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Program Written Summary
Audio-Digest Family Practice
Volume 61, Issue 13
April 7, 2013

Bowel Obstruction – Thomas A. Kintanar, MD
Irritable Bowel Syndrome – Timothy T. Nostrant, MD

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Audio CD $27.99

The following is an abstracted summary, not a verbatim transcript, of the lectures/discussions on this audio program.

Family Practice Program Info  Accreditation InfoCultural & Linguistic Competency Resources

Bowel Dysfunction: Obstruction/Irritable Bowel Syndrome

Educational Objectives

The goal of this program is to improve the management of bowel obstruction and irritable bowel syndrome (IBS). After hearing and assimilating this program, the clinician will be better able to:

1. Identify symptoms and causes of bowel obstruction.

2. Use diagnostic tools to confirm the diagnosis of bowel obstruction.

3. Refer patients with bowel obstruction for appropriate treatment.

4. Recognize factors that may contribute to the development of IBS, such as inflammation, diet, and stress.

5. Describe the role of serotonin and visceral sensitivity in patients with IBS.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose.

Bowel Obstruction

Thomas A. Kintanar, MD, Clinical Associate Professor of Medicine, Indiana University School of Medicine, Fort Wayne

Bowel obstruction: complete or partial blockage of bowel that results in failure of intestinal contents to pass through to elimination; can be mechanical, ileus (dysfunction despite absence of structural problem), paralytic ileus, or pseudo-obstruction

Mechanical causes: intestinal adhesions; hernias; tumors in small intestine; inflammatory bowel disease (Crohn disease or ulcerative colitis); volvulus (rare); polyps; tumors or colon cancer; diverticular abscess; impacted feces; narrowing of colon due to inflammatory changes associated with ulcerative colitis, Crohn disease, or scarring; HANGIV mnemonic — hernias; adhesions; neoplasm; gallstone ileus, intussusception; volvulus

Ileus: hypomotility of gastrointestinal (GI) tract (ie, failed transport of intestinal contents due to impaired bowel muscle); fibers fail to fire due to autonomic dysfunction, resulting in atony; physiologic ileus — resolves in 2 to 3 days; patients present in emergency department (ED) with influenza-type gastroenteritis and ileus pattern on plain abdominal radiography (kidneys, ureter, bladder [KUB]); normal function returns with hydration and resting of gut for 2 days; dynamic or paralytic ileus — persists for >3 days after surgery and spinal anesthesia; risk factors — surgery; inflammation; stroke; metabolic imbalances; trauma; fluid overload; other medical illnesses (eg, renal stones, fractures, myocardial infarctions); worrisome consequences — perforation; ischemia of bowel

Common causes of obstruction: small bowel — adhesions, and others mentioned above; proximal obstructions associated with minimal abdominal retention, but patients have marked emesis; colon — ovarian cancer; intestinal atresia from tumors; pseudo-obstruction; volvulus; cancer; gallstone ileus; pathology of obstruction similar in small and large bowel; intestinal — 60% due to adhesion; 20% due to neoplasm; herniation

Common symptoms: abdominal distention; abdominal fullness and gas; pain and cramping; constipation; diarrhea; fetid breath odor; vomiting

Diagnosis: patient history; physical examination — high-pitched bowel sounds heard in early obstruction; minimal bowel sounds heard in late obstruction, with extreme tenderness (intestinal tract becomes hypotonic); palpable masses; distention; consider location of tenderness and rebound phenomenon (in, eg, patients with history of diverticular rupture or peritonitis); key signs — nausea and vomiting; in early small bowel obstruction, emesis (in large volume) develops early; in large bowel obstruction, emesis develops later (vomit often fecal or fetid), with deep abdominal visceral pain; pain near site of obstruction; distension more common; in complete obstruction, patients have absence of bowel sounds; in partial obstruction, bowel sounds can be high-pitched or tympanitic, and vary based on individual patient and clinical setting

