A 19-month-old girl is brought to the ED because of abdominal pain for the last week, fever for 5 days, and crying on urination together with constipation for 2 days. She had passed several watery stools without mucus or blood prior to the last bowel movement.
On physical examination, the girl appears uncomfortable and mildly dehydrated. Her temperature is 103.1°F (39.5°C), pulse is 148 beats/min, blood pressure is 121/78 mm Hg, and respiratory rate is 28 breaths/min. She has diffuse abdominal tenderness and mild distention without guarding or rebound. Her bowel sounds are normal, and no hepatomegaly or splenomegaly is noted.
The WBC count is 26.8x103/mcL (26.8x109/L), with 77% neutrophils, 5% bands, 13% lymphocytes, and 5% mononuclear cells. Her Hgb is 10.6 g/dL (106 g/L), Hct is 31.3% (0.31), and platelet count is 666x103/mcL (666x109/L). The child has normal serum concentrations of sodium, potassium, chloride, urea nitrogen, creatinine, and glucose. Findings on urinalysis are normal. A radiograph of her abdomen shows dilated loops and fecal material throughout the colon. An imaging test leads to the correct diagnosis.
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Abdominal CT revealed a complex cystic mass involving much of the pelvis. The mass was predominant on the left side but also contiguous with the cecum. This mass represented an abscess that had formed from a ruptured appendix. Evidence of mild hydronephrosis and hydroureter on the left, probably due to the pelvic mass, also was seen. Triple antimicrobial therapy with gentamicin, metronidazole, and ampicillin was initiated and continued for 5 days. Repeat abdominal CT showed a persistent pelvic abscess compressing the rectum. The child underwent transanal drainage of the abscess and was scheduled for elective appendectomy.
Differential Diagnosis
Acute abdominal pain is a common complaint in children. Children, especially young children, are poor at localizing pain to an abdominal quadrant. Therefore, a wide range of possible disorders needs to be considered. The causes of abdominal pain are age-related.
Intussusception occurs typically in infants between approximately 6 months and 2 years of age. The clinical presentation is characterized by attacks of colicky abdominal pain, during which the child draws up the legs, followed by periods of relaxation and sometimes profound somnolence. During the colicky episodes, the child appears pale and returns to having normal color when the pain passes. Currant jelly stools are passed by about 33% of patients and represent mucosal injury. Failure to pass a bowel movement at the usual interval also can occur. On abdominal radiographs, a mass lesion can be seen indenting the colon, with or without signs of bowel obstruction. Plain radiographs also may appear normal in this disorder.
Acute gastroenteritis is the most common diagnosis recorded when appendicitis is missed. The child presents with vomiting, diarrhea, and abdominal pain. The diarrhea may be preceded by severe abdominal pain and abdominal wall rigidity, mimicking acute abdominal inflammation. Bloody stools may cause further confusion because this picture mimics intussusception. Although enteritis due to Yersinia enterocolitica or Y pseudotuberculosis has been named "the great imitator" of appendicitis, affected patients usually have substantial diarrhea.
The symptoms of bowel obstruction include bile-stained vomiting, pain, and abdominal distention, with a paucity or absence of bowel gas distal to the level of the obstruction. In children, the site of the obstruction almost always is in the small bowel. Causes of obstruction include incarceration of a hernia, postoperative adhesive obstruction, malrotation, volvulus, and a Meckel diverticulum causing volvulus or intussusception. Radiologically, the typical pattern of a bowel obstruction is distended loops of bowel proximal to the obstruction, absence of gas distally, and multiple short air-fluid levels, often referred to as a "ladder" pattern.
Appendicitis also can mimic urinary tract infection. Caution must be exercised in interpreting findings on urinalysis because mild pyuria, hematuria, and bacteriuria can be present if an inflamed appendix is located adjacent to a ureter or to the bladder.
Pain may be associated with abdominal masses, with constipation, or less often, with anuria if the mass obstructs the bladder outlet. Imaging is required to identify the originating organ of the mass, to determine its nature (solid or cystic), and in the case of malignant lesions, to aid tumor staging. Ultrasonography usually can identify the organ of origin.
