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Basic Information ⬇

AUTHOR: Fred F. Ferri, MD

Definition

Appendicitis is the acute inflammation of the vermiform appendix.

ICD-10CM CODES
K35.2Acute appendicitis with generalized peritonitis
K35.3Acute appendicitis with localized peritonitis
K35.80Unspecified acute appendicitis
K35.89Other acute appendicitis
K36Other appendicitis
K37Unspecified appendicitis
Epidemiology & Demographics

  • 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 8%.1
  • Approximately 300,000 appendectomies are performed in the U.S. each yr.
  • It is the most common abdominal surgical emergency.
  • Incidence of appendicitis has declined over the past 30 yr.
  • Male:female ratio is 3:2 until mid-20s; it equalizes after age 30 yr.
Physical Findings & Clinical Presentation

  • 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.
  • 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 h. 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.
  • Pain with right thigh extension (psoas sign), low-grade fever: Temperature may be >38° C (100.4° F) if there is appendiceal perforation.
  • Pain with internal rotation of the flexed right thigh (obturator sign) is present.
  • Right lower quadrant (RLQ) pain on palpation of the left lower quadrant (LLQ) (Rovsing sign): Physical examination may reveal right-sided tenderness in patients with pelvic appendix.
  • Point of maximum tenderness is in the RLQ (McBurney point).
  • 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:

  • Fecaliths: 30% to 35% of cases (most common in adults)
  • Foreign body: 4% (fruit seeds, pinworms, tapeworms, roundworms, calculi)
  • Inflammation: 50% to 60% of cases (submucosal lymphoid hyperplasia [most common etiology in children, teens])
  • Neoplasms: 1% (carcinoids, metastatic disease, carcinoma)

Diagnosis ⬆ ⬇

Differential Diagnosis

  • Intestinal: Regional cecal enteritis, incarcerated hernia, cecal diverticulitis, intestinal obstruction, perforated ulcer, perforated cecum, Meckel diverticulitis
  • Reproductive: Ectopic pregnancy, ovarian cyst, torsion of ovarian cyst, salpingitis, tuboovarian abscess, mittelschmerz, endometriosis, seminal vesiculitis
  • Renal: Renal and ureteral calculi, neoplasms, pyelonephritis
  • Vascular: Leaking aortic aneurysm
  • Psoas abscess
  • Trauma
  • Cholecystitis
  • Mesenteric adenitis
  • Table 1 summarizes the differential diagnosis of appendicitis

TABLE 1 Differential Diagnosis of Appendicitis

DiagnosisFindings That Help Differentiate Entity From Appendicitis
Bacterial or viral enteritisNausea, vomiting, and diarrhea are severe; pain usually develops after vomiting.
Epiploic appendagitisFocal 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 adenitisDuration of symptoms is longer; fever is uncommon; RLQ physical findings are less marked; WBC count is usually normal.
PyelonephritisPain 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 colicPain radiates to the right groin; significant hematuria; character of the pain is clearly colicky.
Acute pancreatitisPain and vomiting are more severe; tenderness is less well localized; serum amylase and lipase levels are elevated.
Crohn diseaseHistory of recurrent similar attacks; diarrhea is more common; palpable mass is more common; extraintestinal manifestations may have occurred or be present.
CholecystitisHistory 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 diverticulitisNearly impossible to distinguish preoperatively from appendicitis.
Cecal diverticulitisDifficult to distinguish preoperatively from appendicitis; symptoms are milder and of longer duration; CT is helpful; patients are usually older.
Sigmoid diverticulitisUsually 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 obstructionHistory of abdominal surgery; pain is colicky; vomiting and distention are more marked; RLQ localization is uncommon.
Ectopic pregnancyHistory of menstrual irregularities; characteristic progression of symptoms is absent; syncope; positive pregnancy test.
Ruptured ovarian cystOccurs in the middle of the menstrual cycle; pain is of sudden onset; nausea and vomiting are less common; WBC count is normal.
Ovarian torsionVomiting 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 tuboovarian abscessLonger 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.

CT, Computed tomography; GI, gastrointestinal; IV, intravenous; RLQ, right lower quadrant; STD, sexually transmitted disease; WBC, white blood cell.

From Feldman M et al: Sleisenger and Fordtran’s gastrointestinal and liver disease, ed 10, Philadelphia, 2016, Elsevier.

Workup (FIG. 1

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. Several clinical decision tools such as the Alvarado score (also known as the MANTRELS criteria) are available to assist in the diagnosis of appendicitis (Table 2). Laparoscopy may be useful as both a diagnostic and a therapeutic modality.

TABLE 2 Alvarado Score (MANTRELS Criteria)

CriterionPoint(s)
Symptoms
MMigration of pain to RLQ1
AAnorexia1
NNausea and vomiting1
Signs
TTenderness in RLQ2
RRebound pain1
EElevated temperature1
Laboratory Findings
LLeukocytosis2
SShift of WBCs to left1
Total Score10
Interpretation
1-4Appendicitis unlikely
5-6Appendicitis possible
7-8Probable appendicitis
9-10Surgery indicated

RLQ, Right lower quadrant; WBCs, white blood cells.From Cameron P et al: Textbook of adult emergency medicine, ed 5, Philadelphia, 2019, Elsevier.

