Jason A. Dominitz, M.D. , MHS, John H. Sekijima, M.D., and Mary Watts, M.D.
Abdominal pain is one of the most common causes of visits to a primary care provider, accounting for 2.5 million visits to office-based physicians per year. It is the most frequent cause for gastroenterology consultation.[2,3,4,5] The overall economic and social impact of abdominal pain is staggering. While a specific diagnosis can be obtained in many patients, no identifiable etiology is found in approximately 35%-51% of patients with abdominal pain.[6,7] A thorough review of all causes of abdominal pain is beyond the scope of this chapter. For detailed information regarding the causes of abdominal pain, the standard gastroenterology texts serve as an excellent resource.[8,9]
In compiling this review of abdominal pain, the authors chose selected references from a PubMed literature search through February 1999. The MeSH heading “abdominal pain” was used, as were selected specific causes of abdominal pain. Special attention was devoted to controlled trials and comprehensive reviews. Key references from these articles were also reviewed and are referenced. Special emphasis was placed on articles that provide evidence or guidelines for the diagnosis and management of selected specific causes of abdominal pain.
I.B. General Approach to the Patient with Abdominal Pain
When confronted with a patient complaining of abdominal pain, the provider must first rule out catastrophic causes of pain, such as dissecting aortic aneurysm, perforated viscus, or bowel obstruction. As with all patient encounters, the provider should begin with an appropriate history and physical examination. However, the initial appearance of the patient will guide the nature and urgency of the history and physical. If the patient is hemodynamically unstable, then efforts should be made to rapidly stabilize the patient. If an abdominal aortic aneurysm is suspected, then surgical consultation should be obtained immediately, with the expectation that the patient may require emergent surgery. If an abdominal aortic aneurysm is not suspected and the abdomen is rigid, then abdominal and chest radiographs should be rapidly obtained, along with surgical consultation. The radiographs should be carefully examined for evidence of perforation or obstruction, which may require prompt exploratory surgery. If the radiographs are nonspecific, then other causes of a rigid abdomen should be considered, such as acute pancreatitis, toxins, hematologic or metabolic disorders.
In the absence of a rigid abdomen, or if the patient is hemodynamically stable, the provider becomes challenged with sorting through a long list of possible diagnoses. Unfortunately, 35% of patients admitted with abdominal pain have no identifiable etiology for their symptoms. In the primary care setting, the average abdominal pain episode has been reported to require an average of 1.32 visits and cost $123.36. In 51% of these cases, no specific diagnosis was reached.
We have found that it is helpful to start by determining whether the symptoms are acute (i.e. onset within days to weeks) or chronic. Although atypical presentations can occur for any condition, many causes of abdominal pain have characteristic locations which can help guide the diagnostic approach. Therefore, we suggest that the location of the pain be used next to narrow down the diagnostic possibilities. At this point, the specific historical features, physical examination findings, and routine laboratory tests can either suggest a specific diagnosis or guide the next appropriate investigation (e.g. radiographic study, consultation or endoscopy).
Acute abdominal pain in older patients often results from infectious, inflammatory, or ischemic disorders and bears special mention. Elderly patients may not have the traditional systemic and local features of an infection. In a retrospective review of 103 patients over age 65, the most common causes of hospitalization for acute abdominal pain included biliary disease in 23%, diverticulitis in 12%, intestinal obstruction in 11% and constipation in 9%. Almost 14% of patients had no clear etiology of their pain. In-hospital mortality was nearly 6%.
