Role of imaging in the diagnosis of acute appendicitis in children

Evaluating Changes in Diagnostic Accuracy of Ultrasound for Appendicitis: Does Practice Make Perfect?

BACKGROUND

Ultrasound (US) is the preferred method of initial evaluation for appendicitis in pediatrics. However, limited accuracy of US for appendicitis is an obstacle to implementation of US-first protocols at facilities less experienced with US.

OBJECTIVES

The primary objective was to demonstrate changes in diagnostic accuracy of US for appendicitis over time, after implementation of an US-first protocol. Secondary objectives included evaluating trends in utilization and factors associated with accuracy of US.

METHODS

We reviewed 5 years of pediatric emergency department encounters that included US evaluations for appendicitis. The primary outcome was conclusive US (fully visualized normal appendix or unequivocal appendicitis) vs. equivocal US (partially visualized or nonvisualized appendix). We also analyzed rates of conclusive US over time; accuracy, sensitivity, and specificity of US for appendicitis; and associations of US accuracy with patient gender, body mass index, and ultrasonographer's experience.

RESULTS

A conclusive US report was found in 267 of 1058 encounters (25.2%); overall accuracy rate was 24.5%. Over 5 years, the diagnostic accuracy of US for appendicitis improved significantly from 13.9% to 31.5% (p = 0.001). Overall sensitivity was 80.7% and specificity was 77.6%. Male gender and dedicated US of the appendix were significantly associated with conclusive US (ps < 0.001). Higher body mass index was significantly associated with equivocal US (p < 0.001). Ultrasonographer experience was not significantly associated with conclusive US (p = 0.22).

CONCLUSIONS

An US-first imaging protocol for appendicitis in children shows chronologic improvement in diagnostic accuracy. This may provide encouragement to facilities using computed tomography-based diagnostic protocols to implement US-first protocols to reduce childhood radiation exposure.

Pediatric appendicitis: pathophysiology and appropriate use of diagnostic imaging

Evaluating children for appendicitis can be extremely difficult, and various strategies have been developed to improve the precision of preoperative diagnosis. Among these, ultrasound and computed tomography (CT) are now widely used but remain controversial. Although CT scanning is superior to ultrasound in terms of diagnostic accuracy for appendicitis, the large dose of ionizing radiation from CT and the risk of subsequent radiation-induced malignancy (RIM) are of particular concern in pediatric patients. This article reviews the literature on the pathophysiology, morbidity and mortality of appendicitis, summarizes the data regarding pediatric imaging in appendicitis, provides a practical approach to imaging for clinicians who evaluate pediatric patients, and makes recommendations for reducing the risk of RIM in pediatric patients.

Properties of serial ultrasound clinical diagnostic pathway in suspected appendicitis and related computed tomography use

OBJECTIVES

The primary objective was to determine the diagnostic accuracy of a serial ultrasound (US) clinical diagnostic pathway to detect appendicitis in children presenting to the emergency department (ED). The secondary objective was to examine the diagnostic performance of the initial and interval US and to compare the accuracy of the pathway to that of the initial US.

METHODS

This was a prospective cohort study of 294 previously healthy children 4 to 17 years old with suspected appendicitis and baseline pediatric appendicitis scores of ≥2, who were managed with the serial US clinical diagnostic pathway. This pathway consisted of an initial US followed by a clinical reassessment in each patient and an interval US and surgical consultation in patients with equivocal initial US and persistent concern about appendicitis. The USs were interpreted by published criteria as positive, negative, or equivocal for appendicitis. Children in whom this pathway did not rule in or rule out appendicitis underwent computed tomography (CT). Cases with missed appendicitis, negative operations, and CTs after the pathway were considered inaccurate. The primary outcome was the diagnostic accuracy of the serial US clinical diagnostic pathway. The secondary outcomes included the test performance of the initial and interval US imaging studies.

