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The Incidence Of Negative Appendicectomy Among Teenage Girls

Ike Njere¹, Nada Sudakharan², Ruth Nash³, Bruce Okoye²
¹Department of Paediatric Surgery, Hull Royal Infirmary, London, UK
²Department of Paediatric Surgery, St Georges Hospital, London, UK
³Department of Pathology, St Georges Hospital, London, UK
 

Abstract

Introduction: Acute appendicitis is the commonest surgical cause of an acute abdomen in children and adolescents. It can be a difficult diagnosis to make in the adolescent female. The aim of this study was to identify the negative appendicectomy rate in teenage girls.

Method: A 10 year retrospective analysis (March 1996 - February 2007) of all patients aged 0-16years that presented to our institution and underwent appendicectomy was done. The original histology reports and case records were reviewed. Incidental and interval appendicectomies were excluded. Means were compared using the Student’s t test and medians compared using the Mann-Whitney U test. Discrete variables were compared using the Chi-square test

Result: 424 children with acute abdominal symptoms underwent appendicectomy during the 10 year period. Normal histology of the appendix was identified in 56 (13.2%). The negative appendicectomy rate among females was 19.6% compared to 10.5% in males. (p=0.006) In females aged 13-16, 30% had a negative appendicectomy compared to 9% of males in the same age bracket (p=0.002). Females less than 13 years had a negative appendicectomy rate of 14.4% (p=0.02 vs females aged 13-16). Males less than 13 years had a negative appendicectomy rate of 11%. This was not significant when compared to females in the same age group.

Conclusions: A third of teenage girls undergoing appendicectomy do not have appendicitis. These results suggest that in this age group further investigation may be warranted to reduce the overall negative appendicectomy rates.

Key words: acute appendicitis, negative appendicectomy, teenage girls

 

Correspondence

Ike Njere
Department of Paediatric Surgery
Hull Royal Infirmary
Anlaby Road, Hull. HU3 2JZ, London, UK
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Introduction

Acute appendicitis is the commonest cause of acute abdomen in children and adolescents with an overall life time risk of 6% [1, 2]. It can be a difficult diagnosis to make in the adolescent female with abdominal pain and in the under 5 age group.

Negative appendicectomy rates of 10-20% have been considered acceptable to keep perforation rates down in children [1]. A rate of 19-28% has been noted in adult females [3, 4, 5]. Negative appendicectomy is associated with a complication rate of 6-14%, a case fatality rate of about 1.5% and considerable cost implications [6, 7, 8].The aim of this study was to identify the negative appendicectomy rate amongst teenage girls as compared with younger age groups.

Method

A 10 year retrospective analysis of the records of all patients aged 0-16 years who underwent appendicectomy at our institution between March 1996 and February 2007 was performed. Ethical approval was obtained. The diagnosis of appendicitis was made solely on the histological appearance of the appendix.

Patients who had undergone interval appendicectomy were excluded from the analysis.

Data was extracted and recorded on an excel spread sheet. Statistical analysis was carried out with Stata software version 8.2 (Statacorp Lakeway drive, College Station, Texas, USA.). Means were compared using the Student’s t test and medians compared using the Mann-Whitney U test. Discrete variables were compared using the Chi-square test. The best cut off values for WBC and CRP were obtained by constructing receiver operating characteristics curves (ROC).

Results

In total 424 children underwent appendicectomy. The mean age was 9.8±4.0 years (157 girls, 267 boys). On histology, there was a normal appendix in 56 cases, an overall negative appendicectomy rate of 13 %.

Amongst girls, the overall negative appendicectomy rate was 19% (30/157) compared to 10 % (26/267) in males. (p=0.006). Girls under the age of 13 years had a negative rate of 14% compared to 10 % amongst boys in the same age group (p=0.3 value)

Females aged 13-16 had a negative appendicectomy rate of 30% compared to 8.5% in males of the same age bracket (p=0.002)

The normal appendicectomy rate in girls aged 13 -16 was also markedly higher when compared with that in girls and boys under the age of 13 years. (p=0.02 vs girls, p < 0.01 vs boys) Negative appendicectomy rates did not alter significantly over the period of study. (Fig. 1)

Figure 1: Graph of Inflamed and Normal appendices removed by year

 pic 1

Preoperative investigations

Seventy five (18%) patients had some form of investigation. Ultrasound in 51 (12%) and abdominal CT scan only 3 (0.7%). CT scan correctly diagnosed appendicitis in all three patients. Abdominal x-ray (n=27, 6%).

Abdominal radiography suggested intra-abdominal pathology in 6 (22%) patients who had an x-ray. - appendicolith in 2 and dilated bowel 4.

All 6 had confirmed appendicitis. Ultrasound (n=51, 12% ) – A diagnosis of appendicitis was made on ultrasound scan in 25 patients. Nine were reported as normal whilst 17 had non-specific findings such as free fluid in the peritoneal cavity.

Of the 25 reported to have appendicitis, 24 (96%) were confirmed on histology and one was normal giving ultrasound a positive predictive value of 96%. Five (56%) of the 9 noted to be normal on ultrasound scan had appendicitis while 11 (65%) of the 17 with non-specific findings also had appendicitis.

Patients who had an ultrasound scan and went on to undergo appendicectomy had a normal appendix in 22% (11/51) compared with a negative rate of 12% (45/372) in those that did not undergo any radiological investigation. (p=0.05)

In the 13 to 16 age group, 10 girls had abdominal ultrasound scans. Three were reported as normal of which one had appendicitis. In the two cases reported as showing appendicitis, one was confirmed at surgery. The remaining 5 had non-specific findings on ultrasound scan of which 2 had appendicitis.

