Appendicitis

Appendicitis: Symptoms, diagnosis and modern treatment

Appendicitis is one of the most common acute abdominal surgical emergencies in Denmark. A systematic review of population-based studies found a pooled 21st-century incidence of appendicitis or appendicectomy of 100 per 100,000 person-years (95% CI 91-110) in Northern America and 151 per 100,000 person-years in Western Europe [1]. These are population-level figures, not an individual risk. The condition can occur at any age but is most often seen between the ages of 10 and 30.

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What is appendicitis?

The appendix is a small, finger-shaped tube, 5-10 cm long, that branches off from the first part of the large intestine. When its opening becomes blocked - typically by a small, hard piece of stool (a faecolith), swollen lymphoid tissue, or rarely a tumour - the pressure inside the appendix increases, the blood supply is compromised, and bacteria begin to multiply. The result is inflammation and a risk of perforation (rupture) [3].

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Classic symptoms

• Abdominal pain that starts around the navel and, within 6-24 hours, moves to the lower right-hand side of the abdomen
• Nausea, vomiting, and loss of appetite
• A mild fever (37.5-38.5 °C)
• Pain on pressing and then quickly releasing over McBurney's point (rebound tenderness)
• Pain that worsens with jumping, coughing, or travelling by car

In children, pregnant women, and the elderly, the symptoms can be atypical, and the diagnosis is often more difficult to make [4].

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Diagnosis

The diagnosis is based on a combination of a clinical examination, blood tests, and imaging scans:

• Blood tests: An elevated white blood cell count and C-reactive protein (CRP) level support the diagnosis, but they can be normal in the early stages.
• Ultrasound scan: Recommended as the first imaging test in children and pregnant women to avoid radiation; sensitivity depends strongly on the operator and body habitus and is lower than for CT [5,12]
• CT scan: The most sensitive test in adults with an uncertain diagnosis, recommended by WSES (international surgical guideline) when clinical assessment and scoring are inconclusive [6,12]
• MRI scan: Typically used for pregnant women if an ultrasound scan is not conclusive.

Scoring systems such as the Alvarado and AIR scores are tools for clinicians, not self-tests. WSES strongly recommends (high quality of evidence) using clinical scores to exclude appendicitis and to identify intermediate-risk patients who need imaging. WSES suggests against (weak recommendation, moderate evidence) using the Alvarado score to positively confirm appendicitis in adults, and strongly recommends the AIR and AAS scores as the best performing predictors. In children, WSES suggests against making the diagnosis on scores alone [7,12]. A score never replaces urgent medical assessment of severe or worsening abdominal pain.

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Treatment: surgery or antibiotics?

Surgery (appendicectomy) remains the most commonly used treatment in Denmark and is usually performed laparoscopically (keyhole surgery). The procedure takes 30-60 minutes, and most people can be discharged 1-2 days later [8].

Antibiotic treatment alone has been studied as an alternative for uncomplicated appendicitis in selected adult patients. In the CODA trial (2020, n=1552), antibiotics were non-inferior to surgery on a composite health status measure 30 days after randomisation, and 29% of the antibiotic group had undergone appendicectomy within 90 days [9]. The trial was conducted in the United States in adults with uncomplicated appendicitis. The presence of a faecolith increases the risk of treatment failure.

An appendiceal abscess or phlegmon is often treated initially with antibiotics and sometimes percutaneous drainage. A planned appendicectomy afterwards ("interval appendicectomy") is not a routine decision made at 6-8 weeks. WSES supports a selective approach, where interval appendicectomy may be considered in cases of recurrent episodes, persistent or recurring symptoms, or a concrete suspicion of a tumour [10,12].

Age on its own is not an indication for interval appendicectomy. In patients aged 40 or older who have been treated non-operatively for complicated appendicitis or an appendiceal mass, the recommendation is instead an individual assessment for an underlying neoplasm, typically with contrast-enhanced CT and colonoscopy. That recommendation rests on limited evidence and is conditional [12].

The individual plan is made by the treating surgical department.

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When should you seek urgent medical attention?

Suspected appendicitis needs acute hospital assessment. It is not a condition that can wait for a planned appointment in a specialist clinic.

Call 112 for severe, rapidly worsening abdominal pain, a rigid abdomen, high fever with marked illness, collapse, or pale and clammy skin.

Call 1813 (Capital Region of Denmark) or your regional out-of-hours service the same day if you have:

• Persistent abdominal pain on the right side for more than 4-6 hours
• Abdominal pain accompanied by fever, nausea and vomiting
• Pain that worsens with movement, jumping or coughing

Delayed treatment is associated with a higher risk of perforation and peritonitis. Suspected acute appendicitis therefore needs emergency or same-day medical assessment. You cannot judge for yourself whether it is safe to wait at home. WSES recommends surgery within 24 hours when an operation is indicated, and the short delay studied in the literature is a monitored in-hospital delay after medical assessment, not waiting time at home [11,12].

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After the operation

Most people are back at work within 1-2 weeks after laparoscopic (keyhole) surgery. You can eat normally as soon as you feel able, and physical activity can be resumed gradually. Contact your doctor if you develop a fever, increasing pain, or redness around the wound sites.

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References

1. Ferris M, et al. The global incidence of appendicitis: a systematic review. Ann Surg 2017;266(2):237-41.
2. Sundhedsdatastyrelsen. Landspatientregisteret - appendektomier i Danmark. 2023.
3. Bhangu A, et al. Acute appendicitis: modern understanding of pathogenesis, diagnosis, and management. Lancet 2015;386(10000):1278-87.
4. Snyder MJ, et al. Acute appendicitis: efficient diagnosis and management. Am Fam Physician 2018;98(1):25-33.
5. Doria AS, et al. US or CT for diagnosis of appendicitis in children and adults? A meta-analysis. Radiology 2006;241(1):83-94.
6. Pickhardt PJ, et al. Diagnostic performance of multidetector CT for acute appendicitis. Ann Intern Med 2011;154(12):789-96.
7. Andersson M, Andersson RE. The appendicitis inflammatory response score. World J Surg 2008;32(8):1843-9.
8. Sauerland S, et al. Laparoscopic versus open surgery for suspected appendicitis. Cochrane Database Syst Rev 2010;(10):CD001546.
9. CODA Collaborative. A randomized trial comparing antibiotics with appendectomy for appendicitis. N Engl J Med 2020;383(20):1907-19.
10. Andersson RE, Petzold MG. Nonsurgical treatment of appendiceal abscess or phlegmon: a systematic review and meta-analysis. Ann Surg 2007;246(5):741-8.
11. van Dijk ST, et al. Meta-analysis of in-hospital delay before surgery as a risk factor for complications in patients with acute appendicitis. Br J Surg 2018;105(8):933-45.
12. Di Saverio S, Podda M, De Simone B, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg 2020;15:27. doi:10.1186/s13017-020-00306-3