She had never had a urinary tract infection. Then a 56-year-old woman arrived at a Melbourne emergency department with right flank pain and a fever. Her urine showed infection. Her CT showed a badly swollen right kidney and bulky uterine fibroids, and the fibroids took the blame.
They were not the cause. A wooden toothpick she had no memory of swallowing had worked its way out of her duodenum and bored a channel into her right kidney. It would take another six months of hospital care to find it.
The case was published in BJUI Compass by Hedda Cooper of Flinders University and Jodie McDonald and Shannon McGrath of the urology department at St Vincent's Hospital Fitzroy.
A Diagnosis That Explained Almost Everything
The initial reasoning was sound. Large fibroids can compress a ureter and back up urine into the kidney, and this patient had large fibroids and an obstructed right kidney. Surgeons placed a ureteric stent. When they cannulated the ureteric opening, frank pus came out. They also noted that the ureter narrowed near its upper end.
She was discharged with a plan for a hysterectomy to remove the presumed cause. She had the operation. Afterward, the stent came out heavily encrusted, and her urine grew two species of Candida, which were treated with antifungal medication. And the infections kept coming.
That is the detail that should have reset the picture. The obstruction was supposed to be gone.
The Foreign Body Three Scans Did Not Flag
A follow-up CT intravenous pyelogram showed the kidney still swollen despite the hysterectomy, narrowing at the upper ureter, and a linear foreign body in her gastrointestinal tract. The reporting team called it a fishbone.
A gastroscopy that month found inflammation in the stomach and duodenum but no foreign body. In January 2024, she underwent a rigid cystoscopy and retrograde pyelogram, and contrast injected into her urinary tract turned up in her duodenum. That confirmed an abnormal channel between the two, a reno-duodenal fistula.
She had a repeat gastroscopy the next day. This time, the object came out. It was a toothpick, not a fishbone. At follow-up two months later, contrast no longer crossed into the duodenum, urine cultures were clear, and kidney function was stable.
The authors are direct about the delay. Six months elapsed between her hospital presentation and the diagnosis, during which she underwent several minor procedures and one major operation. She had multiple CT scans, and the team notes that none reported the foreign body at the time of the scan, nor on subsequent review once its presence was known. By their reckoning, more than 18 months separated her first symptom, an isolated episode of back pain whose significance they call unclear, from treatment.
Sharp Objects Behave Differently
Most swallowed objects are harmless. Endoscopic reviews put spontaneous passage at 80% to 90%. Sharp items are the exception, with toothpicks and fishbones associated with gastrointestinal perforation in roughly 10% to 15% of cases and linked in published reports to sepsis, liver abscess, appendicitis, and peritonitis.
Toothpicks are a specific problem. They are easy to swallow without noticing, hard to see on plain films, and the duodenum is the most commonly reported site of lodgement in the upper gastrointestinal tract. A 2014 review in the World Journal of Surgery assembled 136 published cases of accidental toothpick ingestion severe enough to cause gastrointestinal injury.
The anatomy explains the rest. The duodenum lies directly against the right kidney, so a sharp object that perforates the duodenal wall is already in contact with renal tissue. A 2022 report in BMC Infectious Diseases described sepsis from kidney injury caused by a toothpick.
Nor is the fibroid detour unique. A 2024 report in the Journal of Surgical Case Reports describes a 57-year-old woman with six months of recurrent urinary infections and right flank pain, initially attributed to obstruction from uterine fibroids. She too had a hysterectomy that did not resolve her symptoms. She too had a toothpick lodged in the duodenum, fistulating into the right renal pelvis, retrieved endoscopically.
The Warning the Authors Wanted to Leave
Their message is narrow. When treating urinary sepsis, they write, "it is important to consider renal foreign bodies as an alternative diagnosis."
The features that made this case hard to solve are worth noting. The patient had generalized urinary sepsis symptoms that pointed everywhere and nowhere. She had a plausible competing diagnosis for her fibroids. She had no recollection of swallowing anything. And she lacked blood in the urine, which had been present in some previous cases.
These are individual patients, and single cases do not measure risk. But the pattern is one people can act on. Infections that keep recurring after the supposed cause has been surgically removed signal that the explanation is incomplete. Anyone in that position should ask their clinician what else could account for it.
Key Questions Answered
What happened to the patient? A swallowed toothpick perforated her duodenum and created a channel into her right kidney, causing recurrent urinary tract infections, a swollen kidney, and a narrowed ureter. It was removed endoscopically, and she recovered.
Why did the diagnosis take so long? Her swollen kidney was initially attributed to large uterine fibroids, a plausible cause. Her symptoms were nonspecific; she had no memory of swallowing anything, and multiple CT scans did not flag the foreign body.
What is a reno-duodenal fistula? An abnormal channel between the duodenum and the kidney. Here, it was confirmed when contrast injected into the urinary tract appeared in the duodenum.
How often do swallowed objects cause this kind of damage? Rarely. Roughly 80% to 90% of swallowed foreign bodies pass without incident, but sharp objects such as toothpicks and fishbones are associated with perforation in about 10% to 15% of cases.
Why are toothpicks especially dangerous? They are sharp at both ends, hard to see on plain X-rays, easy to swallow unnoticed, and commonly lodge in the duodenum, which lies immediately adjacent to the right kidney.
When should someone push for further investigation? Recurrent urinary tract infections that persist after the presumed cause has been treated warrant a conversation with a clinician about alternative explanations.