I.C. Cost-Effective Approach
In today’s managed care environment, there is increased pressure for the provider to determine the most cost-effective approach to working up a patient with abdominal pain. Clearly, patients bring to the encounter their own fears regarding the etiology of their pain, including malignancies and ulcers. While various studies have been conducted to identify the most cost-effective means of evaluating patients with abdominal complaints (e.g. dyspepsia),[11,12,13,14,15,16,17] there is no clear consensus. In addition, these studies have failed to account for the often intangible benefit derived by the patient from a negative study. Recently, Wiklund et al. studied the benefits of a negative endoscopy in patients with dyspepsia and found that quality of life improves despite persistent symptoms. Therefore, we recommend that providers use an approach which is designed to first exclude acute life-threatening diagnoses such as a dissecting aneurysm, perforation, or obstruction. Once these have been reasonably excluded, the provider should employ a systematic approach to obtain a thorough history and physical with pertinent laboratory, radiologic, and endoscopic procedures. The choice of the most appropriate test is determined by a host of factors which may or may not be directly related to the patient. For example, for patients with uncomplicated dyspepsia, testing and treating for Helicobacter pylori or empiric therapy with acid suppression or promotility agents may be an appropriate first step. However, if the patient is very concerned about the possibility of a malignancy, then endoscopy would be appropriate. As it has been shown that the cost-differential between early endoscopy and empiric therapy may be negligible, this approach is clearly justifiable. For patients with symptoms consistent with the irritable bowel syndrome, appropriate tests will depend upon the specific clinical situation. For example, in a young female patient with cramping lower abdominal pain relieved with defecation, alternating constipation and diarrhea, bloating, and mucus in the stool, it would be reasonable to obtain a routine blood count, pregnancy test, and consider pelvic ultrasound. However, for an older female patient, abdominal/pelvic ultrasound and either sigmoidoscopy or colonoscopy would be recommended.
II. Evaluation of the Patient with Abdominal Pain
The history alone can suggest a specific diagnosis for a variety of causes of abdominal pain. For example, patients with known atherosclerotic disease, weight loss, food avoidance, and post-prandial pain should be considered to have mesenteric angina until proven otherwise. The history should encompass the chronicity, onset, duration, quality, location and radiation of the pain. In addition, associated symptoms as well as alleviating and aggravating factors should be determined. (Table 1) compares the features of some common causes of acute abdominal pain.
While acute pain often appears to be more dramatic or serious than chronic pain, one should not assume that chronic pain is any less significant. Patients with gastrointestinal malignancies may present with chronic pain as their primary complaint. Pain which wakes a patient from their sleep or is acute in onset suggests possible strangulation or perforation of the bowel. Pain which is gradual in onset suggests an inflammatory process, such as appendicitis, or an infectious process, such as an abscess. Sometimes the patient can recall preceding abdominal trauma which may result in something as minor as a bruised rib to something as critical as a ruptured spleen. The duration of pain can often aid in the diagnosis as well. For example, acute pancreatitis can cause pain lasting days while biliary colic typically lasts for several minutes or hours. Cramping or squeezing pain suggests a luminal origin, such as a partial or complete obstruction of a peristaltic organ (e.g. bowel obstruction or renal colic). The visceral peritoneum is innervated by C fibers, which are slow transmitters. These fibers produce dull, crampy pain, usually of insidious onset and poorly localized. The parietal peritoneum, skin, and muscles are innervated by the fast transmitting A – neurons which result in sharp pain, often of acute onset and well localized.
Due to the relatively sparse innervation of the viscera, patients are often unable to localize their pain. In addition, through a process known as functional divergence, a small number of abdominal afferents will stimulate a large number of spinothalamic tract neurons. Functional divergence also results in associated physiologic responses to abdominal pain, such as changes in pulse, blood pressure, muscle tone, and motor and secretory reflexes.[19,20,21] Since most abdominal organs originate as midline structures embryologically, they have bilaterally symmetric innervation. Digestive tract pain, therefore, is generally midline. Abdominal pain which is localized to either side suggests that the pain originates from those organs with innervation which is predominantly one-sided (e.g. kidneys, ureters and ovaries), or from structures with somatic innervation. For some organs with bilateral innervation (e.g. ascending and descending colon and gallbladder), there may be a lateral predominance which can help localize the etiology. The embryologic origin of the abdominal structures determines the clinical pain location as shown in (Table 2). However, due to variability in innervation between patients, pain originating from a particular organ may not be clinically manifest as one might expect. Pain may also migrate over time. When appendiceal inflammation first occurs, the patient generally experiences periumbilical pain due to the bilaterally symmetric innervation of the appendix and its midgut origin. As the inflammation progresses and involves the parietal peritoneum, the pain is experienced in the right lower quadrant. Radiation of pain can also help refine the differential diagnosis. For example, pancreatic pain typically radiates to the back, while cardiac ischemia may produce pain radiating to the neck, jaw, or left upper extremity.