Haematological indices - Of the patients who underwent appendicectomy, the median white blood count (WBC) in patients with appendicitis was 14.7 compared to 9 in those with a normal appendix (p less 0.01). The median WBC for patients with perforated appendicitis was 14.8 (p=0.96 vs non-perforated).

The median C - reactive protein (CRP) for patients with inflamed appendix was 46.1 compared to 5 in those with normal appendix (p < 0.01). The median CRP was 33 in patients with non-perforated appendicitis compared with 125 in patients with perforated appendicitis (p < 0.01).

Perforation rates - The overall perforation rate was 22% with a rate of 40% in the under 5 year olds, 26% in the 5-10year olds and 15% in those aged 10 years and above.

Associated diagnoses - Of the 56 with a normal appendix, 29 (51.8%) had some kind of lesion associated with the appendix. (Table 1).

Table 1. Lesions associated with the non-inflammed appendices 

Lesion

Frequency

Carcinoid

1

Fibrosis

1

Lymphoid Hyperplasia

11

Periappendicular inflammation

6

Pin Worm

8

Vegetable debris

2

Discussion

An overall negative appendicectomy rate of 10-20% has been considered acceptable in children to reduce the incidence of perforation [1]. However negative appendicectomy is not a completely benign procedure [6, 7, 8]. Our negative appendicectomy rate of 13% agrees with the findings of other studies although negative rates as high as 25% in male children and 35% in female children have been reported [9-12].

Negative appendicectomy rates of 33.5% have been reported in reproductive females aged 13-50 years [13]. This correlates closely with our findings in girls in the 13-16 year age group.

Girls in this group therefore present an opportunity for reducing unnecessary surgery. This could be achieved by intensively investigating this group. However, the optimal means of investigation remains unclear and the superiority of imaging or blood tests over regular physical examination is unproven.

Plain abdominal radiograph was not found to be useful in this study. The use of ultrasonography in children with suspected appendicitis has been widely reported. We deliberately did not assess the specificity of ultrasound in this study since we did not study patients who may have been discharged home following a normal ultrasound (presumed true negatives). However, ultrasound only had a sensitivity of 60%, although the positive predictive value was high. It was also noteworthy that more of the patients with a negative appendicectomy had undergone ultrasound then those with proven appendicitis, probably because those with appendicitis were more likely to be diagnosed on clinical grounds. This could however suggest a possible misleading effect of ultrasound on clinical decision making. Several studies have found that ultrasound scan does not improve outcome of patients with appendicitis in terms of reducing perforation rates, hospital stay or postoperative complications [12, 14, 15]. It however was associated with increased cost of care [14, 15]. In general, sensitivity rates of 75 – 100% have been reported for the use of ultrasonography in diagnosing appendicitis [16]. This wide variation in the efficacy of ultrasound would suggest that it is unlikely to reduce negative appendicectomy rates in this group of patients.

There has been a trend in some centers away from the use of ultrasound towards cross sectional imaging. Only 3 patients in our series had a CT scan, reflecting widespread practice in the UK. However, CT scan would appear to have superior sensitivity and specificity when compared to ultrasound. In solely paediatric studies, CT has a sensitivity of 88-97% and a specificity of 94-97% [17]. In addition, it has been shown to reduce negative appendicectomy rates [12, 18]. Unfortunately, there is an associated risk of radiation-induced malignancy (RIM) due to the significant dose of ionizing radiation [19]. The lifetime cancer mortality risks from paediatric CT examination are considerably higher than for an adult [19]. It has been estimated that a 1 year old undergoing abdominal CT would have a lifetime risk of fatal RIM of 0.18% compared to 0.11% if they were 15 years at the time of exposure. In other words 1 in 550 children exposed to a single abdominal CT examination at 1year of age would go on to develop a fatal RIM. On the other hand nearly twice as many 15 year olds would need to be scanned for one to develop a fatal RIM. This is because younger children have more actively dividing cells and more time available for malignant transformation to take place [19]. Therefore, although the risks are considerably less in the older child, they are an important consideration.

Early laparoscopy may be of benefit in this particular group of patients. Some studies have suggested that laparoscopy reduces the rate of negative appendicectomy in doubtful cases and also provides a higher diagnostic accuracy because it enables the surgeon to identify other pathologies [20, 21]. However, many surgeons would remove a normal appearing appendix at laparoscopy in the absence of any other obvious pathology to which the symptoms could be attributed. The use of laparoscopy has therefore also been associated with an increased negative appendicectomy rate [22, 23]. Apart from identifying other pathologies, laparoscopy has not been shown to be superior to clinical observation in other outcome measures [24, 25].

A raised white count and or CRP may be of benefit in making a diagnosis of acute appendicitis when taken in combination with other clinical features but is not sufficiently discriminatory alone to make a firm diagnosis [26, 27].

Therefore, although the negative appendicectomy rates in girls between 13 and 16 years of age appears unacceptably high, it is less clear how to significantly reduce this. It would appear that a more measured approach to the clinical assessment of these girls would be most likely to bear fruit. Indeed, it has been demonstrated that most children with abdominal pain have complete resolution of their symptoms within 48 hours if they do not have a significant pathology28. Also, active observation has been shown to yield consistently low negative appendicectomy rates without a rise in perforation rates [24, 25].

Conclusion

We would advocate a healthy awareness amongst clinicians that a third of girls aged between 13 and 16 undergoing appendicectomy do not have appendicitis on histology. Careful and repeated physical examination is recommended in this group of patients in order to avoid unnecessary surgery.

 

 

 

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