Crossed unfused renal ectopia with pelviureteric junction obstruction associated with nephrolithiasis: a rare troublesome triad managed by robotic surgery

Abstract

We report a rare case of non-fused renal ectopia with pelviureteric junction obstruction and multiple pelvic and renal calculi thereby discussing vascular anatomy of the non-fused ectopic kidney along with robot assisted surgical management of this rare clinical entity which amounts for good preoperative workup for best surgical and clinical outcome.

Background

When a kidney is located on the side opposite that in which its ureter inserts into the bladder, the condition is known as crossed ectopia. Crossed renal ectopia without fusion is rare and found in only 10% of the total cases and most of them are fused. We present the case of a 25-year-old man who presented with right flank pain and on workup was found to have crossed non-fused renal ectopia, with the left ectopic kidney lying inferior and anterior to the right kidney without fusion. Multiple renal and pelvic calculi were also noted along with dilated fusiform bifid pelvis in the ectopic kidney. Renal scan was suggestive of partial obstruction. As the patient was symptomatic, he was planned for robotic pyelolithotomy with pyeloplasty which is the first-ever reported case of robotic pyeloplasty with pyelolithotomy in a crossed unfused ectopia as per available English literature. We highlight the importance of identification of the findings especially in regard to surgical planning of the patient.

Case presentation

A 25-year-old man without any comorbidities presented with right flank pain for 4 years. There was no associated fever, no lower urinary tract symptoms no lithuria, haematuria. Physical examination and laboratory tests as complete blood count, renal function tests were unremarkable. Urinalysis revealed microscopic haematuria with few pus cells and oxalate crystals. Urine culture was sterile.

Investigations

Ultrasound abdomen was suggestive of crossed ectopia with renal calculi. CT angiography of abdomen with CT urography was also done which showed right kidney was normally located at T12–L2 vertebral level (figures 1 and 2) with single right renal artery arising from the aorta and single renal vein draining into inferior vena cava (IVC) (figure 3). The ureter of the right kidney was normal in course and insertion in the urinary bladder (figure 4). The left kidney was ectopically located anterior to right psoas at L2–4 vertebral levels and was also malrotated with hilum facing laterally (figures 1 and 2). The ectopic kidney was normal in size with normal contrast enhancement. The ectopic kidney had dual arterial supply: one branch arising anteriorly from the aorta just proximal to bifurcation, and another from the medial aspect of the right common iliac artery. It also demonstrated dual venous drainage: anterior and posterior renal veins drained separately into medial and lateral surfaces of the IVC (figure 3). Duplex pelvis is seen with upper pole pelvis fusing with the main pelvis just after renal hilum. Marked fusiform dilatation of renal pelvis is noted with contrast fluid level and wall thickening. An 8 mm (1100 HU) calculus noted in upper pole calyx and multiple calculi are seen in renal pelvis largest measuring 21 mm (1250 HU) with upstream dilatation with poor contrast excretion into ureter on the delayed phase. The ureter of the left kidney crossed the midline and entered into the urinary bladder at the usual orthotopic position. There were no accompanying other organ anomalies. Renal scan was done given hydronephrosis and poor excretion and confirmed pelviureteric junction obstruction (PUJO) of ectopic kidney. Differential renal function of the ectopic kidney was 33% with a rising curve. Global Glomerular Filtration Rate (GFR) was 71 (left+right=24+47)

Figure 1.

(A) Contrast-enhanced CT of the abdomen in axial plane showing the right kidney in its normal position (thin arrow). (B) Non-contrast-enhanced CT of abdomen showing an ectopic left kidney situated in the right iliac fossa (thick arrow) with the hilum facing laterally. (C, D) Contrast-enhanced CT of abdomen in axial plane showing multiple renal pelvic calculi (arrow head) and renal calculi in upper pole (chevron arrow).

Figure 2.

(A) Contrast-enhanced CT of the abdomen in coronal plane showing normal right kidney (thin arrow) and (B) ectopic left kidney (thick arrow) with dilated pelvis.

Figure 3.