The patient should be asked if any symptoms are associated with the pain, such as nausea, vomiting, diaphoresis, palpitations, fever, chills, gastrointestinal bleeding, weight loss, jaundice, diarrhea, constipation, steatorrhea, mucus in the stool, change in stool caliber, early satiety, bloating, dysphagia, odynophagia, heartburn, sourbrash (i.e. a sour or bitter taste in the back of the throat), or waterbrash (i.e. excessive salivation). Anorexia may suggest gastric disease, especially when accompanied by epigastric pain and/or early satiety. The relation of vomiting to meals is often helpful. Patients who vomit immediately after eating may have functional vomiting. Vomiting which occurs within 30-60 minutes of a meal suggests mucosal disease of the stomach. Vomiting which occurs hours after a meal is indicative of gastric outlet obstruction or gastroparesis. Aggravated or alleviating symptoms, such as food, dairy products, antacids, physical exertion, stress, and passage of stool or flatus should be determined. Sitophobia (fear of eating due to pain) may be indicative of gastric outlet obstruction, intestinal ischemia, or a gastric malignancy. In women, one needs to obtain a menstrual and sexual history and consider gynecologic pathology. Pelvic inflammatory disease and ovarian cysts may produce pain which can mimic acute appendicitis. Ectopic pregnancy can present with acute or subacute abdominal pain.
Aside from historical features directly related to the abdominal pain, it is important to obtain a thorough history concerning past medical problems (e.g. prior gastrointestinal disease and atherosclerotic disease), past surgical history (e.g. prior cholecystectomy), and family and social history (e.g. Armenian or Sephardic Jewish patients at risk for familial Mediterranean fever).
II.B. Physical Examination
The physical examination of the abdomen should be carefully and thoroughly conducted on all patients. The exam is often unremarkable in patients with uncomplicated diseases. Though fever is often present in patients with infectious or inflammatory processes, elderly patients may not become febrile even with a significant infection. The facial expression may reflect the degree of pain that the patient is experiencing. Bowel sounds may be absent in the presence of perforation or ileus. The presence of a succussion splash more than 2 hours postprandially suggests gastric outlet obstruction. Signs of peritonitis include fever, tenderness and guarding. Patients with peritoneal inflammation will have tenderness elicited by gently jostling the exam table or jarring the patients heal when the leg is extended. Guarding can often be voluntary. By using the stethoscope to apply pressure to the abdomen, the examiner may assess for voluntary guarding. Patients who are apprehensive when the examiners hand is pressed against the abdomen will often relax their abdomen when they believe that the examiner is listening with the stethoscope. In a study of hospitalized patients with acute abdominal pain, the presence of rebound was found to have no predictive value for the presence of peritonitis. The physical exam should also include assessment of the sclera for jaundice, cardiovascular and pulmonary examination for congestive heart failure or pneumonia, pelvic examination for gynecologic causes of abdominal pain, and a careful rectal exam.