RESULTS

Of the 294 study children, 111 (38%) had appendicitis. Using the serial US clinical diagnostic pathway, 274 of 294 children (93%, 95% confidence interval [CI] = 90% to 96%) had diagnostically accurate results: 108 of the 111 (97%) appendicitis cases were successfully identified by the pathway without CT scans (two missed and one CT), and 166 of the 183 (91%) negative cases were ruled out without CT scans (14 negative operations and three CTs). The sensitivity of this pathway was 108 of 111 (97%, 95% CI = 94% to 100%), specificity 166 of 183 (91%, 95% CI = 87% to 95%), positive predictive value 108 of 125 (86%; 95% CI = 79% to 92%), and negative predictive value 166 of 169 (98%, 95% CI = 96% to 100%). The diagnostic accuracy of the pathway was higher than that of the initial US alone (274 of 294 vs. 160 of 294; p < 0.0001). Of 123 patients with equivocal initial US, concern about appendicitis subsided on clinical reassessment in 73 (no surgery and no missed appendicitis). Of 50 children with persistent symptoms, 40 underwent interval US and 10 had surgical consultation alone. The interval US confirmed or ruled out appendicitis in 22 of 40 children (55.0%) with equivocal initial US, with one false-positive interval US.

CONCLUSIONS

The serial US clinical diagnostic pathway in suspected appendicitis has an acceptable diagnostic accuracy that is significantly higher than that of the initial US and results in few CT scans. This approach appears most useful in children with equivocal initial US, in whom the majority of negative cases were identified at clinical reassessment and appendicitis was diagnosed by interval US or surgical consultation in most study patients.

Clinical outcomes in obese and normal-weight children undergoing ultrasound for suspected appendicitis

BACKGROUND

Obesity constitutes an independent predictor for a nondiagnostic screening ultrasound (US) in suspected appendicitis. Furthermore, the imaging route consisting of the screening US with a second US if necessary has a significantly lower diagnostic accuracy in the obese children (83%) than their lean counterparts (93%). However, the effect of this association on clinical outcomes in the obese population is unknown.

OBJECTIVES

In children presenting to the emergency department (ED) undergoing US for suspected appendicitis, the objective was to examine if there is a significant difference in the proportions of those with a "desirable outcome" in the obese group versus their normal-weight counterparts.

METHODS

This was a reanalysis of a recent prospective cohort study conducted at a tertiary care pediatric ED. A consecutive sample of 263 previously healthy children 4-17 years of age undergoing screening US for suspected appendicitis was enrolled. Study patients were divided into obese (body mass index-for-age percentiles [BMI-FAP] ≥ 85%) and normal-weight groups. The main outcome was the proportion of children with the desirable outcome in the obese and normal-weight groups. Desirable outcomes for patients with a nondiagnostic screening US were defined as either 1) nonperforated appendicitis or alternate surgical diagnosis undergoing appropriate surgical procedure within 24 hours of assessment without a computed tomography (CT) scan or 2) no appendicitis, discharged from the ED within 24 hours without a CT scan. Secondary outcomes included hospitalization, CT imaging for any reason within 30 days of initial presentation, length of hospital stay, return visits, time to and length of surgery, and complications.

RESULTS

Of the 263 patients, 76 (28.9%) were obese, and 187 had a normal weight. Ninety-nine children (37.6%) had appendicitis (obese = 24, normal-weight = 75). The desirable outcome was achieved in 46 (64.5%) of the obese patients versus 137 (73.3%) of the normal-weight children (95% confidence interval [CI] for the difference = -0.21 to 0.04). Compared to the normal-weight children, the obese children had similar hospitalization rates (44.7% vs. 45.5%), median length of hospital stay (20.5 hours vs. 23.0 hours), and return ED visit rates (11.8% vs. 9.1%). The median time to surgery (obese = 10.5 hours, normal-weight = 9.0 hours), complications (obese = 25%, normal-weight = 21.3%), perforations (obese = 33%, normal-weight = 31%), and length of surgery (obese 80 [±37] minutes, normal-weight 67 [±25] minutes) were also similar. The rate of CT within 30 days of initial presentation was higher in the obese compared to the normal-weight group (13/76 or 17.1% vs. 13/187 or 6.9%, 95% CI = 0.02 to 0.23).

CONCLUSIONS

Previously healthy obese children undergoing screening US for suspected appendicitis experienced comparable clinical outcomes to their normal-weight counterparts. However, they were three times more likely to receive a CT scan during their investigation. These results argue for continuing current practice of using the screening US in this population, followed by a CT if clinically warranted upon reexamination.

Predictors of non-diagnostic ultrasound scanning in children with suspected appendicitis

OBJECTIVE

To determine predictors of diagnostically inaccurate ultrasound scanning for suspected appendicitis.

