The Application of “Renal Pedicle Rotation” Method in Retroperitoneal Laparoscopic Partial Nephrectomy for Renal Ventral Tumors

Abstract

Objectives:

To present preliminary experience of “renal pedicle rotation” method in retroperitoneal laparoscopic partial nephrectomy (RLPN) for renal ventral tumors.

Methods:

A retrospective analysis of renal surgery database about patients undergoing RLPN was conducted. We identified 14 consecutive cases of all the surgeries from December 2013 to October 2014 with renal ventral tumors. The 14 surgeries were all in the application of renal pedicle rotation method, an intraoperative skill in which surgeons rotates the kidney on renal pedicle axis after separating renal artery and vein for a better tumor exposure.

Results:

A total of 14 patients underwent RLPN. All surgeries were successful without conversion to radical nephrectomy or open partial nephrectomy. The mean operative time was 171.1±47.2 min (range 83–246), the mean warm ischemia time was 15.9±9.8 min (range 7–35) and the mean estimated blood loss was 89.3±102.2 mL (range 10–300). Mean postoperative hospital stay was 6.2±1.9 days (range 4–10) and mean retroperitoneal drainage was 4.2±1.4 days (range 2–8). No intraoperative complications occurred. Postoperative complications developed in four patients. All patients had negative margins and pathological examination revealed 10 (71.4%) clear cell carcinomas, two (14.2%) epithelial renal angiomyolipoma, one (7.1%) papillary carcinoma and one (7.1%) nephrotuberculosis. The review of the early oncologic outcomes revealed no local recurrence and distant metastasis.

Conclusion:

The renal pedicle rotation method might be a feasible and safe procedure to get a better tumor exposure for incision and suture in renal ventral tumors RLPN surgeries with acceptable postoperative outcomes.

Introduction

Through many years of clinical studies, partial nephrectomy in the treatment of renal tumors is with enough safety and effectiveness.¹ Compared with open surgery, laparoscopic partial nephrectomy (LPN) has exhibited a large growth in worldwide popularity for renal tumors with the advantages of minimal invasion, quicker recovery and less analgesic drug application.^2,3 Traditional open partial nephrectomy (OPN) provides excellent oncological and renal functional outcomes at 10 years and beyond.⁴ Recently, the application of LPN has increased in the last decade with a trend to emerge as an alternative to OPN with durable renal function and oncology outcomes.⁵

To date, most LPN series have focused on establishing efficacy for the treatment of easily accessible peripheral tumors. But difficult tumor locations have been previously considered as a relative contraindication to LPN even in the hands of experienced laparoscopists due to complexity of exposing tumor and separating renal vessels and urinary collecting system.⁶ Generally, we define complex or difficult renal tumor locations as hilar/central tumors (renal cortical tumors in direct physical contact with the renal artery, vein, or both, as identified on preoperative imaging and confirmed intraoperatively).⁷ When the tumor location is opposite to operative approach, laparoscopists face difficulties in exposing tumors and suturing. In retroperitoneal laparoscopic partial nephrectomy (RLPN), dealing with renal ventral tumor would be at risks of longer operative time (OT), longer warm ischemia time (WIT) and more estimated blood loss (EBL). Therefore, with the difficulty and potentially increased incidence of complications, some cases converse to OPN.⁸ According to our initial experience in the application of “renal pedicle rotation” method, which is an intraoperative skill in which surgeons rotated the kidney on renal pedicle axis after separating renal artery and vein to make the tumor exposed clearly, it is a feasible and safe procedure for renal ventral tumors.

Materials and Methods

A retrospective review of renal neoplasm surgery database about patients who had undergone RLPN was conducted. We identified 14 consecutive cases of all the surgeries from December 2013 to October 2014 who had renal ventral tumors as research samples. Among these 14 patients of chosen cases, one patient had undergone right kidney partial nephrectomy due to renal clear cell carcinoma in retroperitoneal partial nephrectomy previously. No solitary kidney was present. Seven patients were male (50%) and seven were female (50%) and mean age was 62.1±11.3(range 46–83), the body mass index was 24.4±1.6 kg/m² (range 20.7–26.3), six patients had tumors in left kidney (42.9%) and eight patients had tumors in right kidney (57.1%). Routine preoperative evaluations included a complete record of medical history, physical examination, laboratory investigation, computerized tomography and magnetic resonance imaging of the urinary system. Specifically, renogram is an essential examination for evaluating bilateral kidney function. All of the tumors were confirmed in the ventral location by computerized tomography preoperatively and then evaluated with the R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, anterior/posterior, location relative to polar lines) nephrometry scoring system.⁹ Preoperative imaging was used to obtain tumor characteristics, including tumor size, location and tumor complexity on the basis of R.E.N.A.L. nephrometry scoring system. Charlson comorbidity index and the routine laboratory investigations, including hemoglobin (Hb) and serum creatinine (SCr) levels, were consequential to evaluate surgical results with comparison between preoperative and postoperative conditions. The baseline demographics and perioperative outcomes were based on a retrospective data collected from all 14 patients, shown in Table 1. The R.E.N.A.L. nephrometry scores were generated and verified by two residents, one surgeon and two physicians familiar with the R.E.N.A.L. nephrometry scoring system.

