Pediatric Appendicitis
Authors:
M. Fernanda Bellolio, MD, MS, Assistant Professor of Emergency Medicine, Associate Research Chair, Department of Emergency Medicine, Mayo Clinic, Rochester, MN
Amy O'Neil, MD, MPH, Senior Resident, Emergency Medicine, Mayo Clinic, Rochester, MN
Peer Reviewer:
Samuel H.F. Lam, MD, RDMS, FACEP, Attending Physician, Advocate Christ Medical Center, Oak Lawn, IL; Clinical Associate Professor of Emergency Medicine, University of Illinois at Chicago
The diagnosis of acute appendicitis remains a challenging conundrum for the emergency physician. The differential is exceptionally broad and the presentation can vary from vague nausea to classical McBurney’s point tenderness. Incorporating various imaging modalities in the diagnosis of appendicitis has drastically reduced the rate of negative appendectomies. However, determining which patients warrant more extensive imaging requires an astute physician who maintains a high index of suspicion for the diagnosis. This review will discuss the presentation of appendicitis, analyze the various scoring systems that may be used by the emergency provider, examine laboratory and radiologic adjuncts, and review current management strategies.
— Ann M. Dietrich, MD, FAAP, FACEP, Pediatric Emergency Medicine Reports Physician Editor
"Almost every surgeon has at one time gone in for an acute appendix when the real cause of the symptoms was influenza, beginning pneumonia, diaphragmatic pleurisy,acute gastritis, ureteral calculus, fecal impaction, dysmenorrhea, onset of menstruation in a girl about puberty, tubercular peritonitis, floating kidney, perinephritic abscess, salpingitis, or any number of other rarer conditions."
~ George Blackburne, MD
Journal of the Medical Society of New Jersey, 1922
Executive Summary
- The risk of perforation is significantly increased in obese children, children 0-4 years of age, and patients presenting with a longer duration of symptoms.
- Young children under the age of 2 years can be particularly challenging and may present with fever, irritability, vomiting, grunting, abdominal pain, diarrhea, right hip pain, or limp.
- The Alvarado Score is a 10-point scoring system with sensitivity ranging from 76-90% and specificity of 72-79%. The Pediatric Appendicitis Score is also a 10-point scoring system with a sensitivity ranging from 57-96% and specificity between 74-97%. They should be used to supplement decision-making but cannot be solely relied upon for the diagnosis of acute appendicitis.
- A meta-analysis by Doria et al found that the pooled sensitivity and specificity of computerized tomography (CT) are significantly higher than ultrasonography (US). The sensitivity of US is directly correlated with the experience of the operator.
-
A recommended approach to imaging is to begin with an abdominal US in those patients with intermediate risk of appendicitis followed by CT or surgical
consultation for equivocal exams or when the appendix is not visualized.
Case
A 4-year-old female patient presents to the emergency department (ED) with her mother complaining of nausea, anorexia, and abdominal pain that began this morning. She has been febrile to 38° C. She denies having diarrhea. On physical exam she is laying still and whimpering. She has pain to palpation that is primarily periumbilical without abdominal rigidity.
What evaluation is necessary? Is laboratory testing needed? Are pediatric appendicitis scores useful in determining the course of evaluation? What imaging is indicated? Do antibiotics need to be started and if so, which one(s)? Does the patient need to go to the operating room tonight?
Definition and Etiology
Appendicitis is an inflammatory condition of the appendix that can progress to rupture with suppurative or gangrenous complications if left untreated.1 Though it is frequently encountered by the emergency physician and is the most common surgical emergency in children, the etiology remains unclear.2 The classic teaching is that obstruction occurs within the lumen of the appendix, resulting in a progressive increase in intraluminal pressure and subsequent venous congestion that leads to progressive inflammatory changes and ischemia.3,4 Obstruction occurs in 50-80% of appendicitis and in children is most often due to fecaliths or lymphoid hyperplasia.1 The most common causes of lymphoid hyperplasia are due to catarrhal inflammation secondary to viral or bacterial infections, constipation, trauma, and diet.5 Many cases of appendicitis have been confirmed without any evidence of obstruction, and the cause of appendiceal inflammation in these cases remains unclear.