II.C. Laboratory Tests
The initial laboratory evaluation will depend to a large extent upon the setting in which the patient presents. Laboratory tests should not be ordered frivolously, as unexpected abnormalities can often result from random laboratory error and result in unnecessary additional testing and patient concern. However, these tests are clearly a vital part of the work-up for abdominal pain. For patients presenting to the emergency department with acute abdominal pain, initial labs should include a CBC with differential, electrolytes (i.e. sodium, potassium, chloride, calcium, magnesium and phosphorous), serum chemistries (e.g. bicarbonate, blood urea nitrogen, creatinine, serum glucose, amylase and lipase), liver function tests (ALT, AST, alkaline phosphatase and bilirubin), urinalysis, and possibly coagulation labs and a pregnancy test. Blood may also be necessary for typing and crossmatching, depending upon the clinical situation. Blood cultures should be obtained from febrile patients. In addition, an electrocardiogram should be strongly considered as myocardial ischemia can present as isolated abdominal pain. Although this “shotgun” approach may seem wasteful, it may be necessary to maintain the efficiency of the emergency department setting, especially as these tests can aid in making a more rapid diagnosis and in preparing the patient for possible surgery. For non-acute patients, the laboratory tests should be tailored to the clinical situation and a more stepwise approach may be utilized.
II.D.1. Non-Contrast Studies
An abdominal series of plain radiographs can be vital to the diagnosis of abdominal pain. These films should include a flat plate of the abdomen, and upright view of the abdomen, and an upright chest radiograph. These films can identify evidence of perforation (often best seen on the chest film as free intraperitoneal air under the diaphragm or retroperitoneal air), bowel obstruction, air in the portal venous system or biliary tree, calcium deposits (e.g. gallstones, renal or ureteral stones, appendicoliths, chronic pancreatitis, aortic aneurysm), foreign bodies, and pneumatosis (i.e. air in the bowel wall suggesting possible ischemia). It should be noted that when looking for free air, the patient should remain in an upright position for at least 5 minutes to allow the air to percolate up to the diaphragm. For those patients unable to assume an upright position, a left lateral decubitus film may suffice. The patient should remain with the left side down for at least 10 minutes. It has been estimated that the plain film is diagnostic of gastrointestinal obstruction in 50%-60% of cases, equivocal in 20%-30%, and normal, non-diagnostic, or misleading in 10%-20% of cases. The plain radiograph can also show evidence of an intraabdominal inflammatory or infectious process (e.g. when a normal psoas shadow is obscured by a pelvic abscess).
II.D.2. Contrast Studies
Radiologic contrast studies are often over utilized in the evaluation of abdominal pain. The standard barium upper gastrointestinal series (UGI) can provide information regarding esophageal motility, esophageal stenoses and peptic ulceration. However, the UGI is neither as sensitive nor as specific as endoscopy for mucosal abnormalities, such as erosive esophagitis and peptic ulcer.[28,29,30,31] A barium enema (BE) will demonstrate the colonic anatomy and may also fill the terminal ileum. A BE may show evidence of diverticulosis, strictures, fistulas and mucosal masses (e.g. polyps and cancer). Barium contrast studies should not be utilized for the evaluation of an acute abdomen. Intravenous urography is often used to demonstrate a calculus in the urinary tract.
II.E. Imaging Tests
Abdominal ultrasound is often a useful, non-invasive test to help identify the etiology of abdominal pain. Ideally, patients should have nothing by mouth for several hours prior to their examination.
Ultrasound is commonly used to evaluate right upper quadrant pain to identify biliary abnormalities such as bile duct dilatation, gallbladder wall thickening, pericholecystic fluid, gallstones, and sludge. Ultrasound can also identify pancreatic abnormalities, such as duct dilation and fluid collections, though overlying bowel gas often limits the quality of the examination. Other information elicited by ultrasound includes the presence of ascites or other signs of chronic liver disease (e.g. fatty liver or cirrhotic appearing liver), gynecologic abnormalities (e.g. ovarian cysts, ectopic pregnancy, or uterine fibroids), renal abnormalities (e.g. hydronephrosis, renal cysts) and acute appendicitis.
II.E.2. Computed Tomography
Computed tomography (CT) is a powerful tool in the evaluation of abdominal pathology. However, as its use is associated with significant cost, CT should be reserved for those patients in whom the diagnosis cannot be safely established with less expensive means. Computed tomography is useful for establishing many causes of abdominal pain, such as abdominal aortic aneurysms, intro-abdominal fluid collections, diverticulitis, bowel obstruction, intestinal ischemia, perforated viscus, appendicitis and pancreatitis. It can also identify lesions suggestive of primary cancers or metastatic disease. Unenhanced helical CT has been shown to be quite accurate in the diagnosis of ureteral stone disease.
