Introduction
Appendicitis is a significant public health problem afflicting over a quarter-million patients a year in the United States. It is the most common reason for an abdominal operation to be performed in the acute setting and overall, it accounts for approximately one million hospital days per year. The lifetime risk of developing appendicitis is about 7%. It occurs in any age group, from young children to the elderly, but is most prevalent in adolescents and young adults.

The Appendix and Causes of Appendicitis
The appendix is a tubular appendage from the cecum that originates about 2.5 cms below the ileocecal valve. Its precise position in the right lower quadrant of the abdomen is variable, and can be found in retrocecal, pelvic, paracolic, paraileal, or subcecal orientations. This accounts for the wide variety of presenting symptoms and locations of pain. The appendix serves no known physiologic purpose in humans, although in certain animals it may assist in digestion. The average appendix ranges from 5-10 cms in length and is about 6 mm in diameter.

Appendicitis occurs when the orifice of the appendiceal lumen becomes mechanically obstructed – most commonly from fecal stasis or an impacted fecalith. Other causes of blockage include lymphoid hyperplasia, impacted seeds/nuts, intestinal worms and uncommonly, tumors. Three types of tumors can occur; carcinoid lesions being most prevalent, followed by mucoceles (cystadenoma or cystadenocarcinoma) and quite rarely, primary adenocarcinoma. Appendicitis in the elderly is more frequently associated with an underlying malignancy, and higher mortality from delayed diagnosis.

When obstructed, the appendix swells in size as the lumen continues to produce mucus. Once intraluminal pressure exceeds venous pressure, ischemia of the wall occurs, the mucosa ulcerates and vascular congestion accelerates. Once the mucosa is compromised, bacterial overgrowth within the lumen leads to invasion of the wall with perforation into the abdominal cavity being the ultimate outcome. This can manifest as either a locally contained abscess or frank leakage throughout the peritoneal cavity. Infection in appendicitis is polymicrobial and is characterized primarily by anaerobic and Gram –negative organisms.

Symptoms
Acute Appendicitis remains a clinical diagnosis directed by the history and physical exam. Characteristically it begins with non-specific abdominal pain that worsens over a 6-24 hour period. Initially, the pain is typically located in a mid-abdominal or periumbilical location– reflecting midgut autonomic afferent pain fiber irritation. It is often crampy in nature, and patients indicate that it does not improve with defecation or urination. Nausea and vomiting occur in the vast majority (75%) of patients. Anorexia is a hallmark, but not universal, symptom. A modest fever (<39°) is usually present. Ultimately, the pain migrates to the right-lower quadrant, which becomes tender to touch as the inflamed appendix produces local parietal inflammation. The patient becomes reluctant to move, immobilized by pain from local peritonitis. However, the actual anatomic position of the appendix in the right-lower quadrant is highly variable and this accounts for atypical presentations of symptoms including right flank, groin, or pelvic pain, as well as diarrhea and urinary frequency.

In advanced cases, particularly with delay in diagnosis, local inflammation may progress to perforation. This occurs in about 25% of the patients and is more common in very young children, pregnant women, and adults over 50 years old. Symptoms tend to be longer in duration and more severe. High fever and tachycardia are common and there is evidence of either local or diffuse peritonitis on exam. Morbidity and mortality are significantly higher when the appendix perforates.

In yet other cases, the appendix may perforate, but be contained within a local phlegmon or abscess (subacute appendicitis). The patient will complain of pain that was initially tolerable and subsequently subsided. Ultimately (5-10 days later) the local infection will manifest with fever, ileus, poor oral intake and chronic pain that forces the patient to seek medical attention.

Diagnosis
Appendicitis should be in the differential diagnosis of any patient who presents with abdominal pain. Prompt diagnosis is mandatory in order to prevent progression to perforation with its attendant increase in morbidity and mortality. A thorough history and physical, including a rectal examination, is the cornerstone to diagnosing appendicitis. A complete blood count with differential is useful in demonstrating leukocytosis with a left shift. A urinalysis is helpful in determining if kidney stone disease is the correct diagnosis.

Atypical presentations of other conditions may appear as appendicitis, including Meckel’s diverticulitis, Crohn’s disease, gastroenteritis, sigmoid diverticulitis, renal colic and urinary tract infection. In the subset of women of childbearing age, gynecologic problems such as ruptured ovarian cysts, ovarian torsion, ectopic pregnancy, and pelvic inflammatory disease, must be considered. Pregnancy testing is mandatory as is a formal pelvic exam. Accordingly, the highest percentage of missed diagnoses is in this cohort where negative appendectomy rates range from 15 to 40%.

Imaging techniques such as ultrasonography or CT are not usually required, but may be helpful in equivocal presentations. Findings of appendicial distention, wall thickening, lack of luminal filling with contrast, and local fat stranding on CT are indicative of appendicitis. It remains uncertain whether routine employment of these modalities decreases the rate of perforation or negative appendectomy rates, or if it is cost-effective.

