Lower pole approach in retroperitoneal laparoscopic radical nephrectomy: a new approach for the management of renal vascular pedicle

The Institutional Review Board at the First Bethune Hospital, Jilin University, approved the study protocol. One hundred forty-eight patients were consecutively enrolled into our Urology Center for radical nephrectomy (RN) from January 2008 to December 2010. Those patients were diagnosed as renal cancer based on the combination of ultrasonography, contrast-enhanced computed tomography, intravenous pyelography, and urine cytology. The patients were excluded from this study if he or she had an unresectable tumor or any distant metastases, was medically intolerable for radical resection, or was unwilling to participate in this study. The patients were well informed by an independent research nurse of the technical aspects and drawbacks of the procedures, including RN opening, transperitoneal LRN, and retroperitoneal LRN, and allowed to undergo any procedure at their own will. Informed consent was obtained from each patient before surgery.

All renal tumors were deemed resectable. Moreover, the absence of any distant metastases was confirmed during the preoperative radiological evaluation. All patients exhibited normal renal function reserve, with a serum creatine of 44–115 μmol/L. The endogenous creatine clearance rate of the undiseased kidney ranged from 80 to 120 mL/min.

A surgical team performed all the procedures. A standard protocol of retroperitoneal (extracapsular) LRN was followed. After intubation and combined intravenous and inhalational anesthesia, the patients were placed in the standard kidney position, on the lateral side opposite to the tumor, and with the head tilted down 15° and the feet tilted down 30°. The chest and pelvis were fixed on the operative table using straps, and the wrists were cushioned with soft cloth pads. A standard three-trocar placement was used to establish access ports for either approach (Fig. 1). LPS approach was performed as previously reported [8]. LP approach was described as follows. Dissection of the renal lateroanterior space (Fig. 2 (1)) preceded that of the LPS (Fig. 2 (2)). Upon the establishment of the working space (Fig. 2 (3)), the anterior and posterior renal fasciae were transected 3.0 cm below the lower pole (Fig. 2 (4)). The ureter was mobilized (Fig. 2 (5)), and the anterior and posterior fasciae were further dissected along the inferior vena cava (IVC) for right-sided LRN or the abdominal aorta for left-sided nephrectomy. The lympho-adipose tissues between the perinephric adipose tissue and the IVC were dissected along the surface of IVC towards the renal pedicle (Fig. 2 (6)). The renal vein was dissected (Fig. 2 (7)) preliminarily to expose the renal artery located posterior (right side) or posterosuperior (left side) to the renal vein. The renal arterial sheath was further dissected to mobilize the renal artery (Fig. 2 (8)), which was interrupted using an L-size Hem-o-lok clip (Teleflex Medical, Research Triangle Park, NC) and subsequently transected (Fig. 2 (9)). The renal vein was secured using an XL-size clip and transected as well (Fig. 2 (10)). The ureter was mobilized, interrupted using an L-size clip, and transected appropriately. The upper fasciae and sub-diaphragmatic fasciae were transected to completely mobilize the diseased kidney. A concomitant ipsilateral adrenalectomy was performed in the cases of adrenal involvement, a renal tumor larger than 8 cm, a renal tumor located close to the upper pole, or a T3 tumor. The pressure of pneumoperitoneum was reduced to 4 mmHg, and the dissection surfaces were cautiously examined to exclude any active bleeding. The kidney specimen was removed using a retrieval bag (GT.K Medical, Guangzhou, China) through the laparoscope trocar incision that was extended 4–5 cm. A drain was placed onto the renal fossa through the 5-mm trocar hole. The incisions were appropriately closed using a full-thickness suture. The laparoscopy was converted to an open procedure in the case of uncontrollable bleeding or potentially massive bleeding in the dissection. A red blood cell transfusion was given to the patient with an intraoperative blood loss more than 400 mL at the discretion of the surgeon and the anesthesiologist.

Patients were allowed to resume oral intake on the day of anal passage and start off-bed activities on the second postoperative day. The retroperitoneal drain was removed when the drainage volume fell below 10 mL daily. The patient was discharged if he or she remained uneventful following the drain removal. Patients who were pathologically diagnosed with T1–2 renal cancers received no adjuvant chemo- or radiotherapy and were regularly followed up at 3–6-month intervals for three consecutive years and at 1-year intervals afterwards. T3 patients received adjuvant medication with interleukin-2 at a quarterly or semiannual frequency for two consecutive years, at a semiannual frequency within the third year, and at an annual frequency afterwards. The follow-up tests consisted of a hepatic and renal function test, serum alkaline phosphatase, chest X-ray, and abdominal Doppler ultrasonography or computed tomography scan.

The primary outcome measures consisted of operative duration, volume of intraoperative blood loss/transfusion, rate of abdominal organ or major vessel injury, and frequency of conversion to open procedure. The secondary outcome measures included post-LRN drainage volume, time to remove the drain, and length of hospitalization.

