The following document was written by Mr Vik Veer MBBS(lond) MRCS(eng) DoHNS(eng). You may use the information here for personal use but if you intend to publish or present it, you must clearly credit the author and
This site is not intended to be used by people who are not medically trained. Anyone using this site does so at their own risk and he/she assumes any and all liability. ALWAYS ASK YOUR SENIOR IF YOU ARE UNSURE ABOUT A PROCEDURE. NEVER CONDUCT A PROCEDURE YOU ARE UNSURE ABOUT.

Acute Appendicitis

Commonest surgical emergency, with a life time risk of 6%.


Occurs when the appendix becomes blocked by a:

Occurs less frequently in the extremes of age as:

  1. When young the appendix opening is wide mouthed and well drained

  2. When elderly the appendix is obliterated and all shrivelled up

The obstructed appendix acts like a closed loop so the bacteria are free to proliferate. The bacteria are then able to invade the bowel wall. The bowel wall becomes damaged by pressure necrosis which leads to thrombosis of the end arteries of the appendicular branch of the ileo-colic artery. This leads to gangrene and on to perforation. (this may occur in 12 hours to up 3-4 days!)

Instead of bacteria, the appendix maybe sterile and therefore a mucocele may develop.

Rarely there maybe a direct invasion of the appendix from a lymphatic or haematogenous source (streptococcal appendicitis), although this form is more likely to resolve than a obstructed appendix.

Clinical Features

As the appendix becomes inflamed there is typically a central peri-umbilical colicy pain. This later shifts to the right iliac fossa (over the site of the inflamed appendix) as there is peritoneal involvement. If the appendix is located in the pelvis it can affect the bladder causing urinary frequency, give supra pubic pain and cause diarrhoea (although constipation is more commonly associated with appendicitis).

Anorexia is invariable and vomiting is rarely prominent which usually occurs following the onset of pain.


Variations in this picture include:


Differential Diagnosis

Intra-abdominal disease
Gynaecological emergencies
Urinary tract
Respiratory system

Other – pain from zoster infection of the 11th and 12th dorsal segments.


The treatment is a appendicectomy except if:

Antibiotic treatment is given (metronidazole 1g/8h + cefuroxime 1.5g/8h), peri-operatively to reduce post operative wound infection.

Appendix mass is treated conservatively. The outlines are marked and the patient is put to bed on a fluid diet and a careful watch. Metronidazole is given, but not for a long time as this will produce a chronic inflammatory mass honeycombed with abscesses (antibioticoma). 80% will resolve with this. Sometimes the mass may burst into the rectum or peritonial cavity. After 3 months an elective procedure is carried out.

Appendicitis during pregnancy - Has a high mortality due to the confusion with signs and worries about obstetric emergencies. Due to the pregnant mass the pain from a appendicitis is normally more lateral. During the first trimester there is a high risk of abortion.


The authors of this document have attempted to provide information that is medically sound and up-to-date. The authors nor cannot take any reponsibility for the accuracy or completeness of this article. The reader should confirm the statements made in this website before using the information outside this website.