Minimally Invasive Treatment of Pediatric Extrinsic Ureteropelvic Junction Obstruction by Crossing Polar Vessels: Is Vascular Hitching a Definitive Solution? Report of a Multicenter Survey

Abstract

Background:

This article aimed to evaluate the outcome of laparoscopic vascular hitch (VH) as an effective alternative to dismembered pyeloplasty in the treatment of children with extrinsic ureteropelvic junction obstruction (UPJO) by crossing vessels (CVs), by reporting the experience of three Italian centers of Pediatric Surgery.

Methods:

From 2006 to 2014, 54 children (18 girls and 36 boys, average age 10.7 years) affected by suspected extrinsic UPJO by CV were treated in three different institutions: 51 patients underwent laparoscopic VH, while 3 patients, in which a coexisting intrinsic etiology of UPJO was doubtful, underwent laparoscopic dismembered pyeloplasty. Preoperative diagnostic workup included: ultrasound (US)/Doppler scan, mercaptoacetyltriglycine (MAG3)-renal scan, and functional-magnetic-resonance-urography (fMRU). Symptoms at presentation were recurrent abdominal/flank pain and hematuria. All patients presented intermittent hydronephrosis (range 18–100 mm) on US and an obstructive pattern on MAG3 renogram.

Results:

Average operative time was 108 minutes, and average hospital stay was 1.8 days. As for complications, we reported a small abdominal wall hematoma and a high UPJ distortion without obstruction in 2 patients, not requiring reintervention (grade I Clavien-Dindo). At follow-up (range 12–96 months), all patients reported resolution of symptoms, decrease in the hydronephrosis grade, and improved drainage on MAG3 renogram.

Conclusions:

Our results demonstrated the safety and efficacy of laparoscopic VH for treatment of extrinsic UPJO by CV, registering excellent outcomes in a very selected patient population. The careful selection of patients through intraoperative assessment of anatomical and functional aspects is a crucial step to confirm indications for VH and maintain a high success rate with the procedure. We believe that any concerns regarding the coexistence of intrinsic stenosis should certainly lead to opening the collecting system and to performing a classic dismembered pyeloplasty.

Introduction

Ureteropelvic junction obstruction (UPJO) is a functional impairment of urinary transport from the renal pelvis to the ureter. It represents a heterogeneous condition with variable etiologies combining intrinsic and/or extrinsic causes. Intrinsic causes such as interruption in the development of the circular musculature of the ureteropelvic junction (UPJ) or an alteration of the collagen fibers may lead to muscle fibers becoming widely separated and attenuated, leading to a functional discontinuity of the muscular contractions and ultimately to insufficient emptying.^1,2

Extrinsic obstruction usually refers to the presence of aberrant lower pole crossing vessels (CVs), fibrous band adhesions, or kinks in a normal caliber UPJ. However, an aberrant, accessory or early branching lower pole vessel is the most common cause of extrinsic UPJO.³ The association was first described by Von Rokitansky in 1842.^4,5

Open or laparoscopic dismembered pyeloplasty was first described by Anderson and Hynes (Anderson-Hynes dismembered pyeloplasty [AHDP]) in 1949.⁶ An alternative approach to pure extrinsic UPJO was described by Hellström in the same year; it involved displacing the lower pole vessels cranially and then anchoring them to the anterior pelvic wall using vascular adventitial sutures.⁷ Chapman further modified this technique: he secured a higher position of the lower pole vessels within a wrap of the anterior pelvic wall without using vascular adventitial sutures.⁸ The largest experience with this technique in children was reported in 1999 by Pesce.⁹

Aberrant vessels are usually responsible for intermittent UPJO. These patients usually present a normal perinatal history, followed by the subsequent late onset of clinical signs and symptoms, and detection of intermittent hydronephrosis and normal kidney function on imaging. The aberrant vessels typically cross over the UPJ to perfuse the lower pole of the affected kidney (Fig. 1).

FIG. 1.

