Pediatric Appendicitis

Etiology

The cause of appendicitis is an obstruction of the appendix, either from inflammation of the wall or a fecalith.[4][5]

• Fecalith (hard stools)
• Appendicoliths (calcified deposits)
• Lymphoid hyperplasia: The appendix contains large masses of lymphoid tissue in the mucosa and submucosa, and is, therefore, prone to develop lymphoid hyperplasia resulting in luminal obstruction.

Epidemiology

Annually, up to 250,000 cases of appendicitis are reported. The estimated lifetime risk is 12% for males and 25% for females. Although appendicitis can occur at any age, it most commonly occurs between the ages of 10 and 19 years.

Pathophysiology

Luminal obstruction can cause an increase in pressure within the lumen. The appendix continues to secrete mucosal fluid, leading to distention of the appendix. Organ ischemia, bacterial overgrowth, and eventual perforation follow distention. It is a progressive process in which the patient's symptoms worsen over the course of the illness until perforation occurs.[6]

Beware that the patient may feel temporary relief due to a decrease in intraluminal pressure, but will subsequently become more unwell due to the development of peritonitis.

History and Physical

The most common symptom of appendicitis is acute abdominal pain. Periumbilical, central, or epigastric abdominal pain usually develops after nonspecific symptoms. Pain then migrates to the right lower quadrant of the abdomen. If nausea develops, it typically occurs after the onset of pain. Dysuria or hematuria can occur due to the proximity of the appendix to the urinary tract. Although anorexia is common, it is not universally present.

Beware that typical findings are the exception and not the rule, particularly in children. The usual history is atypical or vague symptoms such as diffuse abdominal pain, possibly associated with vomiting, and a low-grade fever. The presence of diarrhea may delay the diagnosis if the symptoms are mistaken for gastroenteritis rather than appendicitis.

The clinical presentation depends on the anatomic position of the inflamed appendix:

• The retrocecal appendix can present with back pain or flank pain.
• Pelvic appendix can present with suprapubic pain
• Long appendix can present as a right upper quadrant or left lower quadrant pain.

Physical Examination

Tenderness in the right lower quadrant at McBurney’s point (two-third the distance from the umbilicus to the right anterior superior iliac spine). Tenderness in this area is perhaps the most useful clinical finding.

Rebound tenderness and involuntary guarding may suggest peritonitis.

Rovsing's sign is right lower quadrant (RLQ) pain while palpating the left lower quadrant.

Psoas sign is increased RLQ pain with the patient lying on their left side while the provider passively extends the patient's right leg at the hip with both knees extended.

Obturator sign is increased RLQ pain when the patient is supine, and the provider internally and externally rotates the right leg as it is flexed at the hip.

Beware that the presence or absence of any of these findings is not sufficient enough to prove or disprove the diagnosis.

Note that rectal examination does not provide any additional information in the evaluation of appendicitis.

Not a single feature of the history or physical finding can reliably diagnose or exclude the diagnosis of appendicitis.

Evaluation

Practitioners should interpret laboratory evaluations in association with the patient's clinical history and physical examination findings. Although lab results may help to support the clinical diagnosis, it cannot replace a good history and physical examination.[3][7][8]

White Blood Cell Count (WBC)

Although an increase in peripheral WBC with a left shift may be the earliest marker of inflammation, its presence or absence is not significant enough to diagnose or exclude acute appendicitis. Many patients with gastroenteritis, mesenteric adenitis, pelvic inflammatory disease, and many other conditions have an elevated WBC. A normal WBC is also not uncommon in patients with appendicitis.

Urinalysis

Urinalysis is usually normal but may not be due to the inflamed appendix sitting on the ureter or bladder.

Diagnosis

Appendicitis is a clinical diagnosis. Imaging may not be universally required and may be unnecessary when the diagnosis is clear. Imaging is particularly helpful in doubtful cases such as in female patients of child-bearing age. Consider obtaining a surgical consultation before imaging, particularly in patients with the typical presentation. Consultation should not be delayed for testing.