STUDY DESIGN

Prospective emergency department cohort study of 263 previously healthy children 4 to 17 years of age undergoing ultrasound scanning. Ultrasound scanning results were interpreted as positive, negative, or equivocal for appendicitis and classified as diagnostically accurate and inaccurate. The main outcome measure was association between inaccurate ultrasound scanning and age, sex, body mass index percentiles, pain duration, white blood cell count, Faces Pain Score-Revised, clinical probability of appendicitis, and ultrasound scanning operator.

RESULTS

Of the 263 patients, 95 ultrasound scanning examinations were read as positive, 76 as negative, and 92 were equivocal. A total of 162 (61.6%) ultrasound scanning examinations were accurate (TP86, TN76), and 101 (38.4%) ultrasound scanning examinations were inaccurate (FP88, FN13). Children with body mass index percentiles ≥ 85 and clinical probability of appendicitis ≤ 50% had 58.1% probability of inaccurate ultrasound scanning examination (odds ratio, 2.48; 95% confidence interval, 1.48-2.78). In lean children, diagnostic accuracy of the screening ultrasound scanning examination with second ultrasound scanning or clinical reassessment was 93% versus 83% in the obese children (95% confidence interval of the difference, 1-19%).

CONCLUSION

Screening ultrasound scanning for pediatric appendicitis has suboptimal accuracy, particularly in obese children with a low likelihood of appendicitis who should not routinely undergo ultrasound scanning. However, when followed by a second ultrasound scanning or a clinical reassessment, it offers high diagnostic accuracy in lean children.

Pelvic plastron secondary to acute appendicitis in a child presented as appendiceal intussusception. A case report

We report an unusual case of an 11-year-old Greek girl with complicated acute appendicitis. The pelvic plastron that had been formatted secondary to appendix perforation was mimicking appendiceal intussusception in the preoperative ultrasound and computed tomography images. Although acute complicated appendicitis and appendiceal intussusception may represent possible causes of acute abdomen no similar cases have reported in the literature.

Appendicitis in the obese child

BACKGROUND/PURPOSE

Little data exist that examine the surgical challenges of obese children. We hypothesize that obesity affects the presentation, diagnosis, surgery, and postoperative course in children with appendicitis.

METHODS

Cases of all children treated for appendicitis over 6 years were reviewed retrospectively. Demographics, presentation, pathology, and hospital course were examined.

RESULTS

A total of 282 cases were reviewed; 25 were moderately obese and 31 very obese (VO), which were defined, respectively, as greater than 1.5 and greater than 2 standard deviations above the standardized mean weight for age. Groups were similar in age, sex, presentation, use of ultrasound, and surgical management. Compared with the nonobese group, median operative time was higher in the VO group (63.5 vs 55.5 minutes; P = .028), with the association between obesity and longer operative time maintained when stratifying for perforated/nonperforated and open/laparoscopic cases. Almost twice as many VO children were in the hospital for more than 5 days (nonobese 23.6%, VO 40.0% [odds ratio, 2.2; 95% confidence interval, 0.99-4.8]). This association between obesity and longer length of stay was seen when stratifying for both perforated and nonperforated cases. In the perforated group, higher rates of postoperative wound infections and significantly longer times to full diet and ambulation likely contributed to these longer stays.

CONCLUSIONS

Childhood obesity is associated with longer surgery and hospital stays and increased risk of postoperative infections. Obesity should be considered an important variable when looking at surgical outcomes in the pediatric population.

Appendiceal abscess drainage

Appendicitis is the most common abdominal inflammatory process in children, and the most frequent indication for abdominal drainage encountered in pediatric interventional radiology. Imaging in the diagnosis of appendicitis is evolving with CT becoming more common, although the incidence of perforation is not definitely improving. Tailored CT techniques for the diagnosis of acute appendicitis are designed to expedite care, but are not optimal in the diagnosis or characterization of abscesses. In the appropriate clinical setting the CT study needs to be altered for appropriate therapeutic planning. Drainage of appendiceal abscesses utilizes multiple techniques, some of which are more useful in children than adults. Image-guided drainage can facilitate a more limited surgery and can avoid repeat surgery from postoperative abscesses. Radiation doses must be minimized due to the increased risk in children. This article will discuss imaging in children with suspected appendiceal abscesses and drainage techniques.

Ultrasound evaluation of acute abdominal emergencies in infants and children

Ultrasound is extremely beneficial in the evaluation of acute pediatric abdominal disease, such as HPS, intussusception, and acute appendicitis. As techniques and equipment improve, its role in the evaluation of infants and children continues to increase.