Acute colonic pseudo-obstruction: characterized by dilatation of cecum; difficult to delineate in patients due to similarity to other types of large bowel obstructions; associated with underlying disease in 95% of patients; associated with fecal impaction; can be related to wide variety of processes (eg, cardiac, gynecologic; difficult to distinguish between paralytic ileus and acute colonic pseudo-obstruction in postoperative patients); mechanism unknown; presentation similar to that of other types of obstruction; more common in individuals 60 yr of age; physical examination — bowel sounds almost always present, unless perforation noted; tympanitic bowel sounds most common finding; management — placement of rectal decompression tubes; colonoscopy; surgery may be indicated if conservative therapies fail

Complications: electrolyte imbalances; infections with perforations; biliary tract disease; jaundice; perforation; gangrene; ischemia of bowel; consider social history and family support

Diagnostic tools: metabolic panel; complete blood cell count; colonoscopy has limited diagnostic value but can identify level of obstruction, if needed; KUB — can define site and extent; demonstrates air-fluid levels; contrast pills help evaluate motility, dysmotility, and partial obstruction; radiography with barium or diatrizoate 66% and diatrizoate 10% (Gastrografin, MD-Gastroview) contrast; retrograde studies may be helpful; 60% of diagnoses may be based on plain-film radiography (useful in emergent settings); computed tomography (CT) — accurate for diagnosing or ruling out obstruction; in study of 75 patients, accuracy in distinguishing obstruction from pseudo-obstruction 95%; appropriate for further evaluation of patients with suspected obstruction; sensitive for detection of high-grade obstruction; identifies causes, eg, volvulus or strangulation; helical CT has 87% sensitivity and specificity; magnetic resonance imaging (MRI) — may be helpful if CT or x-ray fail to provide sufficient information; absence of contrast material in rectum important sign of complete obstruction; rectal administration of contrast material should be avoided; presence of dilated loops of bowel proximal to site of obstruction suggestive of inflammation (pathology found on subsequent colonoscopy in 50% of patients); American College of Radiology recommends noncontrast CT as initial choice for abdominal imaging; fluoroscopy — helpful in diagnosing patients in whom clinical suspicion of partial intestinal obstruction high; use of water-soluble contrast material may be therapeutic; useful for determining need for surgery; presence of contrast in rectum within 24 hr has 97% sensitivity for spontaneous resolution of intestinal obstruction; ultrasonography — largely replaced by CT, even though sensitivity for evaluation of abdomen high (near 85%); endoscopy — early surgical consultation should be obtained in obstruction setting (endoscopy not recommended); decompression with more invasive methods (eg, colonoscopy, decompression tubes in pseudo-obstruction) may be recommended when all conservative measures fail; endoscopy for evaluation of initial treatment of sigmoid volvulus recommended; therapeutic colonoscopy has limited role in obstruction (as monotherapy or as combination therapy with surgery)

Treatment options: bowel rest; correct physiologic derangements; correct source of obstruction; monitor urine output of hospitalized patients; arterial line or central venous pressure monitoring optional; antibiotics that cover gram-negative organisms and anaerobes; conservative management effective in most clinically stable patients, with higher success rate in those with partial obstruction

Summary: bowel obstruction has varied symptoms and causes, including mechanical causes (eg, ileus, paralytic ileus); imaging modalities useful adjuncts to patient history and physical examination in achieving diagnosis; many cases can be managed conservatively; surgical intervention must be ready consideration

Irritable Bowel Syndrome

Timothy T. Nostrant, MD, Professor of Medicine, University of Michigan Medical School, Ann Arbor

Irritable bowel syndrome (IBS): criteria — abdominal pain that improves with bowel movement; onset of pain associated with change in frequency or consistency of stools; women with IBS have 4 times more surgery on organs; surgeries worsen IBS due to associated increases in visceral sensitivity

Inflammation: present in 33% of patients with IBS; active inflammatory process increases hypermotility in GI tract and visceral hypersensitivity; patients who develop bacterial or viral infection may develop irritability that can persist over long period (commonly seen in missionaries); ask about infection and exposures; ask about acute onset and persistence of symptoms (these suggest IBS)

