Paediatric Appendicitis

7-year-old Tilly is brought to your emergency department at 11 p.m. by her father. She has had abdominal pain for two days, and it has now moved to the right side. She is obviously uncomfortable.

Abdominal pain in children is common, accounting for over 1 in 20 attendances to paediatric emergency departments [1]. Differentiating between self-limiting and surgical conditions can be particularly challenging in younger patients who often present with non-specific symptoms and signs.

Acute appendicitis is the most prevalent paediatric surgical emergency, with more than 11,000 children undergoing appendicectomy in England each year [2]. The classical clinical presentation of periumbilical pain migrating to the right iliac fossa with fever, nausea and vomiting occurs in less than half of paediatric cases, resulting in a high risk of delayed diagnosis and appendiceal perforation.

On the other hand, misdiagnosis of appendicitis can lead to unnecessary surgery, with the rate of negative appendicectomy reported to be as high as 16% in the paediatric population [3]. There is significant responsibility placed on the emergency department clinician who may be faced with a diagnostic dilemma in children presenting with acute abdominal pain.

How does appendicitis present in kids?

Tilly’s father explains that she has been unwell for two days with worsening abdominal pain. She had a low-grade fever and an episode of vomiting before coming to the hospital.

Tilly is normally fit and well, with no significant past medical history. She takes no regular medications and has no known allergies. Her immunisations are up to date.

Symptoms

A careful clinical history can help to elicit the more typical presenting symptoms of appendicitis [4]:

• Anorexia
• Periumbilical pain
• Migration of pain to the right lower quadrant
• Pain with movement: walking or shifting position in bed or on stretcher
• Nausea and vomiting (typically occurring after the onset of pain)
• Fever

Paediatric patients with appendicitis, particularly preschool children, often present with atypical symptoms. Low-grade fever and irritability may be the only hallmarks of evolving appendicitis in a two-year-old child, so be cautious and adopt a lower threshold for further investigation in this age group.

Signs

On examination, Tilly has a low-grade fever (38.1 degrees) with associated tachycardia. Her abdomen is soft with generalised tenderness, maximal in the right lower quadrant.

Before examining a child with abdominal pain, carry out an age-appropriate pain assessment and provide adequate analgesia. Examine them in the position in which they are most comfortable before attempting a supine abdominal assessment.

Important physical examination findings in paediatric appendicitis include [4]:

• Tenderness in the right iliac fossa
• Right lower quadrant tenderness elicited by cough, hopping or percussion
• Involuntary muscle guarding during abdominal palpation
• Fever

More subtle features include a limp or difficulty ambulating, wanting to lie still, irritability, or a quiet/withdrawn child. Always consider acute appendicitis when these features are present in the context of abdominal pain.

The Rovsing, Obturator and Iliopsoas signs – although potentially of use in older children and adolescents – are rarely present and often difficult to elicit in younger children.

Rovsing’s sign

To perform Rovsing’s sign, gently palpate the lower left quadrant of the patient’s abdomen. If this pressure causes the patient to experience pain or tenderness in the lower right quadrant of the abdomen, it is considered a positive Rovsing sign.

When pressure is applied to the left side, it can cause the appendix to move or rotate slightly. This movement or rotation can trigger increased pain or discomfort in the right lower abdomen if the appendix is inflamed.

Danish surgeon Niels Thorkild Rovsing first described this clinical sign in 1907 as part of his work on the diagnosis of appendicitis.

Obturator sign

Flex the patient’s right thigh at the hip with the knee bent at a 90-degree angle. Then, gently internally and externally rotate the leg. This causes the obturator muscle to rub against the inflamed appendix in the lower right abdomen. If this manoeuvre causes pain or discomfort, particularly in the lower right quadrant, it can be considered a positive obturator sign and may suggest an inflamed appendix or other issues in that area.

Illiopsoas sign

Ask the patient to lie on their back. Then, lift the patient’s right leg while the knee is extended and apply upward pressure on the leg. This stretches the iliopsoas muscle. If this manoeuvre causes pain or discomfort in the lower right quadrant of the abdomen, it can be considered a positive iliopsoas sign.

You must perform a scrotal examination in all male patients presenting with acute abdominal pain in order to exclude time-critical differential diagnoses, such as testicular torsion.

What lab tests do you need for acute appendicitis?

Appendicitis remains a clinical diagnosis, and further investigations, such as blood tests, are not always needed to confirm or exclude the diagnosis. However, owing to the atypical presentation and diagnostic difficulty in many paediatric patients, blood tests can be useful in evaluating the likelihood of appendicitis. Laboratory markers should always be used in collaboration with physical symptoms and signs and not in isolation.

White cell count (WCC), absolute neutrophil count (ANC) and C-reactive protein (CRP) are the most frequently reported blood tests in the literature. However,  these inflammatory markers are poorly specific and are not capable of differentiating between other causes of acute abdominal pain in children. Inflammatory markers are generally considered to be more useful in ruling out appendicitis rather than ruling in.

A recently published meta-analysis of 67 studies found that “the best performing single blood tests for ruling out appendicitis are WCC and ANC” [5]. Although there is no clear consensus on the optimal thresholds, a WCC < 10,000 cells/mL and ANC < 7500 cells/mL are the most frequently reported cut-offs.

