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improved outcomes in colon and rectal surgery The specific type of fecal diversion, ileostomy versus colostomy, does not influence anastomotic related outcomes.(25) mechanical bOwel PRePaRatiOn Mechanical bowel preparation before elective resection has been surgical dogma since Halsted’s description of intestinal anasto-mosis in 1887.Empiric-based practice relies on mechanical bowel preparation together with oral antibiotics to reduce the bacterial load of the bowel and, in theory, to decrease the risks of anas-tomotic leak and surgical site infection. Bowel preparation, far from innocuous,is inconvenient and unpleasant for patients and is associated with potentially harmful metabolic and fluid distur-bances. For these reasons, and because the purported benefits of bowel preparation remain unproven, the utility of mechanical preparation has been questioned. A Cochrane review evaluating the efficacy of bowel prepara-tion in its ability to reduce postoperative complications included 1,592 patients from nine randomized, controlled trials stratified to a colectomy group and a low anterior resection group.(26) The clinical leak rate in the colectomy group with and without bowel preparation was 2.9% and 1.6%,respectively (p value not signifi-cant). The clinical leak rate in the low anterior resection group with and without bowel preparation was 9.8% and 7.5%, respec-tively (p value not significant). When the surgical groups were combined, the 6.2% clinical leak rate in the prepared group was significantly higher than the 3.2% rate in the unprepared group (p = 0.003). Meta-analysis of all other infectious complication rates, including surgical site infection, demonstrated no protec-tive effect of mechanical bowel preparation. Despite significant evidence that bowel preparation before elective colorectal resection does not influence infectious com-plications (and may actually increase the anastomotic leak rate) surgical tradition and medico-legal pressure continue to heav-ily influence the practice of colorectal surgery with respect to mechanical bowel preparation. anastOmOtic techniqUe Stapled techniques for low pelvic anastomosis have been rigor-ously evaluated since their introduction into the armamentarium of colorectal surgery. A systematic Cochrane review comparing the outcomes of straight, end-to-end stapled and handsewn col-orectal anastomoses pooled data on 1,233 patients from nine ran-domized,controlled trials.(27) This comprehensive meta-analysis found no statistically significant difference with regard to clinical leaks (stapled 6.3% vs. handsewn 7.1%, p value not significant) or radiologic anastomotic dehiscence (stapled 7.8% vs.handsewn 7.2%,p value not significant). A similarly conducted Cochrane review of four randomized, controlled trials comparing stapled versus handsewn ileocolic anastomoses during colon cancer resection demonstrated signifi-cantly fewer clinical leaks in the stapled group (1%) compared to the handsewn group (4.2%, p = 0.04).(28) Given the fundamen-tal differences between ileocolic and colorectal anastomoses, it is not surprising that they each may have unique technical require-ments to reduce the risks of complications. In addition to evaluating the mechanics of forming the anas-tomosis, the configuration of the anastomosis has been studied with regard to possible reduction in the risk of leak. Of the most common stapled colorectal anastomotic configurations (end-to-end, side-to-end Baker, colonic “J” pouch) there is no optimal configuration that consistently confers a risk reduction benefit. (8, 10, 15, 17, 19, 29) It has also been shown that the size of the circular stapler does not contribute to the leak rate.(14) Omental PeDicle In an effort to quarantine an anastomosis in the event of a leak and to mitigate the consequences of a leak, many surgeons utilize an omental pedicle. To reach a pelvic anastomosis, the omentum is typically mobilized to survive off the left gastroepiploic artery.The influence ofan omental pedicle on anastomotic outcomes was eval-uated in a prospective,randomized study of 705 patients undergo-ing bowel anastomosis and no statistically significant influence on the rate or severity of leak was observed.(30) Another smaller,ran-domized,controlledtrialof 126patientsdemonstratedaprotective effect of an omental pedicle; though, this study could be criticized for a rather high leak rate (22%) in the group of patients without an omentoplasty.