Abdominal imagingCase Type
Ana Paula Borges, Célia Antunes, Paulo Donato, Filipe Caseiro AlvesPatient
82 years, female
An 82-year-old lady presented with a one week history of rotatory vertigo and mild holocranial headache. The only abnormalities on examination were fever (38,6 ºC) and tenderness in the abdominal right upper quadrant. Blood tests revealed leucocitosis (17.7 x 109/L), thrombocitosis (647 x 109/L) and C-Reactive Protein of 16.8 mg/L.
Abdominal ultrasound revealed, besides diffuse liver hyperechogenicity, a heterogeneous fluid collection measuring 110 x 46 mm at the left flank. Subsequent CT scan showed a well-defined fluid collection measuring 10 x 55 x 98 mm, with a thick and enhanced wall. Within the collection there was a spontaneous dense linear image, extending to an area of inflammatory stranding in contact with a small bowel loop, probably representing an ingested foreign body, which perforated the small bowel and originated an abscess.
The patient was submitted to exploratory laparoscopy with the removal of the foreign body (a fishbone) and drainage of the intra-abdominal abscess. At inspection of small bowel no perforation was identified, presumably due to closure of the initial penetrating hole in the small bowel. She was also given intravenous cefthriaxone and metronidazole.
She improved clinically, inflammatory markers normalized, and she was discharged seven days later. At follow-up consult she was asymptomatic.
Foreign body ingestion is not an uncommon problem encountered in clinical practice.  Most foreign bodies travel through the gastrointestinal tract within a week, without complications. However, in a small percentage of cases, they may impact or perforate the gastrointestinal tract.  The perforation of the gastrointestinal tract can lead to severe complications such as the formation of abscess.  Fish bones are the most commonly seen objects leading to bowel perforation, due to their sharp shape.  Ingested fish bones may be forgotten, and there can be a time lag of months or even years between ingestion and the onset of symptoms. Therefore, a clinical history might not be helpful. Moreover, fishbone complications in the gastrointestinal tract manifest with a variety of clinical presentations, ranging from impaction in the upper gastrointestinal tract, dysphagia, bowel obstruction, and silent perforation to frank peritonitis. 
Fishbones are difficult to identify on plain radiography, depending on their size, bony calcification and fish type.  A CT scan of the abdomen is helpful to determine the cause of unexplained and persistent abdominal pain.  In most of the reported cases, CT revealed not only inflammatory alterations but also linear hyperdense objects in the vicinity.  The patient, in this case, was unaware of ingesting the fishbone that was seen on the CT scan, within the abdominal wall abscess.
The management of an ingested foreign body depends on the patient’s signs and symptoms, and the type and location of the ingested object. Conservative treatment is suitable for the great majority of asymptomatic patients. Surgical removal should be considered when there are complications or when a foreign body doesn’t progress through the digestive tract.  For most intra-abdominal abscesses, CT-guided drainage is a useful treatment tool. However, if there is a foreign body embedded in the abscess, as was in this case, an open laparotomy and removal of the foreign body is the treatment of choice. 
The risk of complications increases with a longer duration elapsed between the fishbone ingestion and the attempted retrieval.  Given the fact that the medical history and clinical presentation alone may not be suggestive of fishbone ingestion, clinical suspicion and imaging studies may be of great value to a timely diagnosis and treatment. In this case, CT was extremely useful in detecting the unsuspected cause of abdominal pain, before the development of more severe complications.
 Chien-Kan Chen, Yu-Jang Su, Yen-Chun Lai, Henry Kam-Hong Cheng, Wen-Han Chang (2010) Fish bone-related intra-abdominal abscess in an elderly patient. International Journal of Infectious Diseases 14: 171-172 (PMID: 19541523)
 Kuo CC, Jen TK, Wen CH, Liu CP, Hsiao HS, Liu YC, et al (2012) Medical treatment for a fish bone-induced ileal micro-perforation: a case report. World J Gastroenterol 18: 5994–8 (PMID: 23139620)
 Cho, Min-Kyung et al (2014) Fish bone migration to the urinary bladder after rectosigmoid colon perforation. World journal of gastroenterology 20: 7075–7078 (PMID: 24944504)
 Kuwahara, K., Mokuno, Y., Matsubara, H. et al (2019) Development of an abdominal wall abscess caused by fish bone ingestion: a case report. J Med Case Reports 13: 369 (PMID: 31837708)
 Klein, A., Ovnat-Tamir, S., Marom, T., Gluck, O., Rabinovics, N., & Shemesh, S. (2019) Fish Bone Foreign Body: The Role of Imaging. International archives of otorhinolaryngology 23: 110–115 (PMID: 30647794)