The acute abdomen

CASE 1 Alan Smith (Part 1)

Alan Smith, an 86-year-old man, visits your primary care office complaining of 24 hours of left lower quadrant abdominal pain. He is nauseated and does not feel like eating. He has not had pain like this before. He has a low grade fever (99.6° F) and his heart rate is 100.

1. What elements of the physical examination are essential?

2. What tests should be ordered in your office?

Prevalence and impact

The definition of an acute abdomen is “signs and symptoms of acute intraabdominal pathology requiring treatment by surgical intervention.”¹ However, it should be noted that not all episodes of acute abdominal pain require surgery but rather prompt diagnosis and treatment.² Acute abdominal pain is a common chief complaint for older patients seen in the emergency department (ED),³ and this population consumes a disproportionate amount of time and resources in the ED in comparison to younger patients.⁴ In addition, approximately 50% of older patients going to an ED with abdominal pain will require hospital admission, and 30% to 40% of these patients will eventually require surgical intervention.⁵

Not only does acute abdominal pain in the older population impact the ED, but the aging population has also been predicted to have a significant impact on the field of general surgery. The amount of procedure-based workload in general surgery is expected to increase 31% by 2020.⁶ The aging population will significantly affect not only the number of procedures performed on older patients but also the percentage of emergency operations, because the risk of emergency surgery increases with age.⁷ Previous research demonstrates significant variability in the percentage of emergency operations in the older population, ranging from 14% in a cohort of patients older than 80 years of age who had noncardiac surgery at Veterans Affairs hospitals,⁸ 56% in a cohort of octogenarians undergoing major abdominal surgery,⁹ and 69% to 72% in two cohorts of nonagenarians.¹⁰^,¹¹

Risk factors and pathophysiology

The workup of acute abdominal pain in the older patient is challenging for the following reasons: (1) older patients may have vague or nonspecific symptoms that are not suggestive of a specific pathophysiologic process; (2) older patients often lack the systemic (e.g., fever) or clinical signs (e.g., right lower quadrant tenderness) suggestive of acute intraabdominal pathology; (3) older patients are poor historians, or there is often difficulty obtaining an accurate history owing to memory loss or dementia; (4) older patients may delay seeking treatment or be dependent on others to be sent to a hospital for evaluation (e.g., nursing home residents); and (5) presence of comorbid disease may alter both the clinical presentation as well as the diagnostic evaluation.⁴^,^12–15

Misdiagnosis of acute abdominal pain is common in the older patient for all of the aforementioned reasons, so it is important to maintain a high index of suspicion.¹⁶ Previous research has suggested a higher mortality for older patients with abdominal pain where the diagnosis occurred after admission to the hospital (19%) versus those patients with a correct preliminary diagnosis in the ED (8%).¹⁷ Kizer et al. demonstrated that the sensitivity/specificity of a provisional ED diagnosis was lower for patients older than 65 (82% sensitivity and 86% specificity). In contrast, there was no difference in mortality based on agreement between the provisional ED diagnosis and the hospital discharge diagnosis, although there was a significant increase in disease-related morbidity.¹⁴

Age itself is a risk factor for some causes of an acute abdomen. Not only does the incidence of peptic ulcer disease increase with age, but in a series of 136 patients treated surgically for bleeding or perforated peptic ulcer, 80% of the deaths occurred in patients older than 70 years of age.¹⁸ In addition, it is estimated that 30% to 50% of older patients have underlying cholelithiasis, and 50% to 80% have colonic diverticulosis. The incidence of abdominal aortic aneurysm also increases with age and is present in an estimated 5% of men older than age 65.⁵ The incidence of colorectal cancer also increases with age. The median age of diagnosis for colorectal cancer is 69 years, with 61% of colorectal cancer cases diagnosed in patients 65 years of age or older from 2005-2009 using the National Cancer Institute Surveillance Epidemiology and End Results Program.¹⁹ Previous research has also shown that elderly patients are more likely to have advanced stage colorectal cancer as well as require emergency surgery for complications of advanced colorectal cancer such as obstruction or perforation.²⁰

Advanced age also contributes to mild immunosuppression, which may make the diagnosis of an acute abdomen more difficult in an older patient. The decline in immune competence impairs the ability of the older patient to increase neutrophil production in response to infection, which explains why older patients with acute intraabdominal pathology may have a normal white blood cell count.²¹ A retrospective review of octogenarians with an acute abdomen demonstrated that 30% had a temperature lower than 99.5° F and a normal white blood cell count.²² Comorbid medical disease such as diabetes mellitus, malignancy, or end-stage renal disease may also increase the degree of immunosuppression in an older patient.⁵

Diagnosis of acute abdominal pain is challenging in the older patient—maintain high index of suspicion, and be ready for surgery!

Differential diagnosis and assessment

The potential causes of acute abdominal pain in the older patient are numerous. One approach to classification of abdominal pain consists of determining which of the following four categories the cause of the pain falls into: (1) peritonitis, (2) bowel obstruction, (3) vascular catastrophe, or (4) nonspecific abdominal pain.²³ The differential diagnosis for both surgical and medical causes of acute abdominal pain in an older patient is shown in Box 50-1.