(31) Both of these studies reported overall leak rates including clinical and radiologic leaks. The discrepancy between these two trials is characteristic of many of the studies investigating anastomotic complications. Leaks are low frequency events requiring large,homogenous study populations for accurate evaluation.No firm evidence-based rec-ommendation can be made with regard to omentoplasty and its potential effects on colorectal anastomotic outcomes;bringing an omental pedicle to the pelvis should be done according to the surgeon’s preference. RaDiatiOn Neoadjuvant radiotherapy has been evaluated in terms of poten-tially increasing the risk of dehiscence of pelvic anastomoses. The proposed mechanism of increasing the leak rate is that pel-vic radiation may interfere with healing of the anastomosis due to toxicity in the pelvis. Radiation changes to the colon side of the anastomosis are usually not an issue as the irradiated colon is resected at the time of the proctectomy to ensure that healthy colon is used to form the anastomosis. The Dutch Total Mesorectal Excision (TME) trial randomized 1,414 rectal cancer patients to neoadjuvant short-course radia-tion therapy followed by low anterior resection versus resection alone and demonstrated no significant difference between the two groups with respect to clinical anastomotic leak (neoadju-vant group leak rate 11% versus surgery alone leak rate 12%, p value not significant). However, these results were difficult to interpret because patients in the radiotherapy group were more likely to have a diverting stoma.(19, 22) The Swedish rectal can-cer trial randomized 1,168 patients to short-course neoadjuvant radiation followed by surgery versus surgery alone and also dem-onstrated no significant difference in leak rates between the two study arms.(32) A nonrandomized study comparing 150 patients who received long-course chemoradiation (5,040 cGy) followed by surgery to 531 patients who underwent surgery alone dem-onstrated similar results with 4% overall leak rate in each group (p = 0.86).(10) The notion that neoadjuvant radiotherapy increases the risk of leak is not supported by the majority of the  postoperative anastomotic complications literature and may be incorrectly based on the fact that low pelvic anastomoses in the setting of total mesorectal excision are more likely to leak.(33, 34) Pelvic DRains Pelvic drains are placed by some surgeons to prevent colorectal anastomotic leaks and to diagnose leaks sooner with the hope of initiating treatment before leaking patients clinically decompen-sate. The possible mechanism whereby pelvic drains, theoreti-cally,may protect against colorectal anastomotic leak relies on the characteristics of the extra-peritoneal low pelvis in that the peri-toneum is absent.Violation of the presacral space during proctec-tomy leaves a significant raw surface and without the absorptive abilities of the peritoneum fluid can collect in the dependent dead space created by total excision of the mesorectum. Further com-plicating the matter is the potential for negative pressure in the low pelvis that promotes the accumulation of fluid that can possi-bly disrupt the anastomosis.A pelvic drain can, possibly, prevent accumulation of fluid behind the anastomosis. These theoretical benefits of pelvic drainage together with results of statistically under-powered trials may explain why many surgeons continue to drain pelvic anastomoses. Routine pelvic drainage has been evaluated in retrospective fashion as well as with randomized, controlled trials with regard to a possible influence on the occurrence and diagnosis of col-orectal anastomotic leak. For example, the data collected in the prospective, randomized Dutch TME trial was studied after-the-fact in retrospective fashion to determine the utility of pelvic drainage during low anterior resection.(19) Patients in this trial were randomly assigned whether or not to receive neoadjuvant radiation therapy before TME. At the time of operation, place-ment of pelvic drains was decided at the discretion of the oper-ating surgeon. Multiple regression analysis demonstrated that pelvic drainage was strongly associated with a lower clinical leak rate (leaks occurred in 9.6% of patients with drains compared with 23.5% of patients without drains, p < 0.001). Moreover, the need for re-operation in leaking patients was significantly more likely in patients without preexisting pelvic drainage (97% of leaking patients without drains were re-operated versus 74% of leaking patients with drains, p = 0.006). Other reviews and ran-domized trials regarding the use of drains have been published with contradicting results and conclusions; some attributed an increase in the leak rate to pelvic drainage.(14, 29, 35, 36) Like the retrospective study reviewed above,many of these papers may not have accurately evaluated the utility of drains due to lack of statistical power or suboptimal methodology. To better evaluate the utility of pelvic drainage after colorec-tal anastomosis, a Cochrane review tested the hypothesis that anastomotic drainage after elective colorectal surgery does not prevent the development of complications.