Bowel obstruction (small, large, volvulus)

How does sigmoid volvulus present clinically?

Acute abdominal pain Progressive abdominal distention Anorexia Obstipation Cramps Nausea/vomiting

How long is the duodenum?

12 inches

What is the length of the entire small bowel?

6 meters/20 feet

What are adhesions?

60-75% of cases of mechanical SBO are secondary to adhesions related to prior abdominal surgery. Lower abdominal and pelvic surgery appears to be associated with a higher incidence of adhesions compared to upper abdominal surgery.

What is an important factor in LBO?

A major factor in the clinical course of large bowel obstruction depends on the competence of the ileocecal valve. 10-20% of patients have an incompetent ileocecal valve which allows decompression of the large bowel contents into the ileum. However, in the majority of patients, the ileocecal valve does not allow reflux to occur, resulting in a closed loop obstruction with rapidly increasing intraluminal pressure. This results in impaired capillary circulation, mucosal ischemia, and subsequent bacterial translocation with systemic toxicity. This process ultimately progresses to gangrene and perforation.

What differential diagnoses should be considered when evaluating a patient for suspected SBO?

A post-operative ileus may be caused by several factors, including drugs used for anasthesia and analgesia, and intraoperative manipulation of intestinal loops and the mesentery. Usually it is temporary (3-5 days). If the ileocecal valve is incompetent, the distal small bowel will be dilated, and patients will exhibit abdominal distention, nausea and vomiting. Acute gastroenteritis, acute appendicitis and acute pancreatitis can mimic simple intestinal obstruction, while acute mesenteric ischemia (AMI) must be considered in the differential. The clinical manifestations of chronic intestinal pseudo-obstruction include recurrent episodes of vomiting, crampy abdominal pain and abdominal distention.

How is LBO diagnosed?

Abdominal films will frequently reveal dilated colon outlining the abdominal cavity. The colon can be distinguished from the small intestine by its haustral markings, which do not cross the entire lumen of the distended colon. -A transition point with no distal colonic gas indicates complete obstruction. A CT scan with rectal contrast is the most useful single test for LBO because it can yield information regarding the location and etiology of the bowel obstruction.

How is cecal volvulus diagnosed?

Abdominal plain film; dilated, ovoid colon with large air/fluid level in the RLQ often forming the classic "coffee bean" sign with the apex aiming toward the epigastrium or LUQ (must rule out gastric dilation with NG aspiration) If diagnosis cannot be made by AXR or CT scan, perform water-soluble study (Gastrografin enema).

How does cecal volvulus present clinically?

Acute onset of abdominal or colicky pain beginning in RLQ and progressing to a constant pain, vomiting, obstipation, abdominal distention and SBO; many patients will have had previous similar episodes.

What is Ogilvie syndrome?

Acute pseudo-obstruction of the colon (Ogilvie syndrome) presents with massive colonic distention in the absence of a mechanically obstructing lesion. It is a severe form of ileus that occurs most commonly in systematically ill patients and results from an imbalance in the autonomic tone with subsequent absence of peristalsis. If the patient has no signs of obstruction or perforation, the initial measures include nasogastric suction, rectal tube placement, fluid resuscitation, and correction of electrolyte imbalances. The acetylcholinesterase inhibitor neostigmine is an effective treatment for acute colonic pseudo-obstruction in patients without response to conservative measures.

How is LBO treated?

An operation is almost always required for mechanical large bowel obstructions. The primary goals of treatment are resection of all necrotic bowels and decompression of the obstructed segment.

What does the terminal ileum absorb?

B12, fatty acids, bile salts.

How is sigmoid volvulus diagnosed?

CT scan Sigmoidoscopy Radiographic exam with Gastrografin enema -If sigmoidoscopy and plain films fail to confirm the diagnosis, "bird's beak" is pathognomonic seen on enema contrast study as the contrast comes to a sharp end.

What tests can differentiate partial from complete SBO?

CT scan with oral contrast

What are causes of LBO in adults?

Carcinoma of colon (65%) Diverticulitis (20%) Miscellaneous (10%) Volvulus (5%)

What differential diagnoses should be considered when evaluating a patient for volvulus?

Cecal volvulus must be differentiated from colonic pseudo-obstruction and from other causes of small bowel and colonic obstruction. Sigmoid volvulus mimics other types of large bowel obstruction.

What is cecal volvulus?

