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Evaluating acute abdominal pain in adults

A patient comes into your office practically doubled over in pain. Where should your workup begin? What clues are most revealing? And how do you examine the patient kindly, without increasing the pain?

Katie Cook, PA-C

Ms. Cook works in primary care at the VA Medical Center in Iowa City, Iowa. The author has indicated no relationships to disclose relating to the content of this article.

CME

Earn Category I CME credit by reading this article and "The metabolic syndrome: Modify causes, treat risk factors" and then successfully completing the post-test. Successful completion is defined as a cumulative score of at least 70% correct.

This material has been reviewed and is approved for 1 hour of clinical Category I (Preapproved) CME credit by the AAPA. The term of approval is for 1 year from the publication date of March 2005.

Emergency departments (EDs) see 5 million patients annually with the chief complaint of abdominal pain,¹which remains a leading cause of hospital admission in the United States.²Despite it s frequent occurrence, abdominal pain is difficult to manage because no matter how thorough the workup, a specific diagnosis is not possible in approximately 30% of cases.³The list of possible causes of abdominal pain is long, ranging from aortic dissection to psychogenic pain and including almost anything in between. Presenting signs and symptoms for two patients with the same underlying pathology may look totally different, or they may be similar even though the disease entities are distinct. The practitioner must collect piece after piece of historical, anatomic, physical, laboratory, and imaging data to arrive at an accurate diagnosis that leads to proper management. This review offers strategies for navigating this intricate and often tedious process.

History

A concise, thorough, and accurate history is of utmost importance. In some cases, this crucial first step enables the clinician to assemble most of the diagnostic picture before performing a physical examination or ordering any tests.

The chronological sequence of events may shed more light on the case than any other piece of historical information. Learning the timing of the onset of pain in relation to nausea and vomiting or other constitutional symptoms will begin to narrow the differential diagnosis. Knowledge of whether the pain came on suddenly or became gradually worse over time can be an important determinant.

Ask the patient to describe the pain. Knowing its character, duration, and location will aid in proper diagnosis. The patient may be able to distinguish between visceral and somatic pain, since autonomic nerves innervate the viscera, causing a dull or cramplike pain that is often insidious in nature. Somatic nerves innervate the parietal peritoneal layer; when these fibers are irritated by either chemical or bacterial sources, the patient feels a more localized, sharp, constant pain. Knowing the duration of the pain can help the clinician determine if it is truly colicky, defined as rhythmic with intermittent times of relief. Information regarding referred pain may play a key part in determining origin.

Ask whether anything has relieved the pain. Did the use of heat or ice help? If so, the pain might be musculoskeletal in origin. Has the patient used medications to any substantial benefit? Does eating relieve the pain? For example, suspect duodenal ulcers if the patient complains of pain roughly 2 hours after meals that is then relieved by eating.

It has become common practice to ask the patient to rate the pain’s severity on a 1 to 10 scale. Although the information gathered from a single rating is rarely of much practical clinical help, serial determinants of pain severity can be quite useful in refining the diagnosis. Knowing the pain was at 8 out of 10 at onset but is now a 5 out of 10 after the passage of time or administration of medication can be helpful. The clinician should also elicit the temporal nature of the pain. Does the pain awaken the patient at night? Does it come postprandially or does it occur randomly throughout the day? The most revealing answer may result from simply asking if the patient has felt this type of pain before. Often the patient holds the key to the diagnosis but cannot make the connection.

Conduct a thorough review of systems. This step is crucial while investigating the root of acute abdominal pain. Knowledge of fever, chills, nausea, vomiting, constipation, diarrhea, belching, bloating, or excessive flatulence is valuable. Consider Boerhaave’s syndrome or an incomplete esophageal tear with acute sternal and epigastric pain following prolonged episodes of severe retching or vomiting. It is also important to ask about urinary and bowel habits, as well as any changes in the consistency or caliber of stool. The clinician should question female patients about the last menstrual period and about the sexual and pregnancy histories. Asking patients about any upper respiratory tract symptoms will aid in eliminating or pinpointing lower-lobe pneumonia as the cause of abdominal pain. Acute vomiting and pain accompanied by recent visual disturbances may indicate acute glaucoma.

Take a complete history. Learning the family, social, medication, and medical histories is a key step in the diagnostic process. Acute MI can manifest only as abdominal pain, so it is vital to know the patient’s personal and family cardiac history as well as any history of atrial fibrillation, which may have caused an abdominal vascular infarct. Known conditions such as diabetes or syphilis should be documented, as should heritable conditions such as sickle-cell disease/trait, porphyria, or familial Mediterranean fever. The history should also include questions regarding possible recent or chronic exposures to caustic chemicals, lead, mushrooms, ticks, or spiders. Ask about recent travel, especially to the tropics, or if there is a different drinking water source, such as a new well. Since acute alcohol or narcotic withdrawal or overdose can also cause abdominal pain, query patients about their recent use.

