Original Articles: Gastroenterology
Acute appendicitis is the most common surgical emergency in childhood, representing 10% of all children admitted to the pediatric emergency ward (1). Appendicitis may present at any age, but it is an uncommon entity during the first 3 years of life (2,3). In this population early differentiation between acute appendicitis and other pediatric diseases is often impossible, resulting in a high incidence of perforation, abscess formation, and postoperative complications (4). The difficulties in the clinical diagnosis of acute appendicitis in young children necessitate the use of more accurate diagnostic tools. The object of this study was to assess the reliability of ultrasonography (US) to detect acute appendicitis in children younger than 3 years of age.
PATIENTS AND METHODS
The study included 71 children (28 girls and 43 boys; age range, 8–35 months) who presented from January 1994 to December 2003 with acute abdominal pain and possible acute appendicitis, but who had atypical findings. The inclusion criteria were age younger than 3 years with acute abdominal pain and an equivocal clinical presentation for acute appendicitis. Patients were excluded if they had classic appendicitis with pain migration to the right lower abdomen and rebound tenderness requiring immediate surgery. For all of the patients who underwent appendectomy, the surgical findings, clinical characteristics, and pathology reports were reviewed, and a definite diagnosis was established. The other patients who did not undergo appendectomy were followed clinically until discharge. A 7.0-MHz linear transducer (Acuson, Mountain View, CA) was used to perform the studies. Using the graded compression technique described by Puylaert (5), longitudinal and transverse images of the right lower quadrant were obtained. The US criteria of acute appendicitis are a noncompressible appendix with an anteroposterior diameter that is consistently 6 mm or greater, an appendicolith, the presence of a complex mass in the right lower quadrant, or an interruption in the continuity of the echogenic submucosa. Based on the US findings, the patient was placed into 1 of 2 categories: appendicitis, including suppurative, gangrenous, perforated, or ruptured appendicitis with tumor formation, defined as a phlegmon consisting of an inflamed appendix wrapped by its surrounding soft tissues (6); or other diseases. Patients with US diagnosis of acute appendicitis without tumor formation were taken to undergo surgery. In children with ruptured appendicitis with tumor formation, the timing of operations was determined by the surgeon's clinical decision to undergo immediate or interval appendectomy. Comparison of emergency appendectomy with tumor formation versus interval appendectomy for first hospital stay, white blood cell count at presentation, duration of antibiotic use, postoperative hospital stay, and postoperative complications that required repeat hospitalization, intraabdominal abscess, or ileus were made. Statistical analyses were performed with SPSS software (version 10.0; SPSS, Chicago, IL). The obtained quantitative data were compared by analysis of variance and/or χ2 test in the form of means ± SD and frequency, respectively. P< 0.05 was considered statistically significant. The results of US examinations were analyzed to determine sensitivity, specificity, positive and negative predictive values, and overall accuracy. The definitive diagnosis of appendicitis was confirmed by the pathology reports.
Of the 71 US scans performed, diagnostic results are shown in Table 1. There were 41 positive sonographic results for appendicitis, including 28 patients having ruptured appendicitis with tumor formations. Of the 41 patients, 38 underwent surgery and were proven to have appendicitis by the pathological examinations. Of the other 3 patients who underwent surgery without appendicitis, 2 were found to have colon perforations and 1 had appendiceal vermicularis. The management of 28 patients with ruptured appendicitis and tumor formation by US findings included emergency appendectomy in 18 patients and initial conservative antibiotic treatment with interval appendectomy approximately 2 to 4 months later in 10 patients. All 10 patients who received initial conservative antibiotic treatment had successful gradual resolution of appendiceal mass on the subsequent US examination before interval appendectomy. Table 2 summarizes the comparison between emergency appendectomy and initial conservative treatment with interval appendectomy for ruptured appendicitis with tumor formation. Compared with patients who underwent emergency appendectomy, there was a shorter duration of postoperative hospital stay (3.3 ± 1.0 days vs 8.7 ± 2.3 days; P < 0.01), earlier postoperative oral intake (1.5 ± 0.7 days vs 3.8 ± 2.1 days; P < 0.01), longer duration of antibiotic use (15.5 ± 2.7 days vs 8.6 ± 4.4 days; P < 0.01), and longer duration of total hospital stay (19.6 ± 3.8 days vs 10 ± 4.5 days; P < 0.01) in patients who underwent initial conservative treatment for appendiceal mass detected on US. There was a higher postoperative complication rate in patients who underwent emergency appendectomy with residual intraabdominal abscess (11.1% vs 0%), as well as a higher incidence of ileus (5.5% vs 0%) and a higher readmission rate (5.5% vs 0%), although none of these differences was statistically significant.
Two of 30 patients (6.6%) with initial US results that were negative for appendicitis were subsequently found to have appendicitis. Both false-negative US results were initially reported as severe colitis, and the patients underwent subsequent evaluation for protracted fever and abdominal pain. One underwent laparotomy for the US finding of turbid ascites with bowel stasis, and bowel perforation was suspected. The other had appendectomy for the abdominal computed tomography findings of abnormal calcification and local ileus over the right lower abdomen. Among the other 30 patients with other disease found on US, 15 had colitis, 10 had mesenteric adenitis, 2 had urinary disease, 2 had intestinal volvulus, and 1 had intussusception. During the study period, there were 43 children younger than 3 years of age with definite acute appendicitis, and 3 children were excluded from the study without US evaluation. The clinical characteristics of the 40 children are listed in Table 3. The duration of symptoms from presentation at our hospital was 4.6 ± 3.4 days. Only 2 of the 40 children had acute appendicitis without perforation. The overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of abdominal US to diagnose acute appendicitis in young children with atypical findings were 95.0%, 90.3%, 92.9%, 92.6%, and 93.3%, respectively.