Table 1.

Patients Baseline Demographics and Presentations

Gender (%)
Male	7 (50%)
Female	7 (50%)
Age (years)	62.1±11.3 (46–83)
BMI (kg/m²)	24.4±1.6 (20.7–26.3)
Tumor location (%)
Left	6 (42.9%)
Right	8 (57.1%)
Charlson comorbidity index, age-weighted	1.4±1.9 (0–6)
Preoperative GFR (mL/min)	92.6±27.0 (49.6–166.4)
Preoperative SCr (mg/dL)	0.83±0.17 (0.54–1.22)
Preoperative Hb (g/L)	130.7±11.9 (114–154)
Preoperative tumor size (cm)	3.1±1.0 (1.4–5.2)
R.E.N.A.L. nephrometry scores (%)
4–6	8 (57.1%)
7–9	5 (35.7%)
10–12	1 (7.1%)
(R)adius (diameter) (%)
1	13 (92.9%)
2	1 (7.1%)
3	0
(E)xophytic/endophytic (%)
1	11 (78.6%)
2	3 (21.4%)
3	0
(N)earness of tumor to collecting system or sinus (%)
1	6 (42.9%)
2	5 (35.7%)
3	3 (21.4%)
(A)nterior or (P)osterior or (x) (%)
A	14 (100%)
P	0
x	0
(L)ocation relative to polar lines (%)
1	5 (35.7%)
2	7 (50.0%)
3	2 (14.3%)
“H”ilar location (abutting main artery or vein) (%)
Hilar	5 (35.7%)
Nonhilar	9 (64.3%)

BMI=body mass index; GFR=glomerular filtration rate; Hb=hemoglobin; R.E.N.A.L.=radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, anterior/posterior, location relative to polar lines; SCr=serum creatinine.

RLPN was completed using a standard three-port technique by experienced surgeons as previously described. Routinely, the patient was positioned in the full lateral decubitus position with overextension. A 1.5 cm skin incision was initially made at the cross point of the line 2 cm above the psoas major and the costal margin. A handmade balloon dilating device was then placed to create a retroperitoneal space, and the first 13-mm port was inserted into the retroperitoneal space at a 30° angle to the perpendicular line. After that, a pressure of pneumoperitoneum of 12 mm Hg was achieved. The tumors were in ventral location of among all targets and the effect of exposure was not satisfying enough to operate (Fig. 1). After finishing separating Gerota's fascia and perirenal fat along the surface of kidney for making it skeletonized, we exposed renal artery and vein. Then, the kidney was delicately rotated a suitable angle on renal pedicle axis (Fig. 2) to make appropriate surgery field and for an optimal straight tumor exposure on renal pedicle rotation method (Fig. 3). Laparoscopic bulldog clamps were applied before renal tumor extirpation and then mark the time for WIT. Then we excised the renal tumor and kidney tissue using the laparoscopic scissors with a distance of 0.1–0.5 cm from the tumor margin. In most cases, the use of arterial clamping provided a bloodless incision of the renal parenchyma and a very safe delineation of the plane between tumor and surrounding tissue. In one case in which the feeding blood vessels entered the tumor directly from the main renal artery, we clipped the branch. With deep incision and subsequent collection system damaged, we continuously sutured collection system using 3-0 absorbable suture and then continuously sutured renal parenchyma with 2-0 absorbable suture. After removing the laparoscopic bulldog clamps to restore blood flow, we restored the original location of the kidney by rotating the kidney on renal pedicle axis opposite to the previous clockwise. All patients were treated without ureteral stent. OT, WIO and EBL were recorded.

FIG. 1.

The tumor (arrow points) was in ventral location and the exposure was not satisfying enough.

FIG. 2.

“Renal pedicle rotation” method, rotating the kidney on renal pedicle axis delicately.

