Large-bowel obstruction (LBO) is an emergency condition that requires early identification and intervention. It is important to distinguish colonic obstruction from ileus, as well as to differentiate between a true mechanical obstruction and a pseudo-obstruction; treatment differs. See the image below.
Contrast study demonstrates colonic obstruction at the level of the splenic flexure, in this case due to carcinoma. Radiograph courtesy of Charles J M....
See Can't-Miss Gastrointestinal Diagnoses, a Critical Images slideshow, to help diagnose the potentially life-threatening conditions that present with gastrointestinal symptoms.
A history of bowel movements, flatus, obstipation, and associated symptoms should be obtained. Complaints in patients with LBO may include the following:
Other symptoms that may be diagnostically significant include the following:
Assessment of symptoms should attempt to distinguish the following:
Although a complete physical examination is necessary, the examination should place special emphasis on the following key areas:
See Presentation for more detail.
The following laboratory studies may be helpful:
Imaging modalities that may be considered are as follows:
See Workup for more detail.
Initial therapy in patients with suspected LBO includes the following:
The following are emergencies that call for surgical intervention:
Ileus is treated as follows:
Acute colonic pseudo-obstruction is treated as follows:
Volvulus is treated as follows:
Intussusception is treated as follows:
Colonic masses and strictures are treated as follows:
Diverticular disease is treated as follows:
See Treatment and Medication for more detail.
Large-bowel obstruction (LBO) is an emergency condition that requires early identification and intervention. The etiology of this condition is age dependent, and it can result from either mechanical interruption of the flow of intestinal contents (see the following image) or by the dilation of the colon in the absence of an anatomic lesion (pseudo-obstruction). Causes include neoplasms, inflammatory processes (diverticulitis), strictures, fecal impaction or volvulus.
Abdominal (kidney-ureter-bladder [KUB]) film of a patient with obstipation. Dilatation of the colon is associated with large-bowel obstruction. Radiog....
It is important to distinguish colonic obstruction from ileus, and differentiate between a true mechanical obstruction and a pseudo-obstruction, as the treatment differs.
Colonic obstruction is more common in elderly individuals, due to the higher incidence of neoplasms and other causative diseases in this population. In neonates, colonic obstruction may be caused by an imperforate anus or other anatomic abnormalities. Obstruction may also be secondary to meconium ileus. In the pediatric population, Hirschsprung disease can resemble colonic obstruction.
For patient education information, see Digestive Disorders Center as well as Constipation in Adults and Abdominal Pain in Adults.
See also Ogilvie Syndrome, Ileus, Constipation, Small Bowel Obstruction, and Intussusception.
The prevalence of mechanical large-bowel obstruction (LBO) increases with age as does its main causes, colon cancer and diverticulitis. Sigmoid volvulus and cecal volvulus are also potential causes of this disorder.
Mechanical obstruction of the large bowel causes bowel dilatation above the obstruction, which in turn, causes mucosal edema and impaired venous and arterial blood flow to the bowel. Bowel edema and ischemia increase the mucosal permeability of the bowel, which can lead to bacterial translocation, systemic toxicity, dehydration, and electrolyte abnormalities. Bowel ischemia can lead to perforation, fecal soilage of the peritoneal cavity, and dead bowel.
In cases of closed loop obstructions, such as colonic obstruction in the presence of a closed ileocecal valve or incarcerated hernia, this process may be accelerated.
The pathophysiology of acute colonic pseudo-obstruction (ACPO), or Ogilvie syndrome, is not clear, but it is thought to result from an autonomic imbalance, which results from decreased parasympathetic tone or excessive sympathetic output.[1, 3] This condition usually occurs in the setting of a wide range of medical or surgical illnesses. If untreated, colonic ischemia or perforation can occur.
Acute colonic pseudo-obstruction is characterized by a loss of peristalsis and results in the accumulation of gas and fluid in the colon. The right colon and cecum are most commonly involved. The risk of perforation for acute colonic pseudo-obstruction ranges from 3% to 15%.
Approximately 60% of mechanical large-bowel obstructions (LBOs) are caused by malignancies, 20% are caused by diverticular disease, and 5% are the result of colonic volvulus.[1, 5, 6] The most common causes of adult large-bowel obstruction are as follows:
Obstructions caused by tumors tend to have a gradual onset and result from tumor growth narrowing the colonic lumen.
Diverticulitis is associated with muscular hypertrophy of the colonic wall. Repetitive episodes of inflammation cause the colonic wall to become fibrotic and thickened, leading to luminal narrowing.