BOX 50-1 DIFFERENTIAL DIAGNOSIS OF ACUTE ABDOMEN IN THE OLDER PATIENT

Surgical causes of acute abdomen

Bowel obstruction: large bowel—incarcerated hernia, malignancy, volvulus (cecal or sigmoid); small bowel—adhesions, incarcerated hernia

Peritonitis: appendicitis, cholecystitis, diverticulitis

Perforated viscus: diverticulitis, duodenal or gastric ulcer, large-bowel obstruction with perforation

Vascular: aortic dissection, gastrointestinal hemorrhage, mesenteric ischemia/infarction, ruptured or symptomatic abdominal aortic aneurysm

Medical causes of acute abdomen

Endocrine: diabetic ketoacidosis

Gastrointestinal: constipation, gastroenteritis, gastroesophageal reflux disease, inflammatory bowel disease (e.g., ulcerative colitis, Crohn’s disease), malignancy, peptic ulcer disease

Genitourinary: adnexal mass, cystitis, pyelonephritis, renal calculi, other gynecologic pathology

Hepatobiliary: ascending cholangitis, choledocholithiasis, cholelithiasis, other causes of acute pancreatitis

Pulmonary: empyema, pneumonia, pulmonary embolus, pulmonary infarction

Other: myocardial infarction

Several retrospective reviews have categorized the most common reasons for emergency abdominal surgery in the older patient. Arenal et al. performed a retrospective and prospective review of factors affecting mortality after emergency abdominal surgery in the older patient. The most common reasons for emergent exploration were intestinal obstruction (41%), peritonitis (29%), other etiology (21%), gastrointestinal (GI) bleeding (5%), and vascular mesenteric disorder (4%).²⁴ Zerbib et al. performed a retrospective review of 45 patients older than 85 years of age who underwent emergency abdominal surgery. The most common causes of an acute abdomen were peritonitis secondary to cholecystitis or appendicitis (31%), small-bowel obstruction (SBO) (13%), mesenteric ischemia (13%), perforation secondary to diverticulitis or duodenal ulcer (13%), large-bowel obstruction secondary to sigmoid volvulus or obstructing colon cancer (11%), and other etiology.²⁵ Potts et al. performed a retrospective review of surgical abdomens in patients 80 years and older. The three most common diagnoses were acute cholecystitis (25%), hernia (21%), and bowel obstruction (16%).²² More recent data from the 2005-2009 American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) identified 37,553 patients undergoing emergency laparotomy.²⁶ The most common indications for surgery were obstruction (34%), perforation (24%), other (18%), neoplasm (8%), vascular insufficiency (7%), GI bleeding (4%), GI inflammation (3%), pancreatitis (1%), and fistula (1%).

In general, there are four main categories of a surgical acute abdomen: (1) peritonitis, (2) perforated viscus, (3) bowel obstruction, and (4) vascular.

CASE 1 Alan Smith (Part 2)

The abdominal examination demonstrates tenderness to palpation in the left lower quadrant with mild guarding. Mr. Smith has a past medical history of chronic obstructive pulmonary disease (COPD) on home oxygen, coronary artery bypass graft for coronary artery disease, end-stage renal disease, and radical prostatectomy for prostate cancer. He was hospitalized 1 week ago for a COPD exacerbation and worsening renal function requiring initiation of hemodialysis. He was discharged home on a steroid taper for the COPD exacerbation.

History and physical examination

Critical elements of the history and physical examination when evaluating an older patient with acute abdominal pain are outlined in Box 50-2. Careful attention must be paid to a thorough history and physical examination because the presentation of an older patient with an acute abdomen may be quite varied, ranging from mild abdominal pain to a change in mental status.⁵ One distinction between medical and surgical causes of abdominal pain may be the temporal relation between the onset of pain and vomiting. Abdominal pain requiring an operation often precedes vomiting (e.g., acute appendicitis), whereas vomiting often precedes the abdominal pain secondary to a medical condition (e.g., gastroenteritis).¹

BOX 50-2 PERFORMING A HISTORY AND PHYSICAL EXAMINATION IN AN OLDER PATIENT WITH ACUTE ABDOMINAL PAIN

Patient history

Pain: Time of onset, location, radiation, quality, severity, palliating and provoking factors.

Gastrointestinal function: Anorexia, nausea, vomiting, bowel habits, characterization of emesis (e.g., bilious, bloody) and stool (e.g., diarrhea versus constipation, presence of blood, melena), and last time the patient ate, passed flatus, or had a bowel movement.

Associated symptoms: Generalized symptoms, including fever, chills, and fatigue, as well as organ-specific symptoms (e.g., chest pain, shortness of breath, cough with productive sputum, dysuria, hematuria).

Other medical problems: May elicit clues to the etiology of abdominal pain, especially prior history of diabetes, cardiac, pulmonary, or gastrointestinal disease.

Surgical history: Ask about all previous operations (especially abdominal procedures).

Current medications: Ask about all current medications, especially nonsteroidal antiinflammatory drugs (known association with gastrointestinal hemorrhage), warfarin or dabigatran (Pradaxa) (increased risk for bleeding or thrombotic/embolic event), steroids (immunosuppression), and beta-blockers (may blunt tachycardia).

Physical examination

Vital signs: Monitor for tachycardia, hypotension; older patients are often normothermic or hypothermic.

Abdomen: Inspect for prior abdominal scars; auscultate for absence (e.g., ileus) or presence of bowel sounds (e.g., high pitched may be associated with bowel obstruction); percuss for presence of tympany (bowel obstruction) or pain (peritonitis) or dullness from fluid (ascites); palpate for presence of mass (e.g., phlegmon, malignancy, abdominal aortic aneurysm if pulsatile); and evaluate for hernia in umbilicus, groin, and prior abdominal incisions.

Rectal: Always do rectal to evaluate for tenderness, impaction, rectal mass, and presence of gross or occult fecal blood.