FIG. 3.

The tumor (arrow points) was exposed clearly.

Postoperatively, the specimen was sent for pathological analysis including tumor histology, TNM stage, and margin status. The levels of Hb and SCr were remeasured. Postoperative hospital stay, retroperitoneal drainage and postoperative complications were recorded. With a mean follow-up for 8.1±3.0 months (range 3–13), early oncologic outcomes, local recurrence and distant metastasis were also analyzed. Patient baseline demographics, perioperative outcomes and pathological characteristics were recorded based on a retrospective data collection and telephone interview.

Results

All 14 procedures were carried out successfully and consecutively. Of these procedures, no conversion to OPN or radical nephrectomy occurred. No patients needed blood transfusion during operations. The mean OT was 171.1±47.2 min (range 83–246), and the mean WIT was 15.9±9.8 min (range 7–35). Of all patients, preoperative (0.83±0.17 mg/dL) and postoperative (0.86±0.18 mg/dL) SCr had a nonsignificant difference (p=0.24>0.05). All of the postoperative SCr levels were within normal limits, and no patient required dialysis due to renal insufficiency. The mean EBL was 89.3±102.2 mL (range 10–300). Even though there was a significant difference (p=0.0007<0.05) between preoperative (130.7±11.9 g/L) and postoperative (110.0±8.7 g/L) Hb, no patient had abnormal Hb or only short-term mild anemia and no transfusion were required after surgeries. Mean postoperative hospital stay was 6.2±1.9 days (range 4–10) and mean retroperitoneal drainage was 4.2±1.4 days (range 2–8). Four postoperative complications occurred, including fever in three (21.4%), ileus in one (7.1%). No urinary tract infection, hemorrhage, perirenal fluid collection or urine leak occurred. The four patients recovered with active surveillance and treatment. Detailed patients' intraoperative and postoperative outcomes are shown in Table 2.

Table 2.

Patients' Intraoperative and Postoperative Outcomes Individually

Patient No.	OT (min)	WIT (min)	EBL (mL)	Pre-op. Hb (g/L)	Post-op. Hb (g/L)	Pre-op. SCr (mg/dL)	Post-op. SCr (mg/dL)	Retroperitoneal drainage (days)	Postoperative hospital stay (days)	Complications
1	211	22	100	145	100	0.93	0.95	3	5	No
2	190	16	300	130	107	0.69	0.81	4	8	Ileus
3	151	9	300	141	93	0.54	0.53	5	9	Fever
4	169	20	20	117	110	1.22	1.18	5	8	No
5	109	20	10	120	114	0.77	0.75	4	5	No
6	181	17	200	131	66	0.71	0.67	5	6	Fever
7	83	6	10	154	135	0.89	0.84	2	4	No
8	213	11	80	142	138	0.85	0.87	4	6	No
9	165	8	50	132	126	0.95	0.87	3	4	No
10	169	35	20	120	109	0.78	0.98	5	7	No
11	239	35	20	114	91	0.94	1.10	8	10	Fever
12	246	7	50	136	126	0.86	0.87	4	5	No
13	124	9	60	129	108	0.63	0.61	4	6	No
14	145	7	30	119	106	0.85	0.98	3	4	No
Mean	171.1	15.9	89.3	130.7	110.0	0.83	0.86	4.2	6.2
SD	47.2	9.8	102.2	11.9	18.7	0.17	0.18	1.4	1.9

EBL=estimated blood loss; OT=operative time; Post-op.=postoperative; Pre-op.=preoperative; SD=standard deviation; WIT=warm ischemia time.

All patients had negative margins on the final pathologic examination. And tumors in 14 cases were stage T1 tumors within proportion of T1a and T1b for 13 (92.9%) and one (7.1%), respectively. No lymphatic metastasis or distant metastasis were discovered. Pathological examination revealed 10 (71.4%) renal clear cell carcinomas, two (14.2%) epithelial renal angiomyolipoma, one (7.1%) renal papillary carcinoma and one (7.1%) nephrotuberculosis. Pathological renal Fuhrman grade provided that 1 grade in one (7.1%), 2 grade in 10 (71.4%) and uncertain in three (21.4%). Eleven of 14 (78.6%), were malignant. With a mean follow-up for 8.1±3.0 months (range 3–13), no local recurrence and metastasis occurred. The 14 patients' pathological characteristics and oncological outcomes are shown individually in Table 3.

Table 3.

