Pelviureteric Junction Obstruction Due to Vascular Anomalies in Children - Simple Surgical Options.

Aims: Pelviureteric junction obstruction (PUJO) due to aberrant lower polar artery is conventionally managed with pyeloplasty. We present our experience of managing PUJO due to "vascular" anomalies-aberrant lower polar artery and vascular adhesions with simpler surgical options. Subjects and
Methods: This is a protocol based, retrospective study of PUJO. Preoperative investigations included ultrasonography (USG) and diuretic renogram. An intraoperative methylene blue test (MBT) assessed transit across the Pelviureteric junction (PUJ) after release of vascular compression. Surgical management included adhesiolysis for vascular adhesions and pyelopyelostomy anterior to the aberrant polar artery. Postoperative studies were repeated after 3 and 6 months.
Results: Fourteen of 144 PUJO (9.7%) were "vascular" obstructions. Those with vascular adhesions (six) were largely infants with antenatal hydronephrosis. Children with aberrant lower polar artery (eight) were older, had fleeting symptoms, minimally increased pelvic diameter and subtle impairment on diuretic renogram. Majority were term males with urinary tract infection. The MBT showed normal transit across the PUJ in all. Postoperatively, there was progressive improvement on USG and diuretic renogram after 3 and 6 months. None had any complication or redosurgeries. At a mean follow-up of 41.2 months, all are asymptomatic. Conclusions: PUJO due to extrinsic vascular anomalies is rare. Intraoperative evaluation with the MBT ruled out associated intrinsic pathology. We describe two simple surgical alternatives preserving the normal PUJ - adhesiolysis for vascular adhesions and pyelopyelostomy for aberrant lower polar artery. The preliminary outcomes are comparable to conventional pyeloplasty. Copyright:

INTRODUCTION

Pelviureteric junction obstruction (PUJO) is commonly due to a congenital intrinsic neuromuscular transmission defect. Mechanical, extrinsic, and obstructive factors are relatively rare. The common extrinsic etiology is an aberrant, accessory, or early branching lower polar artery that crosses anteriorly to compress the pelviureteric junction (PUJ).[12] The diagnosis may be obvious preoperatively or be an intraoperative surprise. In general, both forms of PUJO-intrinsic and that due to aberrant lower polar artery have been managed with a conventional Anderson Hynes dismembered pyeloplasty; in the latter, it is fashioned anterior to the anomalous vessel.[1]

This series describes a simpler surgical management for select cases of extrinsic PUJO due to two vascular anomalies-aberrant lower polar artery and a new entity that we describe as “vascular adhesions” with equally gratifying results.

SUBJECTS AND METHODS

This is a single center, retrospective descriptive study conducted at the Department of Pediatric Surgery, at St. John's Medical College Hospital, Bangalore, India, from 2013 to 2017 based on a standard departmental protocol [Figure 1]. All cases of unilateral PUJO due to vascular anomalies based on intra operative findings were included.

Figure 1

Standard protocol of management of unilateral hydronephrosis probably due to pelviureteric junction obstruction

Children with a clinical suspicion of unilateral PUJO underwent ultrasonography (USG) with Doppler sonography. Sonographic measurements included bipolar length, anteroposterior pelvic diameter (APPD), parenchymal thickness, ureteral visualization, and dimensions. A Doppler study was added to detect aberrant lower polar artery. Those with isolated hydronephrosis and an APPD of >15 mm underwent a diuretic renogram (F 0 protocol) on normal oral feeding and an indwelling bladder catheter, and specific observations (renal perfusion, intrarenal transit [IRT], and drainage pattern of the isotope across the PUJ) noted.

The cases with confirmed PUJO based on corroboration of clinical features, USG and diuretic renogram were surgically explored and the anatomy examined carefully. Those with a classic PUJ anatomy underwent a standard Anderson Hynes Pyeloplasty. The “vascular anomalies” were categorized and managed as described below:

Vascular adhesions

These were flimsy adhesions (with well-formed adventitial vessels traversing through them) between the pelvis and upper ureter that kinked the PUJ. When identified [Figure 2a], they were released to straighten the kink [Figure 2b] without devascularizing the region.

