| Discussion: Background: Appendicitis is acute inflammation of the appendix. The appendix is a blind-ending diverticular structure arising from the cecum. Acute appendicitis is a common cause of abdominal pain and the most frequent condition leading to emergent abdominal surgery in children.
Pathophysiology: Appendicitis is due to a closed-loop obstruction of the appendix. The obstruction may be secondary to impacted fecal material or hyperplasia of submucosal lymphoid follicles. Obstruction of the appendix leads to an increase in intraluminal pressure, resulting in mucosal edema, bacterial overgrowth, and increasing wall tension.
As the wall tension rises, a decrease in wall perfusion, a decrease in mucosal integrity, and bacterial translocation occur. If the diagnosis is not made early, the obstruction progresses and the wall of the appendix stretches due to further rise in intraluminal pressure. Eventually, perforation occurs.
When inflammatory fluid and bacterial contents are released into the abdominal cavity, peritonitis develops. Concomitantly, the patient complains of more intense and generalized abdominal pain. In adolescents, the omentum can wall off the inflamed or perforated appendix, causing a focal abscess. In younger children, the omentum is less developed, making a diffuse peritonitis much more likely.
Frequency:
In the US: Appendicitis occurs in all age groups but is rare in infants. The incidence in the United States is 4 per 1000 children.
Mortality/Morbidity:
At the time of diagnosis, the rate of perforation is 17-40%. Younger children have a higher rate of perforation, with reported rates of 50-85%.
The mortality rate for children with appendicitis is 0.1-1%.
Sex:
The male-to-female ratio is approximately 2:1.
Age:
Appendicitis occurs in all age groups.
The mean age in the pediatric population is 6-10 years. Appendicitis is rare in the neonate, and the diagnosis typically is made after perforation.
Younger children have a higher rate of perforation, with reported rates of 50-85%.
History: Understanding typical clinical manifestations is important in making an early and accurate diagnosis prior to perforation. The classic history of anorexia and periumbilical pain, followed by right lower quadrant pain and vomiting, is observed in fewer than 60% of individuals with appendicitis.
Pain
The initial symptom is poorly defined periumbilical pain often associated with anorexia.
Acute onset of severe pain is typically present with acute ischemic conditions such as volvulus, testicular torsion, ovarian torsion, or intussusception.
Nausea and vomiting
In many patients, nausea and vomiting develop shortly after onset of pain.
Generally, for vomiting to occur prior to pain is unusual.
However, in retrocecal appendices, particularly those that extend cephalad along the posterior surface of the right colon, inflammation of the appendix irritates the nearby duodenum, resulting in nausea and vomiting prior to the onset of right lower quadrant pain.
Diarrhea
Likewise, significant diarrhea is atypical in appendicitis. In occasional patients with the appendix located in a pelvic location, inflammation of the appendix results in an irritative stimulation of the rectum.
These patients often complain of "diarrhea."
However, such patients, on closer questioning, relate complaints of frequent, small-volume, soft stools, not true diarrhea.
Shift to right lower quadrant pain
After a few hours, pain shifts to the right lower quadrant due to inflammation of the parietal peritoneum.
When compared to the initial pain, this pain is more intense, continuous, and localized.
This shift of pain rarely occurs in other abdominal conditions.
Fever
Most children with appendicitis are afebrile or have a low-grade fever.
High fever is not a common presenting feature unless perforation has occurred.
According to one study, vomiting and fever are more frequent findings in children with appendicitis than in children with other causes of abdominal pain.
Physical: Children vary in their abilities to cooperate with physical examination. Tailoring the physical examination with respect to age and developmental stage is important. Excluding extra-abdominal causes of abdominal pain is also important. Observation of the child's interaction and gait prior to examination can be extremely helpful.
Abdominal examination
A child with appendicitis typically prefers to lie still due to peritoneal irritation.
The child's facial expression during palpation of the abdomen can be helpful in eliciting the location and intensity of any abdominal pain.