Cecal volvulus often occurs in patients with a hypermobile cecum as a result of incomplete embryologic fixation. The average age of presentation is 53 years. The cecum and terminal ileum are involved in the rotation, so the symptoms generally include those of distal small bowel obstruction. Severe intermittent colicky pain begins in the right abdomen. Pain eventually becomes continuous and the patient will experience the classic symptoms of obstruction: vomiting, distention, and obstipation. Imaging studies are the key to diagnosis. A plain film of the abdomen in later stages may show a hugely dilated ovoid cecum that favors the epigastrium or left-upper quadrant. It is classically described as the "coffee bean" sign.

What are the plicae circulares?

Circular folds of mucosa (aka "valvulae conniventes") in small bowel lumen.

What is the danger of complete SBO?

Closed loop strangulation of bowel leading to bowel necrosis.

What is the most common cause of LBO?

Colon cancer

What are AXR findings of sigmoid volvulus?

Distended loops of sigmoid colon, often in the classic "bent inner tube" or "omega" sign with the loop aiming toward the RUQ.

What major abdominal radiographic findings are associated with SBO?

Distended loops of small bowel air fluid levels on upright film.

What comprises the small bowel?

Duodenum, jejunum and ileum.

How is cecal volvulus treated?

Emergent surgery, right colectomy with primary anastomosis or ileostomy and mucous fistula (primary anastomosis may be performed in stable patients).

When is surgical treatment of sigmoid volvulus indicated?

Emergently if strangulation is suspected or nonoperative reduction is unsuccessful. Most patients should undergo resection during same hospitalization of redundant sigmoid after successful nonoperative reduction because of high recurrence rate.

78 year old male with RLQ and "coffee bean" colonic dilation on XR consistent with cecal volvulus. What is the treatment?

Ex lap with resection with primary anastomosis or ileostomy.

What are the signs of strangulated bowel with SBO?

Fever, severe/continuous pain, hematemesis, shock, gas in the bowel wall or portal vein, abdominal free air, peritoneal signs, acidosis (increased lactic acid)

How are right-sided LBO's treated?

Generally speaking, obstruction lesions of the right colon can be resected in one stage if the patient's condition is stable.

What are risk factors for sigmoid volvulus?

High residue diet resulting in bulky stools and tortuous, elongated colon Chronic constipation Laxative abuse Pregnancy Seen most commonly in bedridden elderly or institutionalized patients, many of whom have history of prior abdominal surgery or distal colonic obstruction

What are classic electrolyte/acid-base findings with proximal obstruction?

Hypovolemic, hypochloremic, hypokalemia and alkalosis

What is the etiology of cecal volvulus?

Idiopathic, poor fixation of the right colon, many patients have history of abdominal surgery.

How is sigmoid volvulus managed?

In contrast, sigmoid volvulus without strangulation is more commonly treated initially by urgent endoscopy. A flexible sigmoidoscopy or colonoscope is advanced to the obstruction. Under direct visualization, the colon is insufflated and the tip of the scope is used to apply gentle pressure.

What are signs of SBO?

Initially, vital signs may be normal, but tachycardia and hypotension usually develop as a result of progressive dehydration. Peristalsis is usually tremendously increased in the early phases of mechanical SBO. This so-called "peristaltic rush" progressively decreases until it disappears in the late phase of obstruction.

What is a cecal "bascule" volvulus?

Instead of the more common axial twist, the cecum folds upward (lies on ascending colon).

What are neoplasms?

Intrinsic small bowel neoplasms can progressively occlude the lumen or serve as a leading point in intussusception.

What are laboratory findings in SBO?

Laboratory findings reflect intravascular volume depletion and dehydration. -Elevated hematocrit: hemoconcentration -Leukocytosis: dehydration and acute stress response -Elevated serum creatinine: hypovolemia and pre-renal failure

What is the treatment of complete SBO?

Laparotomy and lysis of adhesions.

What marks the end of the duodenum and the start of the jejunum?

Ligament of Treitz

How is cecal volvulus managed?

Many techniques have been described for managing patients with cecal volvulus, but the recommended treatment is ileocecectomy.

What is mechanical obstruction?

Mechanical obstruction implies an extrinsic or intrinsic obstacle that prevents the aboral progression of intestinal contents and it may be complete or partial. Simple obstruction occludes the lumen only; obstruction with strangulation impairs the blood supply also and leads to necrosis of the intestinal wall.

What is the initial management of all patients with SBO?

NPO, NGT, IVF, Foley

What is the initial treatment of sigmoid volvulus?

Nonoperative: if there is no strangulation, sigmoidoscopic reduction is successful in 85% of cases; enema study will occasionally reduce. Note: 40% rate of recurrence

How does LBO present clinically?