Figure 2

(a) Operative photograph of a representative case with vascular adhesions kinking the pelviureteric junction. Note the vessels in the adhesion. (b) After adhesiolysis, the instilled methylene blue traverses across the normal caliber pelviureteric junction

Aberrant lower polar artery

The crossing artery was gently dissected off the underlying PUJ and looped with a tape [Figure 3a].

Figure 3

(a) Operative photograph of a representative case with aberrant lower polar artery entrapping the ureter just below the pelviureteric junction (b) Pyelopyelostomy fashioned anterior to the retroposed lower polar artery after pelvic reduction. Note the position of the pelviureteric junction

Thereafter, both the above were subjected to a Methylene Blue Test (MBT) as per our protocol as described below. About 0.3–0.5 ml of dilute methylene blue solution (1:3, normal saline) was instilled through a 26 g needle into the urine in the dilated pelvis well above the PUJ making sure to avert a spill into the operative field. It was ensured that the pelvis was distended before the instillation of the dye. If not, a bolus of intravenous fluids (10–15 ml/kg over 10 min) followed by a diuretic (Frusemide 1 mg/kg) was administered to distend it adequately. The flow of dye across the PUJ [Figure 2b] and its appearance in the tubing of the bladder catheter was noted. Real-time pelviureteric peristalsis propelling the colored fluid bolus across the PUJ was noted in the thin-walled pelvis/upper ureter of infants. If a free flow of dye was seen traversing across the PUJ in a few seconds and the bladder catheter tubing showed a bluish tinge by 2–3 min, an “intrinsic” pathology contributing to the PUJ obstruction was ruled out or considered functionally remote. Of course, it was assumed that the rest of the caudal urinary tract was patent and normal. In the thicker pelvis of older children or with chronic disease, we relied more on the timing of the bluish color appearing in the bladder catheter tubing.

If the MBT was inconclusive or showed a delay in the transit of the dye, a routine Anderson Hynes pyeloplasty was carried out. If it was normal, the surgical management was modified as follows-

No further procedure was necessary.

The pelvis was divided well above the PUJO, the PUJ rerouted anteriorly and pelvis anastomosed (pyelopyelostomy) in front of the retroposed aberrant vessels [Figure 3b]. A large pelvis was trimmed and reduced before the anastomosis.

In a pyelopyelostomy, a double J (DJ) stent and a perinephric drain were placed. After adhesiolysis for vascular adhesions, only a perinephric drain was used. The DJ stent was removed cystoscopically after 2 weeks. The children were followed up closely for a period of 6 months. Besides clinical review and USG at 6 weeks, further imaging (USG, diuretic renogram) was performed after 3 months and 6 months postoperatively. Their demographic details, antenatal history, clinical presentation, physical findings, investigations, surgical details, outcome, and follow-up were collated, tabulated, and analyzed.

For the initial pilot cases, an intraoperative additional consent was obtained before the novel procedures were performed based on intraoperative decisions. Thereafter, an informed preoperative parental consent was taken for these procedures.

RESULTS

There were 144 children with unilateral PUJO diagnosed with the standard protocol, of these 14 (9.7%) were categorized intraoperatively to be due to vascular anomalies, 6 with vascular adhesions and 8 with aberrant lower polar artery. Details of their clinical features, investigations, and follow-up are summarized in Table 1 (vascular adhesions) and Table 2 (aberrant lower polar artery). A larger proportion in the vascular adhesion group (66%) was detected antenatally. In both groups, the majority were males who were born at term. A gross right predominance (75%) was noted with aberrant lower polar vessels. The vascular adhesion group was mostly infants while the aberrant vessel group had older children. Urinary tract infection was the predominant presentation in both groups; flank pain was as common in the older children. A palpable hydronephrosis was rare in either. Two with recurrent UTI [Table 2, Case 3, 4] in the aberrant vessel group had hypertension.

