Appendicitis

• Fred F. Ferri, M.D.

 Basic Information

Definition

Appendicitis is the acute inflammation of the vermiform appendix.

Epidemiology & Demographics

1. •

   Appendicitis occurs in 10% of the population, most commonly between the ages of 10 and 30 yr. Median age is 22 yr. Lifetime risk is 7% to 14%.

2. •

   Approximately 300,000 appendectomies are performed in the U.S. each year.

3. •

   It is the most common abdominal surgical emergency.

4. •

   Incidence of appendicitis has declined over the past 30 yr.

5. •

   Male/female ratio is 3:2 until mid-20s; it equalizes after age 30 yr.

Physical Findings & Clinical Presentation

1. •

   In children with abdominal pain, fever is the single most useful sign associated with appendicitis. Vomiting, rectal tenderness, and rebound tenderness along with fever are more indicative of appendicitis in children than in adults.

2. •

   Abdominal pain: initially the pain may be epigastric or periumbilical in nearly 50% of patients; it subsequently localizes to the right lower quadrant within 12 to 18 hr. Pain can be found in back or right flank if appendix is retrocecal or in other abdominal locations if there is malrotation of the appendix.

3. •

   Pain with right thigh extension (psoas sign), low-grade fever: temperature may be >38° C if there is appendiceal perforation.

4. •

   Pain with internal rotation of the flexed right thigh (obturator sign) is present.

5. •

   Right lower quadrant (RLQ) pain on palpation of the left lower quadrant (LLQ) (Rovsing’s sign): physical examination may reveal right-sided tenderness in patients with pelvic appendix.

6. •

   Point of maximum tenderness is in the RLQ (McBurney’s point).

7. •

   Nausea, vomiting, tachycardia, cutaneous hyperesthesias at the level of T12 can be present.

Etiology

Obstruction of the appendiceal lumen with subsequent vascular congestion, inflammation, and edema; common causes of obstruction are:

1. •

   Fecaliths: 30% to 35% of cases (most common in adults)

2. •

   Foreign body: 4% (fruit seeds, pinworms, tapeworms, roundworms, calculi)

3. •

   Inflammation: 50% to 60% of cases (submucosal lymphoid hyperplasia [most common etiology in children, teens])

4. •

   Neoplasms: 1% (carcinoids, metastatic disease, carcinoma)

    

Diagnosis

Differential Diagnosis

1. •

   Intestinal: regional cecal enteritis, incarcerated hernia, cecal diverticulitis, intestinal obstruction, perforated ulcer, perforated cecum, Meckel’s diverticulitis

2. •

   Reproductive: ectopic pregnancy, ovarian cyst, torsion of ovarian cyst, salpingitis, tubo-ovarian abscess, mittelschmerz, endometriosis, seminal vesiculitis

3. •

   Renal: renal and ureteral calculi, neoplasms, pyelonephritis

4. •

   Vascular: leaking aortic aneurysm

5. •

   Psoas abscess

6. •

   Trauma

7. •

   Cholecystitis

8. •

   Mesenteric adenitis

9. •

   Table 1 summarizes the differential diagnosis of appendicitis.

   TABLE1 Differential Diagnosis of AppendicitisFrom Feldman M, Friedman LS, Brandt LJ: Sleisenger and Fortran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.

