Learning Objectives

 

• • discuss the causes of the abdominal pain.
  • describe the applied anatomy of the abdomen.
  • discuss the physiology and pathophysiology.
  • explain the characteristic clinical presentations of abdominal pain.
  • recognize the usual diagnostic algorithm and procedures that are performed.
  • explain the general approach to the management.

Introduction

The abdomen is a complex structure consisting of multiple spaces and compartments filled with a variety of heterogeneous organs and structures.   The spaces and organs have been compartmentalized, divided and reclassified throughout the course of medical history according to the purposes of the specific group.  For the clinician, dividing the abdomen into quadrants makes clinical sense.  Right upper quadrant symptoms, for example bring certain differential considerations and these are completely different from left lower quadrant symptoms.  For the clinician who thinks embryologically, foregut, midgut and hindgut division makes intuitive sense. For the surgeon who has to decide about an incisional approach, division of the abdomen relates to upper or lower, and right midline or left.  The approach mostly depends on the clinical presentation and can be divided into a focused approach or a global approach.

A focused approach is adopted when a specific diagnosis is in mind.  Thus if the patient is female, 40,  obese and developed right upper quadrant pain after eating a fatty meal and has a focal tenderness in the right upper quadrant and a positive Murphy’s sign, then the “rule out”  diagnosis is acute cholecystitis, and HIDA scan is most appropriate, and surgery is a strong initial consideration.  On the other hand if a 50-year-old man presents with diffuse abdominal pain and tenderness, with no fever and an elevated white cell count, the differential diagnosis is broad, the diagnostic algorithm should include a battery of general blood tests, a computed tomography (CT) scan of the abdomen, and a first step workup before considering a surgical consultation so that the diagnosis can be narrowed down.

Background

Abdominal pain is the pain felt in the region between the chest and the groin. It is a common and often non-specific complaint which is frequently benign, but may be an indicator of serious acute pathology. Approximately 7.5 million people seek emergency care annually in the U.S. for “stomach pain, cramps, and spasms” (1). Clinicians have to distinguish between patients that can be safely observed or treated symptomatically, and those that need further investigation and urgent specialist referral. The description of abdominal pain has limitations, as pain is a subjective phenomenon. Also, children and elderly people may have difficulty localizing pain. Although the overall sensitivity and specificity of history and physical examination is poor for diagnosing benign conditions of the abdomen, the results are better for more serious causes of abdominal pain, alone or in combination with focused investigations (2-4).

Principles

From the initial complaint of pain, the history and physical examination should guide formulation of a differential diagnosis and determine the possible category of disease, which would include infectious, inflammatory, neoplastic, mechanical or vascular causes. The diagnostic and management strategies, including selection of appropriate imaging modalities, will be based on this.  If the patient has a fever, inflammatory and infectious causes are likely. A history of weight loss in an elderly patient would raise concern for a neoplastic process. Colicky pain with abdominal distension, nausea and vomiting suggest a mechanical cause such as obstruction or a stone. A vascular cause is likely in a patient with extensive cardiovascular disease and pain after meals. A critical point to remember is that initial evaluation should determine whether the pain is ‘serious’ or ‘non-serious’, and whether the patient needs urgent surgical intervention. Such patients require appropriate assessment of airway, breathing, and circulation, initiation of resuscitation, judicious administration of analgesics, and urgent surgical consultation, with transfer to an acute care facility if needed.

As mentioned earlier, for clinical purposes, the abdominal pain can be assigned to quadrants of the abdomen – right upper, right lower, left upper and left lower. Pain is also commonly noted in the epigastric region, which is the upper middle abdominal area, and in the lower middle abdominal area, which could indicate pelvic pathology in women. The applied anatomy section details organs within these quadrants, and this helps in identifying organs that are most likely to be involved in the disease process.

Pain of less than a few days duration may be considered to be “acute”, while pain that has remained unchanged for months or years is “chronic”. Clinical judgment must be used in recognizing pain that is worsening, one that is stable, and one that is long-standing with intermittent exacerbations. Any patient with pain of recent onset requires a thorough evaluation. Several well-designed clinical trials have shown that analgesics can be safely used in abdominal pain without significantly impacting diagnostic accuracy of the physical exam, and relief of pain should thus be a standard of care (5, 6).

Applied Anatomy: Abdominal Quadrants and Organs
Right Upper Quadrant
Right lobe of liver, gallbladder, pylorus, the first three parts of the duodenum, head of the pancreas, right adrenal gland, right kidney, hepatic flexure, superior part of ascending colon, right half of transverse colon.

