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'''ACUTE APPENDICITIS '''

Definition Appendicitis is defined as the inflammation of the vermiform appendix which is usually due to infection.

Prevalence Although the lifetime risk of having acute appendicitis is considered to be between 7% - 8% this risk varies with the geographical region, in Africa it is 2%, in Europe 8% and in the USA 9%. There is also variation in diagnostic workup and treatment protocols from various regions. The rate of perforated appendicitis varies from 16% to 40%. This rate increases with the younger age group to 40% -57% and 55% - 70% in patients over the age of 55 years.

The mortality rate of acute non gangrenous acute appendicitis is less than 0.1% and 0.6% for a gangrenous acute appendicitis. A perforated acute appendicitis carries a high mortality rate of 5%.

Aetiology

There is no universally agreed cause of acute appendicitis. The suggested causes for appendicitis is obstruction of the lumen of the appendix which is due to a fecalith, lymphoid hyperplasia, tumors, parasites, vegetable seed, fruit seeds and inspissated barium. Infections that are commonly associated with acute appendicitis are gastroenteritis, upper respiratory infections, Epstein-Barr virus, and other viruses.

Pathological course

The pathological course of an acute appendicitis may be spontaneous resolution, which often reverts back to acute inflamed appendix or it can become gangrenous and perforate resulting in generalised peritonitis or localised appendix abscess.

CLINICAL FEATURES

History

Due to the fact, the symptoms of acute appendicitis overlap with other abdominal conditions the symptoms are therefore not distinctive or exclusive to appendicitis. The patient experiences a progressive and persistent abdominal pain which starts at the periumbilical area and shifts after 6 hours to the right iliac fossa or exactly to site of appendix, this pain is termed migratory right iliac fossa pain. Sometimes a colicky pain may be superimposed on the steady pain. Migratory pain is a common symptom in most patients presenting with acute appendicitis as a result it is included in all clinical scoring systems.

The abdominal pain is aggravated by movement such as coughing and walking and the patient prefers to lie still with the hips and knees flexed. Anorexia is another common symptom of appendicitis and also appears in clinical scoring systems. In the absence of anorexia, other diagnoses should also be considered. The migratory pain is usually followed by nausea and vomiting. Nausea and vomiting are also important symptoms that are also included in clinical scoring systems. There is also a history of altered bowel motions either constipation or diarrhea. There sometimes might be a history of previous milder attacks of similar pain.

'Examination'

On physical examination, the patient has signs of acute illness such as a low grade fever of 37.5 – 38.0 OC and tachycardia. In the presence of fever greater than 38.0 OC, consider another diagnosis such mesenteric adenitis. The patient appears to be flushed, toxic and in pain. Cutaneous hyperesthesia over T10-T12 dermatomal region is a common sign in early appendicitis and it is demonstrated by gentle lifting of the skin or by needle prick. The abdominal pain is aggravated by movement. Fetor oris can also be present. A palpable right iliac fossa mass could be a periappendiceal abscess or phlegmon.

A few signs have been documented as part of the clinical findings that one can elicit when examining the patient and these are Aaron’s sign, Pointing sign, McBurney’s Sign, Dunphy Sign, Rovsing Sign, Obturator Sign and psoas sign.

'''Special investigations '''

Biochemical markers

There is currently no biochemical marker that has a high specify to confirm (rule in) the diagnosis of acute appendicitis.

Leukocytes

In acute appendicitis there is a mild leukocytosis of 10 000 – 15 000/mm3, with left shift (> 75% polymorphonuclear cells) is noted on the peripheral smear. The probability of appendicitis is unlikely with leukocyte count of below 7000/mm3. A combination of leukocytosis and left shift is present in 80% of the patients. A leukocytosis greater than 20 000/mm3 is suggestive of a perforated appendix.

C-reactive protein (CRP)

A CRP has the highest diagnostic accuracy among biochemical test followed by leukocytosis.

Β-hCG

A beta hCG must be done in the female patient presenting with acute appendicitis in order to rule out an ectopic pregnancy.

Urinalysis Urinanalysis is abnormal in 20-40% of the patients and may show leukocytosis and erythrocytes.

Imaging modalities

Imaging modalities are important in the diagnosis of acute appendicitis because the diagnosis is not easily established on history and physical examination alone. The negative appendectomy rate is 15%

Ultrasound

An abdominal ultrasound has sensitivity of 75-90%and a specificity of 81 and 98%. An abdominal ultrasound can confirm diagnosis of appendicitis however, it cannot exclude appendicitis

CT scan

A CT scan has a sensitivity of 96-100%. A CT scan is superior to an ultrasound but is associated with radiation and contrast concerns. A low dose CT with no contrast is advised. A CT scan in children should not be performed until an ultrasound has been considered.

Challenges with acute appendicitis

The signs and symptoms of acute appendicitis are not specific and exclusives to appendicitis only. This makes the diagnosis of acute appendicitis on history and physical examination difficult resulting in a long list of a differential diagnosis. Performing appendectomies based clinical examination only results in a high negative appendectomy rate of 15%. Imaging modalities assist in reducing the number of patients receiving appendectomy but they do have their challenges. Ultrasound has poor diagnostic accuracy and is operator dependent. CT scan has sensitivity close to 100% but its drawbacks are the amount of radiation the patient is exposed to and also the contrast used with CT scans. Another challenge with imaging modalities time delays and the progression of an appendicitis to perforation.