Acute appendicitis is the most common cause of abdominal pain requiring surgery in children. The diagnosis of acute appendicitis is based on clinical findings. However, the initial symptoms of appendicitis in children younger than 3 years of age are often ill-defined and nonspecific (3). During the study period, appendicitis in children younger than 3 years of age accounted for 4% of cases of pediatric appendicitis in our hospital. Because of its rarity, it may not be easily recognized by clinicians. Young children are frequently unable to accurately communicate, and appendicitis in this population is characterized by delay in diagnosis and perforation (7,8). The clinical diagnostic challenge necessitates effective diagnostic tools to decrease the morbidity associated with acute appendicitis in early childhood. In this group, laboratory studies have been shown to be of little value in making a differential diagnosis in recent reports. An increased white blood cell count was noted in only half of the patients in the study by Nance et al (7). The usefulness of abdominal radiographs is also controversial. Alloo et al reported that abdominal radiographs demonstrated a fecalith in 0.1% of cases and may not have provided more specific findings effectively (7–10). Although the value of US imaging in the diagnosis of appendicitis is operator dependent, US has advantages of availability, low cost, and lack of ionizing radiation. Several studies suggest that the sensitivity and specificity of US scanning may be as high as 80% to 100% in the diagnosis of childhood appendicitis (11–13). In early childhood, reports of US in the diagnosis of acute appendicitis are rare and limited to case reports (14). We are unaware of other reports of evaluating the use of US for diagnosis of acute appendicitis in this group.
In our study, the positive predictive value was 92.6%. The 3 false-positive cases were 1 with appendiceal vermicularis and 2 with colon perforations. For patients with colon perforation, US revealed poor peristalsis, turbid ascites, and excessive bowel gas. In the case of vermicularis infection, the patient could not undergo US examination. Technical problems in our false-positive cases included extreme abdominal tenderness in vermicularis infection and excessive bowel gas in colon perforation. The negative predicative value was 93.3%. There were 2 false-negative cases. Findings in those patients were bowel edema and suspected colitis. The reason for the misdiagnosis may be related to the early stage of appendicitis with minimal edematous change, which failed to meet the diagnostic criteria of edematous appendix masked by bowel gases, or may be related to inexperienced US operators. Despite the false results, US is still a valuable tool with high sensitivity (95%) and specificity (90%) for diagnosis.
In our series, 28 of 40 patients (70%) with acute appendicitis were found to have tumor formation by US examination. Appendiceal mass occurs in approximately 10% of children with acute appendicitis (15). The uniquely high percentage of appendiceal mass makes US a potential and viable aid in early childhood appendicitis. Conservative treatment of acute appendicitis with tumor formation in older children may be associated with a lower incidence of complications such as adhesion ileus or intraabdominal abscess (16). Based on the US findings and clinical condition, 10 of 28 patients (35.7%) with ruptured appendicitis with tumor formation received initial conservative treatment. All of the patients were studied via US with successful gradual resolution of the appendiceal mass and received interval appendectomy 2 to 4 months later. Compared with patients who underwent emergency appendectomy, patients who underwent initial conservative treatment appendectomy in our study had a significant smoother postoperative course, including a shorter postoperative hospital stay and faster resumption of diet. The results of our study suggest that conservative initial treatment is safe in managing early childhood appendiceal mass, with lower postoperative complication and readmission rates, although not significantly so. It is associated with higher medical cost, mainly due to a longer duration of antibiotic treatment at hospital. Preoperative US in ruptured appendicitis with tumor formation can also reduce the difficulty of the surgical intervention in explosive laparotomy. The smaller size of the wound in young children may be associated with a better postoperative quality of life. Therefore, US can not only accurately determine acute appendicitis in early childhood but it can also provide more information concerning whether there is localized inflammatory mass, facilitating appropriate management and postoperative course.
This series confirmed the high diagnostic accuracy of US in appendicitis in early childhood. However, the perforation rate is as high as 95% in our study, which is as high as the incidences reported in other published series of appendicitis in children younger than 3 years of age (Table 4). The rarity of appendicitis in early childhood and a lack of awareness in diagnosis among clinicians, as reflected by a mean 4.6-day delay from onset of symptoms to emergency department admission, may explain the high incidence of ruptured appendicitis with tumor formation in our series. Other predisposing factors may be due to a thin-walled appendix prone to perforation in young children (17). In children younger than 3 years of age, diarrhea is reported in as many as 41% of cases of appendicitis and is more common than in older children. The frequent occurrence of diarrhea was often misinterpreted as gastroenteritis. In contrast, local abdominal tenderness is not as frequent as in older children (3,10). The negative predictive value of >93% in this series suggests that US could provide additional benefit by accurately selecting patients in whom admission or operation is not required. It should be emphasized that a history of diarrhea accompanying abdominal pain and fever in early childhood should not be dismissed as gastroenteritis. The primary care physician should understand the clinical picture and obtain timely US examinations and surgical consultation to decrease the incidence of perforation.
In conclusion, the presentation of early childhood appendicitis is often atypical and tends to be delayed, with a greater incidence of perforation with tumor formation. On the basis of our results, we find that children younger than 3 years of age receiving initial conservative treatment for ruptured appendicitis with tumor formation have a safe and smooth postoperative course. US is useful in the diagnosis of early childhood appendicitis for its high accuracy and the frequency of appendiceal masses found in patients at this age. The timely consideration of US for earlier diagnosis is essential in the elimination of the possibility of perforation.
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Keywords:© 2007 Lippincott Williams & Wilkins, Inc.
Appendicitis; Early childhood; Ultrasonography