Children who have mesenteric adenitis present with abdominal pain that may be severe, which raises concern about a disorder requiring surgery, especially appendicitis. Often, there is a preceding history of upper respiratory tract infection. There may be recurrent attacks. Abdominal radiographs show normal results. Ultrasonography reveals enlarged (>1 cm) nodes around the root of the mesentery, occasionally with edema of the mesentery.
Signs and symptoms of inflammatory bowel disease include abdominal pain, weight loss, diarrhea, and the passage of bloody stools. Although adolescents and young adults between 15 and 35 years of age are affected most often, the disease has been diagnosed in infants as young as 18 months of age.
Henoch-Sch?nlein purpura (HSP), a common vasculitic disease affecting children between 2 and 8 years old, results in a constellation of findings, including a purpuric rash occurring on the lower extremities, abdominal pain, renal involvement, and arthritis. However, any of the components may be absent, which often leads to confusion in diagnosing the condition. The second most frequent element of HSP is colicky abdominal pain, which occurs in up to 65% of cases and may be severe and associated with vomiting. The pain may mimic that of acute intraperitoneal inflammatory disease.
Incarcerated hernias usually present with irritability from abdominal pain. Otitis, pharyngitis, and upper respiratory tract infections may present with abdominal pain. Right basal pulmonic consolidation can refer pain to the abdomen. Food poisoning and sickle cell pain crisis commonly present with abdominal pain; in these cases, however, a previous history can narrow the search.
The Condition
Appendicitis is the most common abdominal surgical emergency in infants and young children, but rarely is it considered in children younger than 3 years of age.
In young children, the typical history seldom is obtained. Because the disease can progress rapidly and escape detection, the child often presents with pyrexia and poorly localized abdominal pain, frequently with signs of septicemia, peritonitis, and bowel obstruction. If a pelvic abscess already has developed, diarrhea may be the presenting complaint. Children younger than 2 years of age usually have diarrhea as a primary symptom. Children who have a retrocecal appendix may present with right upper quadrant or flank pain. Due to the difficulty in evaluating these young patients who have abdominal pain, the perforation rate is higher (30% to 65%) than in adults. Because the omentum is less developed in children, perforations are less likely to be "walled-off" or localized, leading to generalized peritonitis.
Laboratory Findings
Leukocytosis and an increased concentration of C-reactive protein usually are present. WBCs may be present in the urine and cause confusion by suggesting urinary tract infection. If the clinical and hematologic findings are sufficiently typical, no radiologic investigation need be undertaken
Radiologic Assessment
Positive radiographic findings include the presence of a fecalith in the RIF (in approximately 30% of cases) and a localized ileus with mildly dilated loops of bowel. As sepsis advances, the properitoneal fat line blurs. Free air in the abdomen (pneumoperitoneum) is not a typical feature of a perforated appendix because the inflammatory mass prevents release of the luminal gas. A subphrenic abscess may occur if the sepsis is untreated and is seen as an air-fluid level in the subdiaphragmatic region.
CT of the pelvis and RIF, especially an intravenous contrast-enhanced procedure, with or without colonic contrast, is a useful and sensitive technique for identifying an inflamed appendix. A calcified appendicolith is well demonstrated by CT, as are postoperative fluid or pus collections.
On ultrasonography, the normal appendix appears as a tubular structure with a maximum transverse diameter of 6 mm located in the RIF, with good visualization of all layers of the bowel. The appearance of an abscess depends on the stage of evolution, but an abscess usually appears as an area of mixed solid and fluid echoes in the RIF. When there is rupture and peritonitis, abscess collections may be found in the pelvis or the subhepatic or subphrenic region.
Management
When perforated appendicitis is suspected, preoperative broad-spectrum antibiotic therapy is indicated because of the high morbidity that results from intra-abdominal abscess, peritonitis, and wound infection. Appendectomy is performed with or without drainage of the peritoneal cavity, and antibiotics are continued for 7 to 10 days. Occasionally, a localized abscess is treated with antibiotics with or without open or percutaneous drainage, with appendectomy scheduled as an elective procedure in 4 to 6 weeks. Children who have nonperforated appendicitis require minimal preoperative preparation with intravenous fluids and antibiotics. Although the use of antibiotics in uncomplicated appendicitis is controversial, it has decreased the incidence of postoperative wound infections.
MD
John H. Stroger, Jr
Hospital of Cook County, Chicago, Ill