(37) This exhaus-tive meta-analysis pooled data on 1,140 patients from six ran-domized, controlled trials. The clinical anastomotic leak rate for patients with drains versus without drains was 2% and 1%, respectively (p value not significant). Stratification of the data according to the height of the anastomosis also showed no ben-efit of drainage even for low pelvic anastomoses. In addition, the re-operation rates between patient groups with and without drains were comparable.This review does not support the prac-tice of routinely draining colorectal anastomoses. The practice of routinely draining colorectal anastomoses is not supported by strong scientific evidence. In addition, there is no compelling literature supporting the notion that pelvic drains facilitate earlier diagnosis of a leak. miscellaneOUs Other factors shown to increase the colorectal anastomotic leak rate include total mesorectal excision (8, 15, 16), height of the anastomosis from the anal verge (5, 20, 33), male gender (5, 20), and prolonged operating time (20).Each of these factors is either difficult or impossible to influence. Due to the large numbers of patients required to study anastomotic complications, many variables may never be studied sufficiently in terms of possibly contributing to anastomotic leak (Table 7.1). Total mesorectal excision, as it was originally described, left a relatively ischemic distal rectum after resection for proximal rec-tal cancer.Tumor specific mesorectal excision for proximal rectal cancer has become popular as it preserves the distal mesorectum without compromising oncologic adequacy and decreases the risk of leak compared with total mesorectal excision.(10, 15, 33, 38) The height of an anastomosis can influence tension across the tissues and, together with prolonged operating time, is likely a surrogate marker for more difficult operations especially in the narrow, male pelvis. It is also postulated that, in low pelvic anas-tomoses, the proximate anal sphincter increases the intraluminal pressure across the anastomosis jeopardizing its integrity. In terms of the surgical approach, the Clinical Outcomes of Surgical Therapy (COST) trial and others have not demonstrated an increased anastomotic failure rate with regard to laparoscopic versus conventional open colectomy.(39–41) Trials evaluating laparoscopic versus open rectal cancer resection with colorectal anastomosis are underway. clinical PResentatiOn The clinical manifestations of anastomotic dehiscence vary depending on the location of the leaking anastomosis, the severity of the leak and whether or not the leak is contained or walled-off. For these reasons, while many patients with anasto-motic dehiscence present acutely with signs and symptoms of sepsis and an abdominal catastrophe, a subset of patients have Table 7.1 Factors with conflicting evidence in the literature that may or may not impact anastomotic leak rates. Smoking or alcohol abuse (33, 46, 59) Obesity (8) Hospital operative caseload (24) Surgeon subspecialty training and volume (33, 60, 61) Diabetes (48) Cardiovascular disease (48) Steroid use (46, 48) Malnutrition (46, 62) Anemia (48) Blood transfusions (46) Intraoperative rectal irrigation ASA score (33) Field contamination  improved outcomes in colon and rectal surgery Table 7.2 The time interval between colorectal anastomosis and diagnosis of a leak. Post Op Day study N of Diagnosisa Range (days) Rullier 1998 (8) 32 11 2–41 Carlsen 1998 (16) 11 8 4–15 Alves 2002 (47) 43 8.1 4–25 Mäkelä 2003 (46) 44 8 3–25 Hedrick 2006 (4) 14 9b 3–137 Matthiessen 2007 (17) 27 8b 3–18 Nicksa 2007 (45) 36 10.1 2–50 Jung 2008 (6) 35 5.5b 2–15 a. Mean. b. Median. a more sub-acute, insidious presentation. This is more typical of walled-off infections and leaks that have sealed on their own. Possibly contributing to a sub-acute presentation of a leak is the use of antibiotics during recovery from colorectal surgery (for pneumonia, urinary tract infection, etc.) that can mask the signs and symptoms of an occult leak. While the majority of patients with colorectal anastomotic leak are diagnosed within a week of operation,a significant proportion of patients are diagnosed well beyond this timeframe (Table 7.2). Patients with a more delayed presentation of a leak have often been released from the hospital only to be diagnosed upon re-admission.(42) Patients with feculent peritonitis or diffuse purulent peritonitis typically become acutely ill,often in dramatic fashion,with classic signs and symptoms of peritonitis, hemodynamic instability and rapid progression to multisystem organ dysfunction. Meanwhile, in a considerable number of patients, recognition of an anasto-motic leak may be difficult due to the significant overlap between the signs and symptoms of a leaking patient and those of a typi-cal patient recovering from major abdominal surgery. Patients may present with any combination of fever, tachycardia, varying degrees of abdominal pain and distension, ileus, diarrhea, mal-aise, failure to thrive, bowel obstruction, and septic shock. Some patients present with symptoms mimicking cardiac complications such as respiratory failure and chest pain. Leaking patients may also fail to clinically progress or recover within a usual timeframe, have increasing narcotic demands,or have decreased urine output requiring fluid boluses.The physical exam of a leaking patient may include focal or diffuse abdominal tenderness, rigidity, guarding, abdominal distension, and evidence of varying degrees of hemo-dynamic collapse.Patients may have leukocytosis,typically with a left shift, leukopenia, metabolic acidosis, or thrombocytopenia. After any intestinal