Appendicitis

Introduction

Appendicitis refers to the inflammation of the appendix. The appendix is an outpouching from the caecum (a portion of the large intestine). Appendicitis is the most common surgical emergency of the abdomen. It affects about 10% of the population. The incidence of appendicitis is about 1 in 500 persons every year. The condition affects all ages but is uncommon in children below two years. It affects men more commonly than women. The condition is very common between the ages of 10 and 30 years.





Cause and Pathogenesis

The infection is acquired from the intestine. Blockage of the appendix is the primary cause of appendicitis. The appendix is blocked by intestinal contents, foreign body, fecalith, tumour, parasites like ascarisetc Obstruction of the lumen is followed by infection When infection occurs the walls are swollen and get filled with purulent material.

Symptoms and Signs


The initial complaint is vague colicky abdominal pain. Abdominal pain starts around the umbilicus and spreads to right lower quadrant of the abdomen within 12 hours. Pain gets localised to this area and is exaggerated by activities like coughing, sneezing, deep breathing, moving about etc. Nausea and vomiting followed by low grade fever is the classic triad described.

Severe vomiting and the presence of high-grade fever suggest other causes of abdominal pain. Alteration in the bowel habits with constipation and at times diarrhoea can occur. Tenderness and guarding in the right lower quadrant of the abdomen.

The site of pain depends on the position of the appendix. The pain may be localised to the flank or the back in cases of retrocaecal appendix. Abdominal swelling can occur in the late stages. The duration of the pain is usually for less than 48 hours but it can be longer in the elderly and those with complications like perforation. In a small number of persons the pain may be longer than two weeks.





Investigations and Diagnosis

Blood counts reveal an elevated white cell count - leucocytosis with neutrophilia . Urine examination may reveal microscopic haematuria and pyuria. A urine analysis is essential to rule out the presence of urinary tract infection, which mimics appendicitis.

Although the diagnosis is clinical, ultrasound examination of the abdomen can accurately diagnose the condition in about 85% of persons. This is especially useful if the condition mimics adnexal disease in women. In patients with suspected perforation CT scan of the abdomen is done to diagnose a periappendiceal abscess. Radionuclide scanning: neutrophils and macrophages are labelled with technetium 99m and injected intravenously and serial imaging is done over four hours

Appendiceal inflammation is indicated by a localised uptake of the tracer in the right lower quadrant. The sensitivity is 90% and the specificity is about 95%. Plain X ray abdomen may or may not reveal any abnormal findings. The fecalith may be seen in about 20% of persons. Other tests that have been done before the availability of the CT scan are the barium enema.

The diagnosis may be confirmed by an explorative laparotomy.

Differential diagnosis (other possible conditions)


Viral gastroenteritis: This condition usually presents with nausea, vomiting and low grade fever and diarrhoea and mimics appendicitis. The difference between the two conditions is that the pain of gastroenteritis is generalised and the tenderness is not well localised.

Acute salpingitis: This should be considered in young women with fever, abdominal pain and bilateral abdominal and pelvic tenderness.

Torsion of the ovarian cyst: In this condition the abdominal pain is sudden and severe.

Ruptured ectopic pregnancy: The abdominal pain is sudden and severe and the patient has diffuse tenderness and features of shock. An ultrasound examination and a positive pregnancy test is diagnostic.

Other conditions that mimic an appendicitis are ureteric colic, pyelonephritis, diverticulitis, crohns disease, perforated peptic ulcer, cholecystitis, mesenteric adenitis etc,





Treatment and Prognosis

Patients with suspected appendicitis should not be fed orally and started on intravenous fluids. Patients with signs of dehydration are given fluid bolus of crystalloids. Analgesics can be given for symptomatic relief. Antibiotics are administered intravenously to those with evidence of septicaemia and as a preoperative preparation. Antibiotics are chosen to cover anaerobic and gram negative organisms. Antibiotics commonly used are ampicillin, gentamycin and clindamycin. Antibiotics have been found to be effective in decreasing the post operative wound infection and the outcome in patients with complications like septicaemia and appendicular abscess. For the treatment of appendicular abscess the initial treatment is use of antibiotics followed by appendectomy as an elective procedure.

The definitive treatment is the surgical removal of the appendix. The conventional method is the removal of the appendix by an open laparotomy. The current treatment followed is ligation and electrocauterisation. For patients who have signs of peritonitis a peritoneal lavage with saline is done. The use of drains is controversial.

The recent method of surgery adopted is the Laparoscopic appendectomy. This procedure makes use of a laparoscope for the removal of the appendix. The advantages are shorter hospital stay, decrease in the incidence of postoperative infection, shorter convalescent period and greater cosmetic acceptance. The disadvantages are longer operating time (about 20 minutes).

Prevention


There are no known preventive measures for appendicitis.

High fibre diet decreases the bowel transit time and the viscosity of the faeces and reduces the formation of fecaliths that predispose to obstruction of the appendix. The incidence of appendicitis is lower in those with a high intake of dietary fibre.