Acute Appendicitis

EPIDEMIOLOGY AND PATHOPHYSIOLOGY

• Males are affected more often than females by appendicitis, with an estimated male-to-female ratio of 1.4:1.

  • Appendicitis has burdened patients in a wide age range. In the United States in 2007, 45% (149,000) of those with this diagnosis were between 15 and 44 years old. Patients younger than age 15 years accounted for approximately 24% (71,000) of patients with appendicitis, and those older than 65 years accounted for approximately 9% (27,000).

  • Occlusion of the appendiceal lumen is believed to be the main etiologic mechanism of acute appendicitis. A variety of different agents may be involved, including feces (fecolith); parasites; enlarged lymph tissue; inflammatory lesions; and, rarely, neoplasms.

  • However, obstruction of the appendiceal lumen does not account for all cases of appendicitis. Another hypothesis suggests that acute appendiceal inflammation may be due to infection with Yersinia organisms, since a high volume of antibodies against these bacteria have been associated with confirmed cases of appendicitis.

  • Once the lumen of the appendix is obstructed, the intestinal mucus that continues to be produced has nowhere to drain. Eventually, the blood supply to the appendix is cut off and intestinal bacteria are allowed to proliferate, leading to inflammation and swelling. Without treatment, the inflamed appendix may become necrotic (gangrenous) and prone to perforation. This inevitably causes spillage of intestinal contents into the peritoneum, and life-threatening peritonitis may ensue.

CLINICAL PRESENTATION

• While the diagnosis of acute appendicitis is mainly clinical, no one sign or symptom is synonymous with this disease. Instead, multiple signs and symptoms are involved.

• The classic presentation of acute appendicitis includes onset of symptoms within 24 to 48 hours of appendiceal inflammation.

• New-onset periumbilical pain may or may not eventually migrate to the right lower quadrant.

• The patient may complain of decrease in appetite, nausea, vomiting, and less commonly, diarrhea and constipation. However, these classic signs are not found in all cases, with women experiencing variation in signs and symptoms more often than men.

• Physical examination may reveal pain located in the right lower quadrant or, more specifically, at a point one-third of the way between the anterior superior iliac spine and the umbilicus (McBurney point).

• Patients may also have a positive Rovsing sign, which is right lower-quadrant pain on palpation of the left lower quadrant. In some cases, patients will have pain when the underlying obturator or psoas muscles are stretched. According to Laméris and colleagues, migration of pain from the epigastric area to the right lower quadrant along with right lower-quadrant tenderness and a rigid abdomen are among the most definitive diagnostic signs and symptoms.

DIFFERENTIAL DIAGNOSIS

• Small-bowel obstruction

• Acute cholecystitis

• Acute pancreatitis

• Acute pyelonephritis

• Acute gastroenteritis

• Ovarian torsion

• Pelvic inflammatory disease.

WORKUP

• CBC: a recent retrospective study discovered that 80% of patients with confirmed appendicitis had an increased WBC count. Based on the values obtained from the CBC, such as the WBC count, along with other determinations, such as the C-reactive protein (CRP) level, which may be elevated , a diagnosis of acute appendicitis can be considered either likely or highly unlikely.

• One such system is the Alvarado score, which combines components of the patient history, physical examination, and laboratory data, assigning points for each component:

• Anorexia, 1 point

• Elevated temperature (37.3°C or higher), 1 point

• Leukocytosis (WBC count >10,000/µL), 2 points

• Migration of pain to the right iliac fossa (right lower quadrant), 1 point

• Nausea and/or vomiting, 1 point

• Rebound tenderness, 1 point

• Shift of differential to the left (more than 75% neutrophils), 1 point

• Tenderness to palpation in the right iliac fossa (right lower quadrant), 2 points.⁹

The higher the score, the more likely the patient is to have acute appendicitis.

Other diagnostic testing may include abdominal CT. Currently, the routine use of abdominal CT for suspected acute appendicitis is controversial because such imaging may increase exposure to radiation and, when contrast is used, can lead to possible renal damage or anaphylactic reaction. That being said, CT may be done more often than not in order to prevent the possibility of legal action. One could also perform an ultrasound (US) examination to look for general loss of peristalsis; however, the sensitivity of US is lower than that of CT and depends on the experience of the operator. Even with the patient history, physical examination, and laboratory and radiologic data, the most experienced clinician may miss a diagnosis of acute appendicitis. Therefore, the recommendation is to use multiple modalities that have been found to be safe and necessary to diagnose the pathology.

SURGICAL TREATMENT

• The gold standard of treatment for acute appendicitis is appendectomy in order to prevent detrimental outcomes resulting from possible perforation.

• Patients should receive nothing by mouth for at least 6 to 12 hours prior to surgery, and they should be given IV hydration and analgesia.

• As with many surgical procedures, antibiotics are given before operation to reduce the chance of postoperative wound infection.

• Appendectomy is achieved by one of two methods. The first method is the so-called open appendectomy, which is performed through an opening at the McBurney point.

• The second method is the laparoscopic approach; it utilizes smaller incisions through which a camera, graspers, and cautery may be inserted. Of the two methods, laparoscopy has become standard of care in most operative cases.

Complications:

• Perforation of the appendix as a result of untreated appendiceal inflammation is the most prominent complication of appendicitis.

• Subsequent spillage may result in peritonitis, which may, in turn, be fatal. Therefore, the threshold to treat suspected appendicitis is low. This low threshold has resulted in an overall mortality rate for acute appendicitis in the United States of approximately 0.1%.

• Among the possible intraoperative complications is allergic reaction to drugs, including malignant hyperthermia. As with other surgeries, postoperative complications may include wound infection, atelectasis, deep venous thrombosis (DVT), and postoperative fever.

• One study found major complications, which included reoperation, abscess formation, and small-bowel obstruction, to be three times higher in patients undergoing appendectomy than in those receiving medical management with antibiotics.

Prognosis:

• Once symptoms begin, prompt diagnosis and treatment will influence patient outcome. Any delay allows increased inflammation and therefore raises the risk of perforation.

• One study illustrated that perforation rates come close to 10% at 24 hours after onset of symptoms. However, differences in morbidity rates do not appear to be clinically relevant when comparing treatment initiated within 6 hours to treatment initiated within 24 hours.

• One must also keep in mind that recurrence rates for patients treated conservatively with antibiotics range from 15% to 35%. Even with the threat of perforation, the prognosis of a patient with acute appendicitis is believed to be excellent if treatment is initiated early.

ANTIBIOTIC THERAPY: A REALISTIC ALTERNATIVE?

• Whether nonsurgical antibiotic treatment for acute appendicitis is a realistic alternative is the subject of much debate among some medical clinicians.

• Advocates of conservative treatment with antibiotics argue that it could help reduce cost and eliminate surgical complications.

• Opponents point out that the risk of recurrence after antibiotic treatment may be too high, reaching 35% in one study.

• Although antibiotic therapy for the treatment of acute appendicitis is not a new idea, it has been met with skepticism in the medical and surgical communities.