Left Upper Quadrant
Left lobe of liver, spleen, most of stomach, jejunum and proximal ileum, body and tail of pancreas, left adrenal gland, left kidney, splenic flexure, superior part of descending colon, left half of transverse colon.

Right Lower Quadrant
Cecum, appendix, most of ileum, inferior part of ascending colon, right ovary, right uterine tube, right ureter.

Left Lower Quadrant
Sigmoid colon, inferior part of descending colon, left ovary, left uterine tube, left ureter.

 

Applied Anatomy: Abdominal Quadrants and Organs: Blood Supply

The colon receives blood from the celiac artery, the superior and inferior mesenteric arteries, and the internal iliac artery, with abundant collateral circulation. However, there are weak points, or “watershed” areas, at the points where the collateral vessels meet at the splenic flexure (Sudek’s point), and at the descending/ sigmoid colon (Griffiths’ point), which are thus susceptible to ischemia.

Applied Pathophysiology

Parietal or somatic pain is sharp and well localized, located directly over the inflamed area. It arises from the parietal peritoneum that is innervated by somatic nerves, responding to irritation from chemical, infectious or inflammatory processes due to release of substance P, bradykinins, serotonin, histamine, and prostaglandins. The intensity of pain depends on the type and amount of material that is irritating the parietal peritoneum. Any change in pressure of the peritoneum, caused by palpation or movement, worsens the pain. There is also associated reflex spasm of the abdominal musculature.

Visceral pain is dull, aching and poorly localized. It arises from the abdominal viscera that are innervated by autonomic nerves, responding mainly to obstruction and distension.

Pain due to vascular disturbances can be severe and diffuse, but may also just be mild initially and last for several days before signs of vascular collapse appear. The early discomfort that occurs is due to hyperperistalsis. The splanchnic circulation receives about 30% of the cardiac output, and protective mechanisms to prevent intestinal ischemia include collateral vessels and autoregulation of blood flow. Vasospasm, arterial or venous occlusive diseases can result in intestinal ischemia. Emboli resulting in disruption of blood flow originate from the heart in the majority of cases, and vasospasm occurs due to severe physiologic stressors like shock and dehydration.

Referred pain is aching and perceived to be near the surface of the body, distant from its source, when cutaneous dermatomes and visceral inputs share the same spinal cord level. Thus, pain from gall bladder pathology may be perceived as scapular pain.

Neurogenic pain occurs due to injury of sensory nerves, has a burning character and is limited to the distribution of affected peripheral nerve (7).

Blood Supply

The colon receives blood from the celiac artery, the superior and inferior mesenteric arteries, and the internal iliac artery, with abundant collateral circulation. However, there are weak points, or “watershed” areas, at the points where the collateral vessels meet at the splenic flexure (Sudek’s point), and at the descending/ sigmoid colon (Griffiths’ point), which are thus susceptible to ischemia.

Upper Abdominal Pain Syndromes: Liver and Biliary Tree
Hepatic pain occurs only when the capsule of the liver is stretched, so most pain in this area is related to the biliary tree, with possible radiation to epigastric area or to the back.

Biliary pain – Contraction of gallbladder in response to a fatty meal, causing a gallstone to press against the gallbladder outlet or cystic duct. Deep or gnawing pain after a fatty meal, occasionally sharp and severe. Increases over a few hours and then resolves completely with multiple recurrences.

Acute cholecystitis – Steady, severe and prolonged pain beginning one hour or more after a fatty meal, low-grade fever. It may be associated with nausea, vomiting, anorexia.

Acute cholangitis – Fever, jaundice, abdominal pain. The triad may be seen only in 50 – 75% of cases.  Viral or drug-induced hepatitis and liver abscess can cause right upper quadrant pain.

Viral or drug-induced hepatitis and liver abscess can cause right upper quadrant pain.

Epigastric Pain: Pancreas and Dyspepsia Syndromes

Pancreatitis – Sudden epigastric pain radiating to the back. Associated nausea, vomiting, anorexia. Risk factors for pancreatitis include gallstone disease (ask about past or current right upper quadrant pain), alcohol use, medications, recent endoscopic retrograde cholangiopancreatography (ERCP).

Dyspepsia – Epigastric pain associated with abdominal fullness, heartburn, nausea. Can occur in reflux esophagitis, peptic ulcer disease, gastric or esophageal cancer. (Pancreatic and hepatobiliary causes should be excluded). Watch for alarm symptoms (detailed in a later section) that would require further investigation.

