Diagnosis of Appendicitis Made Easy

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DIAGNOSIS OF APPENDICITIS

The diagnosis of appendicitis is mainly based on the story (history) given by the patient and the findings on examining the patient.

Laboratory of radiological test for appendicitis are usually used to confirm the suspicion of appendicitis, or disprove it.

Though there are laboratory and radiology investigations that can be ordered, there is no one test that can for sure confirm appendicitis on every occasion.

The common test done for appendicitis includes blood test, urine test and sometimes plain abdominal x-ray, ultrasound, and CT scan.

Blood Test

Most patients suspected of having appendicitis would be asked to do a blood test. 50% of the times, the blood test may be normal. So it is not fool proof in diagnosing appendicitis.

Two form of blood tests commonly done:

FBC (Full blood count) or CBC (Complete blood count), depending on which side of the Atlantic you live in) is an inexpensive and commonly requested blood test. It involves the blood measured for its richness in red blood cells as well as the number of the various white blood cell constituents in it.
The number of white cells in the blood is a usually less than 10,000cells per cubic millimetre. An abnormal rise in the number of white blood cells in the blood is a crude indicator of infection or inflammation going on in the body.
Such rise is not specific to appendicitis alone. If it is abnormally elevated, with a good history and examination findings pointing towards appendicitis, the likelihood of having the disease is higher.
In pregnancy, there may be a normal elevation of white blood cells, without any infection present.
CRP is an acronym for Cryo-Reactive Proteins. It is an acute phase response protein produced by the liver in response to any infection or inflammatory process in the body. Again, like the FBC, it is not a specific test. It is another crude marker of infection or inflammation. Inflammation at ANY site can lead to the CRP to rise.
A significant rise in CRP with corresponding signs and symptoms of appendicitis is a useful indicator in the diagnosis of appendicitis.
It is said that if CRP continues to be normal after 72 hours of the onset of pain, it is likely that the appendicitis will resolve on its own without intervention. A worsening CRP with good history is a sure signal fire of impending perforation or rupture and abscess formation.

Urine Test

Urine test in appendicitis is usually normal. It may however show blood if the appendix is rubbing on the bladder, causing irritation.

A urine test or urinalysis is compulsory in women, to rule out pregnancy in appendicitis, as well to help ensure that the abdominal pain felt and thought to be acute appendicitis is not in fact, due to ectopic pregnancy.

X – Ray

In 10% of patients with appendicitis, plain abdominal x-ray may demonstrate hard formed faeces in the lumen of the appendix (Faecolith).

It is agreed that the finding of Faecolith in the appendix on X – ray alone is a reason to operate to remove the appendix, because of the potential to cause worsening symptoms. In this respect, a plain abdominal X-ray may be useful in the diagnosis of appendicitis, though plain abdominal x- ray is no longer requested routinely in suspected cases of appendicitis.

An abdominal X – ray may be done with a barium enema contrast to diagnose appendicitis.

Barium enema is whitish toothpaste like material that is passed up into the rectum to act as a contrast. It will usually fill the whole of the large bowel. In normal appendix, the lumen will be present and the barium fills it up and is seen when the x-ray film is shot.

In appendicitis, the lumen of the appendix will not be visible on the barium film.

Ultrasound Scan

The normal appendix is not frequently visible on ultrasound scan. If seen, it is most likely that the appendix is inflamed.

Ultra sound scan may demonstrate free fluid around a swollen appendix. An outer thickness of greater than 7mm on scan is also highly suggestive of inflammation of the appendix.

Graded Compression Ultrasound greatly improves the sensitivity of ultrasound scan in the diagnosis of appendicitis in all age groups and sex.

Graded Compression Ultrasound has been demonstrated to have a sensitivity of 100% and specificity of 96 % and accuracy of 98% in the diagnosis of appendicitis during pregnancy (Lim et al, 1992).

CT Scan

CT scan or computed tomography scan is a specialised form of x-ray. The patient is passed through a big doughnut-like machine and x-rays 400 times the normal is used to look at the body in slices of about 5millimeter thickness.

It is used in a very wide selection of medical cases. It is not advised to be used in pregnancy, except where the benefit strongly out weighs the risk.

A dye may be given to help improve the visibility of tissues, by acting as a contrast.

