Investigation

The diagnosis of acute appendicitis is essentially clinical. A full blood count and urinalysis should be performed in all cases. In women of reproductive years, it is wise to obtain a urinary pregnancy test before proceeding to exploration. Pelvic ultrasound is of value in excluding tubal or ovarian disease if suspected. Abdominal ultrasound examination is a useful diagnostic tool, particularly in children, with a diagnostic accuracy of appendicitis in excess of 90 per cent (Fig. 59.11).

In dehydrated or elderly patients or where comorbid conditions dictate, serum urea and electrolytes should be checked. If a diagnosis of intestinal obstruction, intussusception or ureteric colic is being entertained, a supine abdominal X-ray should be performed (Table 59.6).