Since its first documented use in 1865, the use of nephrostomy tubes has diversified from emergency decompression of an obstructed collecting system and is now the initial step in interventions such as percutaneous nephrolithotomy (PCNL), renal biopsy, and ureteral stenting dilation. The devices used for the same have also evolved since their inception, from a simple trocar to the currently used locking devices anchored by a thread loop. However, improper retrieval of the nephrostomy tube or avulsion of the thread during removal can result in the retention of a foreign body in the collecting system, which can act as a nidus for calcification and infection. We present the case where a nephrostomy tube was placed in a transplanted kidney, and following incomplete removal of the thread loop, resulted in an atypical calcification on the thread in the renal pelvis and proximal ureter.

Case Details

A 57-year-old female patient presented to the emergency department in November 2021 with right lower quadrant abdominal pain, urinary frequency, painful urination, nausea, and vomiting. She denies flank pain, blood in the urine, or fevers.

She has a history of end-stage renal disease due to polycystic kidney disease, for which she has been on hemodialysis since July 2017. She underwent a deceased donor renal transplant in October 2018. She was admitted in October 2020 for a 5-mm ureteral stone in the transplant kidney, for which a nephrostomy tube insertion with antegrade stent placement was performed following an unsuccessful retrograde pyelogram. Urine cultures at the time grew Proteus and she was appropriately treated for the same. A repeat CT abdomen showed a stone of 2 mm diameter, suggesting that she possibly passed the previous one. Following the resolution of her symptoms and negative cultures, her nephrostomy tube and stent were removed in November 2020 in the office.

A physical examination revealed right lower quadrant abdominal tenderness but no costovertebral angle tenderness, clinically indicating a pathology in the transplanted kidney. Investigations at the time revealed an elevated serum creatinine (2.23 mg/dL), with a large number of red and white blood cells in the urine; 4+ bacteria were also noted in the urinalysis. An abdominal ultrasound showed hydronephrosis, following which an abdominal CT was performed. A calcified stringlike structure was noted in the renal pelvis of the transplanted kidney, extending into the ureter (Figure 1, A and B).

Figure 1. Non-contrast CT showing atypical renal calcification seen in renal pelvis of transplanted kidney due to retained nephrostomy thread. A, Axial view. B, Coronal view.

Subsequently, a nephrostomy tube was placed in the transplant kidney and her creatinine returned to baseline. PCNL with laser lithotripsy was done in December 2021. The access was obtained using a combination of ultrasound and fluoroscopy (Figure 3, A and B). The tract was dilated from 8Fr to 20Fr using a metal dilator, and an 18Fr mini-nephroscope was used in combination with a flexible cystoscope to visualize the renal pelvis. The procedure revealed the calcified structure to be the retained nephrostomy thread from her first nephrostomy tube placed in October 2020 (Figure 2). The nephrostomy tube was subsequently removed and her renal function has since returned to normal.

Figure 2. Renal calculus formation on retained nephrostomy thread.

Figure 3. Intraoperative fluoroscopic images during percutaneous nephrolithotomy while obtaining access to the transplant kidney.

Discussion

Since the first description of percutaneous nephrostomy (PCN) as a treatment modality for hydronephrosis by Goodwin et al,¹ the use of percutaneous nephrostomy tubes has been widely accepted as a safe and effective means of draining an obstructed collecting system. In addition to this, PCNs are often used in PCNLs, removal of upper tract urothelial tumors, therapeutic instillations of chemotherapy and other drugs, treatment of hydrocalyx, and other renal surgeries which require a percutaneous approach. PCNs are also being used for diagnostic studies such as the Whittaker test and antegrade pyelography.^2,3

Ureteral obstruction and leakage are the most common urological complications encountered in kidney transplant recipients. A number of studies have shown that the use of PCN in transplanted kidneys is safe and highly effective with a very low complication rate, and it has successfully been used as a sole therapy to treat obstruction in transplanted kidneys.^4-6

The design of nephrostomy tubes has evolved over the years and the currently used nephrostomy tubes are self-retaining loop catheters. A synthetic suture runs on the inside of the catheter and leaves the catheter at the proximal end of the loop, only to reenter the lumen at the distal end. While removing the tube, the hub of the tube is cut off, releasing both ends of a locking suture.⁷ Rarely, however, the suture does not come out with the catheter and may be held in the kidney by encrusting material or inflammatory tissue. The suture material may also be avulsed during removal. Retained suture material can provide a nidus for calcification or infection, as seen in our case. We were able to retrieve 3 fragments, with the longest fragment measuring 6 cm and 2 fragments measuring 2 cm each. Given the length of these fragments, we suspect that the nephrostomy thread was avulsed during removal. It is essential to check that the suture is retrieved intact during nephrostomy tube removal.

Funding

No funding was obtained to assist in the collection of information contained in this article.

Conflict of Interest

The authors whose names are listed certify that they have no affiliations with or involvement in any organization or entity with any financial interest or nonfinancial interest in the subject matter or materials discussed in this manuscript.

Ethics Statement

All information was collected with consent of the participant involved and health care information shall remain confidential.