Anatomical view after dissection of Gerota's fascia, before vessel dissection. Transperitoneal approach: through a window in the mesocolon are visualized the lower pole CVs, the normal UPJ, the ureter, and the dilated pelvis. CVs, crossing vessels.

Currently, there are no definitive imaging techniques or intraoperative procedures available to confirm the etiology of UPJO. As stated by Schneider,¹⁰ there is often a wide anatomic variability in the relationship between the renal pelvis and the lower pole vessels. This author has described the aspect of the UPJ during surgery and has classified three different types of intraoperative anatomical relationships among the lower pole CVs, the renal pelvis, the UPJ, and the ureter. Only type 3 with ureteral kinking and normal junction should be proposed for vascular hitch (VH).

In the current literature there is no evidence demonstrating the superiority of laparoscopic VH compared to dismembered pyeloplasty for the treatment of extrinsic UPJO by CV.

This article aimed to evaluate the efficacy of laparoscopic VH as an effective alternative to AHDP for the treatment of children with extrinsic UPJO by CV, by reporting the experience of three Italian centers of Pediatric Surgery.

Materials and Methods

From January 2006 to December 2014, 54 children with a preoperative suspected diagnosis of extrinsic UPJO by CV were treated in three Italian Centers of Pediatric Surgery: 51 patients (17 girls and 34 boys) underwent laparoscopic transposition of aberrant CV (Hellström VH modified by Chapman), while 3 patients (1 girl and 2 boys) received a laparoscopic AHDP.

Surgical indications included two or more of the following conditions: presence of clinical symptoms, obstruction on diuretic renogram (99mTc-MAG3), decrease on relative renal function, clear or suspected image of polar vessels on Doppler ultrasound (US) or on functional-magnetic-resonance-urography (fMRU), and worsening of intermittent hydronephrosis at follow-up. The totality of patients who underwent VH presented four out of the five criteria; only 2/51 patients (3.9%) presented a significant decrease on relative renal function. However, also most of patients who underwent AHDP presented the same characteristics of patients who underwent VH (Table 1).

Table 1.

Patient Demographics, Indications for Surgery, and Outcome Parameters of Laparoscopic Vascular Hitch and Anderson-Hynes Dismembered Pyeloplasty

	Laparoscopic VH	Laparoscopic AHDP	P value
Patients	51	3
Average age at surgery (years)	11.8 [8–17]	9.6 [2–14]	.3
Male/female	34/17	2/1
Average preoperative US AP diameter pelvis (mm)	36 [18–100]	35 [22–60]
Average preoperative MAG3 washout (at 30 minutes after orthostasis and micturition)	25% ± 5.5% (normal values: 50%–100%)	25% ± 3.5% (normal values: 50%–100%)
Average preoperative halftime clearance value	26.7 ± 3.2 minutes (normal values <10 minutes)	25.8 ± 2.9 minutes (normal values <10 minutes)
Average duration of surgery (minutes)	108 [75–230]	195 [120–285]	.01
Average analgesic requirements (days)	1.5 [1–3]	1.5 [1–3]	.3
Average time to resume full oral feeding (hours)	24 [12–36]	24 [12–36]	.3
Average time to ambulation (hours)	7 [4–10]	14 [9–19]	.01
Average length of hospital stay (days)	1.8 [1–4]	3.5 [3–5]	.01
Indications for surgery
Clinical symptoms	51/51 (100%)	3/3 (100%)
Obstruction on MAG3 renogram	51/51 (100%)	3/3 (100%)
Decrease on relative renal function	2/51 (3.9%)	1/3 (33.3%)
Image of suspected CV on Doppler US or fMRU	51/51 (100%)	3/3 (100%)
Worsening of intermittent hydronephrosis	51/51 (100%)	2/3 (66.6%)
Average follow-up (months)	54 [12–96]	48 [18–78]
Complications
Clavien I	2 (3.9%)	0	.3
Success	51 (100%)	3 (100%)	.3
Average postoperative US AP diameter pelvis (mm)	12 [0–25]	13 [0–26]
Average postoperative MAG3 washout (at 30 minutes after orthostasis and micturition)	80% ± 5.0% (normal values: 50%–100%)	75% ± 5.5% (normal values: 50%–100%)
Average postoperative halftime clearance value	7.4 ± 2.2 minutes (normal values <10 minutes)	7.8 ± 1.9 minutes (normal values <10 minutes)

Range values are indicated in brackets.

