflammatory processes, foreign masses, and lesions that develop in the abdominal cavity. Omental flaps can be used in all anatomical areas, including the thorax, abdomen, pelvis, and extremities. The omentum is an organ that deserves the title of the abdominal policeman. It is generally accepted that the omentum should be removed in cases where there is tumor invasion. However, the positive or negative contribution of omental resection in the treatment of abdominal pathologies should be questioned.

The Greater Omentum-A Vibrant and Enigmatic Immunologic Organ Involved in Injury and Infection Resolution

Once thought of as an inert fatty tissue present only to provide insulation for the peritoneal cavity, the omentum is currently recognized as a vibrant immunologic organ with a complex structure uniquely suited for defense against pathogens and injury. The omentum is a source of resident inflammatory and stem cells available to participate in the local control of infection, wound healing, and tissue regeneration. It is intimately connected with the systemic vasculature and communicates with the central nervous system and the hypothalamic pituitary adrenal axis. Furthermore, the omentum has the ability to transit the peritoneal cavity and sequester areas of inflammation and injury. It contains functional, immunologic units commonly referred to as "milky spots" that contribute to the organ's immune response. These milky spots are complex nodules consisting of macrophages and interspersed lymphocytes, which are gateways for the infiltration of inflammatory cells into the peritoneal cavity in response to infection and injury. The omentum contains far greater complexity than is currently conceptualized in clinical practice and investigations directed at unlocking its beneficial potential may reveal new mechanisms underlying its vital functions and the secondary impact of omentectomy for the staging and treatment of a variety of diseases.

The Essential Involvement of the Omentum in the Peritoneal Defensive Mechanisms During Intra-Abdominal Sepsis

Although the abilities of the omentum to alleviate inflammation and prevent infection have been revealed over the past decades, the underlying mechanisms remain largely unelucidated. Here, we demonstrated that the mortality of mice exposed to cecal ligation and puncture (CLP) and omentectomy was remarkably increased compared to those treated with CLP alone. Moreover, the efficacy of the omentum was associated with an impairment in intraperitoneal bacterial clearance together with an increase in the expression of proinflammatory cytokines. Besides, in response to peritoneal infections, the size and quantity of the omental milky spots (MSs) were increased tremendously and they also support innate-like B1 cell responses and local IgM production in the peritoneal cavity. Furthermore, not only the migration but also the functional activities of neutrophils were diminished in the absence of the omentum. These data collectively show that the omentum contributes more to peritoneal immune responses during septic peritonitis than has heretofore been recognized. Thus, harnessing the function of MS-containing omentum to increase its protective effectiveness may exert important biological and therapeutic implications for the control of intra-abdominal infections.

The Contribution of the Omentum to the Outcome From Sepsis: An Experimental Animal Study

The omentum is a large mesenchymal fibro-fatty tissue with remarkable healing capability. It is also rich in immune cells, including macrophages and lymphocytes, within particular structures named milky spots. Clinical observations indicate a high incidence of peritonitis after the removal of the omentum suggesting that it may play a role in sepsis. To test this possibility, male CD-1 mice underwent simultaneous omentectomy and cecal ligation and puncture (CLP), omentectomy-sham operation and CLP alone, and mortality was documented within 72 h post the insults. A significant increase in mortality was observed in mice subjected to omentectomy and CLP in comparison with CLP alone. Mortality was correlated with an increase in cytokine gene expression within the lung after omentectomy and CLP as opposed to CLP alone. However, no differences in bacterial load were observed within the peritoneum or blood between groups. To test the long-term effect of omentectomy, mice were subjected to omentum removal or sham operation, allowed to recover from surgery for 14 or 28 days, and then both were subjected to CLP. In these cases, no differences in mortality were observed between the groups suggesting that the lack of omentum triggers a compensatory mechanism. Finally, omentectomy and sham operation altered the composition of peritoneal immune cells with the disappearance of F4/80 macrophages and the appearance of a new population of F4/80 macrophages within 1 or 14 days post-surgery. The F4/80 positive cells reappeared after 28 days following the procedures. All of these observations suggest that the omentum plays an early role in the outcome from sepsis.