Table 1

Summary of clinical profile, preoperative and postoperative investigations in pelviureteric junction obstruction due to vascular adhesions

Case number	Age (P) months	Sex	Antenatal detection	Gestational maturity	Laterality	Clinical presentation	Ultrasonography (APPD in mm)			Diuretic renogram (IRP, PRT, ODP)			FU months
							Preoperative (P)	Postoperative 3 months	Postoperative 6 months	Preoperative (P)	Postoperative 3 months	Postoperative 6 months
1	4	Male	Yes	Term	Right	UTI	34	24	18	IRP, PRT, ODP	Normal	Normal	48
2	2	Male	Yes	Term	Right	UTI	43	30	24	IRP, PRT, ODP	Normal	Normal	60
3	9	Female	No	Preterm	Left	UTI	36	30	26	IRP, PRT, ODP	PRT	Normal	36
4	36	Male	No	Term	Left	UTI	28	26	22	IRP, PRT, ODP	ODP	Normal	24
5	4	Male	Yes	Term	Right	Flank mass	55	40	32	IRP, PRT, ODP	Normal	Normal	56
6	8	Female	Yes	Term	Left	ASY	42	34	28	IRP, PRT, ODP	PRT	Normal	18

P: At presentation, UTI: Urinary tract infection, ASY: Asymptomatic, APPD: Anteroposterior pelvic diameter, IRP: Impaired renal perfusion, PRT: Prolonged intrarenal transit, ODP: Obstructed drainage pattern, FU: Follow up

Table 2

Summary of clinical profile, preoperative and postoperative investigations in pelviureteric junction obstruction due to aberrant lower polar artery

Case number	Age (P) months	Sex	Antenatal detection	Gestational maturity	Laterality	Clinical presentation	Ultrasonography (APPD in mm)			Diuretic renogram (IRP, PRT, ODP)			FU months
							Preoperative (P)	Postoperative 3 months	Postoperative 6 months	Preoperative (P)	Postoperative 3 months	Postoperative 6 months
1	96	Male	No	Term	Left	UTI	18	16	12	PRT, ODP	Normal	Normal	24
2	48	Male	No	Term	Right	UTI	22	22	20	PRT, ODP	Normal	Normal	33
3	60	Female	Yes	Preterm	Right	Flank pain, UTI, HTN	18	18	17	PRT, ODP	Normal	Normal	48
4	36	Female	No	Term	Right	Flank pain, UTI, HTN	33	28	20	IRP, PRT, ODP	Normal	Normal	60
5	48	Male	Yes	Term	Right	Flank pain	25	25	18	IRP, PRT, ODP	Normal	Normal	58
6	96	Male	No	Term	Left	Flank mass	38	30	22	IRP, PRT, ODP	Normal	Normal	36
7	144	Female	No	Term	Right	UTI	28	26	24	PRT, ODP	Normal	Normal	22
8	108	Male	No	Term	Right	Flank pain	38	31	20	IRP, PRT, ODP	Normal	Normal	54

P: At presentation, UTI: Urinary tract infection, HTN: Hypertension, IRP: Impaired renal perfusion, PRT: Prolonged intrarenal transit, ODP: Obstructed drainage pattern, FU: Follow-up

Preoperative investigations

In the infants of the vascular adhesion group, the preoperative ultrasonographic APPD was relatively higher than the older children with aberrant renal vessels. The diuretic renogram showed impaired perfusion, prolonged IRT, and obstructed drainage pattern in all. In the aberrant lower polar artery group, half had preserved renal perfusion despite the prolonged IRT in most and an obstructed drainage pattern in all. The Doppler study did not detect any of the aberrant lower polar arteries.