CT angiography films showing blood supply of right normal and left ectopic kidney, (A) branch arising anteriorly from the aorta just proximal to bifurcation (arrow head), and another from the medial aspect of the right common iliac artery (arrow). (B, C) It also demonstrated dual venous drainage anterior and posterior renal veins (thin and thick white arrow) drained separately into medial and lateral surfaces of the IVC. IVC, inferior vena cava.

Figure 4.

(A) CT urography in volume rendered image showing normal course of right ureter (black arrow) and normal insertion of ureter and ectopic left kidney with poor function.

Treatment

As the patient was symptomatic; therefore, the patient was planned for the surgical intervention. The anomalous vascular supply as well as the anatomy of the kidney posed a challenging task and therefore robotic surgery was planned for pyelolithotomy and pyeloplasty given better vision and outcome. On intraoperative retrograde pyelogram—jet sign was present, bifid pelvis grossly dilated (figure 5). The patient was placed in the standard left lateral decubitus position. Pneumoperitoneum was created using open technique. A 12 mm trocar was inserted at the umbilicus and Two 8 mm robotic working ports were placed under vision. Another 12 mm assistant port was placed in a midline supraumbilical location. After reflection of ascending Ectopic kidney was seen in right side of pelvis. Ectopic kidney’s pelvis was distended, with narrowing at the PUJ. Rest of ureter was normal in appearance. Crossing vessels were not seen. Multiple calculi were present in renal pelvis. All stones were removed and Pyeloplasty was done with Anderson Hyne’s method (figure 6). The total operating time was approximately 2 hours (including 15 min for port placement and 5 min for docking). Blood loss was insignificant.

Figure 5.

Intraoperative RGP showing multiple pelvic calculi (black arrow—A), jet sign in ectopic kidney suggestive of PUJO (white arrow—B) and bifid pelvis (white arrow—C). PUJO, pelviureteric junction obstruction; RGP, retrograde pyelogram.

Figure 6.

Intraoperative images showing multiple calculi (white arrow—A), large pelvic calculi being removed (asterix—B), DJ stent being placed (white arrow—C), pyeloplasty being performed (white arrow—D).

Outcome and follow-up

The perioperative course was uneventful and the patient had 100% clearance (figure 7). The patient is now under regular follow-up for 6 months and there has been no recurrence so far and follow-up renal scan after 6 months show same differential renal function and non obstructive drainage.

Figure 7.

Preoperative X-ray KUB showing multiple calculi (white arrow—A), postoperative X-ray KUB showing complete clearance with DJ stent in situ (white arrow—B). KUB, Kindney, Ureter, Bladder.

Discussion

Crossed renal ectopia is a rare congenital anomaly in which the ectopic kidney crossed the midline and gets located to the contralateral side of its ureteric insertion which is orthotopic. Crossed renal ectopia is generally fused with only 10% of cases there is no renal fusion seen.¹ Generally, it is an incidental finding but these patients can present as recurrent urinary tract infection, nephrolithiasis, vesicoureteric reflux and hydronephrosis.^{2 3} There is a male predominance of 3:2, and left-to-right cross-over occurs more frequently than a right-to-left cross-over. Crossed unfused renal ectopia is a rare type of renal anomaly.^{4 5} McDonald and McClellan classified crossed renal ectopia into (1) crossed ectopia with fusion, (2) crossed ectopia without fusion, (3) unilateral crossed ectopia (associated with unilateral renal agenesis) and (4) bilateral crossed ectopia without fusion (both ureters cross the midline).⁶ The kidneys are fused in approximately 90% of the total cases.⁷ There is reported incidence of 1 unfused variant for every 75 000 autopsies.⁸ It is an important finding that there is frequent association of congenital anomalies of other organ systems with renal ectopia⁹ For the operative planning, it is of utmost importance to demonstrate the associated anomalies including congenital renal anomalies.¹⁰ In the present case though, there were no other anomalies. The management of stones in patients with congenital renal anomalies, such as crossed renal ectopia is challenging to urologists because the anatomy location, orientation as well as vascular anatomy is quite aberrant and make the task of access and clearance of the calculi difficult. Management choice range from extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery, flexible ureteroscopy (FURS), stone push-up by FURS combined with mini PCNL, pyelolithotomy, nephrectomy depending on anatomy, stone burden, location and function of the affected kidney.¹¹ ESWL is the least invasive treatment modality but as it may require multiple sessions before patients become free of calculi.¹² In our case, stones were on the side of the renal ectopia and was associated with PUJO, and in these cases, it needs good pretreatment planning, including 3 Dimensional CT, renal scan apart from routine investigation.