II.E.3. Magnetic Resonance Imaging
There are few indications for magnetic resonance imaging (MRI) in the evaluation of abdominal pain. The utility of MRI in the performance of cholangiopancreatography (MRCP) is under study. This procedure may replace diagnostic endoscopic retrograde cholangiopancreatography (ERCP) in many settings, and allows for imaging the pancreaticobiliary system in patients whose anatomy prohibits ERCP (e.g. Roux-en-Y surgical anastomosis).
Gastrointestinal endoscopy is another useful test in the evaluation of abdominal pain. Like CT, the cost associated with endoscopy needs to be considered in the management of the patient. Endoscopic procedures commonly utilized include: esophagogastroduodenoscopy (EGD), flexible sigmoidoscopy, colonoscopy, and endoscopic retrograde cholangiopancreatography (ERCP). For many patients, such as those with dyspepsia, EGD can serve several purposes. In addition to establishing the specific etiology for the symptom (e.g. peptic ulcer disease, erosive esophagitis, gastric cancer), tissue can be obtained at the time of endoscopy for histopathology or assessment for Helicobacter pylori. Even if no organic pathology is identified, a negative endoscopy can serve to reassure the patient. Endoscopy is more accurate than contrast radiography[28,29,30,31] and is preferred by patients. Likewise, sigmoidoscopy and colonoscopy can identify a specific cause of the patients symptoms (e.g. sigmoid volvulus, colitis, malignancy and ischemia), exclude the presence of organic pathology (e.g. as in the patient with irritable bowel syndrome) and treat colonic abnormalities (e.g. sigmoid volvulus and colonic polyps). For patients with suspected pancreaticobiliary disorders, ERCP can establish a specific etiology (e.g. chronic pancreatitis, pancreatic cancer and choledocholithiasis) and is often used to treat these conditions (e.g. sphincterotomy and stone extraction for choledocholithiasis or stenting for biliary obstruction). Other endoscopic procedures which are beyond the scope of this chapter include biliary manometry and endoscopic ultrasound. Endoscopic procedures are generally safe and very well tolerated.
III. Specific Causes of Abdominal Pain
III.A. Abdominal Wall Pain
Abdominal pain originating from structures other than the visceral organs should always be considered as part of a complete evaluation. Skin, subcutaneous fat, muscle, and bone are all possible sources of pain. Some examples of causes of abdominal wall pain are shown in (Table 4).
III.A.1. Features of Abdominal Wall Pain
1 Often discretely localized by examining fingertips
2 Constant site of tenderness
3 Superficial tenderness
4 Positive Carnettâ€™s sign
The examiner palpates the abdomen to elicit a localized area of tenderness. The patient is then asked to contract the abdominal musculature by raising the head or straightened legs off the table. With the patient holding this position, palpating pressure is reapplied to the site of discomfort and the patient is asked if the pain decreases or increases in severity. If the pain is truly intra-abdominal, then the contracted abdominal wall should diminish the tenderness by protecting the underlying viscera. In contrast, if the cause of the pain resides in the abdominal wall the elicited pain should at least be as severe and often enhanced.
For pain that is well localized, superficial and positive on Carnettâ€™s testing, a local 2 cc injection of 0.25% bupivacaine hydrochloride or 1% lidocaine can be beneficial. 40 mg of triamcinolone acetate may be mixed with the anesthetic to prolong the effect.
III.B. Peptic Ulcer Disease
III.D. Bowel Obstruction
In adults, bowel obstruction most commonly results from external hernias or postoperative adhesions. Other causes include malignancy, colonic diverticular disease, volvulus, gallstone ileus, and intussusception. In children, obstruction is most commonly associated with intussusception, atresia, or meconium ileus.