Epidemiology
Acute appendicitis has an annual incidence of 37.2 per 10,000 American children between the ages of 0-14 years.6 The highest frequency is in patients between 10-14 years of age.7,8 The lifetime risk of acute appendicitis is 8.6% in boys and 6.7% in girls.2 The incidence of appendicitis tends to be higher in white and Hispanic patients than in African-American and Asian patients.8 The risk of perforation is significantly increased in obese children, children 0-4 years of age, and patients presenting with a longer duration of symptoms.8,9,10,11 An increased risk of perforation for patients living in rural locations and having lower median household incomes has been suggested.9
The mortality of appendicitis in children is very low (< 0.3%); however, it is associated with significant morbidity including peritonitis, sepsis, and paralytic ileus, particularly when complicated by perforation.12,13,14 A 2005 review by Selbst et al found that missed appendicitis is the second most common reason for malpractice claims filed against ED physicians seeing pediatric patients.15
Clinical Features
The classic presentation of appendicitis includes fever, abdominal pain and tenderness, or guarding in the right lower quadrant. (See Figure 1.) Approximately one-third of patients present with atypical symptoms.16 Young children under the age of 2 years can be particularly challenging and may present with fever, irritability, vomiting, grunting, abdominal pain, diarrhea, right hip pain, or limp.4 Their variable presentation is often the cause for delayed diagnosis and increased risk of perforation. One review found that 4.8% of patients with appendicitis were missed on initial presentation and most often misdiagnosed with acute gastroenteritis, constipation, and emesis.17
The presence of right lower quadrant pain is the most useful clinical finding in acute appendicitis and has a positive likelihood ratio (LR+) of 7.89 (95% confidence interval [CI], 7.31-8.46).18 The presence of fever also increases the likelihood of appendicitis (LR+ 3.4; 95% CI, 2.4-4.8); however, it is not very specific.4 Periumbilical pain migrating to the right lower quadrant is less helpful (LR+ 2.06; 95% CI, 1.63-2.60). The presence of abdominal rigidity and rebound tenderness on exam are moderately strong predictors of appendicitis with a positive likelihood ratio of 3.8 and 3.0, respectively.4,18 (See Table 1.)
Patients presenting with symptoms for > 24 hours in duration are more likely to have appendiceal perforation.19 Those patients are also more likely to have guarding on physical exam, while patients with non-perforated appendix are more likely to have McBurney’s point tenderness.20 The presence and degree of fever has not been shown to be reliably associated with an increased risk of perforated appendix.20,21
Figure 1. Location of the Appendix in the Right Lower Quadrant of the Abdomen
Reproduced with authorization from Mayo Clinic.
Table 1. Signs and Symptoms Associated with Acute Appendicitis
| Sign/Symptom | Positive Likelihood Ratio | Negative Likelihood Ratio |
|---|---|---|
Adapted from: Acheson J, Banerjee J. Management of suspected appendicitis in children. Arch Dis Child Educ Pract Ed 2010;95:9-13. |
||
Right lower quadrant pain |
7.89 |
0.14 |
Fever |
3.4 |
0.32 |
Periumbilical pain migration |
2.06 |
0.42 |
Percussion tenderness |
4.07 |
0.50 |
Rebound tenderness |
3.0 |
0.28 |
Differential Diagnosis
The differential diagnosis for patients presenting with suspected appendicitis is broad and contributes to the challenge of appropriately identifying children with appendicitis. (See Table 2.)
Table 2. Differential Diagnosis for Right Lower Quadrant Pain
| Systems | Diagnoses |
|---|---|
Gastrointestinal |
|
Genitourinary |
|
Gynecologic |
|
Extra Abdominal |
|
Laboratory Studies
The laboratory evaluation for acute appendicitis hinges on the presence of leukocytosis, often with neutrophil predominance and inflammatory marker elevation, particularly c-reactive protein (CRP) and procalcitonin (PCT). Additional markers that are more specific to appendicitis, including 5-hydroxyindoleacetic acid (HIAA) in urine, have recently been evaluated, but at this point still require additional research and are not widely available.22,23
The presence of leukocytosis significantly increases the probability of appendicitis with a predictive value that is directly correlated with degree of leukocytosis. The positive likelihood ratio for white blood cell count (WBC) > 10,000/mm3 is 2.47 (95% CI, 2.06-2.95), and increases to 3.47 (95% CI, 1.6-7.8) for WBC > 15,000/mm3.18 The WBC rises earliest in the disease process and appears to be the most useful marker when symptoms are present for < 24 hours.24
An elevation in CRP > 3 mg/dL has a sensitivity and specificity for appendicitis of 95% and 74%, respectively.25 CRP tends to rise slightly later in the disease process and is most useful between 24-48 hours after symptom onset.24
The meta-analysis by Andersson et al found a combination of a leukocytosis and elevation of CRP is strongly predictive of appendicitis; the positive likelihood ratio is 23.32 (95% CI, 6.87-84.79) and negative likelihood ratio is 0.03 (95% CI, 0.0-0.14).26 Although this combination is strongly correlated with appendicitis, patients, particularly those early in the disease process, can still present with both a normal WBC count and CRP and therefore cannot be excluded based on these laboratory studies alone.
