ANATOMY AND PHYSIOLOGY
The colon begins at the ileocecal valve and extends distally to the anal canal. Its primary function is the reabsorption of water and sodium, secretion of potassium and bicarbonate, and storage of fecal material. The ascending and descending colon are fixed in a retroperitoneal location, whereas the transverse and sigmoid colon are intraperitoneal.
Arterial supply to the cecum, ascending colon, and transverse colon is from the superior mesenteric artery by way of the ileocolic, right colic, and middle colic arteries. The remainder of the colon is supplied by the inferior mesenteric artery by way of the left colic, sigmoid, and superior hemorrhoidal arteries and the middle and inferior hemorrhoidal arteries that arise from the internal iliac artery. The inconstant anastomotic artery between the middle colic of the superior mesenteric artery and left colic of the inferior mesenteric artery is called the anastomosis (or arc) of Riolan. The interconnecting arcades in closer proximity to the mesenteric border of the colon are referred to as the marginal artery of Drummond (Fig. 5-1). This amalgamation of anastomotic branches runs around the medial margin of the entire colon, from the ileocolic artery to the sigmoid arteries. Venous drainage from the colon includes the superior and inferior mesenteric veins. The inferior mesenteric vein joins the splenic vein, which joins the superior mesenteric vein to form the portal vein. In this way, mesenteric blood flow enters the liver, where it is detoxified before entering the central circulation. Lymphatic drainage follows the arteries and veins.
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Figure 5-1 • The blood supply to the colon originates from the superior and inferior mesenteric arteries. From Corman RL. Colon and Rectal Surgery. 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2004. |
ULCERATIVE COLITIS
Ulcerative colitis is an inflammatory disease of the colon with unknown cause. An autoimmune basis is suspected. Inflammation almost always involves the rectum and extends proximally toward the cecum to varying degrees. The small bowel is uninvolved except in cases of "backwash ileitis" that may occur in proximal colonic disease. Extracolonic manifestations include inflammatory eye and skin disorders, arthritis, blood disorders, and sclerosing cholangitis.
PATHOLOGY
Inflammation is confined to the mucosa and submucosa. Superficial ulcers, thickened mucosa, crypt abscesses, and pseudopolyps may also be present.
EPIDEMIOLOGY
The incidence is six per 100,000. It is more common in developed countries, especially among Caucasians and the Jewish population. There is no predilection for sex. Approximately 20% of patients have first-degree relatives who are affected, suggesting a genetic basis. Linkage analysis has identified an association with HLA-DR2.
HISTORY
Most patients usually present in the second through fourth decade of life. Patients commonly complain
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of bloody diarrhea, mucus/pus per rectum, fever, abdominal pain, and weight loss. A history of repeated attacks is common. Numerous diseases are associated with ulcerative colitis, including sclerosing cholangitis in 1% of patients, as well as arthritis, iritis, cholangitis, aphthous ulcers, pyoderma gangrenosum, erythema nodosum, hemolytic anemia, and ankylosing spondylosis. These diseases may be part of the initial presentation.
PHYSICAL EXAMINATION
Abdominal pain is common. Rectal tenderness may occur with rectal fissures. The disease may present with abdominal distention as evidence of massive colonic distention, a situation known as toxic megacolon. This may progress to frank perforation with signs of peritonitis.
DIAGNOSTIC EVALUATION
Plain films may show massive colonic dilation, indicating toxic megacolon. Perforation will result in air under the diaphragm. Barium enema may reveal a "stovepipe colon" owing to loss of haustral folds, as well as mucosal ulcerations.
Endoscopy demonstrates thickened friable mucosa. Fissures and pseudopolyps, if present, almost always involve the rectum and varying portions of the colon. Biopsy shows ulceration limited to the mucosa and submucosa. Crypt abscesses arising from the crypts of Lieberkuhn coalesce to form ulcerations.