anastomosis, the surgeon must maintain a high index of suspicion when evaluating patients with unusual signs of sepsis or patients who fail to meet the clinical milestones of normal recovery within a typical timeframe. The potential for delay in diagnosis is significant; delays may impact patient out-comes and have medicolegal ramifications. DiagnOsis Patients with generalized peritonitis consistent with a leak require urgent return to the operating room with concomitant intrave-nous fluid resuscitation and broad-spectrum antibiotics. In this setting, the time to re-operation is critical and a diagnostic jour-ney with imaging studies will only delay potentially life-saving abdominal exploration. Meanwhile, patients with a more subtle clinical presentation do not mandate immediate exploration and may benefit from imaging studies to confirm the diagnosis and direct appropriate management. Although no single radiologic study is ideal for investigating a possible leak, computed tomography (CT) and contrast enemas are the tests of choice in this setting.The advantage of triple con-trast CT scanning with intravenous, oral, and rectal contrast is that it may identify other potential underlying pathologies like ileus, abscess, hematoma, and bowel obstruction. CT scan find-ings consistent with anastomotic leak include extravasation of luminal contrast, perianastomotic fluid, ascites, and varying amounts of extra-luminal gas. With the exception of contrast extravasation,many of the CT findings in leaking patients are not specific and overlap considerably with CT scans of nonleaking patients in the postoperative setting.The mere presence of free air in the postoperative period is not specific for a leak and has been demonstrated by CT in control patients without anastomoses up to 9 days after operation and even later.(43,44) Depending on the clinical circumstances, inconclusive CT findings can be followed up with a contrast enema study,repeat CT or abdominal explora-tion to exclude anastomotic leak. According to some of the literature, CT may be superior to contrast enema when determining the integrity of an anastomo-sis.(42) Potential shortcomings of enema studies in this setting are that the water-soluble contrast can dilute out and compro-mise resolution of a contrast enema and that clinicians may be reluctant, in the early postoperative period, to introduce a suf-ficient column of enema contrast to adequately fill the rectum. On the other hand,some of the retrospective literature strongly favors contrast enema over CT in terms of diagnosing a pelvic anastomotic leak outright as well as after a CT scan fails to dem-onstrate a leak.(9, 45) Extravasation or pooling of rectal contrast outside of the bowel lumen during an enema study is pathogno-monic of leak (Figures 7.1 and 7.2).Water-soluble contrast must be used when evaluating for a possible anastomotic dehiscence as extravasated barium increases the severity of a leak by adding to the inflammatory response in the abdomen. In reality, the choice of imaging study in a particular patient is influenced by the clini-cal presentation, institutional expertise, and available resources. management The management of anastomotic dehiscence in a particular patient depends on the clinical manifestations of the leak and the condition of the patient (Figure 7.3). Common manifesta-tions of a leak from a colorectal anastomosis are asymptomatic, leak without abscess,leak with associated abscess,peritonitis,and colocutaneous fistula. Asymptomatic Early in the experience with circular staplers, routine water-soluble contrast enemas demonstrated that as many as half of patients with pelvic anastomoses demonstrated a radiologic leak during the first postoperative week. Often these are short, sim-ple sinus tracts originating from the anastomosis. In otherwise  postoperative anastomotic complications Figure 7.1 Gastrografin enema demonstrating anastomotic leak (black arrows) from colorectal anastomosis (anterior-posterior view). Figure 7.2 Gastrografin enema demonstrating leak with contained abscess (white arrows) from colorectal anastomosis (lateral view). Anastomotic Leak Peritonitis Laparotomy Antibiotics Resuscitation Colocutaneous Fistula Address any collections Abscess Drainage Antibiotics No abscess No peritonitis Antibiotics Bowel rest Antibiotics Bowel rest Nutrition Fistula Worsens Leak resolves No resolution or Patient worsens No further treatment Resolution No resolution Laparotomy No further treatment Figure 7.3 Management algorithm for patients with anastomotic leak. asymptomatic patients with an anastomotic leak discovered inci-dentally, no intervention is required as the leak is not likely of clinical consequence and will seal spontaneously. Leak without abscess Stable patients with mild symptoms,focal abdominal tenderness, and radiologic evidence of anastomotic leak without abscess may be initially treated nonoperatively with bowel rest and intrave-nous fluids and broad-spectrum antibiotics. These are often minor leaks that can, potentially, seal spontaneously. The dura-tion of treatment is empiric and is based on the clinical