Evidence before this study: Acute appendicitis is the most common general surgical emergency in children. Its diagnosis remains challenging and children presenting with acute right iliac fossa (RIF) pain may be admitted for clinical observation or undergo normal appendicectomy (removal of a histologically normal appendix). A search for external validation studies of risk prediction models for acute appendicitis in children was performed on MEDLINE and Web of Science on 12 January 2017 using the search terms ["appendicitis" OR "appendectomy" OR "appendicectomy"] AND ["score" OR "model" OR "nomogram" OR "scoring"]. Studies validating prediction models aimed at differentiating acute appendicitis from all other causes of RIF pain were included. No date restrictions were applied. Validation studies were most commonly performed for the Alvarado, Appendicitis Inflammatory Response Score (AIRS), and Paediatric Appendicitis Score (PAS) models. Most validation studies were based on retrospective, single centre, or small cohorts, and findings regarding model performance were inconsistent. There was no high quality evidence to guide selection of the optimum model and threshold cutoff for identification of low-risk children in the UK and Ireland. Added value of this study: Most children admitted to hospital with RIF pain do not undergo surgery. When children do undergo appendicectomy, removal of a normal appendix (normal appendicectomy) is common, occurring in around 1 in 6 children. The Shera score is able to identify a large low-risk group of children who present with acute RIF pain but do not have acute appendicitis (specificity 44%). This low-risk group has an overall 1 in 30 risk of acute appendicitis and a 1 in 270 risk of perforated appendicitis. The Shera score is unable to achieve a sufficiently high positive predictive value to select a high-risk group who should proceed directly to surgery. Current diagnostic performance of ultrasound is also too poor to select children for surgery. Implications of all the available evidence: Routine pre-operative risk scoring could inform shared decision making by doctors, children, and parents by supporting safe selection of lowrisk patients for ambulatory management, reducing unnecessary admissions and normal appendicectomy. Hospitals should ensure seven-day-a-week availability of ultrasound for medium and high-risk patients. Ultrasound should be performed by operators trained to assess for acute appendicitis in children. For children in whom diagnostic uncertainty remains following ultrasound, magnetic resonance imaging (MRI) or low-dose computed tomography (CT) are second-line investigations.

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Bilateral femoral hernias are less common in men than in women and rare in young adults. Only one case of a bilateral femoral hernia in a young man has been reported in the literature before. Three main theories have been postulated for femoral hernias. The theory that they are an acquired disease is the most accepted due to the common occurrence of such hernias in multiparous women but the theory lacks enough evidence. We report two cases in young men. Anatomical variations in the femoral canal could be the primary aetiological factor in these patients. A unilateral femoral hernia in young men with acquired aetiological factors requires a clinical examination of the opposite side.

Duplication cysts are an uncommon finding. Majority of these cases are found in the region of the midgut, and many have been reported in literature. However, there has been only one previous case of a midgut duplication cyst lined by respiratory epithelium. This is a rare pathology, of which very little is known about. The pathophysiology of these cases is also difficult to explain. We aim to present a case of a midgut duplication cyst in a paediatric patient, who had other abnormalities as well. We also aim to offer a hypothesis for this case.