III.D.2. Clinical Presentation
Patients with bowel obstruction typically present with fairly sudden onset of crampy abdominal pain, abdominal distention and failure to pass flatus. If the obstruction is partial, the patient may have the same symptoms, though will continue to pass flatus. When the obstruction involves the proximal small bowel, the pain tends to be more sharp, is epigastric in location, and is accompanied by frequent bilious vomiting. When the obstruction involves the distal bowel, the pain tends to be periumbilical in location and is accompanied by less frequent, though often feculent, vomiting. The patient is typically restless and ill appearing. Fever, tachycardia, and orthostatic hypotension may be present, as life-threatening dehydration can occur. Hyperactive bowel sounds with rushes and/or high pitched tinkling sounds are classically found. The abdomen is tender to palpation with involuntary guarding.
In addition to an appropriate clinical presentation, radiographic imaging is a critical component in the diagnosis of intestinal obstruction. Abdominal radiographs reveal dilated loops of bowel, often with air-fluid levels, proximal to the obstruction, with normal caliber or collapsed bowel distally. When the diagnosis is not evident, an abdominal CT scan is frequently regarded as the test of choice in identifying obstruction. A single-contrast water soluble contrast enema may help rule out a large bowel obstruction.
When bowel obstruction is suspected, surgical consultation should be immediately obtained as surgical treatment may be required. Delay in treatment may result in ischemia and infarction of bowel. A nasogastric tube should be inserted and intermittent suction applied to remove gastrointestinal secretions and minimize nausea and vomiting. Intussusception may be reduced with a diagnostic and therapeutic barium enema. Sigmoid volvulus may be initially diagnosed with a contrast enema study and treated with the placement of a rectal tube (e.g. a red rubber catheter) above the level of the volvulus. Alternatively, a sigmoidoscopy may be performed to reduce the volvulus. Surgery is often necessary to remove the involved bowel in order to prevent recurrent volvulus.
III.E. Irritable Bowel Syndrome (IBS)
III.E.1. Epidemiology and Pathogenesis
IBS is a common functional gastrointestinal disorder without identifiable laboratory, structural or histological abnormalities. It has been estimated that at least 8 billion dollars of direct charges are spent annually in the U.S. on physician, laboratory and radiology examinations in patients with this condition. According to one U.S. household survey, IBS individuals were noted to have a 2-3 fold increase in work absenteeism over those without symptoms.
Women are both more commonly affected and more likely to visit a physician with this condition than their male counterparts. Psychosocial factors such as stress, anxiety and depression may significantly modify the expression of IBS but are not diagnostic features.
A variety of motor abnormalities of both the small and large bowel have been observed in IBS patients. However no specific motility disturbance distinguishes the IBS patient from normal subjects in the resting state, and many of the abnormal motor findings do not correlate well with clinical symptoms.
Balloon distention and air insufflation studies of the ileum and colorectum have revealed that patients with IBS report pain at lower volumes and/or pressures than asymptomatic controls. This lower pain threshold has also been referred to as visceral hyperalgesia or hypersensitivity. These findings may help to explain such complaints as urgency, incomplete evacuation, bloating and discomfort.
The diagnosis of IBS is generally made on the basis of clinical manifestations and symptom criteria. (Table 3). Typically, a patient with IBS will present to the office with variable complaints of abdominal pain, altered bowel habits and bloating. The abdominal discomfort may be quite heterogeneous in quality, intensity and location. The pain is characteristically relieved by the passage of stool or flatus and may be exacerbated by eating or emotional stress. Moreover, there appears to be considerable overlap with functional esophageal, gastroduodenal, bowel and anorectal symptoms. In one study of patients presenting with typical IBS symptoms, dyspepsia was found to be the predominant symptom one year later. Extraintestinal complaints such as fatigue, headache, urological symptoms and fibromyalgia are often present as well.[41,45]
Approximately half of the patients with functional bowel disease suffer from depression and anxiety. Previous physical and sexual abuse is also more frequently found and is associated with increased IBS severity and physician visits.[47,48]
Choosing which, if any, laboratory, endoscopic or radiological tests to order will depend on a detailed history and physical examination. New onset complaints in an older patient, nocturnal symptoms, weight loss, fever or a steadily deteriorating course should prompt a diligent search for more ominous diseases such as malignancy or inflammatory bowel disease. A CBC is appropriate and many physicians will also add a chemistry panel, thyroid tests and a sedimentation rate. However, these tests are rarely abnormal in the young patient presenting with symptoms typical of IBS.