Left Upper Quadrant Pain – Spleen

Splenic abscess – fever and tenderness

Splenic infarct – severe left upper quadrant pain. Associated with conditions predisposing to systemic embolism including atrial fibrillation, hypercoagulable states, trauma, torsion due to a ‘wandering spleen’, hemoglobinopathies, and hematologic disorders.

 

Non-Abdominal Etiologies for Upper Abdominal Pain

Consider cardiac, pleural, and pulmonary causes non-abdominal etiologies for upper abdominal pain.  Neuropathic pain of herpes zoster may sometimes precede skin lesions, involving the thoracic dermatomes and causing upper abdominal pain.

Lower Abdominal Pain

Lower abdominal pain syndromes can involve the ileum, colon, appendix, kidneys, bladder, uterus and ovaries.

Colitis/ ileitis – due to inflammatory bowel disease, infections, ischemia or medication-associated. Associated diarrhea, which may be bloody. Check for extraintestinal manifestations of inflammatory bowel disease including iritis, erythema nodosum, clubbing, aphthous ulcers in mouth, perianal disease. Potential causes of ischemic colitis include emboli, thrombosis, vasculitis, circulatory insufficiency, and hematologic disorders. Uncomplicated cases of ischemic colitis usually resolve in 24-48 hrs, and the colon heals itself in 1-2 weeks.

Lower Abdominal Pain: Appendicitis

Appendicitis typically begins as periumbilical pain that localizes to the right lower quadrant. Associated anorexia, nausea and fever.  McBurney’s sign – tenderness at the point that is one-third the distance from the anterior superior iliac spine to the umbilicus on the right (roughly corresponds to the location of the base of the appendix). Rovsing’s sign – palpation of left lower quadrant resulting in pain in the right lower quadrant. Psoas sign – pain due to stretch of psoas muscle, elicited by hyperextension of straightened right leg while lying on the left side. Obturator sign – pain of passive internal rotation of right leg with right hip and knee flexed while lying supine. Atypical presentations may be seen in pregnancy and also because of the position of appendix, such as retrocecal or pelvic positions. Tenderness on rectal exam occurs in retrocecal appendicitis.

Lower Abdominal Pain: Diverticulitis

Diverticulitis typically causes left lower quadrant pain. Right sided diverticulitis is seen in only 1.5 % of patients, and is more common in Asian populations. Pain is often present for several days, and there may be a history of prior similar episodes and associated fever.

Lower Abdominal Pain: Colon Cancer

Colon cancer – In elderly patients, abdominal pain and change in bowel habits can be the first sign of colon cancer. Risk factors including family history of colon cancer should be considered in elderly patients with abdominal pain.

CT Virtual Colonoscopy is a relatively new exam that is being used for the detection of colonic polyps and masses. Virtual  Colonoscopy can represent an attractive alternative to the barium enema and colonoscopy because it is less expensive, minimally invasive, and relatively patient-friendly.

Lower Abdominal Pain: Kidney Stones

Kidney stones – Pain typically develops in waves as the stone moves in the ureter. The site of stone obstruction determines the location of pain. Flank pain occurs due to upper ureteral or pelvic obstruction. Pain radiating to ipsilateral testicle, tip of penis or labia occurs due to lower ureteral obstruction.

Lower Abdominal Pain: Bladder Distention

Bladder distension, bladder outlet obstruction, and  benign prostatic hypertrophy can cause lower abdominal pain. Pelvic pain in women is discussed in a later section.

Diffuse Abdominal Pain Syndromes

Diffuse abdominal pain syndromes can include  mesenteric ischemia and infarction, ruptured aneurysm, peritonitis, intestinal obstruction.

Mesenteric ischemia and infarction:  Severe pain out of proportion to physical findings, i.e., a relatively benign physical examination, decreased or absent bowel sounds, occult bleeding that soon progresses to frankly bloody stool. May lead to intestinal perforation if not diagnosed and treated early, with associated hypotension, tachycardia, and fever. Potential causes, as in ischemic colitis, include cardiovascular disease, ischemia, sepsis, hypercoagulable state, and systemic vasculitis.

Abdominal aortic aneurysm rupture (AAA): Abdominal or back pain, profound hypotension, pulsatile abdominal mass. Risk factors for AAA include previous aneurysm repair, peripheral aneurysms, smoking, coronary artery disease, hypertension, family history of AAA.

Peritonitis: Patients usually lie very still to minimize pain. Evidence of hypovolemia including tachycardia and hypotension. Rebound tenderness and guarding are present, but it may be unnecessary to elicit these, as even gentle palpation worsens pain.