Studies have evaluated PCT levels in appendicitis and found a sensitivity and specificity of 33% (95% CI, 21-47) and 89% (95% CI, 78-95), respectively.27 PCT in the setting of complicated appendicitis is significantly more predictive, with sensitivity and specificity of 62% (95% CI, 33-84) and 94% (95% CI, 90-96).27 Its application is most useful in predicting the presence of complicated appendicitis.
Urinalysis can be helpful to predict simple vs perforated appendicitis. The presence of more than 2.0 red blood cells (RBC)/high power field has a positive likelihood ratio of 4.76, and presence of more than 4.0 WBC/high power field has a positive likelihood ratio of 2.33 for appendicitis.28
Clinical Prediction Rules
Given the complexity of presentations and non-specific laboratory findings, clinical prediction rules have been developed to guide the management of patients with suspected appendicitis. The two most commonly used prediction rules are the Alvarado Score and the Pediatric Appendicitis Score.
The Alvarado Score is a 10-point scoring system with sensitivity ranging from 76-90% and specificity of 72-79%.4 (See Table 3.) A score of ≥ 7 has a positive predictive value of 65% for appendicitis and recommends surgical consultation.4 A score of 4-6 has an intermediate likelihood of appendicitis and recommends evaluation with imaging. A score of ≤ 3 suggests a very low likelihood of appendicitis and recommends against further imaging.
The Pediatric Appendicitis Score is also a 10-point scoring system with a sensitivity ranging from 57-96% and specificity between 74-97%.4 (See Table 4). A score of ≥ 6 recommends surgical consultation, 3-5 recommends further imaging and ≤ 2 recommends no further workup for appendicitis. A score of ≥ 6 has a positive predictive value of 45% for appendicitis.4
While these scoring systems can help to direct the clinician, both lack the sensitivity and positive predictive value needed to reliably make a diagnosis. They should be used to supplement decision-making but cannot be solely relied upon for the diagnosis of acute appendicitis.
Table 3. Alvarado Score
| Feature | Score |
|---|---|
Migration of pain |
1 |
Anorexia |
1 |
Nausea and vomiting |
1 |
Tenderness in the right lower quadrant |
2 |
Rebound tenderness |
1 |
Temperature > 37.5° C |
1 |
Leukocytosis > 10,000/mm3 |
2 |
Left shift |
1 |
Total |
10 |
Table 4. Pediatric Appendicitis Score
| Feature | Score |
|---|---|
Fever > 38° C |
1 |
Anorexia |
1 |
Nausea or vomiting |
1 |
Cough, percussion, or hopping tenderness |
2 |
Right lower quadrant tenderness |
2 |
Migration of pain |
1 |
Leukocytosis > 10,000/mm3 |
1 |
Polymorophonuclear-neutrophilia > 7500/mm3 |
1 |
Total |
10 |
Radiologic Studies
Much controversy has surrounded the choice of imaging to best evaluate for appendicitis in children. The National Ambulatory Medical Care Survey found that the use of computerized tomography (CT) to diagnose appendicitis has increased from nearly 0% in 1992 to 59.8% in 2006.29 Since that time, a heightened awareness of the risks associated with CT imaging and more readily available ultrasonography (US) has led to decreasing use of CT and increasing use of US.30
CT has the benefits of greater sensitivity and accuracy for the diagnosis of appendicitis, the ability to evaluate for other intra-abdominal pathology causing symptoms, and lack of operator variability in accuracy. This comes at the cost of ionizing radiation exposure and potential contrast reactions. The predicted lifetime risk for radiation-induced cancer after receiving one abdominal CT in a 5-year-old child is estimated to be 26.1 per 100,000 in girls and 20.4 per 100,000 in boys.31 In an effort to decrease ionizing radiation exposure, many institutions have initiated low-dose CT imaging with reduction in radiation dose by approximately 60% and found similar sensitivities and specificities in diagnosis.32 While CT has significantly decreased the rate of negative appendectomies, it has not led to a decrease in perforation rate.2
The use of CT is slowly starting to decline, though practice variations in its use are prevalent. A review by Ladd et al found that children initially presenting to a referring hospital, female patients, and patients with a prolonged latency from symptom onset to presentation increased the probability of receiving CT. The presence of rebound tenderness decreased the probability.33 Hospitals designated as children’s hospitals, teaching centers, or in an urban location were also less likely to perform CT imaging alone for appendicitis.34
US offers a safe and less expensive alternative diagnostic strategy, but at the expense of accuracy and operator reliance. Facilities that use US frequently and have technicians who are facile in its application have a much greater sensitivity for detection of appendicitis than low-volume centers.35 However, the hours of US availability are still limited in a number of facilities, often leaving CT as the only option late at night.