Patients' Pathological Characteristics and Oncological Outcomes Individually

Patient No.	Histology	Tumor stage	Fuhrman grade	Margins (±)	Follow-up (months)	Outcome
1	NTB	T1aN0M0		–	12	Alive
2	RCC	T1aN0M0	2	–	10	CT
3	RCC	T1aN0M0	2	–	10	Alive
4	RCC	T1aN0M0	2	–	5	Alive
5	EAML	T1aN0M0		–	7	Alive
6	RCC	T1aN0M0	2	–	10	Alive
7	RCC	T1aN0M0	1	–	13	Alive
8	RCC	T1bN0M0	2	–	10	CT
9	RCC	T1aN0M0	2	–	8	Alive
10	EAML	T1aN0M0		–	3	Alive
11	RCC	T1aN0M0	2	–	5	Alive
12	RCC	T1aN0M0	2	–	4	Alive
13	RCC	T1aN0M0	2	–	7	Alive
14	RCC	T1aN0M0	2	–	9	Alive

CT=chemotherapy; EAML=epithelial renal angiomyolipoma; NTB=nephrotuberculosis; RCC=renal cell carcinoma.

Comment

As recent guidelines have mentioned, active surveillance, surgical excision, thermal ablation are three viable treatment strategies for appropriately selected patients with a clinical stage T1 renal mass.^10,11 Traditional renal tumor guideline suggests that the conventional standard of treatment is surgical excision in open surgery, especially partial nephrectomy.^12,13 However, evidence is accumulating regarding the potential benefits of LPN, although it was initially used primarily in small and exophytic lesions.¹⁴ LPN has compared favorably with OPN in a number of recently published studies and LPN has been shown to be an accepted, safe and feasible treatment option for small renal masses (<4 cm) compared with OPN given its comparable morbidity and oncologic outcomes and improved convalescence according to previous surgical experience during the latest decades.¹⁵ LPN has three basic approaches, transperitoneal approach, hand-assistant approach and retroperitoneal approach. Comparing these laparoscopic approaches, we consider that the retroperitoneal route advantageous for allowing direct access to the posterolateral surface of the kidney and the posterior hilar structures, requiring little dissection to the renal hilum, especially renal artery. And we can decrease the risk of intraperitoneal organ injury and the necessity of bowel mobilization and therefore decrease the rate of ileus, which is considered as a common complication after laparoscopic surgery. Besides, Asian patients, who often have smaller bodies compared with Western patients, with less retroperitoneal fat need not the advantage that avoid excessive retroperitoneal fat of transperitoneal approach.¹⁶

Along with increasing use of imaging technologies, the number of incidentally discovered renal tumors continued to rise, therefore an increasing number of small renal tumors were diagnosed.¹⁷ Actually, when the tumor located in ventral side, including upper pole and lower pole, especially when it is closed to renal hilum with a potentially longer OT and WIT, it is difficult to get a satisfying exposure through RLPN. In other words, if the small tumor is in a complex location to expose, and the size of tumor is not really big, converting to OPN is not a best choice but there may be no suitable alternatives. Thus the situation limits the range of the application of RPLN. Rotating the kidney for a suitable angle to make the tumor a better exposure to excise and suture more conveniently, could solve problems discussed above. A recent report about renal hilar tumor mentioned that the kidney can be fully mobilized and rotation of the kidney for optimal tumor visualization is allowed to expose the hilum clearly and avoid unexpected vessel injury when dislocating adjacent tissues.¹⁶ Generally, surgeons may clamp and pull organs or tissues to get a better exposure for excision. As same as this typical operative procedure, we found that rotating the kidney to a suitable angle is an original skill in this kind of operations and many surgeons from other medical centers reflected the method effective. Based on experience in hilar tumor surgery, renal pedicle rotation method has been attempted in a set number of RLPN dealing with renal tumors in the ventral side of kidney. Different locations of the tumor have different directions and angles for surgeons to complete renal rotation. According to our article, with the retroperitoneal method, the tumors on completely upper pole need to be exposed in direct visualization through rotating the kidney to nearly 180°. Actually, the tumors were on random positions of kidney. Aiming to fit a varied of situations, the angles rotated added or reduced ranging from almost 30° to 180° according to the tumor position and the direction or angle that surgeons could operate conveniently. In general, the renal ventral tumor, especially upper pole tumor, required renal rotation to expose the tumor in direct visualization. We had some discussion with surgeons from other centers about this operative skill and the goodness of renal pedicle rotation is obvious and undoubted. However, there were few academic reports or standardized format describing this method about indication and feasibility.

