Noelle L. Bertelson
David A. Etzioni
Presentation
A 78 year-old female is evaluated in the emergency department with a 2-day history of worsening nausea/anorexia, abdominal pain, and obstipation. Her last bowel movement and flatus were 36 hours ago. She has no significant medical history and no prior abdominal or pelvic surgical procedures; her vital signs are normal. On examination, her abdomen is soft and nontender but is significantly distended. Her white blood cell count is 10.3.
Differential Diagnosis
This patient presents with signs and symptoms of a bowel obstruction. Generally speaking, the differential diagnosis of obstruction can be broadly classified as being infectious, inflammatory, or neoplastic in origin. One of the key elements of this patient’s history is the absence of prior abdominal or pelvic operations. The most likely cause of this type of presentation varies widely depending on the population from which the patient emerges. In most developed countries, this patient should be considered to have a gastrointestinal malignancy—most commonly colon or rectal cancer—until proven otherwise.
Infectious causes may be related to a wide variety of organisms, none of which occur with great prevalence in the United States but include Ascaris species, Taenia species, tuberculosis, and Yersinia. Diverticulitis and inflammatory bowel disease, including Crohn’s, ulcerative colitis, and sarcoidosis, can present with acute/subacute colonic obstruction and on radiologic investigation are indistinguishable from colon cancer. The most common neoplastic disorders of the colon are benign adenomas and their malignant counterpart, adenocarcinoma. Noncolonic carcinoma, either metastatic or extrinsically compressing, also may be involved with the colon. Other less common neoplastic disease entities including lymphoma and carcinoid, followed by sarcoma, plasmacytoma, melanoma, leukemic infiltration, neuroendocrine tumor, medullary carcinoma, and schwannoma are also potential causes of colonic obstruction. Nonneoplastic/noninfectious processes, most notably volvulus and intussusception, can cause acute large bowel obstruction, with volvulus causing 10% of colonic obstructions and intussusception occurring in 1% of all bowel obstructions.
Workup
Initial workup proceeds with a supine x-ray, demonstrating gaseous distention of the right and the proximal transverse colon, with a paucity of gas in the distal colon and rectum (Figure 1). It is worth noting that the small bowel loops are not prominent, and that there is no significant bubble of gastric air. Based on this plain film, a computed tomography (CT) of the abdomen/pelvis with oral and intravenous contrast is ordered (Figure 2). This scan shows an obstructing mass in/around the midportion of the transverse colon. The patient’s liver and intraperitoneal structures (omentum, etc.) do not show any evidence of metastatic disease or ascites. Although contrast enemas (with water-soluble contrast) are performed less commonly, they can be useful in this setting. Contrast enemas can identify the location and evaluate the patency of an obstructing or a partially obstructing mass. Alternatively, a CT scan with the instillation of rectal contrast could be used to obtain this information.
FIGURE 1 • Scout film.
FIGURE 2 • CT scan of abdomen/pelvis.
Diagnosis and Treatment
Colon cancer is diagnosed in over 110,000 individuals in the United States per year, resulting in approximately 90,000 colectomies. While the vast majority of these undergo surgical treatment on an elective basis, a subset are discovered during evaluation for an acute bowel obstruction.
In the management of any patient with a bowel obstruction, a balance must be struck between the possibility of nonoperative resolution of the patient’s problem, and the likelihood of progression to bowel compromise and perforation. The key prognostic feature of this patient’s presentation is the presence of a closed loop obstruction. Nondilated terminal ileum immediately proximal to a distended cecum clearly indicates a competent ileocecal valve. The portion of colon between the ileocecal valve and the obstruction lesion in the transverse colon has no mechanism by which to decompress, and is therefore a closed loop. Any closed loop intestinal obstruction is an indication for urgent/emergent decompression.
As surgeons, we all develop a level of comfort with the initial nonoperative treatment of bowel obstructions. Although this approach may be appropriate for selected patients with partial small bowel obstruction, it is often not the right choice for patients with large bowel obstruction. In this case presentation, without prompt intervention, this patient will progress quickly to compromise of her right colon and perforation. The absence of focal peritonitis or signs of significant systemic toxicity should not be considered reassuring.