Physical examination

Observing the patient's overall appearance during the history-taking process can be quite helpful since facial expressions may suggest whether the pain is constant or crampy. Patients with underlying septicemia or shock may present with diaphoresis, while anemic patients may be pale. Measure orthostatic BP and heart rate for large amounts of third spacing and/or volume depletion.

Examination should usually begin at the head, with special attention paid to any scleral icterus, funduscopic signs of emboli, or carotid bruit. A thorough chest and lung examination is important: Listen for crackles and wheezes primarily at the bases, and check for signs of consolidation suggesting pneumonia. Tachycardia may be a sign of shock. Note whether any murmurs or rubs are pleural, which may signify pleural inflammation causing abdominal irritation.

There are three key steps in the abdominal examination: inspection, auscultation, and palpation. Visual examination of the abdomen can be very helpful in th e diagnostic process. Do you see a rash indicative of herpes zoster? Are there visible pulsatile masses? What is the abdominal pattern with respiration? Does the patient have any scars denoting previous abdominal surgeries, which might be the cause of adhesions?

One of the least revealing components of the examination is determining the character and presence of bowel sounds by auscultation, since no diagnosis can be confirmed or ruled out based on auscultation alone.⁴Not e the presence or absence of abdominal bruits. Palpation is the most important part of the abdominal examination, and if the patient is in pain, it may be one of the hardest from which to gain good information. The clinician should be careful and gentle while palpating, beginning at the point farthest away from the area of maximal tenderness, if possible. Attempting to distract the patient during palpation is useful, especially if psychogenic pain is suspected. Obtaining positive rebound tenderness by a quick release of deep palpation is most often unnecessary, and it is unkind to the patient in pain. Similar information can be gathered by gentle percussion over the abdomen or by asking the patient to cough. One study showed pain with cough to have a sensitivity of 77% and specificity of 80% for peritonitis,⁵while diagnosing peritonitis with positive rebound tenderness has a sensitivity of 81% and a specificity of 50%.⁶Percussion of th e abdomen may also reveal information regarding possible ascites, commonly demonstrated with a fluid wave or evidence of shifting dullness.

No abdominal examination is complete without a digital rectal examination, which may detect masses or gross blood in the vault. The practitioner should also check stool for occult blood; hard impacted stool may be a sign of constipation or possible obstruction. In females, a full pelvic examination is also crucial. The bimanual examination should be performed, noting cervical motion tenderness, adnexal masses, or tenderness. Check all potential hernia sites, and in the male patient, palpate the testicles for evidence of inflammation or torsion.

Laboratory and imaging studies

Tests should be chosen that will help to confirm or rule out the diagnostic possibilities being considered based on the history and physical examination. Common tests include a CBC with differential (looking for nonspecific markers of inflammation or infection), liver function tests (LFTs) and pancreatic enzymes, serum electrolytes, creatinine concentration and serum urea nitrogen (which help determine metabolic causes and consequences of disease pathology), and urinalysis. Every woman of childbearing years must have a urine pregnancy test because a pregnancy, intrauterine or ectopic, has vast implications for further evaluation and treatment.⁷Obtain cultures during the speculum examination to test for chlamydia and gonorrhea. If the patient has any personal or family history of cardiac disease, or if the presentation suggests a possible cardia c cause, include creatine phosphokinase and troponin levels in the blood work.

Imaging usually begins with plain abdominal films taken while upright and supine, as well as an upright chest film. Radiographs may show evidence of intraperitoneal free air or air in the soft tissue or intestinal walls. Free air, mainly due to a perforated viscus, is classically seen as lucency under the crescent of the hemidiaphragm on the upright chest film. Simple radiographs are also 50% to 60% diagnostic of obstruction.⁸

The use of CT has become vital in evaluating patients with intraabdominal infections such as appendicitis and diverticulitis. CT helps the practitioner t o visualize the vasculature of the abdomen, most notably the abdominal aorta and branches. In detecting appendicitis, CT has a 96% to 98% sensitivity and an 83% to 89% specificity.⁹However, CT does have a few inheren t weaknesses because it tends to miss biliary stones and is relatively unreliable in investigating the pelvic organs of females.