Transit: high-amplitude, long-duration ileal contractions associated with pain and profound peristalsis; dynamic CT shows persistent spasms of small intestine; IBS correlated with number and amplitude of contractions; contractility increased in basal state and after eating, and after stimulation with cholecystokinin; functional emptying of gallbladder common in IBS (patients have decreased ejection fraction; not differential diagnosis for cholecystitis); some patients respond to cholecystectomy; however, long history of abdominal discomfort unlikely related to gallbladder; patients with biliary retention likely have biliary origin (consider surgery)

Role of serotonin: 5-HT4 receptor stimulates contraction; 5-HT3 receptor stimulates contraction and decreases visceral sensitivity; 5-HT4 agonists used to treat IBS-associated constipation; antivisceral proprioceptive agents used to reduce IBS-associated diarrhea and other symptoms; 5-HT1 agonists (eg, buspirone) significantly affect upper GI tract and reduce colonic contractility; 5-HT3 antagonists decrease diarrhea, sensitivity, and pain; 5-HT4 agonists have prokinetic properties

Diet: lactase deficiency — common; identified by testing or restriction; malabsorption of fructose — normal; can cause abdominal cramping, bloating, and diarrhea; may be more severe in IBS patients due to increased contractility and visceral sensitivity; sorbitol — 1 stick of sugar-free chewing gum equivalent to 15 mL of lactulose; fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) diet — study found 77% of patients who received fructose developed significant symptom complex, compared with 14% who received glucose; consider referral to nutritionist

Stress: IBS patients do not have increased psychologic predisposition; stress increases colonic motility and visceral sensitivity

Sensory signaling in GI tract: visceral sensitivity — normally, stimuli within bowel (eg, food, drinks) lead to input of data (perceived as normal sensations) via extrinsic vagal and spinal afferent nerves; signals modified at central nervous system (CNS) and upper portion of spinal canal via antinocioceptive pathways; GI tract can be stimulated by larger processes that cause fullness, gas, nausea, and vomiting; stimuli increase visceral sensitivity (particularly, sexual or physical abuse; include inquiry about abuse in history); visceral hypersensitivity — afferent input markedly increased; nociceptive pathways decreased; CNS processes information to different degree; pain — functional MRI shows remarkable difference in pain perception between patients with IBS and patients without IBS; study saw difference in pain perception between patients with IBS and patients without IBS when rectosigmoid junction (RSJ) distended by balloon (patients without IBS perceived pain only at RSJ, but patients with IBS had pain at varying sites); conclusion — varying pain throughout abdomen with change in bowel habits always IBS

Comorbidities: one-third of patients with IBS have gastroesophageal reflux disease (GERD) or nonulcerative dyspepsia; fibromyalgia; interstitial cystitis; sensory disease; vasospastic upper GI tract disease; gallbladder emptying disorders; psychiatric diagnoses can increase over time (patients develop somatization that leads to severe psychiatric illness)

Differential diagnoses and testing: for young patients who present with irritability, major concerns include inflammatory bowel disease; in patients 60 yr of age with similar symptoms, consider colon cancer; in patients with acute diarrhea, consider GI infections; thyroid dysfunction; lactase malabsorption; celiac disease and bacterial overgrowth more common in patients with IBS than in general population; if patient has no alarm signs (eg, weight loss, GI bleeding), test for celiac disease; make decisions about diet (eg, FODMAPs- or lactase-restricted diet); discuss findings and address patient’s concerns (eg, need for surgery or colon cancer)

Small bowel bacterial overgrowth: has multiple etiologies; antibiotics can be effective in patients with comorbid IBS; proton pump inhibitors (PPIs) increase bacterial overgrowth in upper GI tract (stop PPI and wait, or treat with antibiotics, then stop PPI)