Gastrectomy with or without omentectomy for cT3–4 gastric cancer: a multicentre cohort study

Background

Omentectomy is performed widely for locally advanced gastric cancer to prevent disease recurrence. However, its clinical benefit is unknown.

Methods

This retrospective cohort study compared the outcome of gastrectomy with preservation of the omentum (GPO) and gastrectomy with resection of the omentum (GRO) among patients with cT3–T4 gastric cancer who underwent gastrectomy between 2006 and 2012 in one of five participating institutions. A consensus conference identified 28 variables potentially associated with outcome after gastrectomy for the estimation of propensity scores, and propensity score matching (PSM) was undertaken to control for possible confounders. Postoperative surgical outcomes, overall survival and disease recurrence were compared between GPO and GRO.

Results

A total of 1758 patients were identified, of whom 526 remained after PSM, 263 in each group. Median follow-up was 4·9 (i.q.r. 3·1–5·9) years in the GRO group and 5·0 (2·5–6·8) years in the GPO group. The incidence of postoperative complications of Clavien–Dindo grade III or more was significantly higher in the GRO group (17·5 versus 10·3 per cent; P = 0·016). Five-year overall survival rates were 77·1 per cent in the GRO group and 79·4 per cent in the GPO group (P = 0·749). There were no significant differences in recurrence rate or pattern of recurrence between the groups.

Conclusion

Overall survival and disease recurrence were comparable in patients with cT3–4 gastric cancer who underwent GPO or GRO.

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.

Risk Factors for Small Bowel Obstruction After Laparoscopic Ileal Pouch-Anal Anastomosis for Inflammatory Bowel Disease: A Multivariate Analysis in Four Expert Centres in Europe

BACKGROUND AND AIMS

Although laparoscopy is associated with a reduction in adhesions, no data are available about the risk factors for small bowel obstruction [SBO] after laparoscopic ileal pouch-anal anastomosis [IPAA]. Our aims here were to identify the risk factors for SBO after laparoscopic IPAA for inflammatory bowel disease [IBD].

METHODS

All consecutive patients undergoing laparoscopic IPAA for IBD in four European expert centres were included and divided into Groups A [SBO during follow-up] and B [no SBO].

RESULTS

From 2005 to 2015, SBO occurred in 41/521 patients [Group A; 8%]. Two-stage IPAA was more frequently complicated by SBO than 3- and modified 2-stage IPAA [12% vs 7% and 4%, p = 0.04]. After multivariate analysis, postoperative morbidity (odds ratio [OR] = 3, 95% confidence interval [CI] = 1.5-7, p = 0.002), stoma-related complications [OR = 3, 95% CI = 1-6, p = 0.03] and long-term incisional hernia [OR = 6, 95% CI = 2-18, p = 0.003] were predictive factors for SBO, while subtotal colectomy as first surgery was an independent protective factor [OR = 0.4, 95% CI = 0.2-0.8, p = 0.002]. In the subgroup of patients receiving restorative proctocolectomy as first operation, stoma-related or other surgical complications and long-term incisional hernia were predictive of SBO. In the patient subgroup of subtotal colectomy as first operation, postoperative morbidity and long-term incisional hernia were predictive of SBO, whereas ulcerative colitis and a laparoscopic approach during the second surgical stage were protective factors.

CONCLUSIONS

We found that SBO occurred in less than 10% of patients after laparoscopic IPAA. The study also suggested that modified 2-stage IPAA could potentially be safer than procedures with temporary ileostomy [2- and 3-stage IPAA] in terms of SBO occurrence.

Secondary peritonitis: principles of diagnosis and intervention

Secondary peritonitis accounts for 1% of urgent or emergent hospital admissions and is the second leading cause of sepsis in patients in intensive care units globally. Overall mortality is 6%, but mortality rises to 35% in patients who develop severe sepsis. Despite the dramatic growth in the availability and use of imaging and laboratory tests, the rapid diagnosis and early management of peritonitis remains a challenge for physicians in emergency medicine, surgery, and critical care. In this article, we review the pathophysiology of peritonitis and its potential progression to sepsis, discuss the utility and limitations of the physical examination and laboratory and radiographic tests, and present a paradigm for the management of secondary peritonitis.