AHDP, Anderson-Hynes dismembered pyeloplasty; AP; anteroposterior; CV, crossing vessel; fMRU, functional-magnetic-resonance-urography; MAG3, mercaptoacetyltriglycine; US, ultrasound; VH, vascular hitch.

The average age at presentation was 10.7 years (range 2–17 years, median 12 years). All patients in the three centers were studied by US/Doppler Scan and 99mTc-MAG3 renogram, while only 33 patients (61.1%) underwent fMRU (Fig. 2).

FIG. 2.

Functional-magnetic-resonance-urography with vascular and kidney reconstruction showing a left extrinsic hydronephrosis by CVs. CVs, crossing vessels.

None of the children had prenatal diagnosis of hydronephrosis. All patients presented intermittent symptoms: flank pain or renal colic, associated to vomiting; 5 patients also presented hematuria. At US evaluation they presented a mild hydronephrosis (anteroposterior [AP] diameter of renal pelvis ≤20 mm) in absence of symptoms and a marked hydronephrosis with a prominent calyceal and pelvic dilatation (AP diameter of renal pelvis >40 mm) at the time of pain.

The patients received liquid diet and a bowel preparation with simethicone and enemas 24 hours before surgery. During laparoscopy, each case was carefully evaluated regarding presence and position of CV, appearance of the UPJ, ureter course, and response of the dilated pelvis to the diuretic test (DT). The intraoperative DT was performed after CV mobilization, by administering a bolus of normal saline (20 mL/kg intravenous [IV]) starting 10–15 minutes before the laparoscopic vessel mobilization, followed by furosemide 1 mg/kg IV early in the operative course (Fig. 3a, b).

FIG. 3.

Diuretic test: (a) after administration of the saline bolus (20 mL/kg) the renal pelvis is well dilated before vessel dissection and mobilization; (b) with IV furosemide administration (1 mg/kg IV), a rapid emptying of the bloated renal pelvis is observed, followed by normal ureteral peristalsis after vessel mobilization. IV, intravenous.

The main intraoperative criteria for performing a VH procedure included the following: (1) presence of obstructing lower pole CV; (2) a normal appearance, funnel-shaped dependent UPJ without any apparent or stenotic segment and a normal caliber ureter; and (3) decrease of pelvic dilatation at the end of mobilization (when present before dissection) and good peristalsis across the UPJ during the furosemide challenge test without reincrease of hydronephrosis. In agreement with other authors,¹⁰ we considered a sign of absent obstruction for the emptying of the renal pelvis under water load (with diuretic administration) after removal of vascular pedicle.

When patients did not respond to the abovementioned criteria or we were doubtful in regard to a coexisting intrinsic etiology of the UPJO, we preferred to perform the AHDP using laparoscopic approach.

In 51 patients, the CV was identified as cause of extrinsic UPJO, on the basis of a positive DT and anatomical evaluation, in which the CV crossed inferiorly the UPJ, resulting in variable ureteral kinking (Schneider's third type), and the procedure adopted was the laparoscopic Hellström VH modified by Chapman. In 3 patients, the intraoperative DT was negative (no peristalsis neither deflation of the renal pelvis was observed), and the anatomical evaluation was highly suspected for a coexisting intrinsic nature of UPJO, with the CV placed in front of the UPJ that appeared stenotic (Schneider's second type). For this reason, in these 3 patients we decided to perform the AHDP using laparoscopic approach.

All procedures were performed by only three surgeons (one senior surgeon for each participating center).

The study received the appropriate Institutional Review Board (IRB) approval.

