Rudolph's Pediatrics, 22nd Ed.

CHAPTER 413. Acute Appendicitis, Typhlitis, and Chronic Appendicitis

ACUTE APPENDICITIS

J. Craig Egan and John J. Aiken

Appendicitis is the most frequent pediatric surgical emergency, and appendectomy is the second most commonly performed pediatric surgical procedure. The incidence of appendicitis peaks between 10 and 19 years of age.1 In children older than 4 years with an elevated white blood cell (WBC) count, the most common diagnosis is appendicitis.

CLINICAL PRESENTATION AND DIAGNOSIS

Appendicitis is primarily a clinical diagnosis. The classic history of periumbilical pain, with anorexia and nausea, followed by localization of pain in the right lower quadrant is more reliable than right lower quadrant pain itself for diagnosis.2 Findings of fever, right lower quadrant tenderness, a Rovsing’s sign (palpation of the lower left quadrant of a person’s abdomen results in more pain in the right lower quadrant), or percussion tenderness with rebound are all highly suggestive of appendicitis. Right lower quadrant pain during rectal examination may suggest inflammation of a retrocecal appendix. The pain in appendicitis is continuous and generally does not get better. The pain is usually present even when the patient is lying still. Occasionally a child complains of right lower abdominal pain while walking, or refuses to stand up or walk.

Following the onset of pain, fever, tachycardia, and leukocytosis are commonly observed. An elevated WBC count or left shift are helpful markers for the diagnosis of appendicitis in children with nontraumatic acute abdominal pain.3 The diagnostic accuracy of the WBC is better than C-reactive protein (CRP), but even when both are normal, there is a small chance (between 0% and 5%) that appendicitis is present.4

An abdominal x-ray might show the presence of an appendix stone (fecalith) in the right lower area of the abdomen which suggests that appendicitis may be present (eFig. 413.1 ), but a fecalith is only seen on x-ray in a few patients (15%) so routine abdominal xray is not recommended in patients with likely appendicitis.

The introduction of diagnostic testing including ultrasound and abdominal computerized tomography (CT) has marginally improved the diagnostic accuracy for appendicitis. Ultrasound examination is especially useful in teenage girls in whom gynecology conditions such as an ovarian cyst are being considered, and in pregnant women. The typical finding of appendicitis on ultrasound is a round, tender, stiff, blind-ending structure that is greater than 6 mm in diameter, localized next to cecum. Abdominal CT can be up to 96% accurate for prediction of acute appendicitis, with typical findings of an enlarged, swollen appendix with a thickened wall, periappendiceal standing and often a “target sign” (see Fig. 413-1). CT scan may be wasteful and expose the child unnecessarily to radiation if the history and physical findings are highly suggestive of appendicitis such that radiographic testing is useful only patients in whom the diagnosis of appendicitis is unclear.

In the child presenting with severe abdominal pain, a fear of masking a surgical condition, such as appendicitis, has traditionally justified withholding analgesia. However, adult studies and a small number of pediatric studies indicate that analgesia does not impair diagnostic clinical accuracy, so analgesia should not be withheld.5

TREATMENT AND COMPLICATIONS

If a diagnosis of appendicitis is suspected or confirmed, antibiotics should be administered and appendectomy should be performed as soon as possible. In order to prevent infectious complications, broad-spectrum antibiotics, such as ampicillin, gentamicin, and clindamycin or metronidazole, should be administered prior to incision.1

FIGURE 413-1. CT with oral and intravenous contrast of acute appendicitis. There is thickening of the wall of the appendix and periappendiceal stranding (arrow). (From Fauci AS, Braunwald E, Kasper DL et al (eds). Harrison’s Principles of Internal Medicine. 17th ed. New York: McGraw-Hill, 2008.)

Although studies show a slightly higher rate of negative appendectomies among general surgeons compared with pediatric surgeons, overall outcomes are similar.1 Therefore, if pediatric surgical expertise is not readily available, a delay in surgery is not advisable if a general surgeon with experience in pediatric appendectomy is available. The risk of perforation increases with delay in surgery. Younger children have been reported to benefit more from pediatric subspecialty care than older children.6

Open and laparoscopic approaches to appendectomy are both acceptable. The approach chosen is usually subject to surgeon preference and the assessment of each individual patient. Abscess formation after perforated appendicitis has been compared between the open and the laparoscopic approach and has been found to be similar in both groups.7 Postoperative antibiotic treatment is tailored according to the severity of the disease. Obese children tend to have longer surgical times and longer lengths of stay.8

Wound infection rate following appendectomy is reported to be between 0% and 35%. Wound infection is reported to be more frequent after open appendectomy and is higher after perforated appendicitis.1

The incidence of perforation of the appendix at presentation ranges from 30% to 60% of children with appendicitis and is highest in patients less than 5 years old, who have a 70% perforation rate.1,6 The optimal treatment for an uncomplicated perforated appendicitis (no abscess) is controversial.9 Some case control studies suggest that there is a lower complication rate following nonoperative treatment (intravenous antibiotics followed by interval appendectomy). However, failure of nonoperative management ranges from 9% to 40%, and the consequences of failure result in additional hospital days before and after appendectomy such that the average length of hospitalization is the same with either the operative or nonoperative management approach. Because failure of non-operative management is associated with a high complication rate, it is important to make an early decision about appendectomy. Persistence of fever after 24 hours of treatment, bandemia on admission, and multisector involvement on CT scan or presence of bowel obstruction identify most patients who are likely to fail nonoperative management.10,11 When combined with clinical judgment, these are useful indicators to guide early decisions.

