Diagnosing Acute Appendicitis in Children

By Mr Martin C Brett, Consultant General and Gastro-Intestinal Surgeon

Many cases of acute appendicitis occur in teenagers and young adults, but it can occur from infancy to old age. The typical abdominal pain starts in the centre of the abdomen and migrates to the right lower quadrant, is made worse by movement, and accompanied by lethargy and loss of appetite. The pulse rate and temperature may be raised and abdominal examination my reveal tenderness and guarding (muscle tensing) at the site of the pain. Untreated an inflamed appendix may form an “appendix mass”, a palpable swelling in the right lower abdomen formed by adhesion of surrounding organs and possibly containing an abscess. If an inflamed appendix perforates (bursts) and is not contained within a mass, infection may spread rapidly through the abdomen (generalised peritonitis) causing severe, widespread abdominal pain and leading to fatality unless treated rapidly. However, not all presentations are typical, particularly in younger children. Vomiting and diarrhoea may be the dominant symptoms, with abdominal pain and tenderness less marked, and not localised to the right lower abdomen, or the child may simply seem to be “off food”, lethargic and “unwell”.

Many other conditions may mimic appendicitis. Particularly common in children is “mesenteric adenitis”, where a virus infection results in inflammation of the lymph glands in the abdomen. Confusion can arise from urinary tract infections and other less common bowel pathology. In adolescent girls, gynaecological pathology may also cause lower abdominal pain. Vomiting and diarrhoea are more frequently caused by infective agents than an inflamed appendix.

When I was a trainee in the late 1980’s, diagnosis of acute appendicitis, once urine examination had excluded a urinary tract infection, was based on symptoms and signs rather than on investigation. In many equivocal cases the presenting symptoms and signs settled within 24 hours without intervention, but if the cluster of symptoms and signs was considered sufficiently suggestive, appendicectomy was performed, usually through an incision in the right lower abdomen (open appendicectomy). On average about 20% of appendices proved to be normal but were still removed to avoid confusion (negative appendicectomy). Sometimes an alternative diagnosis could be mad, some of which required surgical treatment, but in a proportion no abnormality could be identified. The widely accepted wisdom was that a surgeon with a negative appendicectomy rate of less than 20% was inappropriately delaying appendicectomy and risking perforation. However, if an appendix mass was present initial therapy with antibiotics was considered appropriate.

The NICE guidelines on glue ear outline the presentation of glue ear with a history of repeated ear infections or earache, recurrent upper respiratory tract infections or frequent nasal obstruction and hearing difficulty. The claimant in this case suffered from all of these symptoms and although it may have seemed appropriate that she had been diagnosed with glue ear, there is an overlap in the presentation and symptoms of glue ear and cholesteatoma. The claimant in this case had predominantly unilateral ie left sided ear discharge. Otorrhoea can be seen in glue ear but is less common than the hearing loss that is seen. Persistent and unilateral discharge should have prompted the search for another cause. In addition the hearing loss that was diagnosed was moderate to severe whereas the typical level of hearing loss in glue ear is mild. A misinterpretation of the claimant’s symptoms as being due to glue ear led to a delay in the diagnosis of the underlying cholesteatoma and a delay in the appropriate, curative surgery.

Has the diagnostic process improved over the last 30 years?

C-reactive protein, a blood inflammatory marker is now readily available and with a much wider numerical range than the traditional White Cell Count. Often it only rises after 24 hours and, like White Cell Count is non-specific, but it indicates a more persistent inflammatory response, particularly if the rise continues. Imaging investigations include Computerised Tomography (CT scan), Magnetic Resonance Imaging (MRI) and Ultrasonography (US). Both CT and MRI are approximately 95% sensitive and specific for acute appendicitis. Ultrasound examination is less accurate but useful for establishing the presence of an abscess and useful for investigating possible gynaecological pathology. However, CT scanning involves a substantial X-Ray exposure with the potential, particularly in the young, to increase cancer risk. However, the risk may still be small, particularly with modern lower dose scanners, and of less overall consequence than missing a serious diagnosis. MRI does not involve X-Ray exposure but requires lying in a tunnel with potential for claustrophobia. It may be challenging for children as the scanning time is longer than for CT and movement may result in blurred images. Ultrasound examination involves pressure on a tender abdomen, is less reliable in the obese and is operator dependent. Given the undesirability of repeated investigation in children, timing any imaging may be challenging. The diagnosis may be missed diagnosis if carried out too early or complication and treatment delay may result of it is carried out too late. Many surgeons are reluctant to rely on imaging to exclude appendicitis in the presence of marked and persisting abdominal tenderness, particularly with a raised temperature and / or pulse rate.

In decades past open appendicectomy was regarded as the definitive investigation and treatment. More recently laparoscopic surgical techniques (keyhole surgery) have improved diagnostic capability and reduced surgical stress. Expertise in the application of both imaging and laparoscopic techniques to children is generally higher in specialist tertiary paediatric hospitals, However, most children with acute illness will be managed, at least initially, in the general secondary care sector and referral to a tertiary centre could be another source of treatment delay.

Given the difficulties above I find it difficult to be precise as to what can reasonably be expected of competent practitioners presented with a child or young person in whom acute appendicitis is possible. However, in my view, the following elements are as valid now as they were in the earliest part of my training:

  1. A low index of suspicion for acute appendicitis given the varying presentation.
  2. Careful surgical assessment and frequent re-evaluation to check for worsening symptoms and signs with prompt action if there is any deterioration.
  3. Regular nursing observations including pulse rate and temperature with prompt action on any deterioration.
  4. For those discharged after apparent resolution of symptom / signs without treatment, advice to the parents to return if they have any concerns.
  5. Careful documentation of the above.

In the relatively few adverse events I have encountered related to acute appendicitis in the young I believe that the measures above would largely have been preventative. Hopefully in years to come continued improvements and wider application of imaging and laparoscopic techniques in children will reduce negative appendicectomy rates and the stress of surgical intervention. However, at present I still believe expeditious open appendicectomy to be an acceptable treatment option if there is reasonable likelihood of acute appendicitis.

About the Author:

Mr Martin C Brett, M.B. B.S. M.A. F.R.C.S. ChM is a Consultant General and Gastro-Intestinal Surgeon for both adults and paediatrics and has a broadly based general surgical practice with special interests in upper gastrointestinal surgery, minimal access surgery, hernia surgery and general paediatric surgery.

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