Gas and bloating: normally, 700 to 1000 mL of gas passed per day; gas transit accelerated by high-calorie meals; high calorie intake and intestinal lipids associated with more bloating; upright position (eg, eating while standing) may be helpful; physical activity increases gas transit; dietary restrictions can be helpful, based on symptom complex; in patients with IBS, gas tends to accumulate in jejunum and ileum (ie, in small intestine rather than in colon); diaphragmatic descent — associated positional change may cause abdominal distention in some patients; biofeedback may be helpful; in functional disease, abdomen protrudes due to diaphragmatic descent; in organic disease, abdomen protrudes due to increased gas; patients with retention of gas and bloating have 3-fold increase in gas content; patients given neostigmine had remarkable decrease in GI symptoms but no significant change in bloating; bloating not due to gas alone (likely also due to visceral sensitivity); important to set reasonable expectations of therapy; 92% of patients with IBS have bloating; 84% of IBS patients have small bowel bacterial overgrowth on lactulose breath testing (not recommended by speaker; leads to overdiagnosis); methane, hydrogen, and sulfate gases have different characteristics; methane production associated with constipation; hydrogen production associated with diarrhea


Dr. Kintanar was recorded in Philadelphia, PA, at the American Academy of Family Physicians’ Scientific Assembly, presented October 16-20, 2012. For information about next year’s meeting, please visit Dr. Nostrant spoke in Ann Arbor, MI, at Update in Family Medicine, presented October 4-5, 2012, by the University of Michigan Health System and the Department of Family Medicine. For a calendar of upcoming courses from this sponsor, please visit e/course-calendar. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

Suggested Reading

No authors listed: An unusual cause of large bowel obstruction. Colorectal Dis. 2013 Jan;15(1):e60-1; Accarino A et al: Abdominal distention results from caudo-ventral redistribution of contents. Gastroenterology. 2009 May;136(5):1544-51; Almy TP: Experimental studies on the irritable colon. Am J Med. 1951 Jan;10(1):60-7; Gebhart GF: Pathobiology of visceral pain: molecular mechanisms and therapeutic implications IV. Visceral afferent contributions to the pathobiology of visceral pain. Am J Physiol Gastrointest Liver Physiol. 2000 Jun;278(6):G834-8; Hayakawa K et al: Radiological diagnosis of large-bowel obstruction: nonneoplastic etiology. Jpn J Radiol. 2012 Aug;30(7):541-52; Lin HC: Small intestinal bacterial overgrowth: a framework for understanding irritable bowel syndrome. JAMA. 2004 Aug 18;292(7):852-8; Lombardo L et al: Increased incidence of small intestinal bacterial overgrowth during proton pump inhibitor therapy. Clin Gastroenterol Hepatol. 2010 Jun;8(6):504-8; Longstreth GF et al: Functional bowel disorders. Gastroenterology. 2006 Apr;130(5):1480-91; Mallo RD et al: Computed tomography diagnosis of ischemia and complete obstruction in small bowel obstruction: a systematic review. J Gastrointest Surg. 2005 May-Jun;9(5):690-4; Matta R et al: Celiac disease presenting as acute colonic pseudo-obstruction. J Med Liban. 2012 Apr-Jun;60(2):110-2; Maung AA et al: Eastern Association for the Surgery of Trauma. Evaluation and management of small-bowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012 Nov;73(5 Suppl 4):S362-9; Noah AO et al: Gallstone ileus: a not-so-rare cause of bowel obstruction in the elderly. BMJ Case Rep. 2012 Nov 27;2012; Salvioli B et al: Origin of gas retention and symptoms in patients with bloating. Gastroenterology. 2005 Mar;128(3):574-9; Shen YH, Nahas R: Complementary and alternative medicine for treatment of irritable bowel syndrome. Can Fam Physician. 2009 Feb;55(2):143-8; Staudacher HM et al: Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome. J Hum Nutr Diet. 2011 Oct;24(5):487-95; Trésallet C et al: Improving the management of acute adhesive small bowel obstruction with CT-scan and water-soluble contrast medium: a prospective study. Dis Colon Rectum. 2009 Nov;52(11):1869-76; Whitehead WE et al: Irritable bowel syndrome: physiological and psychological differences between diarrhea-predominant and constipation-predominant patients. Dig Dis Sci. 1980 Jun;25(6):404-13; Zielinski MD et al: Small bowel obstruction-who needs an operation? A multivariate prediction model. World J Surg. 2010 May;34(5):910-9.

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