Treatment of perforated appendicitis with an intra-abdominal abscess consists of percutaneous drainage and prolonged antibiotic therapy (with coverage including enterobacteriaceae, enterococci, and anaerobes). The duration of antibiotic coverage is in part based on resolution of fever and leukocytosis, severity of infection, and clinical response. Following successful treatment, the option of interval appendectomy is usually considered due to reports of recurrent appendicitis in 5% to 37% of cases. A recent retrospective study found that only 8% of patients treated nonoperatively, with no interval appendectomy, returned with recurrent appendicitis. No specific risk factors were identified to predict which patients would experience a recurrence. All recurrences occurred within 3 years of diagnosis, and 80% occurred within 6 months of the initial episode.13 A survey of North American pediatric surgeons indicated that more than 80% offer interval appendectomy.

Small bowel obstruction following surgery for appendicitis has been reported to occur in between 0.2% and 11% of cases with the highest risk being in the first year after surgery. Small bowel obstruction occurred more frequently following open appendectomy (1.5%) compared to laparoscopic appendectomy (0.2%). The same applied to open and laparoscopic approaches for perforated appendicitis (3.1% versus 0.5%).14

CHRONIC APPENDICEAL PAIN

Grzegorz Telega and B U.K. Li

The appendix may be responsible for chronic right lower quadrant pain. Three varieties of chronic appendiceal pain are described. Chronic appendicitis refers to the chronically inflamed appendix infiltrated by mononuclear cells. The condition is rather unusual, accounting for 1% of inflamed appendices. Recurrent appendicitis describes a once-inflamed appendix in which the inflammation resolves spontaneously without surgical intervention, resulting in focal appendiceal fibrosis. Appendiceal fibrosis may be documented in 5% of childhood appendectomies. The final condition is appendiceal colic, which is one cause of chronic right lower quadrant pain in children. Colic results from appendiceal cramping against an intraluminal obstruction (fecaloma, fibrosis, kink-adhesion, foreign body, parasites, carcinoid, and lymphoid hyperplasia).

Appendiceal colic is a controversial subject, with the diagnosis not being recognized as a distinct clinical entity by many pediatric surgeons. Imaging studies are generally not useful because fecalomas are usually noncalcified in children, and there is usually no overt inflammation associated with appendiceal colic. Unless barium outlines a filling defect or shows marked delay in emptying from the appendix on follow-up films, barium upper and lower GI studies are often inconclusive. Appendiceal colic, therefore, remains a clinical diagnosis. The patient with appendiceal colic presents as any other patient with colic. Restless and uncomfortable, the patient may writhe and even scream in pain. Initial anorexia and nausea could progress to vomiting (dry heaves) if inflammation is severe. The pain often occurs in the morning on arising and after eating or drinking (5 to 20 minutes). On physical examination, pressure on the contracting appendix will exacerbate the pain during the episode, but there may be no pain between episodes. In this clinical setting, removal of the appendix often leads to dramatic clinical improvement with a resolution of the recurrent symptoms.15 However, a recurrence of abdominal pain may occur in up to 50% of patients who underwent appendectomy for appendiceal colic, likely reflecting the imprecise nature of diagnosis and suggestive of strong functional component of the disorder.16

TYPHLITIS

J. Craig Egan and John J. Aiken

Neutropenic enteropathy (typhlitis) presents with inflammation and necrosis of the terminal ileum, cecum, and/or the appendix. Malignancy, HIV, and chemotherapy are risk factors. The diagnosis is based upon fever, abdominal pain, and chemotherapy-induced neutropenia. A retrospective review of 38 episodes of typhlitis found that three fourths of patients had hematologic and one fourth had solid malignancies. Onset of symptoms occurs on average 9 days following administration of chemotherapy and 6 days following the onset of neutropenia. Recurrent episodes are common. Radiographic findings include pneumotosis intestinalis, free air and bowel wall edema, shown by both plain film and abdominal computed tomography. Serial abdominal exams and radiographs are helpful to determine if surgical intervention is required. Surgical indications include bowel perforation, severe lower gastrointestinal bleeding, inotropic support, and exclusion of other diagnosis. Appendicitis is uncommon in this setting. Bacteremia is seen in up to a quarter of patients and is associated with a higher risk for mortality. Recovery of gastrointestinal function correlates with the resolution of neutropenia.17 A recent study of 12 patients, most of whom received intravenous nutritional support and granulocyte colony stimulating factor (GCSF), showed a survival rate of 100%, although 2 required surgery.18