Protection from septic peritonitis by rapid neutrophil recruitment through omental high endothelial venules

Acute peritonitis is a frequent medical condition that can trigger severe sepsis as a life-threatening complication. Neutrophils are first-responders in infection but recruitment mechanisms to the abdominal cavity remain poorly defined. Here, we demonstrate that high endothelial venules (HEVs) of the greater omentum constitute a main entry pathway in TNFα-, Escherichia coli (E. coli)- and caecal ligation and puncture-induced models of inflammation. Neutrophil transmigration across HEVs is faster than across conventional postcapillary venules and requires a unique set of adhesion receptors including peripheral node addressin, E-, L-selectin and Mac-1 but not P-selectin or LFA-1. Omental milky spots readily concentrate intra-abdominal E. coli where macrophages and recruited neutrophils collaborate in phagocytosis and killing. Inhibition of the omental neutrophil response exacerbates septic progression of peritonitis. This data identifies HEVs as a clinically relevant vascular recruitment site for neutrophils in acute peritonitis that is indispensable for host defence against early systemic bacterial spread and sepsis.

Is a More Comprehensive Surgery Necessary in Patients With Uterine Serous Carcinoma?

Objective

Uterine serous carcinoma (USC) is an aggressive histologic subtype of endometrial cancer that shares similarities to serous ovarian cancer, with a propensity for spread to the upper abdomen, a high recurrence rate, and a poor prognosis. The aim of this study was to determine whether the traditional surgical staging procedure for endometrial cancer was adequate for USC or whether a more extensive surgery, similar to the staging procedure for ovarian cancer, needs to be performed. Specifically, the roles of omentectomy and sentinel lymph node (SLN) mapping were evaluated.

Methods

We retrospectively identified cases of presumed clinical stage I USC at our institution from April 2005 to March 2014. Medical records were reviewed for the following information: age at diagnosis, preoperative imaging, operative findings, surgical procedure, and final histology with definitive International Federation of Gynecology and Obstetrics stage.

Results

A total of 39 patients with presumed clinical stage I USC were identified. According to the final pathology report, the surgical stage was as follows: 17 stage IA (44%), 8 stage IB (20%), 3 stage II (8%), 2 stage IIIA (5%), 6 stage IIIC1 (15%), 1 IIIC2 (3%), and 2 stage IVB (5%). Therefore, 14 patients (36%) were surgically upstaged, but none of the patients had their clinical disease upstaged by virtue of finding microscopic metastatic disease in an otherwise normal-looking omentum. Sentinel lymph node mapping was performed in 19 patients (42%). Sensitivity and negative predictive value of SLN mapping were 100% when at least 1 SLN was identified.

Conclusions

The detection of microscopic disease in radiologically and clinically normal-appearing omentum seems to be rare in USC. Sentinel lymph node mapping seems to be valuable in the serous subtype of endometrial cancer. A less extensive surgery may be possible in patients with USC as it seems to provide the same information as a more extensive surgery.

A new cecal slurry preparation protocol with improved long-term reproducibility for animal models of sepsis

Sepsis, a life-threatening systemic inflammatory response syndrome induced by infection, is widely studied using laboratory animal models. While cecal-ligation and puncture (CLP) is considered the gold standard model for sepsis research, it may not be preferable for experiments comparing animals of different size or under different dietary regimens. By comparing cecum size, shape, and cecal content characteristics in mice under different experimental conditions (aging, diabetes, pancreatitis), we show that cecum variability could be problematic for some CLP experiments. The cecal slurry (CS) injection model, in which the cecal contents of a laboratory animal are injected intraperitoneally to other animals, is an alternative method for inducing polymicrobial sepsis; however, the CS must be freshly prepared under conventional protocols, which is a major disadvantage with respect to reproducibility and convenience. The objective of this study was to develop an improved CS preparation protocol that allows for long-term storage of CS with reproducible results. Using our new CS preparation protocol we found that bacterial viability is maintained for at least 6 months when the CS is prepared in 15% glycerol-PBS and stored at -80°C. To test sepsis-inducing efficacy of stored CS stocks, various amounts of CS were injected to young (4-6 months old), middle-aged (12-14 months old), and aged (24-26 months old) male C57BL/6 mice. Dose- and age-dependent mortality was observed with high reproducibility. Circulating bacteria levels strongly correlated with mortality suggesting an infection-mediated death. Further, injection with heat-inactivated CS resulted in acute hypothermia without mortality, indicating that CS-mediated death is not due to endotoxic shock. This new CS preparation protocol results in CS stocks which are durable for freezing preservation without loss of bacterial viability, allowing experiments to be performed more conveniently and with higher reproducibility than before.