Treatment
Expeditious surgical removal of the appendix is the preferred treatment in most cases. Intravenous antibiotic therapy, and fluid and electrolyte repletion is indicated prior to the operation, but pain control is restricted until the diagnosis is certain. Preoperative physiologic maximization is appropriate for patients with significant comorbidities.

Appendectomy can be performed with equivalent success, through either the traditional open technique or through the minimally-invasive laparoscopic approach. Although laparoscopy is now employed nearly half the time, the choice of technique is dependant on surgeon expertise and availability of operative and hospital resources. Laparoscopy is particularly useful in young women, obese patients, or patients of either sex with an equivocal diagnosis. It may be more challenging in cases of complicated or perforated appendicitis where conversion to an open approach occurs about 25% of the time.

In the case of perforation, extensive irrigation of the peritoneal cavity is required and intravenous antibiotics should continue in the postoperative recovery period until normalization of the patient’s white blood cell count and temperature. Intraoperatively, a normal appearing appendix should be removed (given its low morbidity) along with a thorough investigation for other intra-abdominal pathologies.

Subacute appendicitis is initially managed non-operatively with intravenous antibiotics, NPO status, and percutaneous drainage of peri-appendiceal abscesses. Once the patient’s pain subsides, oral diet can be slowly resumed and the patient can be converted to oral antibiotics for discharge. Re-imaging of the abdomen is advised to assure resolution of the collection prior to drain removal and to investigate for possible associated or causative factors like malignancy. After a period of 6-8 weeks, an elective appendectomy is customary.

Risks

Expected Outcomes
In uncomplicated appendicitis, most patients resume oral intake within hours of the operation and are hospitalized 1-2 days, regardless of the surgical approach. Complicated cases with perforation may require longer hospital stays for antibiotics and resolution of ileus. There is little evidence to support superior outcomes of laparoscopic over open appendectomy, although return to normal activities occurs sooner with laparoscopy. Overall complications range from 5-25% with both techniques. Mortality is less than 1%. Superficial wound infections occur between 5-15% of the time, and generally less with the laparoscopic approach. Postoperative intrabdominal abscess is uncommon (0.01%) and usually managed by percutaneous drainage and antibiotics. Long-term consequences of both surgical approaches include incisional hernias and intrabdominal adhesions that may ultimately lead to bowel obstructions. A negative appendectomy rate of 15% is universally/classically acceptable.

Tumors are infrequently (1%) found on pathologic analysis of the appendix. For carcinoids, if the tumor is smaller than 2cm, appendectomy alone suffices. For larger carcinoids, a right hemi colectomy with lymph node clearance is indicated.

Qualifications for performing surgery on the pancreas
The qualifications of a surgeon performing any operative procedure should be based on training (education), experience, and outcomes. At a minimum, surgeons who are certified or eligible for certification by the American Board of Surgery, the Royal College of Physicians and Surgeons of Canada, or their equivalent are qualified to treat appendicitis.

Suggested Readings
Khatouda N, Mason RJ, Towfigh S, Gevorgyan A, Essani R. Laparoscopic versus open appendectomy: a prospective randomized double-blind study. Ann Surg. 2005 Sep;242(3):439-48; discussion 448-50.

Marganthaler JA, Longo WE, Virgo KS, Johnson FE, Oprian CA, Henderson WG, Daley J, Khuri SF. Risk factors for adverse outcomes after the surgical treatment of appendicitis in adults. Ann Surg. 2003 Jul;238(1):59-66.

Rao PM, Rhea JT, Rattner DW, Venus LG, Novelline RA. Introduction of appendiceal CT: impact on negative appendectomy and appendiceal perforation rates. Ann Surg. 1999 Mar;229(3):344-9.

Rhea JT, Halpern EF, Ptak T, Lawrason JN, Sacknoff R, Novelline RA. The status of appendiceal CT in an urban medical center 5 years after its introduction: experience with 753 patients. AJR Am J Roentgenol. 2006 Jun;186(6):E23.

Flum DR, Morris A, Koepsell T, Dellinger EP. Has misdiagnosis of appendicitis decreased over time? A population-based analysis. JAMA. 2002 Jan 2;287(1):43-4.

Andersen BR, Kallehave FL, Andersen HK. Antibiotics verus placebo for prevention of postoperative infection after appendicectomy. Cochrane Database Syst Rev 2004; 4: 1-64.

Prystowsky JB, Pugh CM, Nagle AP. Appendicitis. Current Problems in Surgery. 2005; 42 (10): 687-736.

KeyWords - Appendix; Acute Appendicitis; Subacute Appendicitis; Right Lower Quadrant Pain; Appendectomy; Laparoscopic Appendectomy

Written & Revised September 2007
Board Approved 10/08/2007