Swallowed Fish Bone Migrated from Man’s Gut into Liver, Causing Abscess

A 56-year-old man endured 25 days of unexplained fever without abdominal pain, nausea or vomiting. A local clinic prescribed about a week of penicillin, but his fever did not improve.

When he eventually went to Shandong Provincial Hospital in Jinan, China, a contrast-enhanced CT scan revealed a 4.5-by-3.0-centimetre abscess in his liver. A thin, bright line measuring about 3.5 centimetres ran from the wall of his duodenum into the abscess cavity. Only after the scan led doctors to ask more detailed questions about his diet did he recall swallowing a fish bone roughly three and a half weeks earlier. He had not considered it important enough to mention.

Surgeons later removed a 4-centimetre curved piece of bone from the abscess. The case was published in March in Frontiers in Medicine.

The Missing Symptom Was the Main Clue

Gastrointestinal perforation usually causes obvious symptoms: sudden, severe abdominal pain, a rigid abdomen, rebound tenderness and an inability to get comfortable. This patient had none of them. His abdomen was soft and non-tender, and Murphy's sign was negative.

The authors attribute the absence of symptoms to the patient's anatomy. The back wall of the duodenum lies in the retroperitoneum, behind the membrane lining the abdominal cavity. A perforation in that area can leak into a contained space rather than irritate the peritoneum, meaning the usual warning signs do not appear. The infection can then spread quietly through the retroperitoneal tissue toward the liver.

As a result, an abdominal emergency may present simply as a fever of unknown origin. His temperature on admission was only 37.6 degrees Celsius and never exceeded 38 degrees. His inflammatory markers were elevated, including an interleukin-6 level of 72.2 pg/mL and neutrophils accounting for 76.3 percent of white blood cells. However, most of his liver-function tests were normal and tumour markers were negative. Nothing clearly pointed to the digestive tract.

Radiologists Should Trace the Track, Not Just Look for the Object

The medical team said the key diagnostic pattern on contrast CT was a combination of three findings: a liver abscess, a sinus tract connecting the duodenum to the abscess, and inflammation around the duodenal wall.

The foreign body itself may not be visible on scans because it can be concealed by fibrous tissue. Indirect signs, such as haziness between the liver and duodenum or fine linear streaking, should also raise concern. The authors said radiologists should actively trace a possible migration route rather than wait to identify the bone itself.

That approach proved effective in this case. The linear density measured approximately 280 Hounsfield units and was 2 millimetres wide. Inflammation in the fat around the duodenum and enlarged reactive lymph nodes completed the picture.

One Operation Provided Both the Diagnosis and the Treatment

Laparoscopic surgery revealed dense adhesions connecting liver segment five to the transverse colon, omentum and duodenum. Milky pus had collected in the hepatorenal space. A fibrous tract led to a hard mass on the surface of the liver. When surgeons opened the abscess, a sharp tip was seen protruding from the liver tissue.

The extracted bone measured about 4.0 centimetres, slightly longer than the estimate from the CT scan. The authors said this difference was likely because the bone lay at an angle to the scanning plane. The perforation in the duodenum was only a pinpoint opening and had already been sealed by chronic inflammatory scarring. Surgeons reinforced it with sutures.

Managing the patient's other medical conditions also required planning. He had a coronary stent and was taking the antiplatelet drug ticagrelor. Doctors stopped the medication two days before surgery and restarted it after the risk of bleeding had passed.

Blood cultures taken on admission showed no growth after five days of incubation. The source of the infection was identified in the pus, which grew Escherichia coli, Streptococcus anginosus group and Bacteroides fragilis. The combination was consistent with an infection originating in the gut and was already covered by the ceftriaxone and metronidazole treatment he had received. His temperature returned to normal the day after surgery. He was discharged on the fourth day, and follow-up examinations found no recurrence.

Most Swallowed Bones Cause No Problems

The broader context is important, because this case should not be interpreted as a general warning against eating fish.

About 80 to 90 percent of swallowed foreign bodies pass through the digestive tract without causing problems. Around 10 to 20 percent require endoscopic removal, while fewer than 1 percent require surgery, according to figures cited in the report and in the surgical literature on foreign-body perforation. Migration into the liver is even rarer. A review of fish-bone migration published last year described it as an uncommon complication documented in a scattered collection of case reports. Other research groups have reported duodenal perforations caused by fish bones that could be managed endoscopically. A separate case of a liver abscess caused by a fish bone was published in a British medical journal last year.

Guidance from the European Society of Gastrointestinal Endoscopy recommends endoscopy within 24 hours when sharp objects, magnets, batteries or large items remain in the stomach. The practical lesson from this case is narrower and mainly relevant to clinicians: unexplained fever accompanied by a liver abscess should prompt questions about what the patient has been eating. This is a single case report and does not change dietary advice. Anyone with a persistent unexplained fever should be assessed by a medical professional.

Key Questions Answered

What happened to the patient?

A swallowed fish bone perforated the back wall of his duodenum, migrated into his liver and caused an abscess. His only symptom was 25 days of low-grade fever.

Why did he have no abdominal pain?

The back wall of the duodenum lies in the retroperitoneum. A perforation there can leak into a contained space instead of irritating the peritoneum, so the classic signs of an acute abdomen may not appear.

How was the condition diagnosed?

Contrast-enhanced CT showed a liver abscess and a high-density linear object extending from the duodenum into the liver. The scan prompted doctors to ask again about his diet, after which he recalled swallowing the fish bone.

How common is this?

It is very uncommon. Most swallowed foreign bodies pass through the digestive tract naturally, and fewer than 1 percent require surgery. Migration into the liver represents a small fraction of that already uncommon group.

Did he recover?

Yes. Laparoscopic surgery removed the bone, drained the abscess and repaired the perforation. His fever resolved the following day, he went home on the fourth day after surgery, and follow-up found no recurrence.

Should people stop eating fish with bones?

Nothing in this report supports that conclusion. It describes a single case. Anyone who feels a bone become lodged while eating, or develops a persistent unexplained fever afterward, should seek medical attention.

Originally published on Medical Daily