Operative findings

The flimsy “vascular adhesions” described earlier were lysed to straighten the kink at the PUJ. They were dense in the lone older child of 3 years in this group [Table 1, Case 4]. The regional vascularity was maintained in all. All the aberrant lower polar aberrant arteries compressed at the level of the PUJ or just distal to it. The distal ureter was patent to a saline flush after dismembering at the pelvis in all. After release of the obstructive element, none of the PUJ in either group had a gross external narrowing at the PUJ or in the upper ureter.

Postoperative period and follow-up

The immediate postoperative period was unremarkable. The cases in the vascular adhesions group were discharged earlier (72 h.) than those who underwent a pyelopyelostomy (5–6 days). The follow-up period in this study ranged from 18 to 60 (mean 41.2) months overall; 18–60 (mean 40.3) months in the vascular adhesions group and 22–60 (mean 41.9) months in the aberrant renal artery group. All were asymptomatic except an episode of urinary infection in two cases soon after cystoscopic removal of the DJ stent; these were clearly hospital acquired and managed conservatively. The hypertension resolved in the two cases after 12 and 15 months. No further surgical interventions were required in any of the cases.

The serial APPD and findings on diuretic renogram 3 and 6 months after surgery are summarized in Tables 1 and 2. Representative preoperative and postoperative diuretic renogram in two groups [Figures 4 and 5] illustrate resolution of PUJO and restoration of renal parenchymal function over 6 months.

Figure 4

Diuretic renogram in a representative case with left pelviureteric junction obstruction due to vascular adhesions. Preoperative study (upper panel) showing impaired perfusion (a), prolonged intrarenal transit (b) and obstructed drainage pattern (c) in the left renal unit. Postoperative study (lower panel) at 6 months follow-up after adhesiolysis showing improved parameters

Figure 5

Diuretic renogram in a representative case with left Pelviureteric junction obstruction due to aberrant lower polar artery. Preoperative study (upper panel) showing impaired perfusion (a), prolonged intrarenal transit (b) and obstructed drainage pattern (c) in the left renal unit. Postoperative study (lower panel) at 6 months follow-up after pyelopyelostomy showing improved parameters. The photopenic pelvic void in frame b, upper panel is replaced by a filled pelvis with normal intrarenal transit

DISCUSSION

PUJO due to the common intrinsic muscular defect and the less common (6%–11%) extrinsic compression by aberrant lower polar artery have been conventionally managed with an Anderson Hynes dismembered pyeloplasty-open, laparoscopic, or robotic.[34] A vascular hitch procedure (open/laparoscopic, Hellstrom technique-Chapman modification) has been used as an alternative for aberrant lower polar artery with variable success;[567] the failures have been salvaged with a redoconventional pyeloplasty in some. Besides an unravelling of the hitch sutures, a missed intrinsic obstruction may account for some of these.[89] This series describes in detail the clinical profile and management of two groups of patients with extrinsic PUJO due to “vascular” related causes-the commoner aberrant lower pole artery and the less characterized vascular adhesions. They are discussed separately.

Inflammatory adhesions with recurrent UTI have been described to kink and obstruct the PUJ secondarily;[10] however, a developmental origin has not been invoked in the published literature. In this series, though most presented with a UTI, an antenatal diagnosis (4/6) and early infantile presentation (6/7) in the adhesions group suggest a congenital/developmental origin. Their clinical presentation and imaging characteristics were indistinguishable from the other infants with intrinsic PUJO.[11] Serial diuretic renogram showed a prompt recovery evident in the first postoperative study at 3 months, supporting the contention that early intervention in infancy was associated with greater recovery.[12] In the absence of an anastomosis, the hospital stay was limited to removal of the perinephric drain, i.e., 72 h.