Obstipation is a universal feature of complete obstruction, though the patient may pass stool and gas located distal to the obstruction after the initial symptoms begin. Vomiting is a late finding and may not occur at all if the ilececal valve prevents reflux. The onset of symptoms may be acute or gradual, depending on the location/etiology of the obstruction. A patient with fever, leukocytosis, and peritonitis has likely progressed to develop intestinal ischemia and/or perforation.

How are left-sided LBO's treated?

Obstructing lesions of the left colon more commonly require diversion. Ideally the lesion is resected at the initial operation.

What is large bowel obstruction (LBO)?

Obstruction can result from actual pathology of the bowel wall including malignancy and strictures, mechanical problems such as volvulus, incarcerated hernia, and intussusception, or intraluminal factors such as fecal or foreign body impaction. Acute functional obstruction of the colon (Ogilvie syndrome) can cause the same spectrum of clinical symptoms.

What are other cause of mechanical SBO?

Other causes of SBO include Crohn disease, intussusception (which is most often seen in children without an organic lesion and rarely in adults with a neoplastic intraluminal lesion), volvulus as a consequence of intestinal malrotation in children or of adhesions in adults, and foreign bodies.

What is paralytic ileus?

Paralytic (or adynamic) ileus is due to a neurogenic failure of peristalsis to propel intestinal contents with no mechanical obstruction.

What condition commonly mimics SBO?

Paralytic ileus (AXR reveals has discretion throughout, including the colon)

What are symptoms of SBO?

Patients usually present with nausea, vomiting, colicky abdominal pain, and obstipation, although residual gas and stool distal to the obstruction may be expelled. With proximal SBO, emesis is usually profuse, containing undigested food. Abdominal pain is more often described as upper abdominal discomfort associated with epigastric distention. Distal SBO is characterized by diffuse and poorly localized crampy abdominal pain. Feculent vomiting present in longstanding distal SBO is the consequence of bacterial overgrowth and is pathognomonic for a complete mechanical obstruction.

What are the major differences in the emergent management of cecal volvulus versus sigmoid?

Patients with cecal volvulus require surgical reduction, whereas the vast majority of patients with sigmoid volvulus undergo initial endoscopic reduction of the twist.

What is an absolute indication for operation with partial SBO?

Peritoneal signs, free air on xray.

How is SBO diagnosed?

Plain x-rays of the abdomen with the patient in supine and upright position can confirm the clinical diagnosis of SBO. They reveal dilated small bowel loops with air-fluid levels in a ladder-like appearance, and a paucity of air in the colon. CT scan can visualize the specific location of the obstruction. Moreover, CT scan can also reveal the etiology of SBO and demonstrate signs of strangulation including thickening of the bowel wall, air in the bowel wall or portal venous system, and poor uptake of IV contrast by the affected bowel well.

What is the differential diagnosis of paralytic ileus?

Postoperative ileus after abdominal surgery (normally resolves in 3-5 days) Electrolyte abnormalities (hypokalemia most common) Medications (anticholinergics, narcotics) Inflammatory intra-abdominal process Sepsis/shock Spinal cord injury Retroperitoneal hemorrhage

60 year old male with LOW pain and "parrot's beak" on XR, consistent with sigmoid volvulus. What is the treatment?

Proctosigmoidoscopy to decompress initially.

67 year old male smoker on Coumadin for chronic DVT notices LLQ pain after a strenuous coughing spell; LLQ mass detected on physical exam. What is the most likely diagnosis?

Rectus sheath hematoma

When is surgical treatment of SBO indicated?

Regardless of the cause of obstruction, all small bowel loops must be examined and nonviable segments resected. -Criteria suggesting viability include normal pink color, presence of peristalsis, and arterial pulsation Generally, an open procedure is performed through an incision that is partly dictated by the location of scars from previous operations.

What is small bowel obstruction (SBO)?

SBO is one of the most common disorders affecting the small bowel. It is characterized by impairment in the normal flow of intraluminal contents and can be divided into mechanical obstruction and paralytic ileus.

What is the most common type of colonic volvulus?

Sigmoid volvulus (75%)

What is sigmoid volvulus?

Sigmoid volvulus tends to occur in elderly or institutionalized patients who experience high rates of constipation and associated motility disorders. Symptoms include intestinal colic, nausea and obstipation. Distention tends to be more pronounced in sigmoid volvulus. Abdominal x-rays show a markedly distended loop of bowel like a "bent inner tube" that has lost its haustral markings rising up out of the pelvis extending towards the diaphragm. Barium enema reveals a pathognomonic "bird's beak" deformity with spiral narrowing of the upper end of the lower segment.

