Acute Appendicitis

  
Introduction

Appendicitis is defined as an inflammation of the inner lining of the vermiform appendix that spreads to its other parts. Despite diagnostic and therapeutic advancement in medicine, appendicitis remains a clinical emergency and is one of the more common causes of acute abdominal pain.

Pathophysiology

• Reportedly, appendicitis is caused by obstruction of the appendiceal lumen from a variety of causes. Independent of the etiology, obstruction is believed to cause an increase in pressure within the lumen. Such an increase is related to continuous secretion of fluids and mucus from the mucosa and the stagnation of this material. At the same time, intestinal bacteria within the appendix multiply, leading to the recruitment of white blood cells and the formation of pus and subsequent higher intraluminal pressure.
• If appendiceal obstruction persists, intraluminal pressure rises ultimately above that of the appendiceal veins, leading to venous outflow obstruction. As a consequence, appendiceal wall ischemia begins, resulting in a loss of epithelial integrity and allowing bacterial invasion of the appendiceal wall.
• Within a few hours, this localized condition may worsen because of thrombosis of the appendicular artery and veins, leading to perforation and gangrene of the appendix. As this process continues, a periappendicular abscess or peritonitis may occur.

Etiology

• Appendicitis is caused by obstruction of the appendiceal lumen. The most common causes of luminal obstruction include lymphoid hyperplasia secondary to inflammatory bowel disease (IBD) or infections (more common during childhood and in young adults), fecal stasis and fecaliths (more common in elderly patients), parasites (especially in Eastern countries), or, more rarely, foreign bodies and neoplasms.
• Fecaliths form when calcium salts and fecal debris become layered around a nidus of inspissated fecal material located within the appendix. Lymphoid hyperplasia is associated with various inflammatory and infectious disorders including Crohn disease, gastroenteritis, amebiasis, respiratory infections, measles, and mononucleosis.
• Obstruction of the appendiceal lumen has less commonly been associated with bacteria (Yersinia species, adenovirus, cytomegalovirus, actinomycosis, Mycobacteria species, Histoplasma species), parasites (eg, Schistosomes species, pinworms, Strongyloides stercoralis), foreign material (eg, shotgun pellet, intrauterine device, tongue stud, activated charcoal), tuberculosis, and tumors.

Stages of Appendicitis

The stages of appendicitis can be divided into early, suppurative, gangrenous, perforated, phlegmonous, spontaneous resolving, recurrent, and chronic.

Clinical Features

Signs and symptoms

The clinical presentation of appendicitis is notoriously inconsistent. The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases.

Features include the following:

• Abdominal pain: Most common symptom
• Nausea: 61-92% of patients
• Anorexia: 74-78% of patients
• Vomiting: Nearly always follows the onset of pain; vomiting that precedes pain suggests intestinal obstruction
• Diarrhea or constipation: As many as 18% of patients

Features of the abdominal pain are as follows:

• Typically begins as periumbilical or epigastric pain, then migrates to the RLQ
• Patients usually lie down, flex their hips, and draw their knees up to reduce movements and to avoid worsening their pain
• The duration of symptoms is less than 48 hours in approximately 80% of adults but tends to be longer in elderly persons and in those with perforation.

Physical examination findings include the following:

1. Rebound tenderness, pain on percussion, rigidity, and guarding: Most specific finding
2. RLQ tenderness: Present in 96% of patients, but nonspecific
3. Left lower quadrant (LLQ) tenderness: May be the major manifestation in patients with situs inversus or in patients with a lengthy appendix that extends into the LLQ
4. Male infants and children occasionally present with an inflamed hemiscrotum
5. In pregnant women, RLQ pain and tenderness dominate in the first trimester, but in the latter half of pregnancy, right upper quadrant (RUQ) or right flank pain may occur

The following accessory signs may be present in a minority of patients:

• Rovsing sign (RLQ pain with palpation of the LLQ): Suggests peritoneal irritation
• Obturator sign (RLQ pain with internal and external rotation of the flexed right hip): Suggests the inflamed appendix is located deep in the right hemipelvis
• Psoas sign (RLQ pain with extension of the right hip or with flexion of the right hip against resistance): Suggests that an inflamed appendix is located along the course of the right psoas muscle
• Dunphy sign (sharp pain in the RLQ elicited by a voluntary cough): Suggests localized peritonitis
• RLQ pain in response to percussion of a remote quadrant of the abdomen or to firm percussion of the patient's heel: Suggests peritoneal inflammation
• Markle sign (pain elicited in a certain area of the abdomen when the standing patient drops from standing on toes to the heels with a jarring landing): Has a sensitivity of 74%

Investigations

The following laboratory tests do not have findings specific for appendicitis, but they may be helpful to confirm diagnosis in patients with an atypical presentation:

1. CBC: WBC >10,500 cells/µL: 80-85% of adults with appendicitis. Neutrophilia >75-78% of patients
2. C-reactive protein (CRP): CRP levels >1 mg/dL are common in patients with appendicitis. Very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia.
3. Liver and pancreatic function tests
4. Urinalysis (for differentiating appendicitis from urinary tract conditions)
5. Urinary beta-hCG (for differentiating appendicitis from early ectopic pregnancy in women of childbearing age)
6. Urinary 5-hydroxyindoleacetic acid (5-HIAA)

CT scanning

CT scanning with oral contrast medium or rectal Gastrografin enema has become the most important imaging study in the evaluation of patients with atypical presentations of appendicitis.

Low-dose abdominal CT may be preferable for diagnosing children and young adults in whom exposure to CT radiation is of particular concern.

Ultrasonography

• Ultrasonography may offer a safer alternative as a primary diagnostic tool for appendicitis, with CT scanning used in those cases in which ultrasonograms are negative or inconclusive.
• In pediatric patients, American College of Emergency Physicians (ACEP) clinical policy recommends ultrasonography for confirmation, but not exclusion, of acute appendicitis; to definitively exclude acute appendicitis, the ACEP recommends CT.
• A healthy appendix usually cannot be viewed with ultrasonography; when appendicitis occurs, the ultrasonogram typically demonstrates a noncompressible tubular structure of 7-9 mm in diameter.
• Vaginal ultrasonography alone or in combination with transabdominal scan may be useful to determine the diagnosis in women of childbearing age.

MRI

Useful in pregnant patients if graded compression ultrasonography is nondiagnostic.

Management

Emergency department care is as follows:

1. Establish IV access and administer aggressive crystalloid therapy to patients with clinical signs of dehydration or septicemia.
2. Keep patients with suspected appendicitis NPO.
3. Administer parenteral analgesic and antiemetic as needed for patient comfort; no study has shown that analgesics adversely affect the accuracy of physical examination.
4. Appendectomy remains the only curative treatment of appendicitis, but management of patients with an appendiceal mass can usually be divided into the following 3 treatment categories:
• Phlegmon or a small abscess: After IV antibiotic therapy, an interval appendectomy can be performed 4-6 weeks later
• Larger well-defined abscess: After percutaneous drainage with IV antibiotics is performed, the patient can be discharged with the catheter in place; interval appendectomy can be performed after the fistula is closed
• Multicompartmental abscess: These patients require early surgical drainage

Surgical Management

Preoperative Antibiotics

Preoperative antibiotics have demonstrated efficacy in decreasing postoperative wound infection rates in numerous prospective controlled studies, and they should be administered in conjunction with the surgical consultant. Broad-spectrum gram-negative and anaerobic coverage is indicated.

Penicillin-allergic patients should avoid beta-lactamase type antibiotics and cephalosporins. Carbapenems are a good option in these patients.

Pregnant patients should receive pregnancy category A or B antibiotics.

Urgent Versus Emergent Appendectomy

A retrospective study suggested that the risk of appendiceal rupture is minimal in patients with less than 24-36 hours of untreated symptoms, and another retrospective study suggested that appendectomy within 12-24 hours of presentation is not associated with an increase in hospital length of stay, operative time, advanced stages of appendicitis, or complications compared with appendectomy performed within 12 hours of presentation.