CT scan of the abdomen is best done with intravenous (IV) contrast. This is due to the paucity of intra-abdominal fat in children and allows for improved sensitivity in detection of appendicitis compared to CT without contrast.36 Contrast given enterally does not significantly improve diagnostic value and is often vomited, leading to patient discomfort and delays in evaluation.37 The CT findings suggestive of appendicitis include an appendix > 6 mm in diameter, peri-appendiceal inflammation or fat stranding, abscess, or presence of appendicolith.4 (See Figure 2.)
Figure 2. CT of Dilated Appendix with 1.3 cm Appendicolith
The diagnosis of appendicitis on US is demonstrated by an aperistaltic, blind ending structure arising from the cecum that is > 6 mm in diameter, tender, and non-compressible. Inflammatory changes such as wall thickening, increased blood flow, echogenic pericecal fat stranding, and presence of appendicolith or free fluid are also highly suggestive of the diagnosis.14 (See Figure 3.) In approximately 42-47% of US, the appendix is not visualized and further work-up is required.38
Figure 3. US of dilated appendix to 8 mm
A meta-analysis by Doria et al found that the pooled sensitivity and specificity of CT are significantly higher than US.39 (See Table 5.) The sensitivity of US is directly correlated with the experience of the operator.35 One study by Bachur et al also found that the sensitivity of US in detection of appendicitis is increased in patients who present with longer durations of symptoms.2 CT detection of appendicitis is not similarly affected by symptom duration. Many studies have evaluated the effect of obesity on visualization of the appendix with US. Conflicting evidence has been reported, although there does seem to be a trend toward a higher rate of non-diagnostic ultrasounds in obese patients.10,40,41,42,43 These patients then require CT for further evaluation, as there is no decrease in sensitivity of CT for patients who are obese.40
As magnetic resonance imaging (MRI) is becoming more widely available, it may offer an excellent alternative to CT and US for the diagnosis of appendicitis. MRI avoids exposure to radiation while maintaining excellent test performance. The sensitivity and specificity of MRI are 100% and 96-99%, respectively. It has a negative predictive value of 100% and positive predictive value of 83-98%. 44,45 The greatest challenges of MRI at this time are limited availability and cost.
A recommended approach to imaging is to begin with an abdominal US in those patients with intermediate risk of appendicitis followed by CT or surgical consultation for equivocal exams or when the appendix is not visualized.46 This approach has yielded a sensitivity and specificity of 98.6% and 90.6%, respectively.47 Institutional studies that have moved to a protocolized work-up using this staged approach have decreased use of CT by at least 50% and have not found a statistically increased risk of perforation.48,49
Table 5. Pooled Sensitivity and Specificity of CT and US in Diagnosis of Appendicitis
| Pooled Sensitivity % (95% CI) | Pooled Specificity % (95% CI) | |
|---|---|---|
CT Scan |
94 (92-97) |
95 (94-97) |
Ultrasound |
88 (86-90) |
94 (92-95) |
Management
The ED management of appendicitis is primarily focused on correction of dehydration, pain control, and timely antibiotic administration. Patients typically present dehydrated due to anorexia and vomiting and should have an IV established to begin rehydration. This can be accomplished with a 20 mL/kg fluid bolus of isotonic crystalloid until clinical signs of dehydration have resolved. Patients should then be placed on maintenance fluid at 1-1.5 times the calculated rate.