Statistical analysis was carried out using the Statistical Package for Social Sciences (SPSS Inc., Chicago, IL), version 13.0. Significance was defined as P < .05. The categorical variables were compared using χ² Pearson and Fisher tests. The ordinal variables were compared using the Student's two-tailed type 2 t-test. Data were presented as average ± standard deviation.

Surgical technique: laparoscopic VH

Our technique consisted in mobilization of CV using the transperitoneal approach with the patient in a modified lateral decubitus (45°). A bladder catheter and a nasogastric tube were positioned before starting the procedure. As for the instruments we used an optical port of 5 or 10 mm with a 30° laparoscope (according to the patient's age and weight) and two 3-mm working ports, placed in the epigastrium and in the ipsilateral iliac fossa at the midclavicular line, to allow an ideal triangulation during dissection of the aberrant CV and completion of the pelvic wrap. Pneumoperitoneum was induced with a 5–10 mmHg pressure CO₂. We preferred a transperitoneal approach because it provides better anterior access to the renal pelvis and the anterior CV.

The technique consisted in the exposure of the lower pole vessels through a window created in the mesocolon (especially on the left side), or by partial ipsilateral colon flexure mobilization if necessary (especially on the right side). The CV was then dissected and mobilized off the UPJ. After careful dissection of the vascular bundle and release of ureteral adhesions, we usually observed the decrease of size of the renal pelvis. We carefully inspected the appearance of UPJ and ureter for any significant narrowing and stenosis, highly suspected for intrinsic obstruction.

We also evaluated the anatomical relationships among CV, renal pelvis, UPJ, and the ureter, according to Schneider's classification.¹⁰ To be sure of a pure extrinsic obstruction, we temporarily transposed the CV and we observed the peristalsis associated with the easy urine passage across the junction and finally deflation of the pelvis after vessel transposition (intraoperative DT). Sequentially, the vessels were sutured in a tunnel formed by an invagination of the anterior pelvic wall as described in the Chapman procedure.^10–12 One tip was to pass the first suture transparietally, stabilizing and fixing the vascular bundle into the pelvic tunnel to assist the remaining suture. Two/three interrupted 4/0-polydioxanone absorbable sutures (pyelo-pyelic sleeve) may be necessary to achieve an adequate tunnel within the anterior pelvic wall (Fig. 4). No JJ-stent neither drainage was inserted.

FIG. 4.

Laparoscopic Hellström vascular hitch modified by Chapman.

Surgical success after laparoscopic VH procedure was defined as resolution of symptoms, improvement of hydronephrosis on US, and/or postoperatively resolution of the obstruction measured as increased elimination on diuretic renogram mercaptoacetyltriglycine (MAG3).

Results

All VH procedures were completed in laparoscopy without any conversion to open surgery. There was no intraoperative bleeding. Average operative time was 108 minutes (range: 75–230 minutes, median 105 minutes).

As for complications, we recorded one small hematoma of the abdominal wall on the closure of the peritoneum and a high distortion of UPJ without obstruction in 2/51 cases (3.9%). In this last patient, after completing the tunnel formed by invagination of the anterior pelvic wall to suspend CV, we observed a high distortion of the UPJ that intraoperatively appeared not obstructive since we observed a normal drainage across the UPJ after the DT. None of these patients required a reintervention (grade I Clavien-Dindo).

The average hospitalization was 1.8 days (range 1–4 days). The average analgesic requirements were 1.5 days (range 1–3 days). We performed a continuous IV administration of paracetamol and tramadol for the first 24 hours after surgery, then we administered paracetamol only if patients still presented pain. The average time to restart full oral feeding was 24 hours after surgery.

We decided to compare the outcome of the 51 patients who underwent VH versus the 3 patients who underwent AHDP. Our analysis revealed that there was no difference between the two techniques in regard to the average analgesic requirements and the average time to resume full oral diet (P = .3), whereas laparoscopic VH presented a statistically significant shorter operative time (P = .01). Also the average time to ambulation and the average length of hospitalization were significantly shorter in patients who underwent VH compared to AHDP (P = .01). As for the outcome of surgery, no difference was reported between the two techniques in regard to success rate and complication rate (P = .01).

