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Appendicitis

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Written by Neville Dastur   
Thursday, 25 January 2007 10:44

Appendicitis

This is the first in a new series of articles revolving around topics defined in the ST syllabus for general surgery. Feel free to comment / correct and add to the article.

Introduction

The appendix is a blind ending tubular structure attached to the end of the ceacum where the taeniae coli meet. In humans it appears to serve no function. It's proper name is the vermiform appendix meaning a worm like appendage. Inflammation of the appendix is appendicitis.

Appendicitis is common. About 6%of the population will have appendicitis in their lifetime and the HESS data for 2004-5 showed that around 35,000 appendicectomies were carried out during that year period (1).

There is a slight male predisposition to the disease at about 1.3:1 (2) however equal numbers of females and males undergo emergency appendectomy reflecting the increased difficultly in diagnosis in females.

The peak incidence is during the mid teens but appendicitis can occur in any age group from neonates up.

Alvarado Score(3)
Score Feature
1 Migration of pain to the RLQ
1 Anorexia
1 Nausea and vomiting
2 Abdominal tenderness in RLQ
1 Rebound tenderness
1 Elevated temperature
2 Leucocytosis
1 Shift to left in Leucocytes

 

History and examination

Classically, the patient describes a central, colicky abdominal pain which seems to settle in the right iliac fossa over a 24 hour period. This reflects the shift from a generalised visceral pain of the midgut to a localised stimulation of the parietal peritoneum by the inflamed appendix. The patient may feel sick but the commonest feature is a loss of appetite. Diarrhoea may be a feature, especially if the appendix is in a position that overlies the ileum, but constipation is often the case.

I have shown the Alvarado score on the right only for historical purposes really, as it is a score that crops up in questioning from time to time. Scoring systems are sought out due their simplicity and although it nicely lists the features to look out for the score itself has been shown to confer no increase in the sensitivity of making the diagnosis of appendicitis(5). The one point maybe to take from the paper was that 70% of the patients experienced complete anorexia.

On examination the patient is flushed and often lying still in bed. They may be tachycardia and a pyrexia up to 38oC present. Very high temperatures suggests a different pathology. The patient is classically tender in the abdomen at McBurney's point. This is an imaginary point, one third of the way along a line drawn from the anterior superior iliac spine to the umbilicus. The patient may also have a positive Rovsing's sign. Where palpation in the left lower quadrant results in pain in the right side of the abdomen.

On the point of examination, a useful method of examining patients is to ask the patient to suck their stomach in as flat as possible, blow out there tummy as fat as possible and to cough (remembering to feel for hernias as they do so). During these manovers ask the patient about areas of pain. Finally I would agree with a comment made in the Jrn Royal Soc Medicine 1992 from O Adedeji(4) that percussion tenderness is a far superior method of examination than trying to elicit rebound tenderness(5).

Differential diagnosis

This is very much age and sex dependent. In females the main differential diagnosis to consider are those of a gynaecological nature.

  • Ectopic pregnancy
  • Ovarian torsion
  • Pelvic inflammatory disease
  • Ruptured ovarian follicle
  • Endometriosis

In the young mesenteric adenitis is a common mimicker of appendicitis. This is often in the under 12s who have a history of a viral illness in the two weeks preceding. Remember to examine for lymph nodes.

 

Meckel's Diverticulum is a true diverticulum. I.e. it invloves all layers of the gut wall. It is classicaly described as being 2 inches wide, 2 foot from the ileoceacal valve and present in 2% of the population. For interest it can present in a indirect hernia, known as "Hernia of Littre"

Other differential to consider are:

  • Cholecystitis
  • Perforated peptic ulcer
  • Diverticulitis (watch out for the floppy sigmoid over in the RLQ)
  • Right ureteric calculi giving rise to colic
  • Urinary tract infections and pyelonephritis
  • Pancreatitis
  • Gastroenteritis
  • Terminal ileitis (consider Crohn's)
  • Meckel's diverticulitis
  • Rectus sheath haematoma
  • Colonic carcinoma
  • Ceacal volvulus

