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Coexisting intrarenal arteriovenous and caliceovenous fistulae after percutaneous nephrolithotomy: Case report and literature review.

A 58-year-old man was re-admitted to the Urology service with delayed gross hematuria and unstable he-modynamics, following a percutaneous nephrolithotomy (PCNL) procedure performed for an obstructive solitary left lower calyceal stone. A selective left renal angiogram demonstrated an interpolar arteriovenous fistula (AVF), which was treated with successful coil embolization of a sub-segmental feeding branch. Sub-sequent nephrostogram confirmed a coexisting caliceovenous fistula, which was observed and healed spon-taneously. Iatrogenic coexisting intrarenal AVF and caliceovenous fistulae have never been reported and should be considered as a possible cause of delayed severe hematuria with unstable hemodynamics, and/or increase in baseline creatinine after PCNL.


Introduction
Delayed hematuria occurs in approximately 1% of all percutaneous nephrolithotomy (PCNL) patients and is almost always secondary to pseudoaneurysms or interpolar arteriovenous fi stula (AVF) [1,2]. Signifi cant venous injuries during PCNL are under-diagnosed, and most of these lesions are not detected even on angiography [1,2]. Iatrogenic intraoperative renal pelvis and calyceal perforation often occurs during percutaneous tract dilation. It is important to note that caliceovenous fi stula may be missed or cannot be accurately determined by cross sectional imaging [3]. Additionally, when intrapelvic pressure exceeds the systemic venous pressure, as happens in an obstructed kidney, it may cause backfl ow of urine into the patient's circulation via spontaneously developed veno-caliceal fi stula and, in rare circumstances, can increase the serum creatinine level or present as pseudo renal failure [3]. We review the current literature and report an index case of coexisting intrarenal AVF and caliceovenous fi stulae, visualized on angiography and nephrostogram, respectively, after PCNL.

Case Report
A 58-year-old man, presented to our service with delayed hematuria, following a PCNL procedure, performed for an obstructive solitary left lower calyceal stone. During the PCNL procedure, an upper polar calyceal access was successfully obtained to get direct access to stone. The access tract was dilated to 30 French using a Nephro-Max, balloon (Boston Scientifi c). The stone measuring 1.1 × 0.7 × 0.5 cm was removed intact, and the patient was discharged on post-operative day 2.
On post-op day 8, the patient developed gross hematuria and was therefore re-admitted with unstable hemodynamics (heart rate: >100/min and systolic BP: <100 mmHg). Selective left renal angiogram demonstrated early visualization of a segmental interpolar draining vein, consistent with an iatrogenic AVF (Fig. 1). Successful embolization of the segmental branch feeding the AVF was performed using one, 3 mm × 2.5 mm Vortex coil (Boston Scientifi c, Cork, Ireland), and two, 4 mm × 2 mm Tornado coils (Cook Medical, Bloomington, Indiana, USA) (Fig. 2). Subsequent nephrostogram demonstrated immediate fi lling of posterior segmental vein draining into the left renal vein with residual clots in the intrarenal collecting system but without perinephric extravasation and drainage of contrast into the ureter (Fig. 3). These fi ndings confi rmed the diagnosis of a coexisting caliceovenous fi stula. Having performed successful embolization of the AVF, it was decided to leave the nephrostomy tube in situ. Hematuria stopped completely within next 4 h.
A follow-up nephrostogram after 48 h demonstrated free drainage of contrast into the ureter without fi lling of the renal vein (Fig. 4). Nephrostomy tube removal was performed. Hematocrit and creatinine values improved from 18.2%, and 1.39 mg% pre-procedurally, to 26.2% and 0.9 mg% (patient's baseline value), respectively.

Discussion
Recently, the PCNL technique decreased tract related morbidity by limiting the sheath to a size small enough to accommodate a standard rigid nephroscope (19.5-26 French) [4]. Additionally, mini PCNL can be performed with a tract size of 16-20 French [4]. Richstone et al. demonstrated the frequency of postoperative hemorrhage following percutaneous renal interventions [2]. Fifty-seven out of 4695 patients (1.2%) required selective angioembolization (44 PCNL and 13 others). Angiography revealed treatable lesions in 94.7% of patients. Srivastava et al. specifically analyzed vascular complications after single-stage PCNL [1]. All the renal punctures were performed us-

Fig. 1.
A 58-year-old man presented with delayed hematuria following 2-stage PCNL. A selective left renal angiogram demonstrates an inter-polar AVF (white arrows) with early visualization of segmental vein (black arrow)