Ensuring appropriate pediatric analgesia is frequently overlooked, as these patients tend to be under-dosed or do not receive adequate pain control.29 Analgesia is best achieved using parenteral narcotics. Morphine 0.1 mg/kg IV or fentanyl 1 mcg/kg IV are safe and effective options.
Patients with evidence of non-perforated appendicitis should receive prophylactic antibiotics in the ED to decrease the risk of wound infections and intra-abdominal abscess.50 The bacteria most often found in appendicitis is Escherichia coli, followed by Klebsiella pneumoniae, Streptococcus, Enterococcus, and Pseudomonas aeruginosa.51 The American Pediatric Surgical Association recommends the use of broad-spectrum antibiotic coverage using either a single broad-spectrum agent such a piperacillin-tazobactam or double-agent therapy with an advanced generation cephalosporin such as ceftriaxone and metronidazole.52 Cases of uncomplicated appendicitis often do not require postoperative antibiotic treatment. Perforated appendicitis requires a prolonged course with IV antibiotics.52
The management of appendicitis is primarily surgical. One study by Yardeni et al found that patients taken to the operating room (OR) within 6 hours of ED triage did not result in any increase in perforation rate, length of stay, or complications compared to patients taken to the OR between 6 and 24 hours of ED triage.53 If the patient is hemodynamically stable without evidence of septic shock, the patient should be taken to the OR within 24 hours of presentation at a time when resources and staffing are readily available.
Most cases of non-perforated appendicitis are treated operatively and primarily by laparoscopic appendectomy.9 Complications including wound infection, abscess, and bowel obstruction within 30 days of operating are significantly reduced when a laparoscopic approach is used compared to open appendectomy.54,55 A growing body of evidence has found that pediatric patients with early appendicitis may be treated with antibiotics alone without operative intervention; however, studies with longer periods of follow-up to determine risk of recurrence in children are still needed.56 The Non-Operative Treatment for Acute Appendicitis (NOTA) study in adults found an 83% efficacy rate at 2 years follow-up.57
Patients with perforated appendicitis are increasingly being managed nonoperatively with IV antibiotic therapy. Although this can be a successful strategy, it carries approximately a 15-25% failure rate with interval appendectomy required earlier than scheduled and hospital re-admissions.58 The presence of appendicolith increases the failure rate of non-operative management.58,59
Cases of perforated appendicitis that have developed an abscess or appendiceal phlegmon are often managed non-operatively with percutaneous drain placement and IV antibiotics followed by interval appendectomy. A prospective randomized controlled trial by St. Peter et al found that there was no significant difference in length of hospitalization or recurrent abscess when patients were managed with drain placement and interval appendectomy compared to patients taken directly for appendectomy. There was a trend toward longer operating times for patients taken for immediate appendectomy.60
Disposition
Patients need to be stabilized in the ED initially along with prompt surgical consultation. The stable patient may be admitted for appendectomy within 24 hours from presentation. Those who have evidence of septic shock require prompt surgical intervention and potential ICU admission.
Conclusion
Children commonly present with abdominal pain, which has a broad differential. Diagnosing acute appendicitis requires a high degree of suspicion and a logical approach to minimize the morbidity associated with this disease. The judicious use of diagnostic studies including ultrasound and CT may further delineate the clinicians diagnostic concerns for this condition. Timely surgical consultation for further management is a critical aspect to the acute care of these children.
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- Aprahamian CJ, Barnhart DC, Bledsoe SE, et al. Failure in the nonoperative management of pediatric ruptured appendicitis: Predictors and consequences. J Pediatr Surg 2007;42:934-938.
- Zhang HL, Bai YZ, Zhou X, Wang WL. Nonoperative management of appendiceal phlegmon or abscess with an appendicolith in children. J Gastrointest Surg 2013;17:766-770.
- St. Peter SD, Aguayo P, Fraser JD, et al. Initial laparoscopic appendectomy versus initial nonoperative management and interval appendectomy for perforated appendicitis with abscess: A prospective, randomized trial. J Pediatr Surg 2010;45:236-240.
MONOGRAPH: The diagnosis of acute appendicitis remains a challenging conundrum for the emergency physician.
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