The reported incidence of PUJO in ectopic and horseshoe kidney ranges from and from 22% to 37% and 25% to 33%, respectively.¹³ There is no available reported data in the English literature for incidence of PUJO in fusion anomaly other than horseshoe kidneys. It is technically very demanding to perform pyeloplasty in crossed fused ectopic kidneys specially in minimally invasive setting. The problematic factors are proximity of pelvic visceral organs and major blood vessels to the abnormally located pelvic kidney, atypical blood supply to the kidneys and propinquity of the normal ureter to the dilated renal pelvis on the affected side. The basic principles of surgical management remain same and include removal of stenosed pelviureteric junction, excision of redundant pelvis, transposition of any aberrant vessel if presen, and ureteropelvic anastomosis. The laparoscopic and robotic pyeloplasty along with pyelolithotomy are feasible in these patients¹⁴

There is dearth of literature over simultaneous pyeloplasty and pyelolithotomy in a case of crossed ectopia and, this is the first ever case of left to right crossed unfused ectopia in which robotic pyeloplasty and pyelolithotomy has been done. Two previous cases of left to right crossed unfused renal ectopia with renal calculi were reported by Kodama et al and Al-Hamar and Khan^{10 15} (table 1). Management was done by ESWL and conservative respectively. Literature shows that out of all crossed ectopia including fused and unfused variant, no single case has been managed by simultaneous pyelolithotomy and pyeloplasty, ours is the first case in that aspect also and that too by robotically in view of ease of doing procedure due to better visualisation and better surgical outcome.

Table 1.

Review of cases of left to right non-fused cross ectopia with nephrolithiasis

Author and year	Age/sex	Ectopic kidney subtype	Fused	Stone location and size	Preop renal scan	Treatment	Residual stone	Follow-up scan	Second surgey
Kodama10 (2016)	32/M	Left to right	No	Proximal ureter 5 mm	–	ESWL	No	–	No
Al-hamar15 (2017)	53/M	Left to right	No	Both kidneys, not mentioned	–	conservative	Not mentioned	–	Not mentioned
Present case	24/M	Left to right	No	Multiple, 8 mm to 2 cm	33%+67% (left+right) (rising curve suggestive of PUJO of ectopic kidney)	Robotic left pyelolithotomy and pyeloplasty	No	Same as pre opertaive with normal drainage suggestive of post pyeloplasty pattern	No

ESWL, extracorporeal shock wave lithotripsy; M, male; PUJO, pelviureteric junction obstruction.

Patient’s perspective.

I was told by my doctor after all the tests that I have a rare condition in which kidney is not present at its usual location and lie with the opposite side of body with the other kidney. Along with that I was diagnosed to have renal calculi and pelvi-ureteric junction obstruction in the affected kidney which needed surgical procedure to relieve me of symptoms and to save my kidney from deterioration. I first felt a sense of fear but then I gave a go ahead as it was the only way out. I have recovered well after surgery and my follow-up scan show no further deterioration in the kidney and no new calculi so far. I am very happy and content right now.

Learning points.

• Unfused crossed ectopic kidney is a very rare condition.

• It is seldom symptomatic, but can be associated with pelviureteric junction obstruction (PUJO), nephrolithiasis and vesicoureteric reflux leading to recurrent urinary tract infection and flank pain as presenting complaints.

• Multiphasic CT abdomen with 3 dimensional reconstruction preferably is the diagnostic modality of imaging for better surgical planning.

• Robotic surgery is the preferred modality for treatment of crossed unfused ectopia associated with PUJO and nephrolithiasis due to better vision and good surgical outcome.