COMPLICATIONS
Perforation and hemorrhage may occur during a severe attack. Obstruction may develop from stricture as a
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result of chronic inflammation. Toxic megacolon is uncommon but is life-threatening if not controlled with medical therapy. Severe inflammation causes destruction of the myenteric plexus and muscular layer, leading to massive distention and perforation. Patients are invariably septic and mortality high unless emergent subtotal colectomy is performed. Colon cancer occurs frequently, with a risk of approximately 10% within 20 years. Once the diagnosis of ulcerative colitis is made, routine colonoscopic surveillance is mandatory.
TREATMENT
Initial therapy is medical, with fluid administration, electrolyte correction, and parenteral nutrition if necessary. Corticosteroids, other immunosuppressives, and sulfasalazine are all effective. Topical mesalamine, in the form of enemas, is effective for mild and moderate disease. Newer immunosuppressive agents—including infliximab, a monoclonal antibody against tumor necrosis factor—may be useful. High-fiber diet and bulking agents are often useful.
Indications for surgery include colonic obstruction, massive blood loss, failure of medical therapy, toxic megacolon, and cancer. The recommendation of prophylactic colectomy for these patients is being reconsidered on the basis of recent data that suggest the incidence of cancer is not as high as once thought. When elective surgery is performed, sphincter-sparing operations allow the ileum to be anastomosed to the rectal stump or anus, preserving continence and bowel movement. The ileum is fashioned into a J-pouch, which serves the fecal reservoir role of the removed rectum.
DIVERTICULOSIS
Diverticulosis refers to the presence of diverticula, outpouchings of the colon that occur at points where the arterial supply penetrates the bowel wall (singular, diverticulum; plural,diverticula) (Fig. 5-2). These are acquired or false diverticula because not all layers of the bowel wall are included. Most diverticula occur in the sigmoid colon (Figs. 5-3 and 5-4). Diverticulosis is the most common cause of lower gastrointestinal hemorrhage, usually from the right colon. Of people with diverticulosis, 15% will have a significant episode of bleeding.
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Figure 5-2 • Blood supply to the colon (A) and formation of the diverticulum (B). Note the passage of the mucosal diverticulum through the muscle coat along the course of the artery. From Snell RS. Clinical Anatomy. 7th ed. Philadelphia: Lippincott Williams & Wilkins, 2003. |
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Figure 5-3 • Diverticulosis, diverticulitis. Reprinted with permission from Willis MC. Medical Terminology: The Language of Health Care. 1st ed. Baltimore: Williams & Wilkins; 1996:374. |
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Figure 5-4 • Extensive sigmoid diverticular disease with slight spasm but no stigmata of acute inflammation. In the absence of classic symptoms and signs of diverticulitis, surgery is not advised solely on the basis of this radiographic appearance. From Corman RL. Colon and Rectal Surgery. 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2004. |
EPIDEMIOLOGY
Diverticular disease is common in developed nations and is likely related to low-fiber diets. Because of reduced intraluminal stool volume, the normal segmental colonic peristaltic contractions are extra forceful, which increases intraluminal pressure and causes herniation of the mucosa through the circular muscles of the bowel wall where the marginal artery branches penetrate. Men and women are equally affected, and the prevalence increases dramatically with age. Approximately one third of the population has diverticular disease, but this number increases to more than half of those older than 80 years of age.
HISTORY
Patients usually present with bleeding from the rectum without other complaints. They may have had previous episodes of bleeding or crampy abdominal pain, commonly in the left lower quadrant.
DIAGNOSTIC EVALUATION
For patients who stop bleeding spontaneously, elective colonoscopy should be performed to determine the cause of the bleeding. If bleeding continues, diagnostic
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and therapeutic modalities include radioisotope bleed- ing scans, which have variable success rates, and mesenteric angiography, which has an excellent success rate in the presence of active bleeding.
TREATMENT
Asymptomatic individuals require no treatment. In the event of a bleed, 80% will stop spontaneously. Elective segmental or subtotal colectomy is not usually recommended at first episode. However, depending on the ability to accurately determine the site of bleeding, the severity of the initial bleeding episode, and the general status of the patient, it may be indicated. Patients with recurrent bleeding are usually offered surgical resection. Active bleeding is treated colonoscopically if the colon can be cleaned and the bleeding site identified. Embolization of the bleeding vessel may be possible using selective angiography. In the face of massive bleeding, if the above methods fail and no bleeding site is identified, emergent subtotal colectomy is performed. Before embarking on such an irreversible procedure, which involves removing most of the colon, it is of utmost importance to ensure that the bleeding source is not from hemorrhoids or a rectal source. If a colonic bleeding site is identified, segmental colectomy can be performed, usually based on the arterial branch feeding the bleeding site.