Intestinal obstruction: complete or partial obstruction caused by incarcerated hernia, adhesions, intussusception, volvulus, colonic cancer, fecal impaction. Associated constipation, vomiting.

Acute self-limited illnesses including viral or bacterial enteritis or toxin-associated food poisoning may also present with generalized abdominal pain, along with vomiting and diarrhea. Depending on the degree of systemic illness, such patients may only need supportive care.

Non-Abdominal Causes of Diffuse Abdominal Pain

Metabolic causes include diabetic ketoacidosis, Addison’s disease, and hypercalcemia; hematologic causes include hemolysis, sickle cell anemia, acute leukemia, porphyrias; lead toxicity. Black widow spider bites can cause intense pain and rigidity of abdominal muscles and back. C1 esterase deficiency associated with angioneurotic edema can also cause episodes of severe abdominal pain. Familial Mediterranean fever and Fitz-Hugh-Curtis syndrome (right upper quadrant pain in young women, associated with pelvic inflammatory disease) are other causes of pain.

Abdominal Pain in Women

Causes of abdominal pain in women can include pelvic inflammatory disease, adnexal cysts with torsion or rupture, ectopic pregnancy, uterine pain caused by endometritis, and leiomyomas.

Chronic Abdominal Pain

Chronic abdominal pain can be caused by irritable bowel syndrome, celiac disease, and abdominal wall pain.

Most patients have a functional disorder, commonly the irritable bowel syndrome. Organic illness should be differentiated from functional illness, based on history and lab abnormalities.

Functional chronic abdominal pain may be similar to that of organic illness, however, there are no associated findings indicating a high risk of underlying illness, and psychosocial features may be prominent. In patients over 50, a diagnosis of new-onset functional illness should be made with caution because of increased risk of malignancy in this age group.

Chronic pain may originate from the abdominal wall, with pain often related to posture and no relation to meals or bowel function. Carnett’s sign may be positive (increased tenderness during muscle tensing by raising the head or raising both legs at the same time while lying supine). Abdominal wall hernias may also cause chronic pain.

Clinical Evaluation

A detailed history and physical examination can help to narrow the differential diagnosis of abdominal pain, with final diagnosis confirmed by laboratory and imaging tests.

The history should include:

Duration – pain of less than a few days duration may be considered to be acute, and any patient with pain of recent onset requires a thorough evaluation.

Onset – onset and evolution of pain, frequency, prior occurrence of similar pain. Was the pain acute in onset or was it gradual?  A sudden blockage of the ureter or biliary tree may cause immediate spasm and acute pain.

Character or Quality of pain – dull, sharp, tearing, colicky, burning, constant. This depends on the origin of pain being parietal, visceral, neurogenic or secondary to vascular causes. This is discussed in more detail under the applied pathophysiology section. Colicky pain usually occurs in waves or spasms, as opposed to constant pain. Peritonitis, or inflammation of the membrane lining the abdominal cavity, can occur due to various causes, commonly a perforated abdominal organ. Initially, the pain is often dull and poorly localized (involvement of visceral peritoneum) and then progresses to steady, severe, and more localized pain (involvement of parietal peritoneum). If the underlying process is not contained, the pain becomes more diffuse. Patients usually lie very still to minimize pain in peritonitis, as compared to colicky pain where patients move around to try to get into a comfortable position.

Situation or Location of pain – different pain syndromes usually have characteristic locations (quadrants), and provide a clue to the likely organ(s) involved in the disease process.

Severity of pain – grading on a 1 to 10 scale helps in objective assessment of pain severity, particularly in following evolution of pain, and thus should be done on all patients as part of recording vital signs. It should be kept in mind that during initial evaluation, a lower pain scale should not be considered trivial, as some patients are more stoic and may have a higher pain threshold. Elderly patients and children may not be able to grade pain.

Aggravating factors – food, alcohol, stress, position, antacids, bowel movements. An alcohol binge prior to onset of pain is likely due to pancreatitis. Peptic ulcer disease should be considered if spicy foods or alcohol trigger pain. Pain that occurs after eating can also be due to vascular disease and occlusion of the mesenteric vessels.

Relieving factors – Cardiac pain should be considered if pain is relieved by nitroglycerin, and dyspeptic syndromes should be considered if the pain is relieved by antacids.

Radiation  of pain – epigastric pain radiating to the back is characteristic of pancreatitis, while flank pain radiating to the groin area is suspicious for a stone. Pain radiating to chest should always raise suspicion for a primary cardiac event.