Investigation

  • Urine dipstick and pregnancy test in fertile females. Remember that blood / protein and leucocytes may all be present due to irritation of the bladder by an inflammed appendix.
  • Full blood count. Looking particularly for a neutrophilia
  • CRP, but an absence of a rise does not exclude the diagnosis
  • Amylase. Pancreatitis can mimic any abdominal condition
  • The erect CXR (eCXR) and plain AXR have no role in the diagnosis of acute appendicitis. They are investigations if you suspect another pathology. E.g. small bowel obstruction / peptic perforation and so I would advocate the practise of not routinely performing these investigations on under 35s where the diagnosis seems clear.
  • USS - Ultrasound itself has a low sensitivity and specificity for the diagnosis of appendicitis(6). It's use is for establishing other diagnosis. Especially gynaecological pathology in young females rather than putting them through a negative appendicectomy.
  • CT has a much higher sensitivity and specificity(6) (94% and 95% respectivley) but carries the risk of a reasonably high radiation dose. It's use should be restricted to those patients where the diagnosis is uncertain and they would be a particular increased risk from an operation.
  • The role of MRI is current unclear.

A series of CT images demonstrating appendicitis. The first image show the cross sectional appearance of an inflamed appendix marked by a red arrow. The next images are the reformats showing that the appendix is retrocaecal and it's tip just reaches the liver. This matches the operative findings.

 

 

Treatment

Ensure the patient is adequately resuscitated. Remember they feel anorexic and you are about to make them nil by mouth. So ensure that IV fluids are started.

Adequate analgesia should be given. There is no evidence that giving analgesia has any impact on the ability of a clinician to diagnose appendicitis(7).

Antibiotics on the other hand can cause confusion in the diagnosis of appendicitis. One of the features of a patient with appendicitis is the evolving history and examination. This can be masked by the use of antibiotics(9) and so antibiotics should not be given as a matter of course.

Then treatment of choice is an appendicectomy. If the patient is unfit for surgical intervention broad spectrum antibiotics and be given. Appendicectomy can be performed with a traditional open approach or laparscopically. This should be performed within 24 hours of presentation. The evidence for open vs. laparoscopic appendicectomy will be the subject of a later article. For details of performing an appendicectomy see our operative howto guides.

Addendum June 2009:
The terms appendix abscess and appendix mass are often used interchangeably, this is however incorrect. An appendix mass is an inflammatory mass consisting of inflammed appendix, adjacent viscera and the greater omentum. An appendix abscess is a pus containing appendix mass. So a patient with an appendix mass vs abscess will often have a shorter history, the mass may be indistinct and the pyrexia mild as the abscess is generally due to perforation.


References

1) HESOnline http://www.hesonline.nhs.uk

2) Indications for operation in suspected appendicitis and incidence of perforation - R Andersson et al http://www.bmj.com/cgi/content/full/308/6921/107

3) A practical score for the early diagnosis of acute appendicitis - Alvarado A http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=3963537

4) Alvarado score and acute appendicitis. Comment in J Royal Soc Med Aug 1992 O Adedeji http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1293615&blobtype=pdf

5) Meta-analysis of the clinical and laboratory diagnosis of appendicitis - Andersson R. Br J Surg 2004;91:28-37.

6) Systematic review: computed tomography and ultrasonography to detect acute appendicitis in adults and adolescents - Terasawa T, Blackmore CC, Bent S, Kohlwes RJ. Ann Intern Med 2004;141:537-46.

7) Effect on diagnostic efficiency of analgesia for undifferentiated abdominal pain - S. H. Thomas BJS 2003 Vol 90 Issue1 pp 5-9 http://www3.interscience.wiley.com/cgi-bin/abstract/101520548/ABSTRACT?CRETRY=1&SRETRY=0

8) Is Early Analgesia Use Associated with Delayed Diagnosis of Appendicitis? - Steven P. Frei, William F. Bond et al Acad Emerg Med Volume 12, Number 5_suppl_1 18 http://www.aemj.org/cgi/content/abstract/12/5_suppl_1/18

9) Delayed diagnosis of appendicitis in children treated with antibiotics - England RJ, Crabbe DC Pediatr Surg Int. 2006 Jun;22(6):541-5. Epub 2006 Apr 29 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&list_uids=16736226&cmd=Retrieve&indexed=google

 

 

Comments  

 
0 # kyaw kyawsoe 2009-05-02 16:58
i like it
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0 # Guest 2009-10-30 14:40
It is a nice article good for all categories of surgical trainees. Good enough for postgraduate exams.
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0 # hossam shoaib 2009-11-10 19:44
thanks
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