A colonic volvulus results when the colon twists on its mesentery, which impairs the venous drainage and arterial inflow. Symptoms of this condition are usually abrupt. The cecum and sigmoid colon are most commonly affected.
Volvulus typically occurs in elderly, debilitated individuals; patients living in an institutionalized setting; or patients with a history of chronic constipation.Volvulus may also be seen during pregnancy, most commonly occurring in the third trimester when the gravid uterus displaces the colon.
Intussusception is primarily a pediatric disease; however, it is estimated that between 5% and 16% of all intussusceptions in the Western world occur in adults. Two thirds of adult intussusception cases are caused by tumors. Two main types of intussusception affect the large bowel: enterocolic and colocolic.
Enterocolic intussusceptions involve both the small bowel and the large bowel. These are composed of either ileocolic intussusceptions or ileocecal intussusceptions, depending on where the lead point is located.
Colocolic intussusceptions involve only the colon. They are classified as either colocolic or sigmoidorectal intussusceptions.
Acute colonic pseudo-obstruction (ACPO), or Ogilvie syndrome, has many etiologies. ACPO is a functional obstruction; it is typically seen in elderly or debilitated patients who are hospitalized with severe medical or traumatic illnesses. Medications that decrease intestinal motility are also associated with this disorder. In a retrospective review of more than 1400 cases of ACPO, the most common predisposing conditions were operative and nonoperative trauma (11%), infections (10%), and cardiac disease (10-18%).[8, 9]
Mortality is determined by the patient's overall medical condition and the presence of any comorbidities that may influence the patients surgical risk. If large bowel obstruction is treated early, the outcome is generally good. Mortality rates are increased in patients who have developed bowel ischemia or perforation. After surgical decompression, the prognosis is determined by the underlying disease. In general, overall mortality rates for large bowel obstructions are 20%, which increases to 40% if there is colonic perforation.
The mortality rate for acute colonic pseudo-obstruction is 15% with early care; mortality increases to 36% if colonic ischemia or perforation develops.
The morbidity and mortality of large-bowel obstruction are often related to the surgical procedure used to relieve the colonic obstruction and, in the long term, to the underlying disease that caused the obstruction. Thus, complications of large-bowel obstruction may include the following:
Obtain the patient's history of bowel movements, flatus, obstipation (ie, no gas or bowel movement), and associated symptoms. Attempt to distinguish complete bowel obstruction from partial obstruction, which is associated with passage of some gas or stool. Also inquire about the patient's current and past history in an attempt to determine the most likely cause.
Major complaints in patients with large-bowel obstruction (LBO) include abdominal distention, nausea, vomiting, and crampy abdominal pain. An abrupt onset of symptoms makes an acute obstructive event (eg, cecal or sigmoid volvulus) a more likely diagnosis. A history of chronic constipation, long-term cathartic use, and straining at stools implies diverticulitis or carcinoma.
Changes in the patient's caliber of stools strongly suggest carcinoma. When associated with weight loss, the likelihood of neoplastic obstruction increases.
When giving a history of obstipation, patients may state that pants or belts are not fitting properly.
A history of recurrent left lower quadrant abdominal pain over several years is more consistent with diverticulitis, a diverticular stricture, or similar problems.
A history of aortic surgery suggests the possibility of an ischemic stricture.
Complete obstruction is characterized by the failure to pass either stool or flatus with an empty rectal vault (unless the obstruction is in the rectum). If the patient has a partial obstruction, the patient appears obstipated but continues to pass some gas or stools. Partial obstructions are a less urgent condition.
Large-bowel obstruction from an anatomic abnormality leads to colonic distention, abdominal pain, anorexia, and, late in the course, feculent vomiting. Persistent vomiting may result in dehydration and electrolyte disturbances.Pneumaturia, mucinuria, or fecaluria may occur if fistulization of the sigmoid colon to the bladder occurs. This is most often seen in the setting of diverticulitis or cancer.
Large-bowel obstruction is typically characterized by a slow onset of symptoms and may not cause vomiting despite a markedly distended bowel.
Paralytic ileus can be seen in the setting of peritonitis or traumatic injury. Bowel sounds are diminished, and abdominal cramping is less common.
Right-sided colonic lesions can grow quite large before obstruction occurs because of the large capacity of the right colon and soft stool consistency.
Sigmoid colon and rectal tumors cause colonic obstruction much earlier in their development, because the colon is narrower and the stool is harder in that area.
Patients may describe intermittent, crampy abdominal pain that is colicky and relieved by assuming fetal position. Weight loss and fatigue are common.
