{'fraction_non_alphanumeric': 0.027625597388973074, 'fraction_numerical': 0.005245366592842989, 'mean_word_length': 5.190476190476191, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Intravascular double J stent migration: A case report, review, and management algorithm

A double J stent (DJS) is the main therapy for ureteral obstruction when conservative treatment fails. Antegrade migration in the bladder – or retrograde migration in the ureter – are well-known complications. We present a case with intravascular migration of a DJS into the inferior vena cava. Inferior venocavagraphy confirmed the position of the stent, and thrombus formation was excluded at its tip. The stent was retracted endoscopically. After the procedure, limited contrast leakage was seen at the perforation site on venography. The current available literature is reviewed. Based on this, a management algorithm is drawn up. Abstract


INTRODUCTION
The purpose of a double J stent (DJS) is to maintain low-pressure urine flow from the kidneys to the bladder, which can be endangered by ureteral obstruction or ureteral injuries. Retrograde cystoscopic placement is a simple procedure, which may result in hematuria, bacteriuria, urosepsis, migration, fragmentation, and encrustation. Most of these complications can be managed with supportive medical management. [1] We present a case in which vascular migration of a DJS was seen into the inferior vena cava (IVC) and which was retracted endoscopically. This complication has been reported eleven times, in which endoscopic removal of the intravascular DJS was performed thrice. To the best of our knowledge, this article is unique by providing a detailed management algorithm.

CASE REPORT
A 44-year-old male patient presented with bilateral renal colic pain. Renal ultrasound showed mild hydroureteronephrosis on the left side. Blood analysis showed normal leukocytes counts, normal C-reactive protein, and normal creatinine and urea. On nonenhanced computed tomography (NECT), proximal ureteral stones were seen with left-sided hydronephrosis and a 6-mm stone and a right-sided 8-mm stone but no pyelocaliceal dilatation. Renal colic pain persisted despite adequate analgesic therapy. Therefore, the patient was admitted to the hospital and DJS was placed bilaterally. During placement of the DJS on the right side, some resistance was felt. Perioperative kidneys, ureters, and bladder radioscopy showed a somewhat medial position of the right stent, but a nice proximal curl was noted [ Figure 1].
During hospitalization, right renal colic pain persisted, gross hematuria occurred, and kidney function decreased. The next-day follow-up NECT was performed. A perforation in the right distal ureter with intravascular migration of the DJS in a branch of the internal iliac vein up into the IVC -at the level of the left renal vein -was seen in combination with right-sided hydronephrosis [ Figure 2]. Inferior venocavagraphy was performed which confirmed the intravascular position of the stent and excluded the formation of significant thrombus at its tip [ Figure 3a]. The DJS was removed cystoscopically. Immediate inferior venocavagraphy after DJS removal showed limited contrast leakage at the perforation site, and a fully clear image was noted after 10 min [ Figure 3b].
The stones were treated by ureteroscopy and laser lithotripsy 4 weeks later. Another 4 weeks later, the DJS were removed. Follow-up was uneventful, and as far as, we know the patient had no stone remission.

DISCUSSION
Because the ureter is adjacent to the iliac vein and the vena cava, a DJS can be prone to vessel erosion or more rare, intravascular migration. [2] It is suggested that ureteral wall fragility, as a consequence of chronic ureteral trauma by ureteral wall inflammation or urolithiasis, forms a predisposing factor for ureteral perforation. Intravascular DJS migration to the heart or lung vasculature is considered the most severe complication as this possibly leads to tricuspid valve insufficiency, lung embolism, and endocarditis. [1,[3][4][5] Figure 1: Peroperative kidneys, ureters, and bladder X-ray after the placement of double J stents bilaterally in a man with bilateral renal colic pain due to ureterolithiasis. The left stent was positioned correctly. The right stent projected cranially at T12 and showed a somewhat medial position, but a nice proximal curl was noted. Because of the suspicion of an aberrant position, a computed tomography scan was planned Three approaches for the removal of a DJS after intravascular migration have been described, dependent on the position of the distal coil and the formation of thrombus at the stent: endovascular, open, or endoscopic approach [ Table 1]. [1][2][3][4][5][6][7][8][9][10][11] Furthermore, treatment of choice will also be determined by the general condition of the patient, expertise of the surgeon, and infrastructure.
Based on literature, the following algorithm is suggested when thrombus formation is excluded: 1. Endoscopic approach, as described in our case. This is only possible when the distal part of the DJS is in the ureter or bladder lumen. If thrombus formation is excluded, vital signs are stable, abdominal CT excludes retroperitoneal hemorrhage, or active bleeding focus (to exclude the great trauma of the iliac wall) and adhesions are not present, the distal tip of the DJS can be captured by a peripheral snare, and endoscopic retraction of the stent can be expected uneventful. Venous valves, preventing retrograde blood flow, and low pressure in veins prevent the vessel from excessive bleeding and allow a spontaneous wall recovery 2. Endovascular approach which is urgent when there is a complete extrusion of the stent from the urinary tract into the vascular circulation, and endoscopic removal is not an option anymore. For the endovascular procedure to be safe and simple, vital signs must be stable, abdominal CT must exclude retroperitoneal hemorrhage, or active bleeding focus and adhesions should not be present. In this procedure, an access is made in the femoral vessel and the lower end of the DJS is grasped and retrieved under fluoroscopic and angiographic guidance 3. Open surgical exploration is indicated when there is a complete extrusion intravascular, vital signs are not stable, and retroperitoneal hemorrhage and/or  This was followed by right atriotomy. With a sharp dissection, adhesions between the DJS and the tricuspid valve were divided. [9] When thrombus formation is seen, the treatment algorithm changes. There are some strategies for the DJS removal with thrombus formation such as catheter-directed pharmacologic thrombolysis, pharmacomechanical thrombolysis, and surgical thrombectomy. Meissner et al. suggest pharmacomechanical strategies over catheter-directed pharmacologic thrombolysis alone. [12] 1. Pharmacomechanical thrombolysis is indicated when vital signs are stable, abdominal CT excludes retroperitoneal hemorrhage, or active bleeding focus and adhesions are not present 2. Surgical thrombectomy which urges when vital signs are not stable, retroperitoneal hemorrhage and adhesions are present and/or if thrombolytic therapy is contraindicated.
DJS placement has no single, universally accepted, or recommended technique. We conclude that peroperative real-time radioscopy should always be used when inserting a DJS to confirm a correct positioning. In case resistance is felt during placement when there is doubt about the position of the stent or in cases where large urethral obstruction was noted on preoperative imaging, an ascending ureterography should be performed. Some authors even recommend to systematically perform an ascending ureterography during DJS placement, to visualize the renal pelvis and the correct position of the proximal tail. [13] When resistance is felt, it is important not to force the DJS. When intravascular migration has occurred, the location of the stent should be assessed, and thrombus formation should be excluded by inferior venocavagraphy. A high degree of suspicion is needed when the patient presents with severe hematuria, severe (abdominal) pain, or no improvement of renal colic pain. An early intervention is a keystone in avoiding bigger complications.

Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.