   Diagnosis	Findings That Help Differentiate Entity from Appendicitis
   Bacterial or viral enteritis	Nausea, vomiting, and diarrhea are severe; pain usually develops after vomiting.
   Epiploic appendagitis	Focal abdominal pain and tenderness without migration or progression of the pain; patients have a paucity of other GI symptoms such as anorexia or nausea. Laboratory findings are usually normal.
   Mesenteric adenitis	Duration of symptoms is longer; fever is uncommon; RLQ physical findings are less marked; WBC count is usually normal.
   Pyelonephritis	Pain is more likely to be felt in the right flank; high fever and rigors are common; marked pyuria or bacteriuria and urinary symptoms are present; abdominal rigidity is less marked.
   Renal colic	Pain radiates to the right groin; significant hematuria; character of the pain is clearly colicky.
   Acute pancreatitis	Pain and vomiting are more severe; tenderness is less well localized; serum amylase and lipase levels are elevated.
   Crohn disease	History of recurrent similar attacks; diarrhea is more common; palpable mass is more common; extraintestinal manifestations may have occurred or be present.
   Cholecystitis	History of prior attacks is common; pain and tenderness are greater; radiation of pain is to the right shoulder; nausea is more marked; liver biochemical tests are more likely to be abnormal.
   Meckel diverticulitis	Nearly impossible to distinguish preoperatively from appendicitis.
   Cecal diverticulitis	Difficult to distinguish preoperatively from appendicitis; symptoms are milder and of longer duration; CT is helpful; patients are usually older.
   Sigmoid diverticulitis	Usually occurs in older patients; changes in bowel habits are more common; radiation of the pain is to the suprapubic area, not RLQ; fever and WBC count are higher.
   Small bowel obstruction	History of abdominal surgery; pain is colicky; vomiting and distention are more marked; RLQ localization is uncommon.
   Ectopic pregnancy	History of menstrual irregularities; characteristic progression of symptoms is absent; syncope; positive pregnancy test.
   Ruptured ovarian cyst	Occurs in the middle of the menstrual cycle; pain is of sudden onset; nausea and vomiting are less common; WBC count is normal.
   Ovarian torsion	Vomiting is more marked and occurs at the same time as the pain; progression of symptoms is absent; abdominal or pelvic mass often is palpable.
   Acute salpingitis or tubo-ovarian abscess	Longer duration of symptoms; pain begins in the lower abdomen; often there is a history of STDs; vaginal discharge and marked cervical tenderness often are present.
   RLQ, Right lower quadrant; STD, sexually transmitted disease.

Workup

Patients with RLQ pain, nausea, vomiting, anorexia, and RLQ rebound tenderness should undergo prompt clinical and laboratory evaluation. Imaging studies are generally not necessary in typical appendicitis and generally reserved for patients with an equivocal likelihood of appendicitis. They are useful when the diagnosis is uncertain. Laparoscopy may be useful as both a diagnostic and a therapeutic modality.

Laboratory Tests

1. •

   Complete blood count with differential reveals leukocytosis with a left shift in 90% of patients with appendicitis. Total white blood cell (WBC) count is generally lower than 20,000/mm³. Higher counts may be indicative of perforation. Less than 4% have a normal WBC and differential. A WBC count <10,000/mm³ decreases the likelihood of appendicitis. Low hemoglobin and hematocrit levels in an older patient should raise suspicion for GI tract carcinoma.

2. •

   Microscopic hematuria and pyuria may occur in <20% of patients.

3. •

   HCG to rule out pregnancy in females of reproductive age.

Imaging Studies

1. •

   Multidetector computed tomography (Fig. 1) is a useful test for routine evaluation of suspected appendicitis in adults. CT of the abdomen/pelvis without contrast has a sensitivity of >90% and an accuracy >94% for acute appendicitis. A distended appendix, periappendiceal inflammation, and a thickened appendiceal wall are indicative of appendicitis. Table 2 describes CT findings of appendicitis. In children and young adults, exposure to CT radiation is of particular concern. Trials with low-dose CT (116 mGy cm) have shown that low-dose CT is not inferior to standard-dose CT (521 mGy cm) with respect to negative (unnecessary) appendectomy rates in young adults with suspected appendicitis.

   

   TABLE2 CT Findings of Appendicitis: SCALPEL MnemonicFrom Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.

