Abstract: We included two randomised controlled trials with a total of 80 participants in this review. 1. Early versus delayed open appendicectomy for appendiceal phlegmon Forty participants (paediatric and adults) with appendiceal phlegmon were randomised either to early appendicectomy (appendicectomy as soon as appendiceal mass resolved within the same admission) (n = 20), or to delayed appendicectomy (initial conservative treatment followed by interval appendicectomy six weeks later) (n = 20). The trial was at high risk of bias. There was no mortality in either group. There is insufficient evidence to determine the effect of using either early or delayed open appendicectomy onoverall morbidity (RR 13.00; 95% CI 0.78 to 216.39; very low-quality evidence), the proportion of participants who developed wound infection (RR 9.00; 95% CI 0.52 to 156.91; very low quality evidence) or faecal fistula (RR 3.00; 95% CI 0.13 to 69.52; very low quality evidence). The quality of evidence for increased length of hospital stay and time away from normal activities in the early appendicectomy group (MD 6.70 days; 95% CI 2.76 to 10.64, and MD 5.00 days; 95% CI 1.52 to 8.48, respectively) is very low quality evidence. The trial reported neither quality of life nor pain outcomes. 2. Early versus delayed laparoscopic appendicectomy for appendiceal abscess Forty paediatric participants with appendiceal abscess were randomised either to early appendicectomy (emergent laparoscopic appendicectomy) (n = 20) or to delayed appendicectomy (initial conservative treatment followed by interval laparoscopic appendicectomy 10 weeks later) (n = 20). The trial was at high risk of bias. The trial did not report on overall morbidity or complications. There was no mortality in either group. We do not have sufficient evidence to determine the effects of using either early or delayed laparoscopic appendicectomy for outcomes relating to hospital stay between the groups (MD −0.20 days; 95% CI −3.54 to 3.14; very low quality of evidence). Health-related quality of life was measured with the Pediatric Quality of Life Scale-Version 4.0 questionnaire (a scale of 0 to 100 with higher values indicating a better quality of life). Health-related quality of life score measured at 12 weeks after appendicectomy was higher in the early appendicectomy group than in the delayed appendicectomy group (MD 12.40 points; 95% CI 9.78 to 15.02) but the quality of evidence was very low. This trial reported neither the pain nor the time away from normal activities. It is unclear whether early appendicectomy prevents complications compared to delayed appendicectomy for people with appendiceal phlegmon or abscess. The evidence indicating increased length of hospital stay and time away from normal activities in people with early open appendicectomy is of very low quality. The evidence for better health-related quality of life following early laparoscopic appendicectomy compared with delayed appendicectomy is based on very low quality evidence. For both comparisons addressed in this review, data are sparse, and we cannot rule out significant benefits or harms of early versus delayed appendicectomy. Further trials on this topic are urgently needed and should specify a set of criteria for use of antibiotics, percutaneous drainage of the appendiceal abscess prior to surgery and resolution of the appendiceal phlegmon or abscess. Future trials should include outcomes such as time away from normal activities, quality of life and the length of hospital stay.

Plain-language summary: We searched for all relevant randomised controlled trials up to 23 August 2016. We identified two trials involving 80 participants. One compared early versus delayed open appendicectomy in 40 children and adults with appendiceal phlegmon. The other trial compared early versus delayed keyhole (laparoscopic) appendicectomy (where surgery is performed through a very small incision) in 40 children with appendiceal abscess. Studies took place in the USA and India. The age of the individuals in the trials varied between 1 year and 84 years, and 27.5% were females. Both two studies were small and had a number of limitations so we cannot be certain about how the effects of the two surgical approaches compare. From one trial in children and adults comparing open with delayed appendicectomy, there was insufficient evidence to show the effect of using either approach on the overall complication rate or the proportion of participants who developed wound infection. Our certainty in a longer stay in hospital stay and time away from normal activities with open appendicectomy is very low. There were no deaths in the study. Quality of life, and pain were not reported in this trial. The other trial in children with appendiceal abscess receiving either early or delayed keyhole appendicectomy did not report on overall complication rates. The trial did not provide enough evidence to show the effect of using either approach on the length of hospital stay among participants. We have very low certainty that children who had early keyhole appendicectomy had better quality of life compared with children who had delayed keyhole appendicectomy. The study did not report if there were any deaths, and did not provide information on pain, or time away from normal activities. At present the benefits and harms of early versus delayed appendicectomy are not well understood because the current information is based upon very low quality evidence. Both trials were at a high risk of bias. Overall, we judged the quality of the evidence to be very low. Thus, further well-designed trials are urgently needed.