Management of acute colitis and toxic megacolon

Severe colitis is a well-defined condition that can develop in patients afflicted with ulcerative colitis, but typically responds to a variety of medical therapies. Operative intervention is warranted when massive hemorrhage, perforation, or peritonitis complicates the clinical scenario or medical therapy fails to control the disease. Of the operative options, total/subtotal colectomy and end ileostomy is the usual procedure of choice especially if the operation can be performed through a laparoscopic approach.

Technical aspects of ileoanal pouch surgery

Ileal pouch-anal anastomosis has become the surgical procedure of choice for chronic ulcerative colitis. Since the initial description of the technique, various modifications have facilitated its evolution into a safe operation with excellent long-term outcomes. However, some aspects of the operation remain contentious. Our aim is to describe the technical aspects of ileal pouch-anal anastomosis and review the current literature in the areas of controversy.

The omentum: anatomical, metabolic, and surgical aspects

INTRODUCTION

The omentum is acknowledged to have diverse functions in the pathophysiology of intra-abdominal disease. Its angiogenic properties act as a natural defense mechanism in peritonitis and intra-abdominal sepsis. With advancing technology the omentum is revealing itself as a new player in the field of molecular surgery with special reference to cancer, obesity and tissue reconstruction.

MATERIALS AND METHODS

This article reviews the existing and potential surgical applications of the omentum.

Sacral osteomyelitis after ileal pouch-anal anastomosis: report of four cases

PURPOSE

This study describes an institutional experience with sacral osteomyelitis after proctocolectomy and ileal pouch-anal anastomosis.

METHODS

A total of 2,375 patients underwent ileal pouch-anal anastomosis at the Mayo Clinic between January 1981 and January 2002. In addition, we have served as a tertiary referral base for patients with complications after ileal pouch-anal anastomosis performed at other institutions. Review of our ileal pouch-anal anastomosis prospective database and directed search of the central pathology, microbiology, radiology, and surgical records at the Mayo Clinic was performed using these keywords: osteomyelitis, ileal pouch-anal anastomosis, inflammatory bowel disease, chronic ulcerative colitis, and Crohn's disease.

RESULTS

Two of 2,375 patients (0.08 percent) with ileal pouch-anal anastomosis performed at our institution have had sacral osteomyelitis. In addition, two patients have been referred for continuing care after construction of an ileal pouch-anal anastomosis and diagnosis of sacral osteomyelitis at another institution. Two of the four patients maintained normal pouch function after sacral debridement and a period of fecal stream diversion. One patient remains diverted with resolved sacral osteomyelitis after debridement. The last patient died from squamous-cell cancer involving the sacrum.

CONCLUSIONS

Sacral osteomyelitis is a rare and heretofore unreported complication of ileal pouch-anal anastomosis. Conservative measures using antibiotics alone proved unsuccessful, and delaying definitive management may have contributed to the degeneration of a chronic sacral abscess into squamous-cell cancer. With more aggressive treatment comprising sacral debridement, long-term antibiotics, and fecal diversion, pouch function can potentially be preserved.

The use of tissue flaps as an adjunct to pelvic surgery

BACKGROUND

The clinical problems of advanced malignancy with invasion of cancers into adjacent organs or structures, fistulizing complications from radiation therapy, postoperative infections, and delayed postoperative healing continue to challenge pelvic surgeons, regardless of subspecialty. The use of autologous muscle and myocutaneous flaps has been applied to the management and prevention of these clinical problems and found to be most helpful.