Associated symptoms – fevers, chills, weight change, nausea, vomiting, jaundice, change in bowel habits (diarrhea or constipation) and ability to pass stool or flatus, tenesmus (rectal urgency), change in color of urine or stool, blood in stool or vomitus. In a patient with right upper quadrant pain and associated jaundice, with change in color of stool (pale) or urine (dark yellow), the likely diagnosis is choledocholithiasis (stone in the common bile duct causing obstruction). In a similar patient with fever, the diagnostic consideration would be acute cholangitis. Inability to move bowels or pass flatus would indicate obstruction. Bleeding could be due to numerous causes, including peptic ulcer disease, inflammatory bowel disease or malignancy.

Past medical and surgical history – including prior abdominal surgeries, cardiovascular disease, immunosuppression, malignancy.  A history of abdominal surgeries raises suspicion for bowel obstruction and hernias, and presence of cardiovascular disease predisposes to vascular events causing abdominal pain such as an ischemic bowel. Immunosuppression in patients may be secondary to malignancy, drugs such as prednisone or chemotherapeutic agents, or secondary to HIV. These patients are more susceptible to infections.

Family history – of bowel disorders, malignancy. Patients with multiple first-degree relatives who have developed colorectal cancer at a relatively young age are at very high risk of colon cancer.

Habits  – alcohol intake. The amount of alcohol ingestion and the period of ingestion should be noted. This is particularly important in patients in whom liver disease or pancreatitis is suspected.

Travel  – history, ingestion of unusual food or fluids (particularly raw foods), sick contacts may indicate gastroenteritis.

Medications – use of medications, including over-the-counter and herbal medications, supplements and analgesics, particularly NSAIDs, laxatives, antidiarrheals, and recent use of antibiotics. Use of NSAIDs over a long period predisposes to peptic ulcer disease and GI bleeding. Recent use of antibiotics should raise suspicion for infection with Clostridium difficile. Antidiarrheals, which are antimotility agents, should generally be avoided in infectious diarrhea, as this causes decreased clearance of toxins.

Menstrual – sexual, and contraceptive history – pregnancy should always be excluded in women of childbearing age with abdominal pain, and the possibility of ectopic pregnancy with rupture should always be kept in mind.

Physical Examination

Physical examination should include:

1) Vital signs – temperature, pulse, blood pressure, orthostatic changes

2) General examination:
a) Appearance, level of comfort or discomfort, including position assumed by the patient when in pain
b) Eyes for scleral icterus, skin for jaundice
c) Lungs, for signs of consolidation
d) Heart, for irregular rhythm, murmurs or rubs
e) Assess volume status on clinical exam – skin turgor (may be unreliable in older patients), appearance of mucosa, neck veins, blood pressure and heart rate, urine output.

3) Abdominal examination:
a) Visual inspection of abdominal contour for asymmetry or distension, pulsations, vascular changes, location of scars or rashes.
b) Auscultation for bruits over aorta, renal arteries and iliac arteries, and bowel sounds – complete lack of bowel sounds (adynamic ileus, advanced bowel obstruction), high-pitched bowel sounds (bowel obstruction).
c) Palpation for organomegaly, masses, tenderness, guarding, Murphy’s sign, costovertebral angle tenderness. It should be remembered that in seriously ill, debilitated and elderly patients, there might be no detectable tenderness or rigidity. It is also unnecessary to elicit rebound tenderness in suspected peritonitis.
d) Percussion for ascites, shifting dullness

4) Rectal and pelvic examination:
a) Testing for occult blood, tenderness, hemorrhoids, anal fissures, fecal impaction on rectal exam
b) Pelvic exam in women with acute lower abdominal pain (regardless of history of hysterectomy or post-menopausal status)

5) Signs of nerve and muscle wall injury, hernias.

6) Other signs (as described under appendicitis, chronic abdominal pain)

7) Examine spine and back if there is suspicion of thoracic nerve radiculopathy causing referred pain in abdomen.