In this study, 14 patients were in equal proportion of male and female as well as approximate proportion of tumor side. According to baseline demographics, all patients were in normal or basically acceptable health conditions and RLPN became the established treatment for their T1 stage renal tumors. Evaluating the preoperative tumor by computed tomography was a vital procedure to estimate operative complexity. Mean tumor size was 3.1±1.0 cm (1.4–5.2), 13 (92.9%) cases were small tumors (one in radius/diameter) and one (7.1%) case was moderate tumor (two in radius/diameter). Because the tumor size is relatively small, LPN is a suitable treatment strategy in this study.

Intraoperative data such as OT, WIT and EBL provided outcomes of renal pedicle rotation method in early-stage. With surgical field enlarged, intraoperative complications were obviously decreased on condition that all surgeries were completed successfully without conversion to OPN.

Given the technically challenging nature of ventral renal tumor excision within RLPN, considerable laparoscopic expertise is essential to minimize the WIT. After renal artery control, expeditious and precise tumor resection, collecting system closure, and parenchymal reconstruction within the shortest WIT are critically significant for preserving renal function. Hence, providing a better tumor exposure is considered to be an essential part of operation, whatever for resection and suture procedure. In complicated tumors, like renal hilar tumors, the proximity of the renal vasculature increases the risk of hemorrhage, necessitating surgeon familiar with laparoscopic hemostatic techniques and more satisfying operative field.^18,19 In our series, five (35.7%) of all 14 targets had a tumor located in renal hilum according to “H” score of R.E.N.A.L. nephrometry scores. Among the five patients, there were 300 mL blood loss in two (14.2%), and 200 mL blood loss in one (7.1%) and <100 mL blood loss in the rest two (14.2%). Including the five renal hilar tumor cases, all 14 patients had satisfying related outcomes. Postoperative Hb and the result that no transfusion during or after surgeries could be combined to confirm the safety in prevention of hemorrhage of renal pedicle rotation method.

According to previous studies from some centers, it is historically considered safe that WIT duration is less than 30 min. In our series, mean WIT (15.9±9.8 min) is significantly less than standard as well as postoperative (0.86±0.18 mg/dL) SCr, and EBL (89.3±102.2 mL). Normal postoperative SCr levels of our study could confirm prevention of renal dysfunction.

Early pathological outcomes were also collected and analyzed. Dissatisfactory tumor exposure certainly will influence tumor incision. The positive margins or local recurrence rate seems to increase possibly. All 14 patients in our series had negative margins on the final pathologic examination. However, one patient was nephrotuberculosis but treated with LPN. According to urinary tract tuberculosis treatment principle, drug treatment is preferred to early stage or pretreatment before surgery. The patient had no typical tuberculosis symptoms and no imaging evidence to support this diagnosis so that we treated it as kidney tumor. Analyzing oncological information and follow-up result, we confirmed that renal hilar tumors or partial central tumors in ventral location treated successfully in short term.

We have preliminary experience about renal pedicle rotation method till now. There are some potential problems or conditions need to be taken care of. With completely separating the Gerota's fascia and perirenal fat of the renal artery and vein, surgeons should confirm the renal blood supply of affected side. Generally, renal vessels consist of two arteries, two veins and some branches afflux to abdominal aortic and inferior vena cava. Among targets in our study, all 14 patients belong to this condition. Based on the same vessel branch direction, renal pedicle rotation method was simply applied by rotating the kidney on renal pedicle axis delicately. While renal vessels have some anatomic variations branch of iliac vessels, rotating kidney directly increases the risk of catastrophic vascular rupture. According to an example of iliac vessel branch, before renal pedicle rotating, clamping the extra branch with laparoscopic bulldog clamps or clipping extraordinary arteriole within electrocoagulating seems to be effective to solve the problem. It is worth mentioning that after incising the tumor, recovering kidney location and checking hemorrhage should not be ignored.

The limitations of our study include its retrospective, single institution nature. And there were not matched controls. The targets we chose were within tendentious and the small patient cohort limited statistical analysis. Moreover, we only described the RLPN so that further studies referring to applications of renal pedicle rotation method in transperitoneal approach are warranted. Because of the short time for which the method has been applied, there was no long-term follow-up to evaluate the efficacy and the oncological results were preliminary.

Conclusion

Our initial experience suggests that renal pedicle rotation method is a feasible procedure for the renal ventral tumors with difficulty in exposure and suture. This method can effectively rotate the ventral tumor in a relatively dorsal location for a better exposure to incise and suture so as to protect renal function and avoid conversion to open surgery.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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