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DIVERTICULITIS
The narrow neck of a diverticulum predisposes it to infection, which occurs either from increased intraluminal pressure or inspissated food particles. Infection leads to localized or free perforation into the abdomen. Diverticulitis most commonly occurs in the sigmoid and is rare in the right colon. Approximately 20% of patients with diverticula experience an episode of diverticulitis. Each attack makes a subsequent attack more likely and increases the risk of complications.
HISTORY
Patients usually present with left lower quadrant pain; right-sided diverticulitis causes right-sided pain but is less common. The pain is usually progressive over a few days and may be associated with diarrhea or constipation.
PHYSICAL EXAMINATION
Abdominal tenderness, usually in the left lower quadrant, is the most common finding. Local peritoneal signs of rebound and guarding may be present. Significant colonic inflammation may present as a palpable mass. Diffuse rebound tenderness and guarding as evidence of generalized peritonitis suggests free intra-abdominal perforation.
DIAGNOSTIC EVALUATION
Elevation of the white blood cell count is usual. Radiographs of the abdomen are typically normal, except for cases of perforation or obstruction. In cases of perforation, free air is seen under the diaphragms on chest x-ray. Computed tomography (CT) may demonstrate pericolic fat stranding, bowel wall thickening, or abscess. Colonoscopy and barium enema should not be performed during an acute episode because of the risk of causing or exacerbating an existing perforation.
COMPLICATIONS
Stricture, perforation, or fistulization with the bladder, skin, vagina, or other portions of the bowel may develop.
TREATMENT
Most episodes of diverticulitis are mild and can be treated on an outpatient basis with broad-spectrum oral antibiotics. Combination treatment with cipro-floxacin and metronidazole (Flagyl) is appropriate to cover aerobic and anaerobic organisms. For severe cases or cases in older adult patients or debilitated patients, hospitalization with bowel rest and broad-spectrum intravenous antibiotics (e.g., ampicillin, ciprofloxacin, and metronidazole) are required. For patients who do not improve in 24 to 48 hours, repeat CT scan with percutaneous drainage of any identifiable abscess cavity may obviate the need for emergency operation. In the event of free perforation or failure of medical management, surgical exploration with resection and colostomy is usually required (Hartmann procedure; Fig. 5-5). In addition, surgical intervention is indicated in the presence of the complications previously described. With repeated attacks of diverticulitis, the risk of developing complications increases significantly.
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Figure 5-5 • The Hartmann procedure for diverticulitis: primary resection for diverticulitis of the colon. The affected segment (clamp attached) has been divided at its distal end. In a primary anastomosis, the proximal margin (dotted line) is transected and the bowel attached end-to-end. In a two-stage procedure, a colostomy is constructed at the proximal margin with the distal stump oversewn (Hartmann procedure, as shown) or brought to the outer surface as a mucous fistula. The second stage consists of colostomy takedown and anastomosis. From Smeltzer SC, Bare BG. Brunner & Suddarth's Textbook of Medical-Surgical Nursing. 9th ed. Philadelphia: Lippincott Williams & Wilkins, 2000. |
COLONIC NEOPLASMS
Recent evidence suggests that colon cancer follows an orderly progression in which adenomatous polyps undergo malignant transformation over a variable time
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period (Fig. 5-6). For this reason, these polyps are considered premalignant lesions. Fifty percent of carcinomas have a ras gene mutation, whereas 75% have a p53 gene mutation.
