Tuesday, August 31, 2021

Family Medicine Irritable Bowel Syndrome Case File

Posted By: Medical Group - 8/31/2021 Post Author : Medical Group Post Date : Tuesday, August 31, 2021 Post Time : 8/31/2021
Family Medicine Irritable Bowel Syndrome Case File
Eugene C. Toy MD, Donald Briscoe, MD, FA  AFP, Bruce Britton, MD, Joel J. Heidelbaugh, MD, FA  AFP, FACG

Case 40
A 28-year-old white woman presents to your office with a chief complaint of constipation and abdominal pain. On further questioning, she reports she has had this problem since beginning college at the age of 18. Her symptoms have waxed and waned since this time, but never have worsened. She describes her abdominal pain as dull, crampy, and nonfocal but more prominent in the left lower quadrant, and improved with defecation. She denies radiation of pain, nausea, vomiting, fever, chills, weight loss, heartburn, or bloody or dark stool. She reports that over the last 3 months she is having cramps 7 to 10 times per month and having a bowel movement every 1 to 2 days that is hard and feels incomplete. She has tried over-the-counter remedies, including stool softeners and antacids, but only experienced minimal improvement in her symptoms. She only takes birth control pills and denies any use of herbal supplements or laxatives. Her family history is negative, including for colorectal cancer and inflammatory bowel disease, and she reports that her parents and siblings are healthy. She is currently engaged and reports significant stress in preparing for the wedding. On physical examination, you note her to be somewhat anxious, but otherwise in no apparent distress. Her vital signs and general physical examination are normal. Her abdomen has normal bowel sounds, no tenderness on superficial and deep palpation, and no rebound, rigidity, or guarding. Liver and spleen size are within normal limits and no masses are palpable. A pelvic examination is normal. The rectal examination shows normal sphincter tone, no masses, and brown stool that is occult blood negative.

 What is your most likely diagnosis?
 What is your next diagnostic step?
 What is the next step in therapy?

Irritable Bowel Syndrome

Summary: A 28-year-old woman presents with a several-year history of crampy abdominal pain and constipation alternating with diarrhea. She denies any fever, weight loss, heartburn, or bloody stools. Her past medical history and family history are otherwise unremarkable. The physical examination, including abdominal and pelvic examination, are grossly within normal limits.
  • Most likely diagnosis: Irritable bowel syndrome (IBS) (mixed subtype).
  • Most appropriate next diagnostic step: In the absence of any alarm features, a complete blood count (CBC), C-reactive protein (CRP), celiac disease antibody testing for initial screening can be considered to confirm diagnosis by ruling out common conditions that mimic IBS.
  • Next step in therapy: Trial of insoluble fiber supplementation, relaxation techniques, and exercise.

  1. Describe the epidemiology, clinical manifestations, and pathophysiology of IBS.
  2. Learn the diagnostic approach to IBS and rationale for ordering diagnostic studies based on symptom subtype and/ or presence of "alarm features:'
  3. Review current therapeutic strategies in the patient with IBS.
  4. Recognize the role of psychosocial factors in IBS.

This is a young woman with long-standing crampy abdominal pain and constipation. She denies any "alarm features" like weight loss, bloody stools, fever, and refractory diarrhea, and her family history is negative for colon cancer or inflammatory bowel disease. The chronicity and lack of worsening of her symptoms coupled with her young age points to a functional gastrointestinal (GI) disorder, such as IBS. The presence of fever, weight loss, or an abnormal physical examination would be other worrisome findings. Although not required, a reasonable workup in this case could include testing to rule out anemia, inflammatory disease, and celiac disease.

Approach To:
Irritable Bowel Syndrome

IRRITABLE BOWEL SYNDROME: This is a functional GI disorder characterized by chronic abdominal pain and altered bowel habits.

ROME III CRITERIA: Developed by an international working team to standardize patient selection for functional bowel disorder research, it is often used to determine diagnosis of IBS and other functional gastrointestinal disorders. The criteria are approximately 70% sensitive and 80% specific, with a positive predictive value of 40% and negative predictive value of 90%.

The prevalence of IBS is approximately 12% of the North American population and accounts for a large proportion of GI complaints seen both by primary care physicians and gastroenterologists. IBS affects women up to two times more often than men in North America. Patients typically present in the second or third decades of life, although virtually any age group can be affected. The pathophysiology of IBS remains unclear, but appears to be a combination of environmental and host factors. Environmental factors include early history of abuse or other psychosocial stressors, food intolerance, enteric infections, and antibiotic use. Host factors that affect symptoms include altered gut pain sensitivity, altered microbial flora, gastrointestinal permeability, gut immune hyperactivity, and dysregulation of the brain-gut axis through increased reactivity to stress. IBS also commonly coexists with other functional disorders such as fibromyalgia, lower back pain, and chronic headaches.