CRP is also widely used, but sensitivity and specificity vary widely between studies. There is more consistency when CRP is used to assess the severity of appendicitis. In one study of 78 children with histologically confirmed appendicitis, the mean CRP was significantly higher in patients with perforated appendicitis than those with simple appendicitis (92 vs 31mg/L) [6].

Other biomarkers, including procalcitonin, platelet count and lactate, have also been investigated, but there is limited evidence for their utility. In a recently published meta-analysis encompassing over 8000 children with undifferentiated abdominal pain, most laboratory markers had poor test characteristics, emphasising the importance of using blood tests in conjunction with the wider clinical picture [7].

Remember to request a clean-catch urine sample in children presenting with acute abdominal pain –  dipstick urinalysis can be useful in the work-up. Remember to test for urine b-HCG in female patients.

Clinical scoring tools for appendicitis

The recently published Best Practice Pathway Guidance by NHS England recommends using clinical risk scores to assess all children with suspected appendicitis. These structured assessments, combining clinical signs and laboratory markers, risk-stratify patients into low-, medium- and high-risk categories. Clinical scoring tools have improved diagnostic performance in assessing suspected appendicitis in the emergency department.

The earliest of these scoring tools, the Alvarado score, was initially presented in a study of 305 patients with acute abdominal pain [8]. Still, subsequent studies in paediatric cohorts have failed to demonstrate sufficient accuracy. A range of newer, paediatric-focussed scores have since been developed, and NHS England currently recommends the use of either the Children’s Appendicitis Score (CAS) or the Shera Score. A multicentre study comparing 15 different appendicitis risk prediction tools concluded that the Shera score (Figure 1) was the best-performing model [9].

Children with a low Shera score (less than 3) who are otherwise systemically well may be suitable for discharge home with safety netting advice, whereas patients with high scores (8 or more) warrant immediate surgical referral. Patients with intermediate scores (3-7) require further investigation and/or observation to confirm or exclude a diagnosis of appendicitis.

Using a clinical scoring tool has the advantage of providing a standardised framework for evaluating all cases of suspected appendicitis. By using a combination of specific symptoms, physical examination findings and laboratory markers, these scores help to maximise diagnostic performance.

What is the best imaging test for a child with suspected appendicitis?

In children with an atypical presentation or in whom appendicitis cannot be excluded clinically, imaging can be helpful to establish or exclude the diagnosis. Ultrasonography, computerised tomography (CT) and magnetic resonance imaging (MRI) are all used in the evaluation of suspected appendicitis.

Although CT is used widely in adults, concern about radiation exposure and the associated lifetime risk of malignancy limits its use in children.

MRI has excellent diagnostic performance, but its use is limited by cost, availability and the potential need for sedation in younger children.

Ultrasonography is, therefore, generally considered to be the first-line imaging modality. It avoids unnecessary radiation, is relatively inexpensive and is available in most institutions.

Ultrasound has been associated with lower rates of negative appendicectomy. In a meta-analysis of 26 paediatric studies, the pooled sensitivity and specificity of ultrasound for diagnosing appendicitis in children were 88% and 94%, respectively [10]. However, the test performance depends on whether the appendix is visualised or not. Factors which directly contribute to this include the child’s body habitus and the expertise of the sonographer. When the appendix cannot be visualised or the findings are equivocal, and there is ongoing clinical concern for appendicitis, both CT and MRI can have a role.

References

1. Armon, K., Audit: Determining the common medical presenting problems to an accident and emergency department. Archives of Disease in Childhood, 2001. 84(5): p. 390-392.
2. Hospital Admitted Patient Care Activity. NHS Digital 2021-22; Available from: https://digital.nhs.uk/data-and-information/publications/statistical/hospital-admitted-patient-care-activity/2021-22.
3. Bachur, R.G., et al., Diagnostic imaging and negative appendectomy rates in children: effects of age and gender. Pediatrics, 2012. 129(5): p. 877-84.
4. Bundy, D.G., et al., Does This Child Have Appendicitis? JAMA, 2007. 298(4).
5. Fawkner-Corbett, D., et al., Diagnostic accuracy of blood tests of inflammation in paediatric appendicitis: a systematic review and meta-analysis. BMJ Open, 2022. 12(11): p. e056854.
6. Chung, J.-L., et al., Diagnostic value of C-reactive protein in children with perforated appendicitis. European Journal of Pediatrics, 1996. 155(7): p. 529-531.
7. Benabbas R, Hanna M, Shah J, Sinert R. Diagnostic Accuracy of History, Physical Examination, Laboratory Tests, and Point-of-care Ultrasound for Pediatric Acute Appendicitis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2017 May;24(5):523-551.
8. Alvarado, A., A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med, 1986. 15(5): p. 557-64.
9. RIFT Study Group on behalf of the West Midlands Research Collaborative. Appendicitis risk prediction models in children presenting with right iliac fossa pain (RIFT study): a prospective, multicentre validation study. Lancet Child Adolesc Health. 2020 Apr;4(4):271-280.
10. Doria, A.S., et al., US or CT for Diagnosis of Appendicitis in Children and Adults? A Meta-Analysis. Radiology. 2006 Oct;241(1):83-94.