Labs

Laboratory tests should include:

• • Complete blood count with differential, Electrolytes, BUN, Creatinine, Glucose, Calcium, Liver function tests, Lipase. Elevated lipase is very suggestive of acute pancreatitis, but includes other processes that involve the pancreas, such as malignancy. Anion-gap acidosis can indicate serious underlying abdominal pathology, particularly ischemic bowel. Lactic acid should be checked in unexplained high gap acidosis.
  • An anemia panel, including iron studies, Vitamin B12 and folate levels, should be checked if microcytic or macrocytic anemia is detected on blood count. Iron-deficiency anemia in the elderly is suspicious for gastrointestinal malignancy. Vitamin B12 deficiency can occur due to malabsorption secondary to Crohn’s disease or ileal resection.
  • Type and cross-match in patients with GI bleeding and suspected AAA rupture in anticipation of blood transfusion.
    Coagulation profile in liver disease, sepsis, GI bleeding, and in those who may undergo operative intervention.
  • Urinalysis should be done to detect infection, hematuria.
  • Patients with severe symptoms, and immunosuppressed patients, should have stool studies including microscopy for ova and parasites, culture for enteric pathogens, and Clostridium difficile toxin in case of diarrhea. Stool exam for occult blood.
  • Blood cultures in patients with abdominal pain associated with fever, sepsis.
  • Pregnancy test in women of child-bearing age. Gonorrhea and chlamydia cultures or other detection assays (ELISA, fluorescent antibody tests, DNA probes) in suspected pelvic inflammatory disease.
  • IgA, tissue transglutaminase and anti-endomysial antibodies if celiac disease is suspected.
  • ESR and CRP are elevated in celiac disease, inflammatory bowel disease.
  • Perinuclear antineutrophil antibodies (pANCA) are frequently positive in ulcerative colitis, and anti-Saccharomyces cerevisiae antibodies (ASCA) are frequently positive in Crohn’s disease.
  • A 12-lead EKG should be done to exclude cardiac ischemia as a cause of abdominal pain.

Principles in Imaging

Imaging approach can be focused depending on clinical suspicion, and preference of imaging modality may depend on access and availability.

Plain film radiography of the abdomen has utility only in detecting bowel obstruction (air-fluid levels, dilated bowel loops) or perforation (free air). Toxic dilation of the colon can also be seen on plain film. It may be possible to see renal stones (90% radiopaque), most commonly at the pelvicalyceal junction, as the ureter crosses the pelvic brim or at the trigone as the ureter enters the bladder. However, not all radio-opaque stones are visible on KUB. Intravenous urography (IVU) was previously performed, looking for delayed excretion of hydroureter, but the procedure may take a number of hours, and has now been supplanted by CT (without intravenous contrast) when renal stones are suspected. Chest radiographs can detect free air in the subdiaphragmatic location, as well as lower lobe pneumonia and pleural effusion that may be causing abdominal pain.

Abdominal Ultrasound

Abdominal ultrasound is the test of choice in biliary disease, which is most likely in a patient with right upper quadrant pain and abnormal liver function tests. It has higher sensitivity than CT scan for detecting gallstones and measuring biliary dilatation. It is also useful in screening patients at risk of developing aortic aneurysm and for serial documentation of aneurysm size, but CT scans are more accurate and provide details of surrounding structures and their relationship to the AAA. Ultrasound can also provide information on liver, pancreatic and renal lesions. It is relatively inexpensive and non-invasive but may be somewhat operator dependent. It may be limited by some patient factors such as excessive size or presence of bowel gas obscuring the image.

Computed Tomography (CT)

Abdominal computed tomography (CT) scan with contrast is generally done in patients with more non-specific pain, and is perhaps the investigation of choice when the differential diagnosis cannot be narrowed. It is preferred over ultrasound for renal colic or pyelonephritis as it has a higher sensitivity and specificity (>90%) for detecting stones. It will also pick up appendiceal inflammation that ultrasound would clearly not image. It is fast and provides information on the full spectrum of liver, pancreatic and bowel pathologies as well as catching the bases of the lungs and hence possible pneumonias as the cause of the pain. It does however involve a relatively large dose of radiation. Generally, pelvic CT scan is also done at the same time since peritoneal transudate from an upper abdominal structure may indicate no obvious structural change in the upper abdomen, but clues that support the existence of significant disease may only be suspected by the presence of the free fluid in the cul de sac in the pelvis. CT scan is useful in detecting diverticulitis, pancreatitis, colitis, AAA, nephrolithiasis, and appendicitis. It is also useful to identify abscesses, fistulas and sinus tracts in Crohn’s disease.  It should be noted that after administration of oral contrast, enough time (about 2-3 hours) should be allowed for the contrast to reach the distal colon prior to imaging. The administration of IV contrast may enhance some pathologies such as the outer ring of abscesses or the rich vascular supply of tumors. Gas within low attenuation liver lesions is pathognomonic of abscess.

Magnetic Resonance Imaging (MRI)

Abdominal Magnetic Resonance Imaging (MRI) provides equivalent diagnostic accuracy to CT in most pathologies. Though it does not carry the radiation burden of CT, it is more expensive, time consuming and may be more geographically limited and less acceptable to the patient. These factors make it less used than CT as a diagnostic modality.