Emergent Versus Interval Surgery for Perforated Appendicitis

Historically, immediate (emergent) appendectomy was recommended for all patients with appendicitis, whether perforated or unperforated. More recent clinical experience suggests that patients with perforated appendicitis with mild symptoms and localized abscess or phlegmon on abdominopelvic computed tomography (CT) scans can be initially treated with IV antibiotics and percutaneous or transrectal drainage of any localized abscess. If the patient's symptoms, WBC count, and fever satisfactorily resolve, therapy can be changed to oral antibiotics and the patient can be discharged home. Then, delayed (interval) appendectomy can be performed 4-8 weeks later.

Laparoscopic Appendectomy

Initially performed in 1987, laparoscopic appendectomy has been performed in thousands of patients and is successful in 90-94% of attempts. It has also been demonstrated that laparoscopic appendectomy is successful in approximately 90% of cases of perforated appendicitis. However, this procedure is contraindicated in patients with significant intra-abdominal adhesions.

According to the 2010 Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) guideline, the indications for laparoscopic appendectomy are identical to those for open appendectomy.

The 2010 SAGES guideline lists the following conditions as suitable for laparoscopic appendectomy:

• Uncomplicated appendicitis
• Appendicitis in pediatric patients
• Suspected appendicitis in pregnant women
• Perforated appendicitis
• Appendicitis in elderly patients
• Appendicitis in obese patients

Medical Management 

The goals of therapy are to eradicate the infection and to prevent complications. Thus, antibiotics have an important role in the treatment of appendicitis, and all such. Agents under consideration must offer full aerobic and anaerobic coverage. The duration of the administration is closely related to the stage of appendicitis at the time of the diagnosis.

Antibiotic agents are effective in decreasing the rate of postoperative wound infection and in improving outcome in patients with appendiceal abscess or septicemia. The Surgical Infection Society recommends starting prophylactic antibiotics before surgery, using appropriate spectrum agents for less than 24 hours for nonperforated appendicitis and for less than 5 days for perforated appendicitis. Regimens are of approximately equal efficacy, so consideration should be given to features such as medication allergy, pregnancy category (if applicable), toxicity, and cost.

Empiric Therapy Regimens

Preoperative antibiotic prophylaxis should be given in conjunction with surgery for suspected appendicitis. Antibiotics should be stopped after surgery in patients without perforation. In patients with suspected appendicitis who do not undergo surgery, antimicrobial therapy should be administered for at least 3 days, until clinical symptoms and signs of infection resolve.

1. Ampicillin-sulbactam 3 g IV q6h or 
2. Piperacillin-tazobactam 3.375-4.5 g IV q6-8h or 
3. Ticarcillin-clavulanate 3.1 g q4-6h or 1 g IV q24h plus metronidazole 500 mg IV q8h or 1.5 g IV q8h plus metronidazole 500 mg IV q8h or 
4. Cefazolin 1-2 g IV q8h plus metronidazole 500 mg IV q8h or 400 mg IV q12h plus metronidazole 500 mg IV q8h or 500 mg IV daily plus metronidazole 500 mg IV q8h or 
5. Ertapenem 1 g IV daily

Complicated appendicitis

1. Moxifloxacin 400 mg IV daily or
2. Piperacillin-tazobactam 4.5 g IV q8h or 1 g IV q8h or 500 mg IV q8h or
3. Levofloxacin 750 mg IV daily plus metronidazole 500 mg IV q8h or
4. Ciprofloxacin 400 mg IV q12h plus metronidazole 500 mg IV q8h or 2 g IV q8-12h plus metronidazole 500 mg IV q8h or
5. Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h or 1-2 g IV q8h plus metronidazole 500 mg IV q8h or
6. Imipenem/cilastatin 500 mg IV q6h

D/D

• Abdominal Abscess
• Bacterial Gastroenteritis
• Cholecystitis and Biliary Colic
• Constipation
• Crohn Disease
• Cystitis in Females
• Diverticulitis
• Ectopic Pregnancy
• Inflammatory Bowel Disease
• Intussusception
• Mesenteric Lymphadenitis
• Nephrolithiasis
• Omental Torsion
• Ovarian Cysts
• Ovarian Torsion
• Pediatric Meckel Diverticulum
• Pelvic Inflammatory Disease 
• Urinary Tract Infection in Males 

 Courtesy : PDM