Ultrasonography (US) has become the modality of choice for investigating right upper quadrant (RUQ) pain due to cholecystitis or cholelithiasis, as well as any pain suspected to have a gynecologic cause. The specificity and sensitivity of US for detection of gallstones are approximately 99% and 84%, respectively.¹⁰ US ha s also been heralded as a noninvasive, rapid way to diagnose an inflamed appendix, but CT, with sensitivities of 75% to 90% and specificities of 86% to 100%, remains a more reliable imaging tool for this diagnosis.¹¹ In one study of 100 patients with suspected appendicitis, the use of CT prevented unnecessary appendectomies, leading to a savings of $447 per patient.¹² At this time , there is not much use for MRI in the diagnostic workup of acute abdominal pain. Patients with any known cardiac history or risk factors should also have a bedside ECG to rule out MI or acute ischemia.

Four don’t miss diagnoses

Each of the following clinical diagnoses is associated with high patient mortality, and the American College of Emergency Physicians lists them among lifethreatening conditions that have the potential to be missed in the ED.¹³ Every clinician must be able to recogniz e these presentations and act swiftly in patient management. Patients must be kept on NPO status and given pressure and volume support along with supplemental oxygen while prompt surgical consultation is obtained or the patient is transported to an appropriate medical facility. If possible, blood should be typed, matched, and screened to facilitate surgical resuscitative efforts.

Ruptured ectopic pregnancy must be high on the list of possible diagnoses in any woman of childbearing years who presents with acute abdominal pain (see Figure 1). Women with pelvic inflammatory disease (PID), an intrauterine device, or a history of previous ectopic pregnancy or abdominal surgery are at greater risk for ectopic pregnancies. Despite improvement in detection, complications from ectopic pregnancy account for 13% of all deaths related to pregnancy.¹⁴ Patients may present with syncope, vaginal bleeding or spotting, an d nausea, as well as acute onset of unilateral lower quadrant pain. A history of late or missed menses is usually present as well.

Vascular diseases such as ruptured abdominal aortic aneurysm or aortic dissection can cause acute abdominal pain. Shock symptoms will be evident, and th e patient will display hypotension, tachycardia, severe pain, and a decreased level of consciousness. Patients will report sudden onset of excruciating back pain that may radiate to the flanks, causing clinical confusion with either muscle spasm or renal colic. These patients will decompensate quickly. Obtain the BP gradient between arms as a clue to a potential acute aortic dissection. Physical examination will commonly reveal a pulsatile abdominal mass. Discolored toes may indicate lower leg ischemia.

The presentation of intestinal obstruction varies depending on the stage and location of obstruction. Generally speaking, the higher up the obstruction, the more severe the symptoms. Vomiting is an almost universal symptom, though in lower bowel obstruction patients may have only anorexia and nausea. The pain from obstruction is usually severe at onset, caused by intestinal peristaltic waves attempting to overcome the blockage. Patients will show worsening signs of reduced intestinal peristalsis: decreased flatulence, increased cramping, and abdominal distention. Plain radiographs will reveal dilated loops of bowel. Common causes of obstruction are adhesions, incarcerated hernias, intussusception, volvulus, and colonic carcinoma. Strangulation of the bowel can occur with obstruction due to vessel occlusion and lead to gangrene.

Cardiovascular, ischemic, or arteriosclerotic disease may produce symptoms of mesenteric ischemia or infarct. Pain will be acute, severe, and diffuse in nature. Patients who complain of diffuse postprandial pain, nausea, vomiting, diarrhea, and weight loss may have the more chronic mesenteric ischemia sometimes referred to as intestinal angina. On examination, the clinician should pay attention to systemic signs of atherosclerotic disease. Patients with bowel infarction will present looking more toxic than in shock, with fever, elevated WBC counts, and possible altered mental status. The diagnostic gold standard is mesenteric and celiac artery angiography.

Four quadrants of pain

When the clinician can assess the exact location of th e pain, a differential diagnosis can be developed by location. Atypical presentations are always possible, so use the patient’s assessment of location only as a guide as the investigation continues. Be more concerned with atypical presentations of pain in special population groups (see Table 1).

RUQ pain is often due to biliary disease or hepatitis. Inflammation from an ascending appendix, MI, or renal disease should be excluded from the differential. In the condition that is sometimes inappropriately termed biliary colic, the pain is steady rather than paroxysmal. The pain of biliary colic is generally described as a constant gnawing that increases over a few hours postprandially and then subsides totally; it is due to increased pressure buildup in the gallbladder as an outlet obstruction causes it to contract. Acute cholecystitis occurs with prolonged blockage in the duct system; patients will present with steady, severe pain that may radiate to the subscapular region; nausea, bilious vomiting, and anorexia are common. If fever is present, the diagnosis is more likely to be cholecystitis than simple biliary colic. On physical examination, the most accurate diagnostic findings for acute cholecystitis are a positive Murphy’s sign, with a positive likelihood ratio (LR) of 2.8, 95% confidence interval (CI) 0.8 to 8.6, and RUQ pain, with a negative LR of 0.4, 95% CI 0.2 to 1.1.¹⁵

Other disease processes of the biliary system includ e acute cholangitis occurring when a stone lodges in the biliary or hepatic duct system, causing dilation and infection. The patient with acute cholangitis may present with jaundice, fever, and abdominal pain; laboratory studies may show a high WBC count, elevated bilirubin and pancreatic enzymes, and possible elevation in LFT results.

