Acute Appendicitis

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

Pathology

Occurs when the appendix becomes blocked by a:

• Faecolith


• Foreign body


• Hyperplasia of lymphatic glands


• Fibrous stricture from previous inflammation


• Filarial worms


• Carcinoid tumour near the base.


• Proximal to a caecal obstructing tumour

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.

Signs

• Pyrexia and tachycardia


• Furred tongue, foetor oris, flushed (may appear to be toxic)


• Peritonitis – lying still, coughing hurts, tenderness, guarding, rebound tenderness, bowel sounds absent, distended abdomen, tympanitic.


• Rectal examination shows tenderness on the right side.


• Rovsing’s sign – pain more in the right iliac fossa than in the left iliac fossa (LIF) when the LIF is pressed


• Polymorph leucocytosis

Variations in this picture include:

• The infant with diarrhoea and vomiting.


• The school boy with vague abdominal pain who will not eat his favourite food.


• The shocked and confused elderly patient who is not in pain.

Complications

• Peritonitis with later infertility in girls


• Appendix mass (inflamed appendix surrounded by a omental mass)


• Appendix abscess

Differential Diagnosis

Intra-abdominal disease

• Non-specific mesenteric adenitis – in young children, followed by a upper respiratory tract infection.


• Meckel’s diverticulitis – should be looked for if the appendix is normal on examination.


• Acute Crohn’s disease – young adults


• Obstruction – with colic and vomiting but noisy bowel sounds and a distended bowel on X-ray.


• Gastroenteritis – diarrhoea and vomiting but more diffuse and less severe tenderness. Vomiting usually precedes any colic.


• Perforated peptic ulcer – sudden onset, RIF pain as the fluid tracks down the paracolic gutter.


• Acute cholecystitis – the pain is usually foregut, although a distended gallbladder may descend to the RIF.


• Pancreatitis – a central pain which radiates to the back and has raised serum amylase.


• Acute colonic diverticulitis – tends to be older age group with a mobile sigmoid or a caecal diverticulum.

Gynaecological emergencies

• Acute salpingitis – has a more diffuse bilateral lower abdominal pain and vaginal discharge.


• Ectopic pregnancy – common mistake (every woman is pregnant unless proved otherwise)

Urinary tract

• Testicular torsion – peri-umbilical pain and vomiting. Must examine the genitalia in all patients with abdominal pain to rule out torsion and maldescent.


• Renal colic and acute pyelonephritis – the urine must be tested for blood and pus cell in every case of acute abdominal pain. The patient with ureteric colic is usually restless and moving about, with pain from the loin to the groin. However an inflamed appendix may be adherent to the ureter or bladder causing dysuria and microscopic haematuria or pyuria.

Respiratory system

• Basal pneumonia and pleurisy – may be referred to the abdomen especially in children.

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

Treatment

The treatment is a appendicectomy except if:

• The patient is moribund with advanced peritonitis – only hope here is to put up a IV drip, naso-gastric aspiration, antibiotics and other resuscitative measures.


• If the attack is resolving – elective procedure should be advised.


• An appendix mass has formed with no peritonitis.

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.

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