Clinical scoring systems / clinical decision rules

Scoring systems are available to assist with workup of appendicitis for examples in adults the Appendicitis Inflammatory Response (AIR) score, Adult Appendicitis Score (AAS), RIPASA (Raja Isteri Pengiran Anak Saleha Appendicitis) score and Alvarado score are used. In the paediatric patients 2 common scoring systems are used i.e. Paediatric appendicitis score (PAS) and Alvarado score. Of note, none of the scoring systems have any imaging categories or criteria. It is strongly recommended that clinical scores be used to exclude acute appendicitis and identify intermediate-risk patients that need imaging for diagnostics. The addition of clinical scoring systems in the diagnostic workup pathway avoids underuse and overuse of imaging modalities. The Alvarado score should not be used to positively confirm clinical suspicion of an acute appendicitis in adult patients. The AIR (Appendicitis Inflammatory Response) and AAS scores are strongly recommended clinical predictors of acute appendicitis. Some of the advantages of using clinical scoring are reducing hospital admissions, optimize the use of diagnostic imaging and reduce negative surgical explorations.

Alvarado score for acute appendicitis

The Alvarado score also known as the MANTRELS score has sensitivity of 96% and specificity of 81% therefore this scoring system may be used for ruling out acute appendicitis and not for ruling in acute appendicitis. Three broad categories are used to score patients for the risk of having acute appendicitis. The first category is symptoms which consist of anorexia, migratory right Iliac fossa pain nausea/vomiting, the second category is signs which tenderness in the right Iliac fossa, rebound tenderness in right Iliac fossa and a low grade fever >37.5°C and the third category is laboratory findings which are Leukocytosis > 10 000 and a left shift. Table 12.3 shows the specific categories and what they consist of. The Alvarado score has a total of 10 points. The patients are ranked according to the risk of having an acute appendicitis. Low risk patient are those that have 0-3 points, moderate risk patients have 4-6 points and high risk patient have 7-10 points.

'''Appendicitis Inflammatory Response (AIR) '''

The AIR score has a sensitivity of 92% and a specificity of 63%. In contrast to the Alvarado score, the AIR score has five broad categories which are Symptom, Signs Polymorphonuclear leucocytes, Leucocytes and CRP. The Appendicitis Inflammatory Response score has a total of 12 points. The AIR score is considered to be more accurate than the Alvarado score. The score utilises more infection and inflammation markers as compared to the Alvarado score. A score of 0-4 is low risk, 5-8 is intermediate risk and 9-12 is high risk.

'''Adult Appendicitis Score (AAS) '''

Similarly, to the Appendicitis Inflammatory Response (AIR) score, the Adult Appendicitis Score risk stratifies patients into low risk, intermediate risk and high risk patients. As with the AIR score, this reduces unnecessary hospital admissions, allows for selective and judicious use of imaging modalities and also reduces the negative appendectomy rate. The Adult Appendicitis Score (AAS) take into consideration two factors, which are the length of time passed since the onset of symptoms and also the diagnostic difficulties in the child bearing female patient. in terms of diagnostic accuracy the adult appendicitis score is superior to both the Alvarado score and the Appendicitis Inflammatory response score.

RIPASA (Raja Isteri Pengiran Anak Saleha Appendicitis) score The RIPASA score was studied in the Asian and the Middle Eastern populations and has a sensitivity of 85.39% and specificity of 69.86%.

'''Paediatric Appendicitis Score (PAS) '''

This scoring system was developed in 2002 by Dr Madan Samuel. Since its development in 2002, other studies have validated the PAS. The sensitivity and specificity of the PAS are roughly 98.1 % and 94.75 % respectively. It is used in patients aged 3 to 18 years who present with symptoms within a period of 4 days and less. The PAS is superior to the Alvarado score in children. The PAS similar to the Alvarado score has sub criteria of symptoms, signs, and lab findings. The difference in the PAS is that right iliac fossa rebound tenderness is not part of PAS, another sub criteria of cough/percussion/hopping which causes pain in the right lower quadrant is added to the PAS and scores 2 points; and leucocytosis score 1 point instead of 2 points in the PAS.

Differential diagnosis of acute appendicitis •	Mesenteric adenitis •	Meckel’s diverticulitis •	Acute Crohn’s ileitis •	Acute intestinal obstruction •	Gastroenteritis •	Perforated peptic ulcer •	Acute cholecystitis •	Pancreatitis •	Acute colonic diverticulitis •	Ureteric colic and acute pyelonephritis •	Testicular torsion •	Acute salpingitis •	Ectopic pregnancy •	Ruptured ovarian cyst

'''Treatment of acute appendicitis  Surgical treatment '''

Due to the understanding that acute appendicitis is an irreversible progressive disease which will lead to perforation, appendectomy is still considered to be the gold standard choice of treatment. Appendectomy should be complemented with antibiotic coverage, Ceftriaxone 2 gm single dose and metronidazole 500mg single dose for example.

Laparoscopic appendectomy vs open appendectomy The more recommended surgical approach is laparoscopic appendectomy over open appendectomy; however, the decision will be based on the availability of tools and the skill capability of the surgeon. Advantages of performing a laparoscopic appendectomy are shorter hospital stay, less intermediate care needed, fewer complications and lower mortality rates. The disadvantages of laparoscopic appendectomy are increased risk of an intra-abdominal abscess, longer operating time and increased costs.

'''Medical treatment '''

In situations where the choice has been taken to treat the patient medically, the following medication regimens are advised. For an uncomplicated appendicitis, Augmentin 1 gram three times daily for 5 days can be used. Alternatives are Ceftriaxone 2 grams daily for 5-7 days or Cefotaxime 1 g every 8 hours with metronidazole 500mg intravenously every 8 hours for 5 – 7 days. Medical management has the risk of progressing to complicated appendicitis, recurrence which occurs in 5-44% of the patients and missing an appendix carcinoma which has an occurrence rate of 6 %.

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