METHODS

Records of patients undergoing abdominopelvic procedures in a single unit during the 15-year period from 1990 to 2005 were reviewed, and patients undergoing autologous tissue flaps were reviewed with respect to indications, complications, and outcomes.

RESULTS

Thirty-four patients underwent 35 autologous muscle or myocutaneous flaps for the following indications: large anticipated defects in primary or reoperative cancer surgery (13 patients); malignant, traumatic, inflammatory, or radiation-induced fistulae (12 patients); excision of (an) adjacent organ(s) with need for reconstruction (7 patients); and chronic nonhealing pelvic wounds (2 patients). Wound complications occurred in 41% of patients; however, primary healing of flaps occurred in 88% of patients.

CONCLUSIONS

The use of autologous tissue flaps in select patients can be a useful adjunct in pelvic surgery in dealing with a wide variety of problems, specifically in filling large defects, providing vascularized tissue for fistula closure, and avoiding delayed wound healing commonly seen after high-dose radiation.

[Optimization of staging in colon cancer using sentinel lymph node biopsy]

Routine determination of the nodal status in colon cancer is strongly dependent on the individual quality and technique of histopathological assessment and surgical lymph node dissection. We evaluated whether sentinel lymph node biopsy (SLNB) could contribute to an improvement in staging. At least one SLN (median n=2) was detected (detection rate 84%) in each of 38 of 45 patients with primary colon cancer. Ten of these 38 were found to have lymph node metastases by HE staining (26%), six of them in the SLN. Nine of the 28 patients that were initially nodal-negative by HE revealed one micrometastasis and eight cases of isolated tumor cells by immunohistochemical (IHC) staining (32% upstaging response). Including the IHC-positive cases, 19 of the 38 patients were nodal-positive (50%), 15 of them with tumor-infiltrated SLN (overall sensitivity of SLNB 79%). Using the dye method, SLNB is clinically practicable and leads in the majority of the patients to the detection of SLN. The selective, intensified histopathological assessment of SLN identifies small tumor cell deposits in a relevant percentage of patients with little and clinically practicable effort.

Role of peritoneal mesothelial cells in peritonitis

Background

Peritoneal mesothelial cells have a remarkable capacity to respond to peritoneal insults. They generate an intense biological response and play an important role in the formation of adhesions. This review describes these activities and comments on their relationship to surgical drainage, peritoneal lavage and laparostomy in the management of patients with peritonitis.

Methods and results

Material was identified from previous review articles, references cited in original papers and a Medline search of the literature. The peritoneal mesothelium adapts to peritonitis by facilitating the clearance of contaminated fluid from the peritoneal cavity and inducing the formation of fibrinous adhesions that support the localization of contaminants. In addition, the fluid within the peritoneal cavity is a battleground in which effector mechanisms generated with the involvement of peritoneal mesothelial cells meet the contaminants. The result is a complex mix of cascading processes that have evolved to protect life in the absence of surgery.

Conclusion

Future advances in the management of patients with severe peritonitis may depend upon molecular strategies that modify the activity of peritoneal mesothelial cells.

Omental transposition for low pelvic anastomoses

Surgeons' opinions differ regarding the role of the omentum in low pelvic intestinal anastomoses. This study was undertaken to define the anatomy and surgical technique of omental transposition to the pelvis. We studied 45 cadavers to elucidate surgical aspects of omental mobilization, lengthening, and transposition into the pelvic cavity. In addition, intraoperative studies of omental transposition to the pelvis were performed in 20 patients with chronic ulcerative colitis, familial adenomatous polyposis, and rectal cancer who were undergoing ileal J-pouch anal anastomosis or low anterior resection. The most important anatomic variables for omental transposition are three variants of arterial blood supply: (1) In 56% of patients, there is one right, one (or two) middle, and one left omental artery. (2) In 26% of patients, the middle omental artery is absent. (3) In the remaining 18% of patients, the gastroepiploic artery is continued as a left omental artery but with various smaller connections to the right or middle omental artery. The first stage of omental lengthening is detachment of the omentum from the transverse colon mesentery. This must be performed carefully, as the omentum is closely adherent to the right transverse mesocolon. The second stage is the actual lengthening of the omentum. The third stage is placement of the omental flap into the pelvis. Creation of an omental pedicle is a simple surgical procedure. This procedure can be performed quickly, does not involve significant blood loss, and may reduce the frequency of complications after low pelvic anastomoses.