What are endoscopic stents?

Stents may be considered for palliation in high-risk patients whose obstructing cancers are not resectable.

What is the etiology of mechanical obstruction?

The causes of mechanical obstruction can be divided into three groups according to the relationship to the intestinal wall: (1) intraluminal; (2) intramural; and (3) extrinsic. The three most common etiologies are intra-abdominal adhesions, hernias and neoplasms.

What portion of the colon is at greatest risk of perforation due to LBO?

The cecum has the largest diameter and therefore, by the law of LaPlace, is at greatest risk for perforation. The normal diameter is approximately 7 cm. The risk of perforation is high if the diameter increases acutely or to a size of greater than 10-12 cm.

How is volvulus managed?

The first step in the management of these patients is fluid resuscitation and the correction of electrolyte imbalances. Vital signs and urine output should be monitored and a nasogastric tube placed.

What are hernias?

The most common cause of SBO in patients with no history of prior abdominal surgery is a hernia. In patients who have undergone previous surgery, incisional hernias represent another potential cause of SBO especially after laparotomy, in overweight or obese patients, in patients on steroid therapy or with wound infections.

What is the prognosis of volvulus?

The outcome for patients with volvulus depends on comorbidities, the urgency of the surgery, and the presence of strangulation or perforation. The mortality rate for patients with cecal and sigmoid volvulus is less than 10%, but this increases to 30-50% if perforation or strangulation has occurred.

What is the prognosis of LBO?

The prognosis depends upon the age and general condition of the patient, the extent of vascular impairment of the bowel, the presence or absence of perforation, the cause of obstruction and the promptness of surgical management. The overall mortality rate is about 20%. Cecal perforation carries a 40% mortality rate.

What is cecal volvulus?

Twisting of the cecum upon itself and the mesentery (25% of colonic volvulus).

What is colonic volvulus?

Twisting of the colon on itself about its mesentery, resulting in obstruction and, if complete, vascular compromise with potential necrosis, perforation or both.

What is the prognosis of SBO?

Vast majority of patients (>80%) of patients with adhesive SBO do not need an operation, since they improve with medical therapy. Among patients who require surgery, perioperative mortality rate for non-strangulating obstruction is <5%; most of these deaths occur in elderly patients with significant comorbidities.

How is SBO treated?

Vigorous fluid resuscitation and correction of electrolyte disorders (hypochloremic, hypokalemic metabolic alkalosis) is mandatory. A urinary catheter should be placed to monitor urinary output. Gastrointestinal decompression with a nasogastric tube provides relief of symptoms, prevents further gas and fluid accumulation proximally, and decreases the risk of aspiration. Obstruction that occurs in the early postoperative period is usually partial and only rarely associated with strangulation. Therefore, a period of prolonged total parenteral nutrition and hydration is warranted.

What is the epidemiology of volvulus?

Volvulus accounts for 5% of all cases of LBO in the US. -Most cases involve the cecum or sigmoid colon In pregnant women, volvulus accounts for 25% of intestinal obstructions, most commonly in the third trimester.

What is volvulus?

Volvulus involves rotation of a segment of the intestine on an axis formed by its mesentery. This results in a closed-loop obstruction and is therefore a surgical emergency.

What is sigmoid volvulus?

Volvulus or "twist" in the sigmoid colon

What is the pathophysiology of small bowel obstruction?

With the onset of obstruction, gas and fluid accumulate and distend the intestinal loops proximal to the site of obstruction. Fluid from the extracellular space also fills the lumen proximal to the obstruction, due to the impaired bidirectional flow of salt and water and fluid secretion enhanced by substances (endotoxins, prostaglandins) released from proliferating bacteria in the intestinal lumen. As a consequence, intraluminal and intramural pressures rise until microvascular perfusion to the intestine is impaired, leading to intestinal wall ischemia, and ultimately necrosis. Activity of the smooth muscle of the small bowel is increased in an attempt to propel its contents past the obstruction consuming all energy sources. At this point the intestine becomes atonic and enlarges further. When full thickness necrosis of the intestinal wall occurs, luminal content with an elevated bacterial load enters the peritoneal cavity and is absorbed by the peritoneum, causing septic shock.

Can a patient have complete SBO and bowel movements and flatus?

Yes; the bowel distal to the obstruction can clear out gas and stool.