Colon obstructions can be decompressed effectively using nonsurgical and surgical approaches. The only reasonable nonsurgical options would involve the endoscopic placement of a self-expanding metallic stent (SEMS). This stent would be used as a “bridge” to surgery, potentially allowing for the operation to be performed electively with a preoperative bowel preparation. Colonoscopic stenting is usually performed for left-sided lesions, but there is an emerging literature regarding their use for right-sided colonic tumors. In small series, they appear to be safe, but there is reason to be skeptical about the effectiveness of this approach: A recent trial examining stenting versus surgery for stage IV left-sided colorectal cancer was closed due to a high rate of serious complications in the stenting arm.
In considering the utility of a colonoscopic stent, it seems sensible to consider the risks of stent placement compared with the benefit (risk reduction) they might provide. In general, ileocolic anastomoses are robust and safe, with leak rates routinely reported at <2%. In this patient, the risks of a procedural complication from stent placement are almost certainly greater than any risk reduction that might be obtained in converting the operation from an urgent to a planned procedure.
What about problems related to the absence of a mechanical bowel preparation? The utility of a mechanical bowel preparation in elective colorectal surgery has been studied extensively. While the majority of the literature in this topic is of poor quality, the overall synthesis (including two large, well-conducted trials) of existing knowledge is that these efforts provide little, if any, benefit. Placing a stent with the goal of being able to perform bowel preparation would not be justified. Furthermore, in this patient, the bowel (terminal ileum and descending colon) do not demonstrate fecal loading, thereby obviating any benefit of the preparation.
An important issue in planning for this patient is what efforts should be made to ensure that the portion of colorectum that will remain after the resection is free of neoplasia. Case series have documented a 6% to 10% rate of synchronous carcinoma in patients presenting with obstructing colonic tumors. While the proximal dilated portion will necessarily be removed with surgical resection, an intraoperative colonoscopy with minimal insufflation performed to the level of the tumor is a useful and important test.
The best treatment plan for this patient is to proceed to the operating room for intraoperative colonoscopy and subtotal colectomy.
Surgical Approach
The usual administration of prophylactic antibiotics and subcutaneous heparin should be performed. Patient positioning in a low lithotomy position will facilitate both the colonoscopy and the planned operation. While there has been a small case series of laparoscopically managed large bowel obstructions, the extent of distention of the dilation of proximal bowel generally precludes safe laparoscopic mobilization of the colon and should not be performed.
Once the abdomen has been explored through a generous midline incision, the right colon will be easily identified, usually tensely distended and potentially demonstrating early signs of impending perforation (discoloration, deserosalization, etc. Table 1). After placing a pursestring suture, a decompressive colotomy in the anterior surface of the proximal right colon will greatly facilitate the procedure. Careful attention to avoiding unnecessary stool spillage will minimize the potential risks from this maneuver.
TABLE 1. Key Technical Steps and Potential Pitfalls to Right Colectomy in Presence of Transverse Colon Obstruction
With the right colon decompressed, dissection proceeds along the right paracolic gutter, moving toward the hepatic flexure. The dissection is carried medially to the level of the anterior surface of the second portion of the duodenum. Great care should be taken in retracting the colon medially, in order to avoid avulsion of the pancreaticoduodenal veins in this region. It is a generally accepted oncologic principle that the omentum is resected en bloc with any transverse colon carcinoma, so the omentum should be removed from the greater curvature of the stomach. This exposes the lesser sac and the transverse mesocolon. Continuing distally, the splenic flexure should be mobilized in order to facilitate an anastomosis between the descending colon and the terminal ileum.
The distal extent of the resection is controversial, but for tumors distal to the midtransverse colon, a resection that encompasses the ascending branch of the left colic artery is prudent. An anastomosis to the splenic flexure of the colon is potentially risky because of potential problems with blood supply in this watershed area, especially in older patients or those with known vascular disease. The descending colon is a preferred location for the ileocolic anastomosis.