All patients had a clinical evaluation and a renal US 1 and 6 months following surgery and then annually. A diuretic renogram (MAG3) was performed 6 months following surgery in all operated patients.

Follow-up (range:12–96 months, average 54 months, median 50 months) showed complete resolution of symptoms (pain, hematuria) and decrease in hydronephrosis grade in all patients (average preoperative AP diameter pelvis 36 mm versus average postoperative AP diameter pelvis 12 mm, P = .01). Although none of the children displayed significant improvement in relative renal function, all of them showed improved drainage on 99mTc-MAG3-renogram and became unobstructed.

The preoperative MAG3 renogram showed impaired drainage on diuretic renogram in all patients (washout evaluated 30 minutes after orthostasis and micturition (average value): 25% ± 5.5%). The postoperative MAG3 renogram showed a statistically significant improvement of drainage and resolution of the obstructive pattern (washout evaluated 30 minutes after orthostasis and micturition (average value): 80% ± 5.0%) (P = .01) in all operated patients.

Also the average preoperative halftime clearance values (26.7 ± 3.2 minutes) showed a marked improvement after surgery (7.4 ± 2.2 minutes) (P = .01) in all operated patients.

All patient demographics, indications for surgery, and outcome parameters are reported in Table 1.

Discussion

Usually UPJO is caused by the presence of an aperistaltic dysplastic segment of the UPJ. However, also extrinsic factors, as aberrant lower pole CV, may be the causative factor. These aberrant vessels are usually normal morphologic vessels of the lower pole segment, arising from the aorta or from branches of the aorta.¹³ The incidence of extrinsic UPJO by CV in children has been reported in a range from 11% to 15%,¹⁴ but it was reported as high as 58% in a series of older children with symptomatic UPJO and a history of normal antenatal renal ultrasonography.¹⁵

The open-AHDP described by Anderson and Hynes in 1949 remains the gold standard surgical treatment of intrinsic and extrinsic UPJO.⁶ In the last years, the open technique has gradually given way to laparoscopic repair and more recently to robotically assisted AHDP with comparable results. The alternative approach, Hellström VH modified by Chapman,^7,8 has been described in children by Pesce who reported a series of 61 children treated by open-VH with excellent outcomes.⁹

The UPJO by CV is typically intermittent and must be suspected in older children with recurrent renal colic pain and intermittent hydronephrosis. The renal function may be normal in children with UPJO without urinary tract infection.^3,11,16,17 In our series, only 3 children had a major loss of kidney function, probably because of the high delay in the diagnosis (patients with hydronephrosis > 4 cm). Similar results have been reported by Hacker¹⁶ who found that children with UPJO by polar vessels had decreased relative renal function and delayed surgical management.

We reviewed the literature and we found very few published series reporting on laparoscopic relocation of lower pole CV in children with intermittent UPJO. The most recent series were reported by Schneider and Chiarenza-Bleve, with a success rate of 95% and 97%, respectively, after a careful selection of candidates.^10,18

In 2003, Meng and Stoller were the first authors reporting vascular relocation using the Hellström technique through laparoscopic approach. They reported this procedure in 9 adults, with resolution in all cases.⁸ Another important condition is the existence of several anatomic variations as studied by Sampaio.¹⁹ Sometimes double vascular bundles form a vascular window and could facilitate a UPJ prolapse with increasing obstruction.¹¹ Vascular compression in these cases is not in the UPJ but in the proximal ureter. Therefore, the junction is certainly healthy, and correcting the herniation is all that is needed.^10,12,20

On the basis of our large experience, we would like to express our opinion on surgical treatment of extrinsic UPJO by CV in pediatric patients. Essential to the success of the VH procedure is the careful pre- and intraoperative selection of candidates: only patients with pure extrinsic UPJO can be treated with this procedure; so any associated intrinsic UPJ abnormality must be ruled out.²¹

We think that selection of patients must follow three criteria as follows: preoperative patient selection, accurate diagnostic studies, and intraoperative assessment of anatomical and functional aspects to confirm the extrinsic nature of the UPJO. First, we believe that a careful evaluation of the clinical history remains the basis for correct patients' selection. In our series, no patients had history of prenatal hydronephrosis. They all presented with intermittent colicky flank pain, sometimes associated with vomiting or hematuria. All showed a marked hydronephrosis when they were symptomatic, which resolved shortly after they became asymptomatic.