response, the patient’s condition, and the surgeon’s judgment. An initial treatment period of several days is reasonable after which par-enteral nutrition or re-operation often need to be addressed. Clearly, failure to improve or clinical deterioration requires sur-gical intervention.It is difficult to predict which patients will suc-cessfully recover without re-operation in the setting of a leak;this treatment pathway requires dedicated attention on the part of the surgeon with frequent hands-on re-evaluation. Leak with associated abscess Stable patients with CT evidence of a contained leak with an abdominopelvic abscess should,initially,be treated with drainage and appropriate antibiotic therapy (Figures 7.4 and 7.5).Drainage  improved outcomes in colon and rectal surgery Figure 7.4 Abdominal CT scan demonstrating a large abdominal abscess (arrows mark cavity). is usually performed percutaneously or trans-anally through the anastomotic defect. There are situations where operative drain-age is required due to inaccessibility of an abscess by less invasive routes, but these are quite uncommon. As before, patients who fail nonoperative treatment require exploration.A contained leak can rupture freely into the abdomen; depending on the clinical circumstances, repeat imaging, or urgent exploration would be required in this situation. Peritonitis Patients with generalized peritonitis consistent with a leak require urgent exploration with aggressive fluid resuscitation and intrave-nous antibiotic administration on the way to the operating room. Typically,these patients decompensate quickly and become unstable and must be treated in urgent fashion.As reviewed earlier, in these situations, there is no benefit to pursuing diagnostic studies as the consequences of delaying operative intervention may be dire. Colocutaneous fistula Fistulization to the skin, typically through a drain site or skin incision, may be a late manifestation of anastomotic leak. Once a fistula is observed clinically, a CT scan is helpful to evaluate for any undrained collection which would need to be addressed. In general, once the local sepsis has been controlled, most anasto-motic fistulae will close with bowel rest. Optimizing nutritional status and attention to wound care are important in these patients. Specific circumstances that may preclude spontaneous resolution of a fistula are distal obstruction, associated anastomotic stric-ture, radiation, and steroid therapy. Patients who fail nonopera-tive treatment may benefit from operative intervention. OPeRative inteRventiOn The goals of re-operation for anastomotic leak are to control the source of sepsis, remove any purulence or contamination and prevent ongoing leak. While preservation of function is impor-tant, it must be emphasized that these are life-saving operations.  Figure 7.5 CT scan of a percutaneous drain in an abscess. There are a number of options available to the surgeon returning a patient to the operating room to address a leaking anastomosis and the particular procedure performed is decided at the time of exploration based on clinical judgment and the unique presenta-tion of the patient on the table. As most patients undergoing reoperation for suspected leak require some form of fecal diversion that may be permanent, potential sites for stoma formation should be marked preopera-tively. In the operating room, it is helpful to have the patient in either split leg position or in lithotomy stirrups to facilitate access in case proctoscopy is required.In terms of the surgical approach to re-operation in the setting of a leak, the quickest approach is likely conventional laparotomy. Laparoscopic exploration has potential benefits, especially if the original operation was per-formed laparoscopically or if the diagnosis of anastomotic leak is not clear, but a minimal-access approach to anastomotic leak should only be performed by surgeons with expertise in advanced laparoscopic techniques. Microbial cultures of the peritoneal fluid encountered during re-operation for anastomotic leak most often demonstrate polymicrobial flora and are of questionable benefit in terms of directing patient management.(23) Resection of the leaking anastomosis and colostomy creation Traditionally, the surgical approach for a colorectal anastomotic leak has been to dismantle the anastomosis, bring out the colon as an end stoma,close the rectum as a Hartmann pouch,washout the abdomen, and place drains.(12) This modified Hartmann procedure is very effective at removing the septic source and alleviating the abdominal sepsis.A major drawback of this oper-ation is that end colostomy reversal is technically challenging and carries its own risk of morbidity. It is not surprising that these end colostomies become permanent in a substantial pro-portion of patients.(4,23,46) Exteriorization of the rectal stump as a mucus fistula (typically described in staged resections for fulminant proctocolitis) can be considered in the rare circum-stance of a difficult to control rectum.(47) ... - tailieumienphi.vn
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