Once the colon is mobilized, the mesentery is divided and a high ligation is performed for all feeding vessels (ileocolic, middle colic, ascending branch of left colic). An anastomosis is then constructed between terminal ileum and descending colon. There are several options for reconstruction. A hand-sewn end-to-end anastomosis with an inner layer of running absorbable 3-0 (e.g., vicryl) suture and an outer layer of 3-0 interrupted silk sutures is a commonly employed technique. A stapled side-to-side/functional end-to-end anastomosis may also be performed. There are no good data to support one technique as preferred. There is some evidence that leak rates are lower in stapled ileo-transverse anastomoses after right colectomy, but it is uncertain whether this finding can be applied to ileo-descending anastomoses.
After anastomosis, the mesenteric defect may be approximated, and the abdomen is irrigated, and the fascia and skin closed.
Special Intraoperative Considerations
Perforation
In the setting of cecal perforation secondary to distention and ischemic compromise of the bowel wall, resection of the ischemic segment of bowel as well as the tumor is mandatory—in this case, the subtotal colectomy as planned. If the patient is unstable secondary to intra-abdominal sepsis from the perforation, judgment must be exercised in deciding whether to construct an anastomosis. A double-barreled stoma, incorporating the terminal ileum and a corner of the proximal colon, will avoid the risk of anastomotic leakage and allow for stoma reversal in the future without a formal laparotomy.
Duodenal/Pancreatic Invasion
Rarely, a transverse colon carcinoma may involve the duodenum or the head of the pancreas. Intraoperatively, any points of adherence between a known carcinoma and adjacent structures should be considered invasion and mandate consideration for en bloc resection. The magnitude of benefit compared with risk of such a resection needs to be considered on a case-by-case basis. Pancreaticoduodwenectomy can be performed in the setting of invasion into the pancreatic head, and there does appear to be some long-term survival in some patients with small case series quoting up to 55% 5-year survival. Duodenal invasion usually does not require a pancreaticoduodenectomy. When feasible, resection with primary repair should be performed. In cases of more extensive resection, a Roux-en-Y reconstruction with a duodenojejunostomy may be required.
Metastatic Disease
At the time of surgery, it is not uncommon to discover metastatic disease that was not clearly detected on preoperative imaging studies. Metastatic disease should not be considered a contraindication to a palliative resection, though the presence of gross peritoneal disease or a significant burden of hepatic disease may prompt an end stoma or intestinal bypass over anastomosis. In the setting of unexpected hepatic disease, intraoperative ultrasound can assist in further characterizing and identifying lesions. In an otherwise stable patient, isolated metastases amenable to simple wedge resection can reasonably be addressed at the time of the initial operation. However, in an unstable patient, metastatic disease should be noted, confirmed with biopsy, and addressed at a later date. Though outcomes are similar for synchronous resection of colon malignancy with liver metastases, unexpected necessity for a major liver resection of multiple segments or a lobectomy should be discussed with the patient and is likely to great of a physiologic stressor at the time of operation for obstruction.
Postoperative Care
Patient who demonstrate hemodynamic instability in the operating room or who experience unexpected massive fluid shifts/blood loss may require an intermediate level of care; most other patients should not need elevated levels of care. Nasogastric decompression is unnecessary. While early feeding has been associated with some improved outcomes and shorter hospital stays in elective cases, the obstructed patient may have a prolonged ileus, such that feeding should be delayed until the abdomen is flat and the patient is without nausea or emesis. There is no role for routine postoperative antibiotics beyond a 24-hour perioperative period. Prophylaxis for deep venous thromboembolism should be employed routinely, including subcutaneous heparin injections and sequential compression devices for the legs. Discharge can be expected when the patient is tolerating oral feeding and has had a bowel movement. Inpatient oncology consultation and outpatient surveillance are elements of care, which are also part of the standard of care for these patients.
TAKE HOME POINTS
· Obstructing colon cancer is a surgical emergency, especially in the presence of a competent ileocecal valve (closed loop obstruction); clinical findings of focal peritonitis and/or systemic toxicity are late findings.