Symptoms of acute colonic pseudo-obstruction (ACPO), or Ogilvie syndrome, are similar to large-bowel obstruction and usually develop over 3-7 days, or less commonly, over 24-48 hours. Abdominal distention is the earliest sign. Late symptoms are similar to those seen with large-bowel obstruction.
Nausea and vomiting are not predominate complaints, but fever may be present in the setting of colonic ischemia or perforation.
Although a complete physical examination is necessary, key elements of the physical examination should focus on a thorough examination of the abdomen, groin, and rectum.
Perform the examination in standard fashion, that is, inspection, auscultation, percussion, and palpation.
Abdominal distention may be significant in patients with a large-bowel obstruction (LBO). The bowel sounds may be normal early on but usually become quiet, and the abdomen is hyperresonant to percussion.
Palpation of the abdomen may reveal tenderness. Fever, severe tenderness, and abdominal rigidity are ominous signs that suggest peritonitis secondary to perforation. The cecum is the area most likely to perforate (following the Laplace law that states, in a long pliable tube, the site of largest diameter requires the least pressure to distend ; thus, in a distal large-bowel obstruction, with a competent ileocecal valve, the cecum is the most common site of perforation. ).
The presence of true involuntary guarding or peritoneal signs may be indicative of another intra-abdominal process, such as an abscess. Rebound tenderness is best elicited by having the patient cough or by shaking the bed.
Sigmoid diverticulitis and a perforated sigmoid secondary to carcinoma are clinically difficult to differentiate. Guaiac-positive stool may be seen with carcinoma or diverticulitis.
A rectal or lower sigmoidal mass may be palpated on rectal examination. An abdominal mass or fullness may be palpated if a tumor is present in the cecum.
Evaluation of the inguinal and femoral regions should be an integral part of the examination in a patient with suspected large-bowel obstruction.
Incarcerated hernias represent a frequently missed cause of bowel obstruction. In particular, colonic obstruction is often caused by a left-sided inguinal hernia with the sigmoid colon incarcerated in the hernia. Any old surgical scar should also be examined for the possibility of an incarcerated incisional hernia.
Perform a digital rectal examination (DRE) to verify the patency of the anus in a neonate. The examination focuses on identifying rectal pathology that may be causing the obstruction and determining the contents of the rectal vault.
Hard stools suggest impaction; soft stools suggest obstipation. An empty vault suggests obstruction proximal to the level that the examining finger can reach.
Fecal occult blood testing (FOBT) should be performed. A positive result may suggest the possibility of a more proximal neoplasm.
Given the potential morbidity and mortality associated with large bowel obstruction, the recommended diagnostic approach focuses on rapid evaluation and prompt surgical consultation. Relief of pain, control of vomiting, and correction of fluid and electrolyte abnormalities should occur simultaneously with diagnostic evaluation. Laboratory studies are used to assess the degree of dehydration and electrolyte imbalance, and to evaluate for infection, anemia, and ischemia. Radiographic studies are used to confirm obstruction, to identify its cause if present, and to idenitify other pathology that may be causing the patient's symptoms.
Although at times helpful in the evaluation of suspected bowel obstruction, plain radiography has largely been supplanted by computed tomography (CT) scanning owing to the latter's abilily to provide far more accurate and detailed images of the relevant pathology.
An upright chest radiograph is useful to screen for free air (see first image below), which would suggest perforation and ileus rather than obstruction. Flat and upright abdominal radiographs can help distinguish severe constipation from bowel obstruction. Plain films may also help localize the site of obstruction (large vs small bowel).
Sigmoid or cecal volvulus may have a kidney-bean appearance on the abdominal films (see the second and third images below, respectively). Intramural air is an ominous sign that suggests colonic ischemia. The absence of free air does not exclude perforation (this finding may be absent in half of all perforations).
This chest radiograph demonstrates free air under the diaphragm, indicating bowel perforation in a patient with large-bowel obstruction. Radiograph co....
Massive dilatation of the colon due to a sigmoid volvulus. Radiograph courtesy of Charles J McCabe, MD†.
Abdominal (kidney-ureter-bladder [KUB]) radiograph depicting massive dilatation of the colon due to a cecal volvulus. Radiograph courtesy of Charles J....
Contrast studies include an enema with water-soluble contrast (ie, Gastrografin) (see the following images). Contrast studies that reveal a column of contrast ending in a "bird's beak" are suggestive of colonic volvulus.
Gastrografin study in a patient with obstipation reveals colonic obstruction at the rectosigmoid level. Radiograph courtesy of Charles J McCabe, MD†.
