hours and at weekends, further limiting its usefulness. Its first line investigative role is greater in paediatric populations, who typically have thinner musculature, less abdominal fat than adults and a greater need for radiation avoidance. Computed tomography In adolescent and patients, computed tomography has become the most accepted imaging strategy. In the USA, it is used in 86% of patients, with a sensitivity of 92.3%. This has led to a normal appendectomy rate of 6%. Uptake outside of North America is lower due to concerns over risk of radiation exposure in children and young adults, differing hospitals remuneration systems, unavailability outside of normal hours and absence of scanners in low resource hospitals. In one RCT comapring low-dose versus standard-dose CT in 891 patients, the normal appendectomy rate was 3.5% versus 3.1% respectively, although these advanced technology scanners are not in widescale use. For older patients at higher risk of malignancy, pre-operative CT is recommended to identify malignancy masquerading as (or, causing) appendicitis. Selective CT based on clinical risk scores is likely to target its use and justify radiation exposure (figure 3). Magnetic resonance imaging (MRI) MRI for patients with an acute abdomen may eliminate the risks associated with radiation use in young patients. However, little is know about the exact utility and accuracy in acute abdomen. For one, there are few units worldwide able to provide immediate access MRI at present. Second, MRI currently has no better accuracy than ultrasound in discriminating perforated appendicitis. Diagnostic strategies in young female patients In fertile female patients, the initial approach includes urinary pregnancy test to identify possible ectopic pregnancy and transvaginal ultrasound to identify ovarian pathology. In equivocal cases, a thorough clinical assessment (including pelvic examination) by on-call gynaecologists can differentiate alternative pathology and direct further investigations. Early laparoscopy has been suggested as a method to improve diagnosis in female patients with an equivocal diagnosis, having so far been assessed in single centre randomised trials. When compared to clinical
hours and at weekends, further limiting its usefulness. Its first line investigative role is greater in paediatric populations, who typically have thinner musculature, less abdominal fat than adults and a greater need for radiation avoidance. Computed tomography In adolescent and patients, computed tomography has become the most accepted imaging strategy. In the USA, it is used in 86% of patients, with a sensitivity of 92.3%. This has led to a normal appendectomy rate of 6%. Uptake outside of North America is lower due to concerns over risk of radiation exposure in children and young adults, differing hospitals remuneration systems, unavailability outside of normal hours and absence of scanners in low resource hospitals. In one RCT comapring low-dose versus standard-dose CT in 891 patients, the normal appendectomy rate was 3.5% versus 3.1% respectively, although these advanced technology scanners are not in widescale use. For older patients at higher risk of malignancy, pre-operative CT is recommended to identify malignancy masquerading as (or, causing) appendicitis. Selective CT based on clinical risk scores is likely to target its use and justify radiation exposure (figure 3). Magnetic resonance imaging (MRI) MRI for patients with an acute abdomen may eliminate the risks associated with radiation use in young patients. However, little is know about the exact utility and accuracy in acute abdomen. For one, there are few units worldwide able to provide immediate access MRI at present. Second, MRI currently has no better accuracy than ultrasound in discriminating perforated appendicitis. Diagnostic strategies in young female patients In fertile female patients, the initial approach includes urinary pregnancy test to identify possible ectopic pregnancy and transvaginal ultrasound to identify ovarian pathology. In equivocal cases, a thorough clinical assessment (including pelvic examination) by on-call gynaecologists can differentiate alternative pathology and direct further investigations. Early laparoscopy has been suggested as a method to improve diagnosis in female patients with an equivocal diagnosis, having so far been assessed in single centre randomised trials. When compared to clinical
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