Patients with IBS may complain crampy abdominal pain with a predominant pattern of constipation, diarrhea, alternating constipation with diarrhea, or periods of normal bowel habits that alternate with either constipation and/ or diarrhea. The location and the nature of the pain in IBS are subject to great variability. The pain often has variable intensity and is improved or relieved with defecation. The crampy pain usually does not wake a person up from sleep. Other gastrointestinal symptoms seen in IBS include the passage of mucus with stool, bowel urgency, bloating, and the sensation of incomplete stool evacuation. Up to 50% of people with IBS also suffer from upper GI symptoms such as dyspepsia, nausea, and gastroesophageal reflux.

In an effort to objectively identify patients with IBS, the Rome criteria (Table 40-1) were developed and subsequently revised two times. Based on the presence of positive symptoms and the absence of structural or biochemical explanation of the symptoms, a patient may be diagnosed with IBS. Physicians are encouraged to avoid unnecessary and expensive studies and instead to use judicious cost-effective diagnostic testing.

rome lll diagnostic criteria for irritable bowel syndrome

Data from the Rome Foundation. Available at: www.romecriteria.org/. Accessed May 12, 2015.

A thorough history should be obtained using open-ended, nonjudgmental questions. The physical examination should focus on ruling out organic pathologic processes that are inconsistent with IBS. Importance should be paid to all medications and dietary habits that may worsen or mimic the symptoms of IBS.

The differential diagnosis of IBS can be very broad. Patients should be asked for the presence of "alarm features," (Table 40-2) which include fever, anemia, involuntary weight loss greater than 10 lb, hematochezia, melena, refractory or bloody diarrhea, and a family history of ovarian cancer, colon cancer, celiac or inflammatory bowel disease. The presence of alarm features usually points to an underlying organic etiology and warrants a further workup.

In the patient with IBS (all subtypes) and the absence of alarm features, a complete blood count and age-appropriate colon cancer screening are appropriate initial tests. In IBS cases with diarrhea or mixed subtypes, testing for inflammation (CRP) and celiac disease testing (IgA tissue transglutaminase antibody or antiendomysial antibody) are recommended. Testing for bile malabsorption (fecal bile acids) can also be considered. Patients with severe constipation subtype may need physiologic testing. If there is a family history of ovarian cancer, a CA-125 can be obtained.

IBS is a chronic, recurring condition with a wide range of symptoms. As with most chronic pain syndromes, the cornerstone of management is a therapeutic relationship between the physician and the patient. Setting goals for functional improvement, not cure also improve perceptions of success in a syndrome where

alarm features warranting further workup

the patient's mental state actively influences symptoms. The treatment approach should be individualized, and will depend on the intensity of symptoms.

Based on the predominant symptom subtype, empiric therapy can be initiated to control a patient's symptoms.

Abdominal Pain
  • Antispasmodics, such as dicyclomine and hyoscyamine, may be used on an as needed basis, especially when pain is mild and infrequent.
  • Low-dose tricyclic antidepressants (TCAs) should be considered when pain is more frequent and severe.
  • Selective serotonin reuptake inhibitors (SSRIs) may be beneficial when depression or anxiety disorders are comorbid with IBS.
  • Rifaximin, an antibiotic used for traveler's diarrhea, may be considered for patients without constipation symptoms.
  • Probiotics and peppermint oil may be helpful for some.
Constipation-Predominant JBS
  • Soluble fiber either via dietary fiber, synthetic fiber, or natural fiber, is recommended.
  • Polyethylene glycol can improve symptoms of constipation, but has limited evidence for global functional improvement.
  • Lubiprostone (Amitiza), which selectively activates intestinal chloride channels and increases fluid secretion is Food and Drug Administration (FDA) approved for IBS in women with constipation, but has a side effect of nausea in significant percentage of patients. Cost is often an issue with this medication.
  • Linaclotide (Linzess) stimulated 3',5' -cyclic guanosine monophosphate (cGMP) production which increased intestinal motility and fluid secretion. Cost can be a factor in this medication also.
Diarrhea-Predominant JBS
  • Loperamide may reduce the frequency of loose stools, as well as decrease bowel urgency.
  • Alosetron (Lotronex) is FDA approved for severe diarrhea symptoms of at least 6 months but is currently restricted for use due to risk of ischemic colitis.
  • Rifaximin (Xifaxan) is a gut-specific bacteriostatic agent FDA approved for traveler's diarrhea that can be used off label for nonconstipation IBS. Cost can be a barrier to using this medication.
Pharmacologic agents should be used as adjuncts in the overall treatment plan. A multifactorial approach, including modification of diet, exercise, psychological support, patient education and reassurance, and medication therapy is often required.

  • See also Case 31 (Abdominal Pain and Vomiting in a Child).