Ultrasound (US)

Use of ultrasound is increasing, particularly in children in whom the risks of ionizing radiation are greatest. The advantages include decreased cost relative to other imaging modalities and lack of ionizing radiation exposure. However, it is operator-dependent.

The visualization of a thickened, non-compressible appendix greater than 6 mm in diameter is diagnostic. If the US is non-diagnostic, further imaging with CT or MRI, particularly in pregnancy, is required. In practice, a positive ultrasound can be used to reduce CT scan utilization. However, a negative or non-diagnostic result is not sufficient to rule out appendicitis. During childbearing age, it can be helpful to exclude a tubo-ovarian abscess.

CT Scan

CT of the abdomen and pelvis is considered the modality of choice for definitive assessment of patients being evaluated for possible appendicitis. However, a major concern with CT scan is radiation exposure, particularly in children. Practitioners should, therefore, use these scans judiciously. Limited-range CT scans have been proposed in children to reduce the radiation dose. The following findings may be seen:

• Dilated appendix greater than 6 mm with a thickened wall (greater than 2 mm)
• Peri-appendiceal inflammation (peri-appendiceal fat stranding)
• Appendicolith
• Appendiceal or abscess
• Free fluid

If the practitioner does not visualize the appendix, appendicitis is not ruled out.

MRI

MRI is a reliable modality which is particularly useful for pregnant women and children when ultrasound is inconclusive. Since intravenous (IV) gadolinium can cross the placenta, it should not be used during pregnancy. Also, patients with renal insufficiency should not receive IV gadolinium.

The following factors limit MRI use:

• Higher cost
• More time required to acquire images
• Skilled radiologist required to interpret MRI
• Not widely available

Also, MRI is not a test of choice for unstable patients and young children in whom sedation may be required. In recent years, the utility of rapid MRI without contrast agents or sedation has been assessed for a diagnosis of pediatric appendicitis.

Treatment / Management

If practitioners are evaluating the patient for appendicitis, they should also obtain an early surgical consultation.[9][10](B3)

Do not give anything by mouth (NPO).

Intravenously administer isotonic crystalloid fluid.

Antibiotic prophylaxis, which is coverage for gram-negative and gram-positive aerobic and anaerobic bacteria, and anaerobes (Bacteroides fragilis and Escherichia coli), is recommended. However, its administration should be timed in consultation with the surgical service to ensure that high antibiotic levels coincide with the operative procedure.

Treat nonperforated appendicitis with cefoxitin or cefotetan.

In a perforated appendicitis consider the following choices:

• Carbapenem
• Ticarcillin-clavulanate
• Piperacillin-tazobactam
• Ampicillin-sulbactam
• Provide adequate analgesia

The primary treatment for appendicitis is surgery. Doctors should make operative decisions in consultation with the surgical service, and they should discuss the risks and benefits with patients or their families.

Increasingly laparoscopic surgery has replaced open surgery for appendicitis. The principal factor that determines whether an open or laparoscopic surgery should be performed is the preference or the expertise of the treating surgeon. Generally, the laparoscopic approach is preferred if the surgical expertise and equipment are available.  This technique has the following advantages.

• Less 
• Quick recovery and shorter hospitalization
• Lower infection rate

In children, minimally invasive technique for Transumbilical Laparoscopic Assisted Appendicectomy has also been described. Laparoscopic-assisted single-port appendectomy (SPA), although has not yet evolved as the gold standard but has also been performed in children and found to be safe. 

Differential Diagnosis

• Intussusception
• Meckel diverticulum
• Ectopic pregnancy
• Testicular torsion
• Kidney stones
• Viral and bacterial gastroenteritis
• PID

Complications

• Perforation
• Shock
• Pelvic abscess
• Wound infection
• Bowel obstruction