All the numeric data were expressed as means ± standard deviation (SD) and compared by using the Student t test. All the categorical data were expressed as n (%) and compared using Fisher’s exact probability test. A P value less than 0.05 was considered statistically significant.

Twelve patients were excluded from this study due to surgical contraindications (n = 8) or rejection for the RN procedure (n = 4), and four patients were assigned for open (n = 2) or transperitoneal (n = 2) LRN as the patients required. One hundred thirty-two patients were finally scheduled for elective retroperitoneal LRN. Out of 132 patients, 78 (59.1%) patients underwent LRN via LP approach and 54 (40.9%) patients underwent LRN via LPS approach (Fig. 3). Thirty-six (36/78, 46.2%) patients in the LP group underwent ipsilateral adrenalectomy compared to 19 (19/54, 35.2) patients in the LPS group (P > 0.05). The baseline characteristics of the two groups are shown in Table 1. The two groups were comparable in age (57.0 ± 2.1 years vs. 57.1 ± 2.1 years, P > 0.05) and sex (41/37 vs. 31/23, P > 0.05). The patients undergoing LRN via LP approach had a higher body mass index (BMI; 27.0 ± 1.7 kg/m² vs. 24.5 ± 1.8 kg/m², P <  0.0001) and a larger tumor size (6.9 ± 3.5 cm vs. 4.1 ± 3.3 cm, P <  0.0001) than those undergoing LRN via LPS approach. Additionally, the two groups exhibited a different location profile of the tumor (P <  0.05). The LP group was more frequently afflicted with a renal tumor located on the medial portion compared to the LPS group (57.7 vs. 37.0%, P <  0.05), whereas the LP group was less apt to have a renal tumor located at the lower pole (19.2 vs. 35.2%, P <  0.05). The two groups were also comparable in the patients’ previous history of abdominal surgery (3.8 vs. 1.9%, P > 0.05) and pre-existing medical conditions (hypertension, 25.6 vs. 22.2%, P > 0.05; diabetes mellitus, 25.6 vs. 18.5%, P > 0.05; cardiovascular diseases, 15.4 vs. 27.8%, P > 0.05).

Surgical outcomes are shown in Table 2. LP approach appeared to shorten the operative duration significantly (125.2 ± 5.8 min vs. 135.4 ± 11.9 min, P <  0.0001). Moreover, the LP approach reduced the volume of blood loss and transfusion significantly compared to LPS approach (135.3 ± 17.2 mL vs. 219.6 ± 30.9 mL, P <  0.0001; 55.6 ± 28.3 mL vs. 141.1 ± 50.4 mL, P <  0.0001). Additionally, LP group had a slightly higher drainage volume compared to LPS group (225.8 ± 43.2 mL vs. 212.0 ± 22.4 mL, P <  0.05). Furthermore, the LP approach seemed to delay the postoperative recovery (2.1 ± 0.3 days vs. 1.8 ± 0.3 days, P <  0.0001), start of off-bed activities (2.6 ± 0.2 days vs. 2.3 ± 0.3 days, P <  0.0001), and removal of the drain (5.1 ± 0.6 days vs. 4.4 ± 0.2 days, P <  0.0001) compared to the LPS approach. Finally, the overall length of hospital stay was comparable between the two groups (10.7 ± 3.5 days vs. 11.4 ± 2.8 days, P > 0.05).

The two approaches had a favorable safety profile and were comparable in the frequencies of abdominal organ injury (1.3 vs. 1.9%, P > 0.05), retroperitoneal hematoma (1.3 vs. 3.7%, P > 0.05), and subcutaneous emphysema (1.3 vs. 1.9%, P > 0.05). However, the frequency of incidental injury of major vessels was lower in the LP group than in the LPS group (1.3 vs. 9.3%, P <  0.05). Of note, the LP approach also reduced the risk of conversion to the open procedure caused by the potential or uncontrollable pedicular bleeding as compared to the LPS approach (1.3 vs. 7.4%, P < 0.05) (Table 3). Additionally, one patient in the LPS group required conversion to transperitoneal LRN rather than open procedure due to uncontrollable bleeding from the injured renal pedicle vessels. No urinary tract infection, bleeding, renal failure, tumor dissemination, or mortality occurred following LRN via either approach.

LRN via either approach achieved a 100% R0 resection rate, and no lymph node metastasis was detected pathologically. The pathological type and staging of renal tumors are shown in Table 4. The pathological patterns of renal tumors were comparable between the two groups (P > 0.05 for any specific subtype). However, the LP group exhibited a more advanced tumor profile as compared to the LPS group, less frequent pT1a tumors (6.4 vs. 31.5%, P < 0.0001), but more frequent pT3a tumors (38.5 vs. 11.1%, P < 0.0001). The two cohorts were followed up for 2–38 months, showing no local recurrence or distant metastasis. Additionally, all patients exhibited normal renal function on routine serum creatine and blood urea nitrogen tests at the follow-up visits.