Figure 1 Suggested Algorithm for the Approach to the Patient with Possible Appendicitis

CT, Computed Tomography; Lap, Laparoscopic.

!!flowchart!!

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Laboratory Tests

  • 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 gastrointestinal tract carcinoma.
  • Microscopic hematuria and pyuria may occur in <20% of patients.
  • Human chorionic gonadotropin to rule out pregnancy in females of reproductive age.
Imaging Studies

  • Multidetector computed tomography (CT; Fig. 2) 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 3 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.
  • Ultrasonography (Fig. E3) 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.
  • 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.
Figure 2 Appendicitis, Computed Tomography (CT) with Intravenous (IV) and Oral Contrast

This CT Demonstrates Classic Findings of Appendicitis in an 18-Yr-Old Male with Right Lower Quadrant Pain, as Seen with CT with IV and Oral Contrast. Studies Suggest that CT Without Contrast Has Similar Sensitivity and Specificity. An Enlarged Appendix is Seen Near the Cecum as a Right Lower Quadrant Tubular Structure in Short-Axis Cross Section, Giving It a Circular Appearance. The Surrounding Fat Shows Stranding, a Smoky Appearance Indicating Inflammation (Compare with Normal Mesenteric and Subcutaneous Fat, Which is Nearly Black). The Appendiceal Wall Shows Enhancement, a Brightening after Administration of IV Contrast. This Slice Also Shows an Appendicolith, an Occasional Finding of Appendicitis. It Does Not Appear to Be Within the Appendix in This Slice, Because the Appendix Bends in and Out of the Plane of This Slice. An Appendicolith Usually Appears as a Calcified (White) Rounded Structure, Visible Without any Contrast. A, Axial CT Image. B, Close-Up.

From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.

TABLE 3 Computed Tomography Findings of Appendicitis: SCALPEL Mnemonic

TermDescription
StrandingFat stranding suggests regional inflammation, possibly because of appendicitis.
CecumThe appendix originates from the cecum, which should be identified first to help localize the appendix. The cecum may show wall thickening, suggesting appendicitis.
AirAir outside of the lumen of the appendix is pathologic and suggests perforation. Air within the appendiceal wall is also abnormal.
LargeThe normal appendix is <6 mm; an enlarged appendix >6 mm suggests appendicitis. Wall thickening >1 mm also suggests appendicitis.
PhlegmonInflammatory 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.
EnhancementThe wall of an abnormal appendix enhances with IV contrast and appears brighter than the normal bowel or the normal psoas muscle.
LithAn appendicolith is a calcified stone sometimes found in the lumen of an inflamed appendix.

IV, Intravenous.

From Broder JS: Diagnostic imaging for the emergency physician, Philadelphia, 2011, Saunders.

Figure E3 Ultrasound Image of a Normal Appendix (Top) Illustrating the Thin Wall in Coronal (Left) and Longitudinal (Right) Planes

In Appendicitis, There is Distention and Wall Thickening (Bottom, Right Arrow), and Blood Flow is Increased, Leading to the So-Called Ring of Fire Appearance. A, Appendix.

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Treatment ⬆ ⬇

Nonpharmacologic Therapy

  • Nothing by mouth
  • Do not administer analgesics until the diagnosis is made
Acute General Rx

  • Urgent appendectomy (laparoscopic [Fig. E4] or open), correction of fluid and electrolyte imbalance with vigorous intravenous (IV) hydration, and electrolyte replacement.
  • 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). For patients who undergo appendectomy, antibiotics should be discontinued postoperatively.1
  • If nonoperative treatment is anticipated, then the administration of a long active parenteral antibiotic (ertapenem or ceftriaxone). Along with high dose, once daily metronidazole can facilitate early discharge. Parenteral antibiotics are followed by oral regimen of metronidazole plus advanced generation cephalosporin or fluoroquinolones for 7 to 10 days.1

Management of Complicated Appendicitis:

  • Fig. E5 is an algorithm for managing the patient with delayed presentation of appendicitis and possible diffuse peritonitis
  • The management of the pregnant patient with possible appendicitis is illustrated in Fig. E6
Figure E4 Laparoscopic Appendectomy

(A) Visualization and Upward Retraction of Appendix. (B) Division of the Mesoappendix Using Harmonic Scalpel. (C) Application of Endoloops to the Appendix. Two Loops are Used to Secure the Base; a Third Loop is Applied Distally to Avoid Spillage of the Luminal Contents. The Specimen is Then Divided Between the Endoloops. (D) View of Completed Appendectomy after Removal of the Specimen. (Note: Depending on the Surgeon’s Preference, an Endoscopic Stapling Device May Be Used to Divide the Mesoappendix and Appendix Instead of the Harmonic Scalpel and Endoloops.)

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Figure E5 Suggested Algorithm for Managing the Patient with Delayed Presentation of Appendicitis

CT, Computed Tomography; Or, Operating Room.