   Term	Description
   Stranding	Fat stranding suggests regional inflammation, possibly because of appendicitis.
   Cecum	The appendix originates from the cecum, which should be identified first to help localize the appendix. The cecum may show wall thickening, suggesting appendicitis.
   Air	Air outside of the lumen of the appendix is pathologic and suggests perforation. Air within the appendiceal wall is also abnormal.
   Large	The normal appendix is <6 mm; an enlarged appendix >6 mm suggests appendicitis. Wall thickening >1 mm also suggests appendicitis.
   Phlegmon	Inflammatory changes surrounding the appendix suggest a perforated appendix. A heterogeneous collection called a phlegmon may be seen. If the appendix has ruptured, a pericecal phlegmon may be the only remaining evidence, because the appendix itself may not be seen.
   Enhancement	The wall of an abnormal appendix enhances with IV contrast and appears brighter than the normal bowel or the normal psoas muscle.
   Lith	An appendicolith is a calcified stone sometimes found in the lumen of an inflamed appendix.

2. •

   Ultrasonography (Fig. 2) has a sensitivity of 75% to 90% for the diagnosis of acute appendicitis, although it is highly operator dependent and difficult in patients with large body habitus. Ultrasound is useful, especially in pregnancy and in younger women when diagnosis is unclear. Normal ultrasonographic findings should not deter surgery if the history and physical examination are indicative of appendicitis.

   

3. •

   MRI of the abdomen and pelvis can also be used to accurately diagnose acute appendicitis in pregnant patients (100% sensitivity, 93.6% specificity) without exposure to ionizing radiation.

Treatment

Nonpharmacologic Therapy

1. •

   Nothing by mouth

2. •

   Do not administer analgesics until the diagnosis is made

Acute General Rx

1. •

   Urgent appendectomy (laparoscopic or open), correction of fluid and electrolyte imbalance with vigorous IV hydration and electrolyte replacement

2. •

   IV antibiotic prophylaxis to cover gram-negative bacilli and anaerobes (ampicillin/sulbactam 3 g IV q6h or piperacillin/tazobactam 4.5 g IV q8h in adults)

Pearls & Considerations

Comments

1. •

   Perforation is common (20% in adult patients). Indicators of perforation are pain lasting >24 hr, leukocytosis >20,000/mm³, temperature >102° F, palpable abdominal mass, and peritoneal findings.

2. •

   In general, prognosis is excellent. Mortality rate is <1% in young adults without complications; however, it exceeds 10% in elderly patients with ruptured appendix.

3. •

   In approximately 20% of patients who undergo exploratory laparotomy because of suspected appendicitis, the appendix is normal.

4. •

   An increasing amount of evidence supports the use of antibiotics instead of surgery for treating patients with uncomplicated appendicitis. A recent trial assessing the feasibility of nonoperative management for uncomplicated acute appendicitis in children using either IV piperacillin-tazobactam or ciprofloxacin metronidazole therapy for at least 24 hours followed by oral antibiotics for 10 days revealed that 90% of children managed nonoperatively had no progression within 30 days.¹ Another trial among patients with CT-proven, uncomplicated appendicitis revealed that antibiotic treatment did not meet the prescribed criterion for noninferiority compared with appendectomy. Most patients randomized to antibiotic treatment for uncomplicated appendicitis did not require appendectomy during the 1-yr follow-up period, and those who required appendectomy did not experience significant complications.² It remains to be determined whether the benefits of potentially avoiding an operation with antibiotics-first approach are outweighed by the burden to the patient related to future appendicitis episodes, more days of antibiotic therapy, lingering symptoms, and uncertainty that may affect quality of life.³

Suggested Readings

• K. Kim, et al.: Low-dose abdominal CT for evaluating suspected appendicitis. N Engl J Med. 366:1596–1605 2012 22533576

• P. Pickhardt, et al.: Diagnostic performance of multidetector computed tomography for suspected acute appendicitis. Ann Intern Med. 154:789–796 2011 21690593

• C. Vons, et al.: Amoxicillin plus clavulanic acid versus appendicectomy for treatment of acute uncomplicated appendicitis: an open-label, non-inferiority, randomized controlled trial. Lancet. 377:1573–1579 2011 21550483

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