MRCP (Magnetic Resonance Cholangiopancreatography) is a non-invasive alternative in patients with suspected ascending cholangitis, when therapeutic intervention is not immediately necessary or in patients with high risk for invasive procedures.

Principles in Imaging: Small Bowel Barium Study

Small bowel follow-through with barium can be used to detect pathology including Crohn’s disease or malignancy in the area of small bowel that is not accessible by upper endoscopy or colonoscopy. The radiologic findings of Crohn’s disease include “cobblestoning” from longitudinal and transverse ulcerations involving the small bowel, and “string sign” due to segments of luminal narrowing that occur as a result of circumferential inflammation and fibrosis. Barium enema shows fine mucosal granularity, shortened and narrowed colon, and loss of haustrations (“lead pipe colon”) in ulcerative colitis, however, colonoscopy is better to assess disease extent and severity in ulcerative colitis.

Principles in Imaging: Angiography

Angiography is the gold standard for diagnosis of mesenteric ischemia.

Principles in Imaging: Nuclear Medicine

A Nuclear Medicine HIDA (dimethyl iminodiacetic acid) scan is helpful in diagnosis of cholecystitis when the diagnosis remains unclear.

Principles in Imaging: Pelvic Transvaginal Ultrasound

Pelvic transvaginal ultrasound can be used to detect uterine and ovarian pathology.

Principles in Imaging: Upper Endoscopy

Upper endoscopy should be used to investigate dyspepsia with alarm symptoms, with the potential for biopsy. Patients with dyspepsia without alarm symptoms can be managed with a therapeutic trial of antisecretory medication. Patients having no alarm symptoms but unresponsive to antisecretory therapy, or those with alarm symptoms and a negative upper endoscopy, should be reassessed for pancreatic or biliary etiology with epigastric presentation.

Principles in Imaging: ERCP

ERCP (Endoscopic retrograde cholangiopancreatography) should be done to visualize the common bile duct and as a therapeutic intervention in ascending cholangitis.

MRCP (Magnetic resonance cholangiopancreatography) is a non-invasive alternative when therapeutic intervention is not immediately necessary or in patients with high risk for invasive procedure. In patients with pancreatitis and elevated transaminases, gallstone etiology should be suspected even in the absence of ultrasound findings. ERCP/MRCP can be considered in such cases.

Potential Complications

Serious potential complications can occur depending on underlying pathology, including bowel perforation, bowel infarction and sepsis. Symptoms may also be due to underlying gastrointestinal malignancy which may be missed.

Principles of Management

Several well-designed clinical trials have shown that analgesics can be safely used in abdominal pain without significantly impacting diagnostic accuracy of the physical exam, and relief of pain should thus be a standard of care (5, 6).

Initial care depends on the severity of presentation. A patient with exsanguinating intraabdominal bleeding or with suspected mesenteric ischemia needs immediate surgical intervention, while stabilizing airway, breathing and circulation.

Patients should initially be kept NPO until pathology is identified, with IV fluids for patients who are volume depleted (care should be taken in patients with history of congestive heart failure). Strict monitoring of intake and output should be done in sicker patients to guide volume resuscitation, with insertion of a Foley catheter if needed.

If ileus, bowel obstruction or upper GI bleeding is suspected, then a nasogastric tube should be inserted for decompression or lavage.

Labs and imaging studies should be obtained based on clinical suspicion.

Narcotics and analgesics should not be withheld. NSAIDs should generally be used with caution or avoided in the elderly due to gastric irritation and propensity to cause GI bleeding.

Acetaminophen and opioids should be used with caution in liver dysfunction, with lower dosing or longer administration intervals. IV morphine is generally effective for pain control, but is generally avoided in biliary disease because of the theoretical possibility of spasm of sphincter of Oddi. In this situation, IM meperidine has been preferred. However, its neurotoxic metabolite poses a concern for administration in alcoholic pancreatitis, with patients at risk for neurologic complications from alcohol withdrawal. IM ketorolac has been compared to meperidine in the treatment of biliary colic, with no significant difference in pain relief (9).

Empiric antibiotic coverage should be initiated in patients in whom sepsis, cholangitis, appendicitis, diverticulitis, or peritonitis is suspected, with gram negative and anaerobic coverage.

Specific therapy should be instituted for underlying disease process causing abdominal pain.