The pain of hepatitis is rarely acute at onset. The entire liver is tender to palpation, and pressure placed laterally over the intercostals will elicit pain; this characteristic helps to distinguish hepatitis from biliary tenderness, which is felt mainly over the right hypochondrium. Elevated bilirubin levels will cause the classic signs of jaundice as well as scleral icterus. Ascites may also be present due to underlying portal hypertension caused by chronic liver disease, and laboratory studies will show elevated LFT results early in the disease process. The pain from MI can be high in the epigastrium and thus may be difficult to differentiate from biliary pain. Biliary colic and acute cholecystitis are two of the most common noncardiac reasons patients are admitted to cardiac care units.¹⁶

Left upper quadrant (LUQ) pain may be attributable to pathology involving the spleen and the pancreas. Acute pancreatitis manifests as rapid onset, steady pain boring straight through to the back. Leaning forward may provide some relief from the pain, which is usually accompanied by nausea and vomiting. Acute pancreatitis due to alcohol use typically occurs 1 to 3 days after a drinking episode; thus, it is important to take an accurate history. Gallstones are the most common cause of pancreatitis in the United States,¹⁷ causing pain and inflammation when a stone lodges in the ampulla of Vater, blocking pancreatic drainage. Laboratory results may show hyperglycemia and glycosuria, as well as elevated serum and urinary amylase levels. An elevated serum amylase level is not specific for pancreatitis as it is also a finding in cholecystitis, high intestinal obstruction, perforated ulcer, and acute renal insufficiency.¹⁶ Discoloration of the flank s (Grey Turner’s sign) or of the periumbilical region (Cullen’s sign) may be due to hemorrhagic pancreatitis.

Splenic abscess and splenic infarct are two common disease processes of the spleen associated with LUQ pain. Infarct may be common in patients with a history of atrial fibrillation or sickle-cell disease/trait. Splenic rupture rarely occurs without a history of blunt trauma to the abdomen; patients are initially hypertensive and tachycardic but quickly develop hypotension and shock. They may complain of acute left shoulder pain (known as Kehr’s sign) in addition to the LUQ pain. A low threshold of suspicion is advised for splenic rupture in teenagers presenting with severe LUQ pain, no history of trauma, and symptoms consistent with mononucleosis.

Other causes of upper quadrant pain include lower-lobe pneumonias, pericarditis, MI, and the myriad of conditions coming under the heading of dyspepsia. As defined by the Rome Criteria, dyspepsia is “. . . persistent or recurrent abdominal pain or abdominal discomfort centered in the upper abdomen.”¹⁸ Acute pain from dyspepsia is most likely an exacerbation of a chronic condition; thorough questioning may elicit a previous history of this discomfort. These conditions include gastroesophageal reflux disease, inflammatory bowel disease, stomach or intestinal malignancies, irritable bowel syndrome, diabetic gastroparesis, and drug-induced or psychiatric dyspepsia.

Right lower quadrant (RLQ) pain is classically caused by appendicitis. Patients usually report having periumbilical pain, which then radiates to the RLQ. Traditionally, pain is felt maximally at McBurney’s point, which is one third the distance from the right anterior superior iliac spine and the umbilicus. The order of events is of importance when differentiating appendicitis from many other conditions that mimic it: With appendicitis, pain occurs first, followed by nausea, vomiting, anorexia, radiating tenderness, fever, and, lastly, leukocytosis.¹⁶

Left lower quadrant (LLQ) pain indicates diverticulitis in 70% of patients with this condition in the Western world.¹9 Patients with this pancolonic process present very similarly to those with appendicitis—with a few noteworthy exceptions, such as more pronounced changes in bowel habits. Fever and leukocytosis ar e more prominent in diverticulitis, while one often sees anorexia, vomiting, and nausea in appendicitis. Initial pain with diverticulitis is usually hypogastric rather than epigastric and radiates to the left iliac crest or suprapubic area. Patients suffering from an acute attack of diverticulitis probably have experienced this type of pain before; if elicited in the history, this information can thus give a good diagnostic clue.