!!flowchart!!

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Figure E6 Suggested Algorithm for Managing the Pregnant Patient with Possible Appendicitis

CT, Computed Tomography; IV, Intravenous; MRI, Magnetic Resonance Imaging; Or, Operating Room; Pt, Patient; Us, Ultrasound.

!!flowchart!!

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Pearls & Considerations ⬆ ⬇

Comments

  • Perforation is common (20% in adult patients). Indicators of perforation are pain lasting >24 h, leukocytosis >20,000/mm3, temperature >102° F (38.9° C), palpable abdominal mass, and peritoneal findings (Fig. E7).
  • In general, prognosis is excellent. Mortality rate is <1% in young adults without complications; however, it exceeds 10% in elderly patients with ruptured appendix.
  • In approximately 20% of patients who undergo exploratory laparotomy because of suspected appendicitis, the appendix is normal.
  • An increasing amount of evidence2,3 supports the use of antibiotics instead of surgery for treating patients with uncomplicated appendicitis.4 Fig. E8 illustrates an algorithm for the nonoperative management of appendicitis. A 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 h followed by oral antibiotics for 10 days revealed that 90% of children managed nonoperatively had no progression within 30 days. 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. A 5-yr follow-up of antibiotic therapy for uncomplicated acute appendicitis in the APPAC randomized clinical trial revealed that among patients who were initially treated with antibiotics for uncomplicated acute appendicitis, the likelihood of late recurrence within 5 yr was 39.1%. A more recent trial also confirmed that antibiotics are not inferior to appendectomy on the basis of a health status questionnaire; however, in the antibiotics group nearly 3 in 10 participants had unresolved appendectomy by 90 days and those with an appendicolith had a higher risk for appendectomy and for complications. 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. Factors associated with primary nonresponsiveness to antibiotics in adults with uncomplicated are the presence of an appendicolith, appendiceal diameter of ≥15 mm on imaging, and fever >38° C.5

Figure E7 Delayed Diagnoses of Appendicitis

Sagittal (A) and Coronal (B) Computed Tomography Images Demonstrate an Appendiceal Abscess in a Patient Who Presented with a 2-wk History of Abdominal Pain and was Found to have a Palpable Mass on Examination. The Arrows Point to a Periappendiceal Abscess Cavity. She was Successfully Managed with Percutaneous Drainage and Antibiotic Therapy. Image C is a Similar Case in Which the Patient Presented with an Appendiceal Phlegmon and was Successfully Treated with Antibiotics Alone. The Arrow Points to the Phlegmon. (Note the Mass Effect on the Bladder.)

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Figure E8 Suggested Algorithm for the Nonoperative Management of Appendicitis

CT, Computed Tomography; IV, Intravenous; MRI, Magnetic Resonance Imaging; Pt, Patient; Us, Ultrasound.

!!flowchart!!

From Townsend CM et al: Sabiston textbook of surgery, ed 21, St Louis, 2022, Elsevier.

Related Content

Appendicitis (Patient Information)

Related Content ⬆

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    1. Talan D.A., Di Saverio S. : Treatment of acute uncomplicated appendicitisN Engl J Med. ;385(12):1116-1123, 2021.
    2. Minneci P. : Association of nonoperative management using antibiotic therapy vs laparoscopic appendectomy with treatment success and disability days in children with uncomplicated appendicitisJ Am Med Assoc. ;3246:581-593, 2020.
    3. a randomized trial comparing antibiotics with appendectomy for appendicitisN Engl J Med. ;383:1907-1919, 2020.
    4. Salminen P. : Five-year follow-up of antibiotic therapy for uncomplicated acute appendicitis in the APPAC randomized clinical trialJ Am Med Assoc. ;320(12):1259-1265, 2018.
    5. Haijanen J. : Factors associated with primary nonresponsiveness to antibiotics in adults with uncomplicated acute appendicitis: a prespecified secondary analysis of a randomized clinical trialJAMA Surg. ;156(12):1179-1181, 2021.
    6. Flum D.R. : Acute appendicitis-appendectomy or the “antibiotics first” strategyN Engl J Med. ;372:1937-1943, 2015.
    7. Kim K. : Low-dose abdominal CT for evaluating suspected appendicitisN Engl J Med. ;366:1596-1605, 2012.
    8. Minneci P.C. : Feasibility of a nonoperative management strategy for uncomplicated acute appendicitis in childrenJ Am Coll Surg. ;219:272-279, 2014.
    9. Pickhardt P. : Diagnostic performance of multidetector computed tomography for suspected acute appendicitisAnn Intern Med. ;154:789-796, 2011.
    10. Salminen P. : Antibiotic therapy vs appendectomy for treatment of uncomplicated acute appendicitis, the APPAC Randomized trialJ Am Med Assoc. ;313(23):2340-2348, 2015.
    11. Vons C. : Amoxicillin plus clavulanic acid versus appendicectomy for treatment of acute uncomplicated appendicitis: an open-label, non-inferiority, randomized controlled trialLancet. ;377:1573-1579, 2011.