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Figure 5-6 • Model of colorectal carcinogenesis. (Redrawn from Fearon ER, Vogelstein B. A genetic model of colorectal cancer tumorigenesis. Cell 1990;61:759.) From Corman RL. Colon and Rectal Surgery. 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2004. |
EPIDEMIOLOGY
Colon cancer is the second most common cause of cancer-related death in the United States. Risk factors include high-fat and low-fiber diets, age, and family history. Ulcerative colitis, Crohn's disease, and Gardner syndrome all predispose to cancer, and cancer develops in all patients with familial polyposis coli if they are not treated.
PATHOLOGY
Adenomatous polyps are either tubular or villous, with some lesions exhibiting features of both. The higher the villous component, the higher the risk of malignancy. As the lesion grows in size, the likelihood of its having undergone malignant transformation increases significantly. Although tubular adenomas <1 cm contain malignancy in only 1% of cases, lesions >2 cm contain malignancy 25% of the time. For villous adenomas, the numbers are 10% and 50%, respectively. Ninety percent of colon cancers are adenocarcinomas, and 20% of these are mucinous, carrying the worst prognosis. Other types include squamous, adenosquamous, lymphoma, sarcoma, and carcinoid. Three percent of tumors are synchronous (occurring simultaneously), and metachronous tumors (multiple primary cancers developing at intervals) also occur in 3% of cases.
SCREENING
Screening is aimed at detecting polyps and early malignant lesions. In theory, colon cancer is a preventable disease, because if all patients underwent thorough screening and timely polyp removal, the mortality rate from colon cancer would be drastically reduced. The current screening recommendations from the American Gastroenterological Association divide people into two groups: average risk and increased risk. Average-risk persons lack any identifiable risk factors. Increased-risk persons have either a personal history of adenomatous polyps or colorectal cancer, first-degree relatives with colorectal cancer or adenomatous polyps, a family history of multiple cancers, or a history of inflammatory bowel disease. Screening should begin at age 50 years for average-risk patients and age 40 years for increased-risk patients. American Cancer Society guidelines for the early detection of colorectal cancer include the following:
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Patients with positive test results should be followed up with colonoscopy.
STAGING
Generations of medical students have been confused by the various staging systems used for classifying colon cancer. Although the Dukes classification system devised in 1932 was simple and uncomplicated, it was eventually found to be inferior with respect to prognostication than the subsequently developed Astler-Coller system. Since 1991, the American Society of Colon and Rectal Surgeons have endorsed the TNM staging system, which has become the standard for modern cancer staging (Fig. 5-7).
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Figure 5-7 • Understanding cancer: the stages of cancer (I-IV). |
The TNM (tumor, nodes, metastases) classification system is as follows:
Staging is based on a combined evaluation of characteristics involving the tumor, lymph nodes, and presence of metastasis.
HISTORY
The clinical presentation of colon cancer is often dependent on the location of the lesion. Small proximal ascending colonic neoplasms are often asymptomatic. Occult blood in the stool and weight loss from metastatic disease may be the only signs. As the size of a lesion increases, right colon cancers usually cause bleeding that is more significant, whereas lesions in the left colon typically present with obstructive symptoms, including a change in stool caliber, tenesmus, or constipation. In general, this is due to fecal matter entering the right colon in liquid form and easily transiting a large cecal lesion, whereas desiccated stool in the left colon tends to obstruct when confronted with malignant luminal narrowing.
Rectal bleeding from a low rectal cancer should never be mistakenly explained away as symptomatic hemorrhoids. Simple digital rectal examination will demonstrate the tumor and prevent delay in diagnosis. Rectal cancer also can present with passage of mucus per rectum, arising from tumor surface secretions.
Complete acute large bowel obstruction may also occur. Any older adult patient who lacks a history of prior abdominal surgery or recent colonoscopy who presents with a large bowel obstruction must be considered to have obstructing colon cancer until proven otherwise. Any sizable lesion may produce abdominal pain. Perforation typically causes frank peritonitis. Constitutional symptoms, including weight loss, anorexia, and fatigue, are common with metastatic disease.
PHYSICAL EXAMINATION
Rectal examination may reveal occult or gross blood, and for low rectal cancers, the lesion can be directly palpated. For large bulky tumors, a mass may be noted on abdominal examination. Stigmata of hereditary disorders, including familial polyposis syndrome or Gardner syndrome, may be present.