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.

Small bowel obstruction after total or subtotal colectomy: a 10-year retrospective review

BACKGROUND

The aim of this retrospective study was to determine the cumulative incidence of adhesive small bowel obstruction (SBO) after total or subtotal colectomy and to investigate the site of the obstructive adhesions in the abdominal cavity.

METHODS

The records of 234 patients who underwent colectomy from 1985 to 1994 were reviewed for SBO, potential risk factors for SBO, and the site of adhesions causing obstruction. Mean follow-up, which was complete in 215 patients, was 63 months.

RESULTS

SBO occurred in 56 patients (24 per cent) of whom 42 (18 per cent) had adhesive obstruction. The risk of SBO due to adhesions within 1 year was 11 per cent, increasing to 30 per cent 10 years after colectomy. With univariate analysis no risk factor for adhesive SBO, including previous laparotomies, septic complications and omental resection, was identified. The most common site of obstructing adhesions was the pelvis (ten of 28 patients).

CONCLUSION

The incidence of SBO after colectomy is high. Colectomy may be a suitable model for studies of adhesion prevention.

The pathobiology of peritonitis

The peritoneum is more than a mechanical covering that allows for the easy gliding of opposed peritoneal surfaces. The peritoneal mesothelial cells facilitate the action of powerful innate immune mechanisms. In addition, the peritoneal-associated lymphoid tissues contain unique cells that may play a crucial role in the localization of intraperitoneal infection. A clearer understanding of the molecular and cellular events underlying peritoneal functions in both the unstimulated and stimulated state will aid future treatment of peritonitis.

Current status of incidental surgery

PURPOSE

Incidental surgery is a common occurrence in abdominal operations. This article is a review of recent publications on the safety and efficacy of such secondary procedures.

METHODS

A recent review of the literature as well as incorporation of some original data were conducted.

RESULTS

Incidental surgery is safe, but the indication should be clear in the surgeon's mind, including epidemiologic risk of disease in such organs as the gallbladder and appendix.

CONCLUSION

Factors that must be included into a decision to perform incidental surgery should be the age and general health of the patient, prognosis, setting of the original operation (emergency vs. nonemergency), and epidemiologic risk of disease when incidental surgery is performed prophylactically.

Obstruction after ileal pouch-anal anastomosis: a preventable complication?

Small bowel obstruction is a common complication after ileal pouch-anal anastomosis. This review of 460 patients examines the frequency of small bowel obstruction and determines potential risk factors. The leading indication for ileal pouch-anal anastomosis was ulcerative colitis (83 percent). In 142 patients (31 percent), loop ileostomy was rotated 180 degrees to facilitate emptying of the ileostomy. Ninety-four patients (20 percent) had 109 episodes of obstruction. Obstruction occurred after creation of the pouch (40 episodes), closure of the ileostomy (29 episodes), or developed during the subsequent follow-up period (40 episodes). Operative intervention was required in 39 percent of the episodes (7 percent of all patients). At operation, the most common point of obstruction was at closure of the ileostomy (n = 22/42, 52 percent). In 16 of these patients, the ileostomy had been rotated. Multiple risk factors, including age, sex, primary diagnosis, surgeon incidence, pouch type, prior colectomy, steroid usage, stomal rotation, technique of closure of the ileostomy, and prior obstruction, were examined by univariate and multivariate analysis. Of all factors, only stomal rotation was statistically significant (P = 0.0005, chi-squared analysis). Rotation of the loop ileostomy during ileal pouch-anal anastomosis, although an apparent technical refinement, is unnecessary and predisposes to obstruction.