Because of the bilateral nature of the renal and reproductive systems, pain arising from disease pathology of these systems may manifest on either side or as general abdominal pain. Kidney stones usually become symptomatic as they exit the kidney and enter the ureter; patients will complain of severe, paroxysmal pain, the location and radiation of which depend on where the stone is at presentation. Renal colic pain commonly refers to the groin, and patients will most likely writhe around on the bed, finding it almost impossible to lie still. The majority of patients will present with hematuria as the main laboratory value of diagnostic importance. Although simple radiographs may show some stones, CT is the gold standard for diagnosis.²⁰

Gynecologic pain

In women, high acuity sources of abdominal pain o f pelvic origin include ovarian torsion, ovarian cyst rupture, and spontaneous or threatened abortion. Ovarian torsion is an acute surgical emergency because extended torsion can cause infarct of the tube and affected ovary. Pain from torsion is described as sharp or knifelike; it occurs suddenly and is often accompanied by nausea and vomiting. The pelvic exam will reveal a tender adnexal mass. Because the symptoms are nonspecific and no laboratory or imaging studies are diagnostic, definitive diagnosis of torsion comes only with surgical exploration.²¹

Functional ovarian cysts are classified as follicular o r corpus luteum. There may be an acute, short-lived pain associated with the rupture of a follicular cyst; however, when a corpus luteum cyst ruptures, its high vasculature means hemorrhage may occur. Pain associated with a ruptured corpus luteum cyst cannot be clinically distinguished from pain associated with a ruptured ectopic pregnancy. Serial ß-hCG (beta human chorionic gonadotropin) levels as well as pelvic US should be used to help differentiate the two processes.

There are many lower acuity gynecologic causes of abdominal pain, including tubo-ovarian abscess (TOA), hydrosalpinx, and pelvic inflammatory disease (PID), which leads all gynecologic causes of ED visits at approximately 350,000 a year.²² Pain related to PID may b e subtle at onset, worsening with coitus or jarring movements, and frequently is associated with menses. Abnormal uterine bleeding, vaginal discharge, urethritis, fever, and chills may also be present, but none of these symptoms is specific to PID. Both TOA and PID occur as a result of bacterial seeding of the upper genital tract; these infections will cause cervical motion tenderness on pelvic examination. The laboratory workup may show an elevated ESR and C-reactive protein (CRP) level; the latter is currently considered a more sensitive marker of PID than either the ESR or WBC count elevation.²¹ One study found that the most sensitive singl e test of PID is an elevated WBC count in vaginal fluid at 78%, compared to serum WBC count elevation at 57%, and an elevated ESR and CRP at 70% and 70%, respectively. However, the specificity of increased WBCs in vaginal fluid was only 39%.²³ A large metaanalysis has concluded that no single test or combination of tests yields both high sensitivities and specificities for PID diagnosis.²⁴

Four causes of diffuse abdominal pain

There are times when patients cannot pinpoint the location of their abdominal pain. As discussed previously, mesenteric ischemia and infarct are possible diagnoses. Other causes of diffuse abdominal pain include peritonitis and gastroenteritis.

Peritonitis may cause a patient to try to lie strictly immobile, often with knees bent. Pain from peritonitis becomes more diffuse as the infection spreads away from the originating organ. Patients will generally be febrile, tachycardic, and hypotensive, and abdominal examination will reveal a diffusely tender abdomen, even with gentle palpation.

Gastroenteritis can cause abdominal pain, especially cramping, along with diarrhea, nausea, and vomiting. Knowledge of recent exposure and illnesses within close contacts or the community can help lead to this diagnosis. Most cases are self-limiting, but special concern and treatment may be necessary for immunocompromised and elderly patients.

In cases where patients cannot accurately locate their abdominal pain, multiple pieces of historical, physical, laboratory, and imaging data should be collected so that appropriate diagnostic and management decisions are made.

Conclusion

Clinicians must develop a thorough, efficient, and systematic approach to evaluate acute abdominal pain. Te data obtained from the history and physical examination are crucial to a proper diagnosis but may take considerable time to elicit. Because of the wide variety of conditions that must be considered, providers must develop an appropriate differential diagnosis while not overlooking uncommon yet potentially fatal causes (see Table 2). The clinician should use laboratory and imaging studies prudently and appropriately, based on the information gathered during the history and physical examination. Sir William Osler said, “ The art of the practice of medicine is to be learned only by experience; ’tis not an inheritance; it cannot be revealed. Learn to see, learn to hear, learn to feel, learn to smell, and know that by practice alone can you become expert.”²⁵

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