DIAGNOSTIC EVALUATION
Laboratory evaluation should include a hematocrit, which often reveals microcytic anemia from chronic occult blood loss. The liver is the most common site
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for metastases, and liver function tests may be abnormal. Carcinoembryonic antigen may also be obtained; although it is not a useful screening test, it is valuable as a marker for recurrent cancer.
Colonoscopy has the advantage of examining the entire colon while also performing confirmatory biopsy for tissue diagnosis. Flexible sigmoidoscopy reaches up to 70 cm of the most distal large intestine, whereas colonoscopy can examine the entire colon and even intubate the distal ileum. Approximately 70% of lesions should be detected by flexible sigmoidoscopy. Rigid sigmoidoscopy is only useful for examining the lower 25 cm and is therefore often used to evaluate rectal cancers.
Radiologic evaluation can be performed with double-contrast barium enema, which uses both a radio-opaque contrast medium (barium) to coat the colon wall and air to provide luminal distention. The classic finding on barium enema is a constricting filling defect, known as an apple core lesion (Fig. 5-8). CT is useful for evaluating extent of disease and the presence of metastases, particularly in the liver.
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Figure 5-8 • Adenocarcinoma of the colon presenting as an "apple core" lesion. Image from a barium enema study demonstrates a circumferential mass (arrows). This mass has disrupted the normal mucosal pattern and has irregular overhanging edges. From Kelsen DP, Daly JM, Kern SE, et al. Gastrointestinal Oncology: Principles and Practice. Philadelphia: Lippincott Williams & Wilkins, 2002. |
Magnetic resonance imaging may be better for evaluating liver metastases but usually does not add more overall information than that which is obtained with CT.
Positron-emission tomography scan is useful for showing metastatic disease or else late recurrence in a patient who previously underwent resection and who has an increasing carcinoembryonic antigen level. For rectal lesions, endorectal ultrasound is the standard of care for assessing the depth of tumor invasion and the presence of lymph node metastases.
TREATMENT
Surgical therapy of colon cancer is based on complete removal of the malignant lesion and associated lymph nodes. The oncologic principles underlying segmental colon resection for malignancy are based on the blood supply of the segment of colon containing the lesion, as well as the distribution of the parallel draining lymph node network. For cancers of the cecum and ascending colon, right hemicolectomy is indicated. Tumors of the transverse colon require transverse colectomy, with removal of the hepatic and splenic flexures. Descending colon tumors require left colectomy, and sigmoid tumors are treated with sigmoidectomy. Most rectal tumors are treated with low anterior resection, whereas the very low rectal cancers near the anus occasionally require abdominoperineal resection, which entails resection of the anus with closure of the perianal skin and creation of a permanent end colostomy, because anastomosis may not be technically feasible. Examples of the extent of resection for different types of colectomy are shown in Figure 5-9.
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Figure 5-9 • Types of colectomy. (A) Sigmoid colectomy; (B) transverse colectomy; (C) left colectomy; (D) right colectomy. Adapted from Kelsen DP, Daly JM, Kern SE, et al. Gastrointestinal Oncology: Principles and Practice. Philadelphia: Lippincott Williams & Wilkins, 2002. |
Historically, open surgery has been the standard approach for colon resection; however, the laparoscopic technique has gained rapid acceptance, given the reduced morbidity compared with open surgery, in addition to studies showing the less invasive approach to be equally effective as open surgery in terms of survival. The widely quoted randomized trial results by the Clinical Outcomes of Surgical Therapy (COST) Study Group, published in 2004, showed no difference in either recurrence or 3-year survival between laparoscopic or open groups. These findings were subsequently supported by other randomized trials, such as the Conventional Versus Laparoscopic-Assisted Surgery in Colorectal Cancer (CLASSIC) trial from the United Kingdom, published in 2007. In summary, despite the development of new surgical techniques, the basic oncologic
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goals and extent of resection should be identical, regardless of the approach.
