Approach

History and physical examination form the initial approach in the evaluation of a patient with possible appendicitis.[2] It is routine practice in the US to request a computed tomography (CT) scan for patients presenting to the emergency room with features of acute appendicitis.[26]

Validated clinical decision tools such as the Alvarado score demonstrate high sensitivities and are useful for excluding appendicitis, but lack specificity.[27][28][29]

Ultrasound or magnetic resonance imaging (MRI) of the abdomen are recommended if the patient is pregnant.[10][30] Women of childbearing age should have a pelvic examination to rule out other pelvic pathology.[31]

History

Abdominal pain is the main presenting complaint. Pain typically starts at the mid-abdominal region and later (1 to 12 hours) shifts to the right lower quadrant. Pain is usually constant in nature and with intermittent abdominal cramps and is usually worse on movement and coughing.

Location of the pain may vary depending upon the position of the appendix:

  • Retrocecal appendix may cause flank or back pain

  • Retroileal appendix may cause testicular pain due to irritation of the spermatic artery or ureter

  • Pelvic appendix may cause suprapubic pain

  • A long appendix with tip inflammation in the left lower quadrant may cause pain to that region.

Anorexia is another important symptom almost always associated with acute appendicitis.[32] Without anorexia the diagnosis of acute appendicitis is in question. Nausea and vomiting are also present in 75% of patients.[32] Absolute constipation is a late feature. 

The sequence of presentation in 95% of patients with acute appendicitis usually starts with anorexia, followed by abdominal pain and then vomiting.[32] However, in pregnant patients, the only features shown to be significantly associated with a diagnosis of appendicitis are nausea, vomiting, and local peritonitis.[33]

Complicated appendicitis (perforation or intra-abdominal abscess) is more likely the greater the duration of symptoms and in older patients (>50 years).[34][35]

Physical exam

Usually, there are no significant changes in vital signs. Patients may have a low-grade fever. In patients presenting with a high-grade fever, another diagnosis should be considered.[36] Tachycardia may also be present.[37]

A classic sign is right lower quadrant abdominal tenderness (McBurney sign) and localized rebound tenderness, if appendix is anterior. There may also be pain in the right lower quadrant after compressing the left lower quadrant (Rovsing sign).

Pain may be elicited in the right lower quadrant with the patient lying on their left side and slowly extending the right thigh to cause a stretch in the iliopsoas muscle (psoas sign) or by internal rotation of the flexed right thigh (obturator sign).

Bowel sounds may be reduced, particularly on the right side compared with on the left.

Classic abdominal findings may not be present if the appendix is in an atypical position.

Patients with perforation may present acutely ill with hypotension, tachycardia, and a tense, distended abdomen with generalized guarding and absent bowel sounds.

A palpable mass may be felt with appendiceal perforation that has been contained by the omentum, resulting in a periappendiceal abscess.

In children, pain with coughing and hopping can support the diagnosis.[38] Analgesia may be useful to facilitate abdominal exam if pain limits the examination. Analgesia does not lead to missed diagnoses in children.[39][40]

Investigation

All patients with abdominal discomfort should have a complete blood count taken. Mild leukocytosis (10,000 to 18,000/microliter) with increased neutrophils is usually present. In children, CRP level on admission ≥10 mg/L and leukocytosis ≥16,000/microliter are strong predictive factors for appendicitis.[10]

Some form of imaging is usually warranted. Most nonpregnant patients presenting to the emergency room with abdominal pain suggestive of appendicitis will have a CT scan of the abdomen and pelvis.[30][10] Preoperative imaging with a CT scan of the abdomen (ultrasound or MRI for pregnant women) now forms the usual standard of care. Women and children, in particular, may benefit from preoperative imaging.[26][41][38]

Choice of imaging modality

Although CT scan has greater sensitivity and specificity than ultrasound in diagnosing appendicitis, the latter is readily available, rapid, and able to be performed at the bedside.[42][43][44] In children, ultrasound may be preferred over CT scan in order to limit radiation exposure. There is evidence to suggest enhanced sensitivity and specificity of ultrasound in children compared with adults.[41][45][46] If, on ultrasound, a normal appendix is visualized in its full length, then acute appendicitis can be excluded. However, this is rarely the case, and the greatest utility for ultrasound is to detect an alternative cause of abdominal pain that excludes appendicitis.[47]

Appendiceal CT scan is increasingly used as the initial diagnostic test for acute appendicitis, and it is routine practice in the US to request a CT for patients presenting to the emergency room with features of acute appendicitis.[26] A CT is also indicated in atypical presentations.[30][48] However, delayed surgery subsequent to CT scan for presumed appendicitis is associated with an increased rate of appendiceal perforation.[49] Intravenous contrast-enhanced CT scan with or without oral contrast has up to 100% sensitivity compared with 92% sensitivity in nonintravenous contrast-enhanced CT scan.[50][51]com.bmj.content.model.Caption@7b30553f[Figure caption and citation for the preceding image starts]: CT abdomen - thickened appendix.Nasim Ahmed, MBBS, FACS; used with permission [Citation ends].

In pregnant women presenting with features of appendicitis, an abdominal sonogram should be performed to identify the appendix. If the sonogram examination is inconclusive, an abdominal MRI (particularly in early pregnancy) may be appropriate.[31][30] However, a negative or inconclusive MRI does not exclude appendicitis and surgery should still be considered if clinical suspicion is high.[10]

In children, point-of-care ultrasound is the most appropriate first-line diagnostic tool, if an imaging investigation is indicated based on clinical assessment. In children with inconclusive ultrasound results, a second-line imaging technique (CT or MRI) can be chosen based on local availability and expertize.[10] Low-dose CT is preferred in young people if they have a negative ultrasound.[10] 

Tests to exclude other causes

A urinalysis should be performed to exclude possible urinary tract infection or renal colic. Sexually active women of childbearing age should have a urinary pregnancy test.

Venepuncture and phlebotomy: animated demonstrationVenepuncture and phlebotomy: animated demonstration

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