it is postulated that these cause luminal obstruction resulting in subsequent acute inflammation of the mucosa . appendicoliths are composed of inspissated faecal material , mucus with trapped calcium phosphate and inorganic salts . dropped appendicoliths from appendicectomy are rare , but the surgeon and radiologist ought to consider them as a potential source of intra - abdominal complications . until recently , the presence of an appendicolith was considered 100% specific for the diagnosis of acute appendicitis . however , 13% of patients without acute appendicitis showed an appendicolith on ct ( 2 ) . presence of an appendicolith is also associated with a high incidence of perforation , particularly in children . appendicoliths can be detected by plain abdominal radiographs in 10 to 15% of patients with acute appendicitis . with the recent popularity of ultrasound and the appendicoliths can drop at the time of resection of the appendix , during forceful extraction through the umbilical port or if the appendix perforates . complications associated with retained faecoliths following appendicectomy are becoming more prevalent with the increased use of the laparoscopic technique , similar to the increase in dropped gallstones following the introduction of laparoscopic cholecystectomy ( 2 ) . the time between laparoscopic appendicectomy and representation with abscess ranged from 2 months to 4 years ( 2 ) . the natural history of dropped appendicoliths is not yet known but there is some early evidence that they have a significant association with abscess formation , with the appendicolith acting as a nidus for infection . ct - guided percutaneous drainage of intra - abdominal abscess secondary to retained appendicoliths is only successful in the short term . formal surgical drainage and removal of the appendicolith is required for long - term success ( 2 ) . ultrasound has been described as a useful adjunct for intra - operative localisation of the appendicolith ( 4 ) . a 17-year - old female presented to the emergency department , with intermittent right upper quadrant pain , nausea and vomiting . she was previously fit and well , with her only background history being a laparoscopic appendicectomy for perforated appendicitis the previous year , aged 16 . abdominal examination revealed tenderness to palpation in the right upper quadrant and no palpable masses . bloods tests revealed raised inflammatory markers . computed tomography of the abdomen was performed and revealed a 43 cm structure of low attenuation posterolateral to segment 6 of the liver with surrounding irregular wall and a central 15 mm high density lesion , suggestive of a peritoneal foreign body , possibly a retained appendicolith from previous surgery ( figure 1 ) . abdominal ct scan showing a radio - opaque faecolith in the right upper quadrant ( arrowed ) it was felt that this could be removed via ultrasound guidance through a small intercostal incision under local anaesthetic . this was attempted but failed secondary to an iatrogenic pneumothorax and failure to localise the lesion . once the peritoneum was opened purulent fluid discharged and on exploration of the cavity the faecolith was found ( figure 2 ) . the patient s post - operative course was uneventful and she was discharged home the following day in a stable condition , afebrile and with normal serum inflammatory markers . appendicectomy , especially in cases of perforated appendicitis , is associated with postoperative abscess formation in up to 20 per cent of cases ( 1 ) . though this treats the abscess , it does not necessarily treat the root cause and nidus of infection  the appendicolith . in cases of retained appendicolith , failure to do so may result in recurrent intra - abdominal abscesses , wound infection and occasionally fistula formation ( 5 ) . retained appendicolith has been reported in different sites including the pelvis , gluteal region , hepatorenal pouch ( of morrison ) and subhepatic region . it can be detected by ultrasound or computed tomography scan as fluid collection containing a focus of high attenuation which may be single or multiple . occasionally , plain radiograph film may show these retained appendicolith , though the sensitivity is only 10% ( 1 ) . the literature reveals few cases of subhepatic abscesses due to retained appendicolith and most of them required operative intervention , whether laparoscopic or via the open approach . a high index of suspicion ought to be maintained in patients presenting with recurrent intra - abdominal sepsis and a history of appendicectomy . the risk of retained appendicolith may be reduced by ensuring that the distal end is intact after division of the appendix . the authors advise gentle manipulation when handling an acutely inflamed appendix to avoid appendicolith spillage . in the event of spillage , the appendicolith ought to be retrieved , as failure to do so may lead to subsequent complications . definitive treatment depends on removal of appendicolith , and the authors advocate that this can be safely accomplished via the laparoscopic method .
appendicectomy is one of the commonest emergency operations performed worldwide . in cases of perforated appendicitis , 
 the prevalence of post - operative abscess formation is up to 20 per cent ( 1 ) . 
 most cases can be managed with drainage and antibiotics . however 
 , a minority of these will leave a retained appendicolith.we present a case of a 17 year old female patient who presented 1 year after laparoscopic appendicectomy for perforated appendicitis , with right upper quadrant pain and sepsis.computed tomography ( ct ) of the abdomen was performed and revealed a retained appendicolith with perihepatic abscess formation in the right upper quadrant . 
 she underwent laparoscopic drainage of this perihepatic abscess and removal of the faecolith . 
 she was discharged home the following day and remains well .