For diarrhea predominant patients, stool evaluation for ova and parasites, Giardia antigen, occult blood and qualitative fat are important considerations. Measurement of serum carotene can aid in the evaluation of malabsorption. Moreover, a 48-72 hour stool collection for weight and fat can be crucial in distinguishing IBS from a more serious condition. Absence of steatorrhea (< 7 gms of stool fat/24h ) and total stool output (< 200-250 gms/24h ) in patients consuming a diet containing 100 gms of fat per day are consistent with functional disease. Flexible sigmoidoscopy is appropriate in patients with chronic diarrhea to rule out significant mucosal disease. Colonoscopy should strongly be considered for any individual over the age of 50 with new symptoms or a family history of colorectal neoplasms. Furthermore, in the female patient with predominantly lower abdominal pain, a careful pelvic examination is mandatory and a gynecologic referral or pelvic ultrasonography may be indicated as well. III.E.4. Treatment A strong physician-patient relationship is critical and allows for effective education and reassurance. Dietary modification is appropriate when gas-forming vegetables and fruits, excessive caffeine, fructose or sorbitol containing products exacerbate the symptoms. Similarly, a 2 week trial of a lactose free diet is a practical consideration. Although the efficacy of fiber supplementation in IBS has never been definitively proven, a therapeutic trial is recommended. Natural fiber such as wheat bran or supplements like psyllium, polycarbophil, and methylcellulose may all cause bloating and discomfort, but these symptoms usually resolve within a few weeks. Tailoring the medications to particular symptoms should be the rule. For patients with predominant pain, antispasmodics or anticholinergic agents may be of benefit. In addition, low dose tricyclic antidepressants may be useful by directly modulating sensory nerve pathways, via antidepressant effects or by anticholinergic side effects. For diarrhea prone patients judicious usage of loperamide is often helpful. Further information regarding the diagnosis and management of IBS are available in recent reviews.[51,52] III.E.5. Indications for Referral 1 Severe or refractory symptoms 2 Diagnosis is unclear 3 Evidence of rectal bleeding III.F. Ischemic Bowel Disease III.F.1. Acute Mesenteric Ischemia III.F.1.a. Clinical Features Acute mesenteric ischemia (AMI) is increasingly common, accounting for 0.1% of hospital admissions. It is a highly morbid condition, with a mortality rate exceeding 60%.[53,54] Risk factors for AMI include cardiac arrhythmias, advanced age, low cardiac output, atherosclerosis, congestive heart failure, severe valvular cardiac disease, recent myocardial infarction, and intra-abdominal malignancy. Causes of AMI include mesenteric arterial occlusion (either embolus or thrombosis), mesenteric venous occlusion, and nonocclusive events (e.g. vasospasm). While approximately 50% of cases of AMI are attributable to embolization of the superior mesenteric artery, 25% of AMI cases result from thrombosis of a pre-existing arthrosclerotic lesion, and approximately 25% of AMI cases result from nonocclusive mesenteric ischemia (NOMI). Given the numerous underlying etiologies, the clinical presentation can be quite variable. Abdominal pain is classically out of proportion to the physical exam findings of tenderness. The pain may initially be colicky in nature, it generally progresses to a continuous, less severe pain. Associated symptoms include vomiting and diarrhea, with or without hematochezia. Patients may be asymptomatic or have only mild symptoms (e.g. ischemic colitis or â€¦