Clinically, these children were different from those with intrinsic PUJO or infants with vascular adhesions. As described earlier, they were typically older children presenting with mild, fleeting symptoms of flank pain localized to the side of the urinary tract dilatation.[1314] Antenatal diagnosis was rare. Despite the older age, the APPD was only modestly increased (18–38 mm). The USG and Doppler study had failed to identify the abnormal artery in any. However, the diuretic renogram showed subtle changes of obstructive drainage patterns and prolonged IRT, even though the renal perfusion was preserved in half. Like Harper et al., we have relied on the prolonged IRT as the sensitive predictor of deterioration to decide on proceeding to surgical exploration.[15] A high index of suspicion led us to a preoperative diagnosis in half, in the rest it was an operative surprise. Probably, a functional magnetic resonance imaging would have clarified the anatomy and function in all,[16] this is not a routine in our protocol and requires additional anesthesia in small children. Schneider et al. describe three anatomical variations in the location of crossing polar vessels: Type 1 – in front of the dilated pelvis, type 2 – in front of the PUJ, and type 3 – distal to the PUJ involving the upper ureter. They associate the crossing of the artery in front of the PUJ with “intrinsic” stenosis and recommend that it should be managed with a pyeloplasty; they reserve the vascular hitch procedure for type 3.[16] We believe our cases had a mix of type 2 and type 3 anatomy, but none of them showed a delayed transit in the MBT and hence considered to be purely extrinsic in obstructive pathology. Although histological examination of resected specimens of the PUJ due to aberrant lower polar has shown variable inflammation and fibrosis, electron microscopic studies have not shown significant structural changes in muscle/collagen content or nerve distribution on immunohistochemistry as compared to controls.[6] We contend that any clinically relevant intrinsic obstructive element would be identified by the MBT and qualify for a pyeloplasty.

There are no standard imaging techniques or procedures to confirm that the mechanical extrinsic factor in the aberrant lower polar artery or vascular adhesions is solely responsible for the obstructive pathology. Some proponents of the vascular hitch procedure emphasize that a careful selection of candidates with an intraoperative “diuretic test”[14] or a “water charge test”[17] rules out an associated intrinsic abnormality and improves the success rate. These tests advocate an objective demonstration of pelvic emptying with an induced diuresis after dissection of the artery off the entrapped PUJ before opting for a vascular hitch procedure. Similarly, we have relied on our observations of the intraoperative anatomy and the results of the Methylene Blue after the release of the PUJ from the vascular adhesions/compressive lower polar artery to assure us of the following: (a) relief from the primary obstructive pathology-the kinking adhesions or the compressive artery and (b) the lack of significant associated intrinsic obstruction that would have necessitated a conventional pyeloplasty. We have induced a diuresis if the pelvis was not already distended. However, we concede that a MBT pre- and postprocedure might have provided a more robust comparison. Both procedures described by us preserve the normal PUJ. The risk of anastomotic problems and other complications with a pyelopyelostomy is also conceivably less than a pelviureteric anastomosis as the anastomosis is wide and does not involve any ureteral spatulation.

Furthermore, since we had employed a new intervention in each group, we had scheduled an early imaging (USG, Doppler sonography, and diuretic renogram) 3 months after surgery (instead of our usual practice at 6 months after surgery) to detect any misadventures and plan interim remedial interventions.

CONCLUSIONS

This study describes the clinical profile and management of a hitherto sparsely documented cause of PUJO due to congenital vascular adhesions. It presents an intraoperative test-the MBT to evaluate the presence or otherwise of an intrinsic obstructive pathology at the PUJO in addition to an identified extrinsic vascular compression-vascular adhesions or aberrant lower polar artery. Based on these pathophysiologic principles, we have suggested a simple operative procedure in each of the vascular PUJO, i.e., “adhesiolysis” for vascular adhesions and “pyelopyelostomy” for aberrant lower polar artery instead of the more elaborate Anderson Hynes dismembered pyeloplasty, both preserving the physiological PUJ. The preliminary results of these technically simple and attractive alternatives have been gratifying and comparable to the conventional gold standard pyeloplasty; however, a greater experience and longer follow-up would be more conclusive.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.