Contrast study of patient with cecal volvulus. The column of contrast ends in a "bird's beak" at the level of the volvulus. Radiograph courtesy of Cha....
Contrast study demonstrates colonic obstruction at the level of the splenic flexure, in this case due to carcinoma. Radiograph courtesy of Charles J M....
CT scanning is the imaging of choice if a colonic obstruction is clinically suspected; this imaging modality can confirm the diagnosis and identify the cause of large-bowel obstruction. Contrast-enhanced CT (PO and IV) can help to delineate between partial and complete obstruction, ileus, and small-bowel obstruction, as well as exclude large-bowel obstruction. Gastrografin (water-soluble contrast) should be used preferentially if bowel perforation is suspected.
Laboratory studies are directed at evaluating the dehydration and electrolyte imbalance that may occur as a consequence of large-bowel obstruction (LBO) as well as at ruling out ileus as a diagnosis.
Routine complete blood cell (CBC) count, serum chemistries, and urinalysis should be evaluated. A serum lactate level should be ordered if bowel ischemia is a consideration. A decreased hematocrit level, particularly with evidence of chronic iron-deficiency anemia, may suggest chronic lower gastrointestinal (GI) bleeding, particularly due to colon cancer. A stool guaiac test should be performed.
Obtain a prothrombin time (PT) as well as a type and crossmatch.
Although bowel obstruction, or even constipation, may mildly elevate the white blood cell (WBC) count, substantial leukocytosis should prompt reconsideration of the diagnosis or increase the suspicion for perforation. Ileus secondary to an intra-abdominal or extra-abdominal infection should also be considered.
Initial therapy in patients with suspected large-bowel obstruction (LBO) includes volume resuscitation, appropriate preoperative broad-spectrum antibiotics, and timely surgical consultation.
A nasogastric tube should be considered for patients with severe colonic distention and vomiting. The patient's intravascular volume is usually depleted, and early intravenous fluid (IVF) resuscitation with isotonic saline or Ringer lactate solution is necessary.
Surgical intervention is frequently indicated, depending on the cause of the obstruction. Closed loop obstructions, bowel ischemia, and volvulus are surgical emergencies.
Transfer to another facility is indicated if adequate surgical management or backup is not available.
Adynamic ileus is treated with conservative measures. This involves correction of fluid and electrolyte imbalances, and treatment of the underlying disorder. Nasogastric decompression may be helpful if the patient is vomiting. Medications that slow colonic motility should be stopped, if possible.
If no perforation is present, pseudo-obstruction is treated with conservative management for the first 24 hours. This includes bowel rest, hydration, and management of underlying disorders.
Pharmacologic treatment of acute colonic pseudo-obstruction with neostigmine or colonoscopic decompression may be effective in cases that do not resolve with conservative management. Colonoscopic decompression may be successful in as many as 80% of patients with acute colonic pseudo-obstruction.
Surgical intervention for acute colonic pseudo-obstruction is associated with a high mortality and morbidity. This treatment is reserved for refractory cases or cases complicated by perforation.
Endoscopic reduction and decompression of a sigmoid volvulus can be performed in the absence of peritoneal signs. This procedure is also contraindicated when evidence of mucosal ischemia is present on endoscopy. An experienced person should perform the procedure.
Recurrence after decompression is as high as 50%; thus, surgical resection is indicated. In healthy patients who have undergone successful decompression, an elective resection should follow. Emergency surgery is indicated in patients with evidence of perforated or ischemic bowel, or if attempts at endoscopic reduction and decompression are not successful.
The preferred treatment for cecal or transverse colon volvulus is surgical resection and anastomosis. Endoscopic detorsion and decompression is an option when the patient is a poor surgical candidate.
A contrast enema (barium or air) can successfully reduce 60-80% of intussusceptions. It is often successful in children in whom a pathologic leading point for the intussusception is unlikely. This procedure should be performed by an experienced radiologist, because the risk of perforation is significant.
In adults, a pathologic leading point for the intussusception is usually present. Reduction with a contrast enema is far less likely, and patients are more likely to require surgery.
Surgery is indicated if there are signs of peritonitis or bowel perforation, or if attempts at reduction by contrast enema are unsuccessful.
Intussusception may recur in approximately 3% of patients after contrast enema reduction and 1% of patients after operative repair.
Endoscopic dilation and stenting of colonic obstruction is helpful in selected cases and may be an alternative to multistage surgery. The procedure may be palliative in a high-risk patient with an unresectable malignancy, or it may be preparatory to surgical resection.[14, 15]
In cases in which the stent is deployed before surgery, this procedure permits relief of the acute obstruction, resuscitation of the patient, and allows for a mechanical bowel preparation before colonic resection and reanastomosis, thus avoiding temporary or permanent colostomy.