Helical CT scan has greatly improved the diagnosis of appendicitis. It is rapidly becoming the only diagnostic tool with some certainty. The future will tell if it will be able to diagnose appendicitis with 100% accuracy.

Scoring Systems in Appendicitis

In the diagnosis of appendicitis, some physicians have come up with a scoring system, which compiles all the clinical signs and symptoms a patient have, gives it a mathematical number, and if the score reaches a particular total or threshold, a diagnosis of appendicitis is said to be very likely.

Scoring systems are not frequently used, but the following are the available scoring systems in appendicitis diagnosis.

MANTRELS or Alvarado Scoring. The Alvarado scoring system in appendicitis, also called the MANTRELS scoring, makes use of clinical signs, symptoms and laboratory findings. Each of the alphabets represents a sign or symptom, and a score of 1 is award to each, where they exist, except T and S that are scored 2 each. The components are as follows:
M = Movement of pain to the right iliac fossa
A= Anorexia
N = Nausea and Vomiting
T = Tenderness in the right iliac fossa
R = Rebound tenderness
E= Elevated temperature …and …
L = Leucocytosis greater than 10,000/mm2
S = Shift in white blood cell count to the right.
A total score of 10 is the maximum that can be accumulated.
A score of 8 – 10 is said to be highly predictive of appendicitis and is a call for immediate appendicectomy or operation for the removal of the appendix.
A score of 7 – 8 is indicative of appendicitis. 5 – 6 means there is the possibility of appendicitis, and 1 – 4 makes the diagnosis of appendicitis unlikely.
Any one scoring 5 – 8 needs regular clinical re-evaluation and re-assessment with a view to confirming the diagnosis and operate.
A score of greater than 6 in children makes the possibility of appendicitis up to 100% likely.

The Paediatric Appendicitis Scoring abbreviated PAS Scoring in children is another predictive scoring system used in the diagnosis of appendicitis.

This scoring system is designed for use in children between the ages of 4 – 15 years. It is more or less a modified Alvarado or MANTRELS scoring. It uses 8 variables (laboratory findings as well as sighs and symptoms), to which a score is of 1 or 2 is given to each variable, where they exist. The maximum score that can be accumulated is 10.

The presence of Anorexia, Pyrexia, Nausea or Vomiting, Leucoystosis greater than 10,000, migration of pain, and high neutrophils are given a score of 1 each. Tenderness on coughing, hopping or percussing the abdomen is given a score of 2. So too is the presence of tenderness in the right lower abdominal region. A Paediatric Appendicitis Score of 6 and above is highly indicative of appendicitis in children.

Tzanakis Scoring. Tzanakis and colleagues, in 2005 published a simplified system, now called the Tzanakis scoring system for appendicitis, to aid the diagnosis of appendicitis. It incorporates the presence 4 variables made up of specific signs and symptoms (presence of right lower abdominal tenderness = 4points and rebound tenderness = 3), laboratory findings (presence of white blood cells greater than 12,000 in the blood = 2) as well as ultrasound findings (presence of positive ultrasound scan findings of appendicitis = 6), to which scores are allocated, in the computing of a scoring to predict the presence of appendicitis.
A total score of 15 is the maximum that can be scored. Where a patient scores 8 or more points, there is greater than 96 percent chance that appendicitis exists.

Fine Catheter Peritoneal Cytology

This is a rather old fashioned test for appendicitis, and it is hardly used today for the diagnosis of appendicitis.

Abbreviated FCPC, fine catheter peritoneal cytology when used, has a high predictive value for diagnosing appendicitis.

It involves the introduction of a fine catheter into the abdominal cavity below the level of the umbilicus or navel, and then the catheter is directed to the right iliac fossa and peritoneal fluid aspirated, and stained in the lab with Giemsa stain.

If over half of the cells in the aspirate are white blood cells (neutrophils), the test is said to be positive, and appendicitis is most likely.

The draw back of this test is in women where a positive test can also occur with a pelvic inflammatory disease.

To differentiate appendicitis from a host of other causes of abdominal pain, please see the section on differential diagnosis of appendicitis.

Reference:

Samuel M. Pediatric appendicitis score. J Pediatr Surg 2002 Jun; 37:877-81.

Tzanakis NE, Efstathiou SP, Danulidis K, et al: A new approach to accurate diagnosis of acute appendicitis. World J Surg 2005 Sep; 29(9): 1151-6, discussion

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