Fig. 2.
Selective left renal angiogram demonstrates successful coil embolization (white arrow) of a sub-segmental branch feeding the AVF ing the bull's eye technique. Twenty-seven out of 1854 patients had signifi cant bleeding after PCNL. On angiography, the off ending lesion was successfully embolized in 24 cases. No lesion was found in 3 cases. Clearly, with segmental and interlobar arteries and veins in close approximation, multiple injuries can occur [1,2]. In Richstone et al. series, 10/57 patients had >1 angiographic fi nding. Srivastava et al. reported combined pseudoaneurysm and AVF in 4 out of 27 cases. However, no patient in any of the above studies had a coexisting caliceovenous fi stula but learning point is that failure to identify multiple lesions at angiography and or serial imaging can lead to embolization failures. Chan et al. reported fi rst case of veno-caliceal fi stula confi rmed on imaging that developed non-iatrogenically due to high intrapelvic pressure secondary to stricture of a graft ureter in a renal allograft recipient [3]. The renal graft biopsy was negative for rejection. Despite the negative scintigraphy fi nding, and in view of rapid increase in creatinine from baseline value of 2.1 mg% to 10.5 mg% at 3 months post-transplantation, percutaneous drainage of the graft kidney was performed. Antegrade pyelogram demonstrated a prominent renal pelvis, simultaneous opacifi cation of the transplant renal vein without visualization of the graft ureter. Follow-up nephrostogram at 2 weeks after ureteric re-implantation demonstrated free fl ow of contrast into the bladder, spontaneous closure of veno-caliceal fi stula, and stabilization of serum creatinine to 1.6 mg%. This confi rmed pseudo renal failure as the cause of persistently increased serum creatinine levels in the setting of normal scintigraphic fi ndings. Geara et al. reported the fi rst documented case of pyelovenous backfl ow during antegrade pyelogram [5]. The patient presented with left sided hydronephrosis and pyelonephritis secondary to an obstructing ureteral stone. Antegrade pyelogram performed during left nephrostomy tube placement demonstrated fl ow of contrast into the left renal vein. Contrary to the non-iatrogenic development of veno-caliceal fi stula or pyelovenous backfl ow as reported above, our case developed AVF, as well as, a caliceovenous fi stula due to inadvertent injuries to sub-segmental artery, vein and an interpolar calyx likely Additionally, only 30% of AVFs become symptomatic but 70% of them resolve spontaneously within 1-2 years [6]. Symptomatic AVFs can result in persistent hematuria and renal transplant dysfunction due to signifi cant arteriovenous shunting secondary to "intrarenal steal phenomenon" [6]. It is likely that the coexisting AVF and iatrogenic caliceovenous fi stula caused recirculation of urine into our patient's blood, resulting in rise of serum creatinine.
Contrary to arterial bleeding, intraoperative renal pelvis perforation (3.4%) and calyceal perforation, which often occurs with tract dilation and venous bleeding secondary to caliceovenous communication, are usually not so severe and are generally self-limiting [1,2,7]. Within 24-48 h, the urothelium heals, provided that the collecting system is adequately drained [8]. Rise in creatinine with persistent delayed hematuria should, however, raise a red fl ag, especially when associated with residual stone fragments or clots from coexisting AVF as happened in our case causing intermittent obstruction to urinary fl ow, and resultant rise in intrarenal collecting system pressure responsible for recirculation of urine into the venous tree. It is likely that chances of coexisting fi stulae in our case could have been decreased by sound anatomic knowledge, using a precise initial pos-terolateral puncture, preferably with a bull's eye technique, graduated and limited tract dilatation (26 French or less), and choosing a pediatric nephroscope due to unfavorable collecting system anatomy (non-capacious intrarenal pelvis). Additionally, the decision to allow caliceovenous fi stula to heal spontaneously was justifi ed by (1) complete clearance of stone/calyceal obstruction and (2) disappearance of fl ow to intrarenal AVF intraprocedurally, and (3) residual blood clots in the pelvicalyceal system will lyse spontaneously because of the endogenous urokinase, thus allowing normalization of the pressures in the intrarenal vascular tree and intrarenal collecting system.

Conclusions
In summary, coexisting intrarenal AVF and caliceovenous fi stula should be considered as a possible cause of delayed severe hematuria after PCNL. Based on this case, it appears reasonable to allow the caliceovenous fi stula to heal spontaneously following traditional successful embolization of the intrarenal AVF.

Funding sources
The author(s) received no fi nancial support for the research and/or authorship of this article.

Confl ict of Interests
The author(s) declared no confl icts of interest with respect to the authorship and/or publication of this article.