Patients with abdominal pain and diarrhea exceeding two weeks with negative cultures, systemically unwell patients, immunosuppressed patients, and suspected inflammatory bowel disease require evaluation with colonoscopy or flexible sigmoidoscopy to clarify diagnosis. Video capsule endoscopy can be considered in diagnosis of obscure GI bleeds and also to visualize Crohn’s lesions involving the small intestine.

In patients over 50, malignancy should be excluded with imaging modalities and endoscopy.

All patients should have serial abdominal examinations. A definitive diagnosis may sometimes be elusive at the time of initial examination, and watchful waiting with repeated exams may reveal the true nature of illness. An experienced physician or surgeon may decide for surgical intervention on clinical grounds alone even if there is lack of clear anatomic diagnosis.

 

Red Flags

There are several important factors not to miss when evaluating a patient with abdominal pain.

• • age over 50
  • weight loss
  • persistent vomiting
  • dysphagia
  • anemia
  • hematemesis or bright red blood per rectum or melena
  • palpable abdominal mass
  • family history of GI malignancy
  • previous gastric surgery

Patient Information

Abdominal pain is common, and while the pain may be due to a non-serious cause, the patient should seek medical opinion, especially in the following circumstances (11):

Seek emergency care if:

1) pain in abdomen is sudden and severe, or you have associated chest pain or radiation to chest/ neck/ shoulder.
2) vomiting blood or have blood in stool or black tarry stools
3) abdomen is tender to touch and feels stiff or rigid.
4) unable to move bowels, especially with vomiting

See a doctor if:

1) Abdominal discomfort lasts one week or longer
2) Diarrhea for more than five days
3) Fever (over 100°F for adults or 100.4°F for children) with pain
4) A burning sensation when you urinate or frequent urination
5) Pain that develops during pregnancy (or possible pregnancy)
6) Persistent vomiting
7) Prolonged poor appetite
8) Difficulty swallowing
9) Unexplained weight loss
10) Family history of cancers in the abdomen

If the pain is mild, avoid solid food for the first few hours. If there is vomiting, wait 6 hours and then eat small amounts of mild foods. Drink water or clear liquids to keep well-hydrated.

If the pain is higher up in the abdomen and occurs after meals, it may be due to indigestion and antacids may provide some relief. In this situation, avoid citrus, high-fat foods, fried, greasy or spicy foods, tomato products, caffeine, alcohol, and carbonated beverages. One can try H2 blockers (like Pepcid or Zantac) available over the counter. If any of these medicines worsen the pain, seek medical attention.

Avoid any aspirin, ibuprofen or similar medications until you check with a doctor. Tylenol is generally safe, but one should avoid it or check with a doctor if there is a history of any liver abnormalities.

 

References
1) National Hospital Ambulatory Medical Care Survey: 2004 Emergency Department Summary. Number 372, June 23, 2006. CDC Advance Data, accessed at http://www.cdc.gov/nchs/data/ad/ad372.pdf

2) Heikkinen M, Pikkarainen et al. GP’s ability to diagnose dyspepsia based only on physical examination and patient history. Scand J Prim Health Care 2000; 18:99

3) Bohner H, Yang Q et al. Simple data from history and physical examination help to exclude bowel obstruction and to avoid radiographic studies in patients with acute abdominal pain. Eur J Surg 1998; 164:777

4) Trowbridge RL, Rutkowski NK et al. Does this patient have acute cholecystitis? JAMA 2003; 289:80

5) Gallagher EJ et al. Randomized clinical trial of morphine in acute abdominal pain. Ann Emerg Med 2006 Aug; 48:150-60.

6) Thomas SH, Silen W. Effect on diagnostic efficiency of analgesia for undifferentiated abdominal pain. Br J Surg 2003; 90: 5-9.

7) Kasper DL, Braunwald E, Fauci AS et al. Harrison’s Principles of Internal Medicine. 16th edition. Abdominal Pain 82-84

8) Fishman MB and Aronson MD. Differential diagnosis of Abdominal Pain in Adults. UpToDate online, accessed at http://uptodateonline.com/utd/content/topic.do?topicKey=pri_gast/2173&view=print

9) Dula DJ et al. A prospective study comparing I.M. ketorolac with I.M. meperidine in the treatment of acute biliary colic. J Emerg Med. 2001 Feb;20(2): 121-4.

10) Van den Broek NT et al. A randomized controlled trial of four management strategies for dyspepsia: relationships between symptom subgroups and strategy outcome. Br J Gen Pract 2001; 51:619

11) Medline Plus

Information on abdominal pain is available at:

– Medline Plus,

– American College of Gastroenterology

– eMedicine – Abdominal pain in elderly persons

– eMedicineHealth – Abdominal pain in adults