Localization of pain depends on the position of the appendix.
Typically, maximal tenderness can be found at McBurney point in the right lower quadrant.
Rovsing sign is pain in the right lower quadrant in response to left-sided palpation and strongly suggests peritoneal irritation.
To perform the psoas sign, place the child on the left side and hyperextend the right leg. A positive response suggests an inflammatory mass overlying the psoas muscle (retrocecal appendicitis).
Perform the obturator sign by internally rotating the flexed right thigh. A positive response suggests an inflammatory mass overlying the obturator space (pelvic appendicitis).
The cough sign (ie, sharp pain in the right lower quadrant after a voluntary cough) is suggestive of peritoneal irritation.
Rectal examination
Perform rectal examination last.
Rectal examination may reveal impacted stool, a mass, or right-sided tenderness.
Tenderness is the least reliable sign during rectal examination.
Causes: Appendicitis is caused by a closed-loop obstruction of the appendix.
Impacted fecal material or hyperplasia of submucosal lymphoid follicles may cause the obstruction. Rarely, foreign objects or nematodes may cause luminal obstruction.
Obstruction leads to increasing intraluminal pressure, mucosal edema, and decreased wall perfusion, resulting in an exudate to form on the appendiceal serosal surface.
When the exudate touches the parietal peritoneum, a more intense and localized pain develops in the right lower quadrant.
As the obstruction develops, bacteria within the appendix proliferate and increase intraluminal pressure.
If the diagnosis is not made early, the obstruction progresses, the wall of the appendix stretches due to the rise in intraluminal pressure, and perforation occurs.
When inflammatory fluid and bacterial contents release into the abdominal cavity, peritonitis develops. At this point, the extent of peritonitis (diffuse or localized) depends on the degree to which the omentum and adjacent bowel loops can contain the spillage of luminal contents and its associated intense inflammatory response.
Imaging Studies:
Abdominal radiographs
Plain x-rays are rarely helpful.
Abdominal radiographs are normal in many individuals with appendicitis; therefore, do not obtain abdominal radiographs routinely.
The presence of a calcified appendiceal fecalith occurs in fewer than 10% of persons with the inflammation.
Radiographic signs suggestive of appendicitis include convex lumbar scoliosis, obliteration of right psoas margin, right lower quadrant air-fluid levels, air in the appendix, or localized ileus.
In rare incidents, a perforated appendix may produce pneumoperitoneum.
Indications for abdominal radiographs include suspected free air, diffuse peritonitis, or small bowel obstruction.
Ultrasound
Ultrasound is the preferred imaging modality in the evaluation of pediatric acute appendicitis.
The advantages of ultrasound include its noninvasiveness, lack of radiation, no contrast medium, and minimal pain.
The downside of ultrasound is that the examination is operator dependent.
In experienced hands, ultrasound has an overall sensitivity of 85% and specificity of 94% in pediatric patients.
Specific findings of ultrasound can support the diagnosis.
The finding of a noncompressible dilated appendix is a strong indicator of nonperforated appendicitis.
After perforation, ultrasound can identify a periappendiceal phlegmon or abscess formation.
Additional supportive findings include appendicoliths, fluid in the appendiceal lumen, focal tenderness over the inflamed appendix, and a transverse diameter of 6 mm or more.
Ultrasound examination is also useful in diagnosing alternate pathology (eg, tuboovarian abscess, ovarian torsion, ovarian cyst, mesenteric adenitis).
Nonvisualization of the appendix during sonographic examination is not synonymous with a negative ultrasound examination.
Computed tomography (CT) scan
CT scan is used widely when diagnosing appendicitis in adults. However, in children, the use of CT scan has a limited role.
CT scans are useful when ultrasound findings are equivocal.
CT scan also may be beneficial in complicated cases with abscesses formation and bowel wall thickening.
Histologic Findings: Typically, histologic findings range from acute inflammatory infiltrate most apparent in the submucosal level in early appendicitis to transmural infarction in perforated appendicitis.