With respect to the extent of resection, guidelines from the American Joint Committee on Cancer, the American College of Pathology, and the National Comprehensive Cancer Network recommend 12 or more lymph nodes to be sampled during surgery. Thorough sampling and examination of the draining lymph nodes is thought to improve staging accuracy, which allows more appropriate adjuvant chemotherapy administration. By upstaging patients, some investigators believe patients will therefore be offered more aggressive treatment that will likely result in improved overall survival.
COLECTOMY: THE OPERATION
Traditional preoperative preparation has included mechanical and antimicrobial bowel cleansing; however, this practice is currently undergoing critical review (see Preoperative Issues in Chapter 1 for expanded discussion). Most open resections are performed via a midline incision. The rationale and extent of excision for various tumors is described above and in Figure 5-9.
Mobilization of the right or left colon involves incising the white line of Toldt on the respective side. Care is taken to avoid the ureter, which can be injured as the colon is mobilized. Consideration of a
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ureteral stent should be made if the tumor is bulky and there is concern about identifying the ureter intraoperatively. The transverse colon is intraperitoneal and does not require mobilization. Once adequate length of colon has been mobilized, the peritoneum overlying the mesentery is incised to its root, and all the mesenteric vessels in the specimen are li-gated. In the open technique, noncrushing clamps are usually placed alongside the resection margin to reduce spillage, and the ends of the bowel are usually stapled and the specimen removed. Reconstruction of bowel continuity is performed with either hand-sewn or stapled anastomosis. For low colon or rectal anastomosis, use of an end-to-end anastomosis stapler placed through the anus is a preferred technique.
ANGIODYSPLASIA
Angiodysplasia is being recognized with increasing frequency as a significant source of lower gastrointestinal hemorrhage. These anomalous vascular lesions are histologically similar to telangiectasia and arise most commonly in the cecum and right colon.
EPIDEMIOLOGY
Angiodysplasia is one of the most common causes of lower gastrointestinal bleeding. The prevalence increases with age, to an incidence of approximately one fourth of the older adult population. Age and resulting bowel wall strain are thought to cause vascular tissue proliferation, leading to angiodysplastic lesions.
HISTORY
Patients usually present with multiple episodes of low-grade bleeding. In 10% of cases, patients present with massive bleeding.
DIAGNOSTIC EVALUATION
Diagnosis can be made with arteriography, nuclear scans, or endoscopy.
TREATMENT
Endoscopic treatment includes electrocautery and argon plasma coagulation. Angiography with highly selective embolization or vasopressin infusion is often effective. Because many angiodysplastic lesions rebleed, definitive treatment may occasionally require segmental colectomy.
VOLVULUS
Volvulus occurs when a portion of the colon rotates on the axis of its mesentery, compromising blood flow and creating a closed-loop obstruction (Fig. 5-10). The sigmoid colon (75%) and cecum (25%) are most commonly involved. The relative redundancy of the sigmoid loop causes torsion around the mesenteric axis, whereas poor fixation of the cecum in the right iliac fossa leads to either axial torsion (cecal volvulus) or anteromedial folding (cecal bascule).
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Figure 5-10 • Volvulus. |
EPIDEMIOLOGY
The incidence of volvulus is approximately two in 100,000. Risk factors include age, chronic constipation, previous abdominal surgery, and neuropsychiatric disorders.
HISTORY
The patient usually relates the acute onset of crampy abdominal pain and distention.
PHYSICAL EXAMINATION
The abdomen is tender and distended, and peritoneal signs of rebound and involuntary guarding may be present. Frank peritonitis and shock may follow.
DIAGNOSTIC EVALUATION
Abdominal radiographs may reveal a massively distended colon with a "corkscrew" or "bird's beak" at
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the point of torsion. The distended colonic loop has the appearance of a bent tire or large coffee bean.
TREATMENT
Sigmoid volvulus may be reduced by enemas or endo-scopy. Rectal tubes are sometimes used to prevent acute recurrence and aid decompression. Because of the high rate of recurrence, operative repair after resolution of the initial episode is recommended. In the acute setting and depending on the operative findings, fixation of the untwisted loop to the respective fossa may suffice for cases of viable bowel; otherwise, resection is performed with either primary anastomosis or end colostomy (Hartmann procedure) in cases of sepsis and gangrene. Treatment of cecal volvulus is usually operative at the outset, because nonoperative intervention is rarely successful, and the incidence of gangrenous ischemic changes is high.