It is also important to perform a complete preoperative workup to give correctly the indication for surgery and to use it as the basis to check the patient after surgery. As preoperative evaluation, various imaging modalities have been used, including Doppler/US, spiral-CT, MRI, and rarely diuretic urography.²² None of these modalities has an accuracy of 100% in the diagnosis of pure extrinsic UPJO caused by lower pole CV. The MRI has a higher sensibility and specificity compared to US, but it has the limitation to require sedation in younger children; so we preferred to perform it only in older patients who collaborated during the examination and did not need sedation. This is the main reason for which only some patients in our series (61%) underwent preoperative MRI.

We reported a 100% success rate in our series. A careful intraoperative functional and anatomical assessment is crucial to guide the choice between VH and AHDP, considering that most of patients who underwent AHDP in our series presented preoperatively the same characteristics and surgical indications of patients who underwent VH.

The main drawback of our study is the retrospective study design with its inherent selection biases. Other limitations of the present study, beyond its retrospective nature, are mainly represented by the difficulty in providing a reproducible pathway to select adequate indications based on objective criteria. Although the children that are potentially eligible for this technique present with a rather typical clinical picture (intermittent loin pain, episodes in late childhood, and absence of prenatal diagnosis) and show subjective hints of absence of intrinsic obstruction (regression of pelvic dilatation after vessel mobilization and normal aspect of UPJ), these criteria do not formally preclude the presence of an intrinsic obstruction.

Another fact is that the intraoperative inspection of the UPJ peristaltism on DT cannot definitely rule out an accompanying intrinsic etiology. A further limitation is that the follow-up period is limited (12 months) in some cases. A longer term follow-up, as well as a prospective and multicentric study, is required to confirm the relevance of the results of the present study.

Comparing the outcome of the two techniques, we found no difference in regard to success rate and complication rate (P = .01). One of the great advantages of the VH is the preservation of the UPJ integrity; in this way there is almost no chance of leakage or urinoma and therefore no need for internal stent placement or drainage. In fact, we found that the average time to ambulation and the average length of hospitalization were significantly shorter in patients who underwent VH compared to AHDP (P = .01).

Furthermore, VH is less technically demanding than laparoscopic dismembered pyeloplasty, resulting in a shorter operative time compared to AHDP (P = .01). In fact, AHDP requires advanced laparoscopic skills such as ability in intracorporeal knot-tying and suturing. In our experience with VH, our learning curve plateaued and our operative time decreased significantly after 2–3 cases. Obviously, the surgeons involved in our study had a strong laparoscopic expertise^23,24; we did not include trainees or young residents to eliminate bias.

The careful patient selection and preoperative workup, the intraoperative evaluation of the anatomical relationship between CV and UPJ, and an improved pelvic emptying on DT after CV mobilization were associated, in our series, with very favorable outcomes. These findings allow us to conclude that laparoscopic Hellström VH may be a safe, feasible, and effective treatment option for extrinsic UPJO by CV, presenting an useful alternative to dismembered pyeloplasty in the management of symptomatic children where CV is deemed the sole etiology.

The advantages of a shorter operative duration together with a minimal risk of violation of the collecting system made the laparoscopic VH procedure an attractive option, especially for pediatric UPJO repair. However, this technique should be adopted only in a highly selected population of patients and the ultimate choice between VH and AHDP should be taken intraoperatively after ruling out with high probability a coexisting intrinsic etiology of the UPJO. We believe that any concerns regarding the coexistence of an intrinsic stenosis should certainly lead to opening the collecting system and to performing a classic dismembered pyeloplasty.

Footnotes

Disclosure Statement

No competing financial interests exist.

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