Use of a decompression tube may be a feasible, safe, and effective bridge to surgery for acute malignant left-sided colonic obstruction. Surgical treatment of left colon carcinoma includes resection without primary anastomosis or resection with primary anastomosis and intraoperative lavage.[17, 18] Endoscopically placed self-expandable metal stents (SEMS) can be used to relieve the large-bowel obstruction, thus allowing for a primary colorectal anastomosis.
Right colonic obstructions are treated with a right colectomy and a primary anastomosis between the ileum and the transverse colon. Patients with high-risk features for surgery (advanced age, complete obstruction, or severe comorbidities) may benefit from stent placement until the patient can be optimized for a surgical procedure.[20, 21] Palliative colorectal stents are an option in patients who are poor surgical candidates or have advanced cancer.
Endoscopic dilation and stenting of colonic obstruction should be performed only by an endoscopist experienced in such procedures. Surgical consultation and backup should be available, as the risk of perforation is increased during attempts at such procedures, with a potentially catastrophic result. Studies in recent years have identified the following as predictive factors for outcomes after SEMS for large-bowel obstruction:
In addition, SEMS appears to significantly improve histopathologic edema as compared with transanal drainage tube and emergency surgery after failure of decompression for malignant colorectal obstruction.
Patients with persistent obstruction secondary to diverticular disease despite appropriate medical management are treated surgically. Surgical resection follows the same principles as the treatment of carcinomas. Elective colonic resection is offered to patients with recurrent disease.
For obstructed defecation syndrome (ODS) with rectocele, surgery is a last resort. In a study of 90 rectocele patients with functional constipation, 64 responded to treatment with fiber supplements and biofeedback training with significant improvements in ODS symptoms, including 15 of the 17 patients with rectocele and concomitant intussusception[24, 25] ; the remaining 26 required surgical intervention.
In this study, median cumulative ODS scores improved from 15.0 before treatment to 10.5 after treatment in the medical management group (P < .001) and from 13.5 before surgery to 10.5 after surgery in the surgical intervention group (P < .001).
Care after discharge following surgical management of large-bowel obstruction (LBO) focuses on surgical convalescence and, if relevant, the need to care for the disease that caused the obstruction.
Aggressive screening for colorectal cancer in individuals who are older than 50 years or who have a strong family history of colorectal cancer, as indicated by current guidelines, should reduce the future incidence of malignant colonic obstruction.
If the patient has received a colostomy or ileostomy, a decision regarding whether it is temporary or permanent may have been made at the time of discharge, depending on the patient's diagnosis, comorbidity, and postoperative convalescence.
In addition, the remaining colon, both proximally and distally, must be evaluated radiographically or endoscopically to rule out synchronous colonic lesions, such as neoplasms.
Bowel obstruction frequently necessitates surgical intervention. However, antibiotics should be started in the ED. Coverage must include gram-negative aerobic and gram-negative anaerobic organisms. The following antibiotics do not represent an all-inclusive list.
Clinical Context: Clindamycin is a lincosamide that is useful in treating serious skin and soft-tissue infections caused by most staphylococcal strains. This agent is also effective against aerobic and anaerobic streptococci, except enterococci.
Clindamycin acts by inhibiting bacterial protein synthesis via inhibition of the peptide chain initiation at the bacterial ribosome, where it preferentially binds to 50S ribosomal subunit, thereby inhibiting bacterial growth.
Clinical Context: Metronidazole is an imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. This agent is used in combination with other antimicrobial agents (but used alone in Clostridium difficile enterocolitis).
Clinical Context: Cefoxitin is a second-generation cephalosporin that is indicated for the management of infections caused by susceptible gram-positive cocci and gram-negative rods. This agent is effective against aerobic and anaerobic gram-negative organisms.
Clinical Context: Second-generation cephalosporin indicated for management of infections caused by susceptible gram-positive cocci and gram-negative rods.
Clinical Context: The combination of imipenem and cilastatin is effective against aerobic and anaerobic gram-negative organisms.
Clinical Context: Meropenem is a bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. This agent is effective against most gram-positive and gram-negative bacteria
Clinical Context: Piperacillin-tazobactam inhibits the biosynthesis of cell wall mucopeptide and is effective during the stage of active multiplication. It has antipseudomonal activity.
Antibiotic therapy must cover all likely pathogens in the context of this clinical setting.