APPENDICITIS
Appendicitis is the most common reason for urgent abdominal operation. The causes of appendiceal inflam- mation and infection are related to processes that obstruct the appendiceal lumen, thereby causing distal swelling, decreased venous outflow, and ischemia. The most common extraluminal cause of obstruction is the swelling of submucosal lymphoid tissue in the wall of the appendix in response to a viral infection. This is illustrated by the incidence of viral syndromes often seen in pediatric patients shortly before developing appendicitis. The most common intraluminal cause of obstruction is from a fecalith (small, firm ball of stool). Cases of obstruction with fecaliths have a higher incidence of perforation.
EPIDEMIOLOGY
Children and young adults between ages 5 and 35 years are most commonly affected. Appendicitis will develop in approximately 5% of people over their lifetime. Perforation at the time of surgery is more often seen in very young children and in older adults as a result of delayed diagnosis.
HISTORY
Patients typically complain of epigastric pain that subsequently migrates to the right lower quadrant. The initial discomfort is thought to be due to obstruction and swelling of the appendix and the latter due to peritoneal irritation. Retrocecal appendicitis may cause pain higher in the right abdomen, whereas appendicitis located in the pelvis may cause vague pelvic discomfort. Anorexia is an almost universal complaint. Nausea and emesis may occur after the onset of pain. Up to 20% of patients report experiencing diarrhea, which often leads the examiner to make an incorrect diagnosis of gastroenteritis. Generalized abdominal pain may signify rupture and diffuse peritonitis.
PHYSICAL EXAMINATION
Low-grade fever is typical. Nearly all patients have right lower quadrant tenderness, classically located at McBurney's point, two thirds the distance from the umbilicus to anterior superior iliac spine. Rebound and guarding develop as the disease progresses and the peritoneum becomes inflamed. Signs of peritoneal irritation include the obturator sign (pain on external rotation of the flexed thigh) and the psoas sign (pain on right thigh extension). Rovsing's sign is eliciting pain in the right lower quadrant on palpation of the left lower quadrant. In cases of contained perforation, the omentum walls off the infectious process, occasionally resulting in a palpable mass in thin patients. If the perforation is free and not contained, then diffuse peritonitis and septic shock may develop. Rectal examination may reveal tenderness if the appendix hangs low in the pelvis.
DIAGNOSTIC EVALUATION
The white blood cell count is usually mildly to moderately elevated. Urinalysis should be performed to rule out a urinary tract infection.
Depending on a patient's age, presenting history and physical examination, and available resources, radiologic studies may include ultrasound or CT scanning. Plain abdominal x-rays (supine and upright) usually provide no useful information in confirming the diagnosis of appendicitis. Ultrasonographic evidence of appendicitis includes appendiceal wall thickening, luminal distention, and lack of compressibility. Ultrasound is also useful in female patients for demon- strating ovarian or other gynecologic pathology. CT scanning may show appendiceal enlargement, periappendiceal inflammatory changes, free fluid, or right lower quadrant abscess (Fig. 5-11).
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Figure 5-11 • Computed tomographic appearance of appendicitis. From Harwood-Nuss A, Wolfson AB, Linden CH, et al. The Clinical Practice of Emergency Medicine. 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2001. |
CT scanning is also useful for ruling in or out alternative diagnoses, thereby reducing the negative appendectomy rate in many hospitals.
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TREATMENT
Uncomplicated appendicitis requires appendectomy. Both open and laparoscopic techniques are appropriate. Laparoscopic appendectomy is associated with less postoperative pain, a shorter hospital course, better cosmesis, and faster return to work. Selected advanced cases with appendiceal abscess may initially be managed nonoperatively with antibiotics and percutaneous CT-guided abscess drainage. Once the infection has abated and the inflammatory process resolved, interval appendectomy may be performed at a later date.
KEY POINTS