Rarely, a vasculitis involving the mural vessels results in appendicitis in such conditions as Kawasaki disease.
The finding of an apparently normal appendix at surgery requires careful follow-up of the histologic findings. Occasionally, early appendicitis is identified histologically and correlates clinically with the resolution of preoperative symptoms. Additionally, unsuspected findings of luminal nematodes should indicate further anthelmintic therapy (eg, mebendazole [Vermox]).
Staging: The clinical staging of appendicitis has important implications in the postoperative treatment of the child. While somewhat subjective at the time of surgery, appendicitis may be divided into 3 broad categories: acute (nongangrenous) appendicitis, suppurative or gangrenous (nonperforated) appendicitis, and perforated appendicitis. Perforated appendicitis can be divided further into cases with diffuse peritonitis and those with localized peritonitis.
Acute (nongangrenous)
Early appendicitis without mural gangrene or infarction requires no further antibiotic therapy in most settings.
The child may be discharged home as soon as diet and oral pain medications can be tolerated.
Suppurative or gangrenous (nonperforated)
Persons with exudative appendicitis, particularly in individuals with mural gangrene, have an increased rate of postoperative intraabdominal and wound infections, even in the absence of demonstrable perforations.
As such, antibiotic therapy frequently is extended for 48-72 hours after surgery.
Perforated
Perforated appendicitis is associated with a postoperative infection rate in as many as 30% of patients.
Children with localized peritonitis require longer antibiotic therapy, typically for 5-7 days.
Diffuse peritonitis may require antibiotic therapy for 10 days or more.
Medical Care: Making a timely diagnosis is a difficult challenge when evaluating children with abdominal pain. Classifying patients with abdominal pain into the following 3 major categories may be helpful:
Diagnosis not consistent with appendicitis
This group includes patients whose history and physical examination are not consistent with appendicitis or any significant abdominal process.
Performing a complete physical examination, including rectal palpation and urinalysis, before discharge is important.
Classic history for appendicitis
Patients with a classic history require prompt surgical consultation.
Maintain nothing by mouth status in patients with suspected appendicitis and start intravenous fluids to restore intravascular volume.
Ensure adequate hydration for patients who present with suspected appendicitis.
Even in early acute appendicitis, children frequently have not had sufficient oral intake and present with some degree of intravascular dehydration.
Antibiotic therapy is an important aspect of the treatment of ruptured appendicitis.
Direct antibiotic therapy against gram-negative and anaerobic organisms (eg, Escherichia coli, Bacteroides species).
Discuss the use of antibiotics in persons with nonperforated appendicitis with the surgical consultant.
Unclear diagnosis
In these children, the history may be consistent with appendicitis; however, the examination is not supportive.
Conversely, the examination may be suggestive in the face of unremarkable history.
In this group, obtaining laboratory studies and radiographs is helpful.
Serial examinations along with test results may help to clarify the diagnosis.
Reevaluate the patient over a few hours to determine the need for surgical consultation.
If uncertainty persists after a period of observation, obtain surgical consultation.
Ultrasound may be useful when the diagnosis is equivocal.
Surgical Care:
Appendectomy
The definitive treatment for appendicitis is appendectomy.
Appendectomy has a 10-20% false-positive rate due to the difficulty of diagnosis in infants and toddlers.
Nontoxic patients with localized abscess that is walled off may be candidates for initial medical treatment with antibiotics, with or without percutaneous drainage procedures, followed by an elective interval appendectomy.
Laparoscopy
The use of laparoscopic appendectomy is an alternative to traditional open appendectomy.
Potential advantages of laparoscopic appendectomy include reduced postoperative pain and lower wound infection rate.
Diagnostic laparoscopy also can be useful or diagnostic in the adolescent female.
Disadvantages include longer operation time and increased cost.
Consultations:
Pediatric consultation
General surgery consultation
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12 Y/O MALE WITH ABDOMINAL PAIN/FEVER