· Self-expanding metallic stents have no role in the treatment of tumors that are within the scope of a subtotal colectomy (tumors proximal to splenic flexure).
· Intraoperative colonoscopy is an important exam in the stable patient and may lead to changes in the operative plan.
· Primary ileocolic anastomosis should be performed except in cases of hemodynamic instability and gross feculent peritonitis.
SUGGESTED READINGS
Bat L, Neumann G, Shemesh E. The association of synchronous neoplasms with occluding colorectal cancer. Dis Colon Rectum. 1985;28(3):149–151.
Brehant O, Fuks D, Bartoli E, et al. Elective (planned) colectomy in patients with colorectal obstruction after placement of a self-expanding metallic stent as a bridge to surgery: the results of a prospective study. Colorectal Dis. 2009;11(2):178–183.
Choy PY, Bissett IP, Docherty JG, et al. Stapled versus handsewn methods for ileocolic anastomoses. Cochrane Database Syst Rev. 2007;(3):CD004320.
Contant CM, Hop WC, van’t Sant HP, et al. Mechanical bowel preparation for elective colorectal surgery: a multicentre randomised trial. Lancet. 2007;370(9605):2112–2117.
Dronamraju SS, Ramamurthy S, Kelly SB, et al. Role of self-expanding metallic stents in the management of malignant obstruction of the proximal colon. Dis Colon Rectum. 2009;52(9):1657–1661.
Etzioni DA, Beart RW Jr, Madoff RD, et al. Impact of the aging population on the demand for colorectal procedures. Dis Colon Rectum. 2009;52(4):583–590; discussion 590–591.
Fujiwara H, Yamasaki M, Nakamura S, et al. Reconstruction of a large duodenal defect created by resection of a duodenal tubulovillous adenoma using a double-tract anastomosis to a retrocolic roux-en-y loop: report of a case. Surg Today. 2002;32(9):824–827.
Gash K, Chambers W, Dixon A. The role of laparoscopic surgery for the management of acute large bowel obstruction. Colorectal Dis. 2009.
Gordon PH, Nivatvongs S. Principles and Practice of Surgery for the Colon, Rectum, and Anus. 3rd ed. New York, NY: Informa Healthcare USA, Inc, 2007.
Jemal A, Siegel R, Ward E, et al. Cancer statistics, 2007. CA Cancer J Clin. 2007;57(1):43–66.
Jung B, Pahlman L, Nystrom PO, et al. Multicentre randomized clinical trial of mechanical bowel preparation in elective colonic resection. Br J Surg. 2007;94(6):689–695.
Lee WS, Lee WY, Chun HK, et al. En bloc resection for right colon cancer directly invading duodenum or pancreatic head. Yonsei Med J. 2009;50(6):803–806.
Lustosa SA, Matos D, Atallah AN, et al. Stapled versus handsewn methods for colorectal anastomosis surgery. Cochrane Database Syst Rev. 2001;(3):CD003144.
Moug SJ, Smith D, Leen E, et al. Evidence for a synchronous operative approach in the treatment of colorectal cancer with hepatic metastases: a case matched study. Eur J Surg Oncol. 2010;36(4):365–370.
Saiura A, Yamamoto J, Ueno M, et al. Long-term survival in patients with locally advanced colon cancer after en bloc pancreaticoduodenectomy and colectomy. Dis Colon Rectum. 2008;51(10):1548–1551.
Slim K, Vicaut E, Launay-Savary MV, et al. Updated systematic review and meta-analysis of randomized clinical trials on the role of mechanical bowel preparation before colorectal surgery. Ann Surg. 2009;249(2):203–209.
van Hooft JE, Fockens P, Marinelli AW, et al. Early closure of a multicenter randomized clinical trial of endoscopic stenting versus surgery for stage IV left-sided colorectal cancer. Endoscopy. 2008;40(3):184–191.
Vitale MA, Villotti G, d’Alba L, et al. Preoperative colonoscopy after self-expandable metallic stent placement in patients with acute neoplastic colon obstruction. Gastrointest Endosc. 2006;63(6):814–819.