40.1 A 65-year-old man reports a lifelong history of IBS with alternating bouts of constipation and diarrhea. He denies any so-called alarm symptoms, but does report that his symptoms have worsened over the last several months. He reports never having a colonoscopy before. Stool is negative for blood and leukocytes. Which of the following is the most important next step?
A. Esophagogastroduodenoscopy (EGD).
B. Begin trial of polyethylene glycol.
C. Explore possible underlying psychiatric symptoms.
D. Colonoscopy.
E. Increase fiber intake.

40.2 A 37-year-old woman reports a 10-year history of intermittent abdominal pain and constipation alternating with diarrhea. She has no weight loss, fever, or worrisome features on examination. Which of the following agents is clinically indicated as a first-line treatment for mild-to-moderate abdominal pain associated with IBS?
A. Amitriptyline
B. Lubiprostone
c. Dicyclomine
D. Fluoxetine

40.3 A 27-year-old graduate student in psychology is evaluated for intermittent abdominal pain. She is diagnosed with IBS. She asks whether there is a relationship between psychiatric disorders and IBS. Which of the following statements is most accurate?
A. IBS is usually caused by the underlying psychiatric disorder.
B. Psychiatric conditions may worsen coexisting IBS.
C. Successfully treating the psychiatric comorbidity causes remission of IBS.
D. No evidence supports a relationship between IBS and psychiatric disorders.

40.4 A 26-year-old college student has been increasingly stressed before final examinations. She has been using over-the-counter antacids more days out of the week than not for an upset stomach and feeling full immediately after eating. She typically has one bowel movement per week and there is no blood in the stool. She feels immediate relief after passage of stool and flatulence. For the patient with constipation-predominant IBS, which of the following is the best first-line therapy?
A. Hyoscyamine
B. Sertraline
C. Psyllium
D. Loperamide

40.5 A 25-year-old woman comes to your office worried that she might have IBS, which she heard about on the news. She reports abdominal pain and diarrhea for 3 months. She also reports observing blood in her stool several times. She is worried what impact her constantly having to use the bathroom is having on her job as a lawyer. Her physical examination is normal except for a hemoccult-positive test after a rectal examination. While looking over her records you notice that she has lost 20 lb since she last saw you 3 months ago. Which of the following is an appropriate next step?
A. Refer her for cognitive behavioral therapy.
B. Offer her symptomatic relief with loperamide.
C. Recommend that she take fiber for better bowel regulation.
D. Obtain colonoscopy.


40.1 D. Age-appropriate cancer screening (colonoscopy) is indicated, even in the setting of an established diagnosis of IBS, because of the high pretest probability of detecting an underlying neoplasm.

40.2 C. Dicyclomine, an antispasmodic anticholinergic medication, can be used on an as-needed basis for mild-to-moderate abdominal pain associated with IBS. For more persistent and severe pain, low-dose TCAs, like amitriptyline, are beneficial. Lubiprostone is indicated in women with constipation-predominant IBS as a second-line agent.

40.3 B. Comorbid psychiatric disorders typically worsen IBS symptomatology, but have not been shown to cause IBS directly. Successfully treating an underlying psychiatric disorder may improve symptoms of IBS, but will not likely resolve all symptoms of IBS.

40.4 C. Fiber supplementation is considered first-line therapy in constipation predominant
IBS. It is effective and safe, and available without prescription.

40.5 D. This patient presents with alarm signs of blood in the stool and weight loss. Although psychiatric problems or irritable bowel syndrome are possible, more serious conditions should be evaluated and ruled out. A CBC, CRP, testing for celiac disease, and endoscopy or radiologic study assessing for inflammatory bowel disease would be prudent.


 The cornerstone of management of IBS is the therapeutic relationship between patient and the physician who can collaborate on an individualized plan of care that best manages the patient's symptoms. In the absence of alarm features, be prudent with laboratory testing.

 Alarm features may indicate an underlying organic pathology and require additional diagnostic workup that may include laboratory, radiologic, and/or endoscopic studies.

 Treatment should be symptom-specific and should include appropriate use of medication, dietary and lifestyle changes, and examination of any psychosocial factors that contribute to IBS symptoms.


Chey WD, Kurlander MD, Eswaran S. Irritable bowel syndrome: a clinical review. N Eng ] Med. 2015;313(9):949-958. 

Owyang C. Irritable bowd syndrome. In: Kasper D, Fauci A, Hauser S, et al., eds. Harrison's Principles of Internal Medicine. 19th ed. New York, NY: McGraw-Hill Education; 2015. Accessed May 12, 2015. 

Weinberg OS, Smalley W, Heidelbaugh JJ, Shahnez S. American Gastroenterological Association Institute guideline on the pharmacologic management of irritable bowel syndrome. Gastroenterology. 2014;147(5):1146-1148. 

Wilkins T, Perpitone C, Alex B, Schade RR. Diagnosis and management of IBS in adults. Am Fam Physician. 2012;86(5):419-426.


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