What is the likelihood of appendicitis (inflammation of the appendix) without abdominal pain?

From the Guidelines

It is rare for someone to have appendicitis without experiencing abdominal pain, with approximately 95-99% of appendicitis cases presenting with some form of abdominal pain. However, atypical presentations without pain can occur in about 1-5% of cases, particularly in certain populations such as the elderly, pregnant women, young children, and immunocompromised patients 1. These patients might instead present with nonspecific symptoms like general malaise, low-grade fever, or gastrointestinal disturbances. The absence of pain occurs because appendicitis typically causes inflammation that irritates the peritoneum (abdominal lining), which normally triggers pain signals. In atypical cases, the appendix may be positioned differently in the abdomen, or the patient may have altered pain perception due to medications, neurological conditions, or age-related changes.

Some key points to consider in the diagnosis of appendicitis include:

• The Alvarado score, a clinical scoring system, can be used to predict the likelihood of appendicitis, but it is not foolproof and may not be reliable in all cases 1.
• Imaging modalities such as CT scans and ultrasound can be useful in diagnosing appendicitis, especially in cases where the diagnosis is uncertain 1.
• The management of appendicitis typically involves surgical removal of the appendix, although antibiotic therapy may be considered in some cases 1.
• Delayed treatment of appendicitis can lead to higher complication rates, including perforation and peritonitis, which can have serious consequences for the patient's morbidity, mortality, and quality of life.

In terms of the likelihood of appendicitis without abdominal pain, the current evidence suggests that it is a rare occurrence, but one that should not be ruled out entirely, especially in high-risk populations. A high index of suspicion and thorough evaluation, including imaging and laboratory tests, are necessary to make an accurate diagnosis and provide appropriate treatment 1.

From the Research

Appendicitis without Abdominal Pain

• The likelihood of appendicitis without abdominal pain is a rare occurrence, but it has been documented in some cases 2.
• A study reported two cases of painless acute appendicitis, where the abdominal pain disappeared during the evolution of the disease, but the patients still had an inflamed appendix confirmed by imaging and laboratory studies 2.
• Another study found that the absence of abdominal pain does not rule out appendicitis, and that imaging tests such as ultrasound and computed tomography scans are essential in diagnosing the condition 3, 4.
• The Alvarado score, Pediatric Appendicitis Score, and Appendicitis Inflammatory Response score can help stratify patients as low, moderate, or high risk for appendicitis, but these scores may not be effective in cases where abdominal pain is absent 4.

Diagnostic Challenges

• The diagnosis of appendicitis can be challenging, especially in cases where abdominal pain is not present 3, 4.
• Imaging tests such as ultrasound and computed tomography scans can help diagnose appendicitis, but they may not always be accurate 3, 5, 6.
• Laboratory tests such as white blood cell count and C-reactive protein can also be used to aid in the diagnosis of appendicitis, but they may not be specific to the condition 5, 6.

Clinical Decision Rules

• A clinical decision rule has been developed to rule out appendicitis in patients with nondiagnostic ultrasound results, which can help reduce the number of imaging investigations in patients with suspected appendicitis 6.
• The decision rule selects patients for discharge and next-day reevaluation without initial computed tomography or magnetic resonance imaging if fewer than two of the following predictors are present: male sex, migration of pain to the right lower quadrant, vomiting, and white blood cell count higher than 12.0 × 10(9) /L 6.
• The negative predictive value of the decision rule was found to be 94% in the validation set, which is comparable to the negative predictive value of computed tomography and magnetic resonance imaging 6.