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Chin Med J (Taipei) 1997;59:232-9.

The Clinical Experience of Gaseous Retroperitoneoscopic and Gasless Retroperitoneoscopy-Assisted Unroofing of Renal Cyst

Yen-Chuan Ou1, Chi-Rei Yang1, Yuen-Yaw Chang1, Jehn-Hwa Kuo1, Hsi-Chin Wu2

1Division of Urology, Department of Surgery, Taichung Veterans General Hospital; 2Division of Urology, China Medical College Hospital, Taichung, Taiwan, R.O.C.


Background. The aim of this study is to compare the application of gaseous retroperitoneoscopic (GR) and gasless retroperitoneoscopy-assisted (GLRA) unroofing of renal cysts.

Methods. Fourteen patients with symptomatic simple renal cysts had undergone unroofing of the cyst with GR in seven cases and GLRA in seven others. Three trocars (10 mm, 10 mm and 5 mm) were inserted in the GR procedure. A 3 cm flank muscle-split incision was made and retroperitoneoscopy was performed through the same incision in the GLRA procedure. Then, the cyst was unroofed.

Results. The mean operative time was 104.3 minutes in the GR group and 52.1 minutes in the GLRA group, respectively (p=0.001). The mean requirement of postoperative meperidine hydrochloride injection was 21.4 mg in the GR group and 71.4 mg in the GLRA group, respectively (p=0.017). In the GR group, the mean postoperative stay was 3.7 days, and the time needed for return to normal activity was 7 days. In the GLRA group, the mean postoperative stay was 4.6 days, and the time needed for return to normal activity was 8 days.

Conclusions. GR and GLRA techniques for unroofing of renal cysts are safe, effective and minimally invasive. GLRA is easy to perform and a more time-saving procedure when compared to GR, however, the patients of GLRA suffered more postoperative pain than after GR. GLRA is recommended in patients who had received retroperitoneal surgery or who have multiple renal cysts.

[Chin Med J (Taipei) 1997;59:232-9.]

Keywords: cyst, kidney, peritoneoscopy, retroperitoneum

Received: June 18, 1996.

Accepted: November 29, 1996.

Address reprint requests to: Dr. Yen-Chuan Ou, Section of Urology, Department of Surgery, Taichung Veterans General Hospital, No. 160, Sec. 3, Taichung-Kang Rd., Taichung, Taiwan, R.O.C.


Renal cysts are commonly discovered by sonography or computerized tomography (CT) of the abdomen for other diagnostic purposes. Most cases require no treatment. Indications for surgical intervention include pain, hematuria, hypertension, recurrent infection, compression to the collecting system or ambiguity about whether the cyst is simple, complex, and/or malignant [1,2]. Treatment options for symptomatic renal cysts include open surgery [3], percutaneous needle aspiration of the cyst with or without injection of a sclerosing agent [4-10], percutaneous resection of the cyst wall [11] and ureteronephroscopic marsupialization of peripelvic cyst [12].

Urologists are now using laparoscopy or retroperitoneoscopy for the management of renal cysts [1,2, 13-14]. It has been reported as an effective and minimally invasive procedure. GR unroofing of the cyst is time-consuming during both the creation of a working space and the approach to the cyst. GLRA unroofing of the cyst through a small incision ensures better access to the cyst. The aim of this study is to compare the application of GR and GLRA unroofing of the renal cysts.

Materials and Methods

From November 1994 to June 1996, sixteen patients with symptomatic renal cysts were treated with laparoscopic approach. Two patients receiving GR failed unroofing of the cysts, and were then converted to open surgery. Those two patients are excluded from this series, but 14 patients were enrolled: 7 patients received GR, and 7 patients received GLRA unroofing of their cysts. The patients' clinical data are presented in Table 1. Two patients in each group had already submitted to at least one percutaneous aspiration of the cyst and intracystic injection of lipiodol, and they were suffering from recurrence. All patients belonged to the American Society of Anesthesiologists (ASA) class I or II [15]. The indications for surgical intervention included pain (nine cases), pain with compression of the collecting system (two cases), pain with hypertension (two cases) and hematuria with infection (one case). All patients were fully informed about the retroperitoneoscopic procedure and the possibility of conversion to open surgery.

The GR procedure is described as follows (Figure 1): Following endotracheal tube general anesthesia, the patient was placed on the lateral decubitus position. The operator stood at the side of the patient's back. A 1.0 cm skin incision was done on the lumbar triangle (Petit's). A Visiport optic trocar (United States Surgical Corporation, USSC, Norwalk, CT, USA) was introduced under camera vision. The optic cutting device was deepened layer by layer, passing through the subcutaneous layers, muscle layers, lumbodorsal fascia and finally entering the retroperitoneal space. The Visiport cutting device was removed. A 0-degree laparoscope was inserted through the sheath. Carbon dioxide was insufflated to 15 mmHg, and the laparoscope with pneumodissection was advanced into retroperitoneal space. The direction of dissection depended upon the location of the renal cyst (anterior, posterior, or central aspect; upper, middle, or lower pole). The laparoscope was removed. Then, a modified balloon dissector was made with the middle finger of a No. 7.5 latex surgeon glove. It was cut out and tightened to the tip of an 18 French Robison tube. The balloon dissector was put into the retroperitoneum via the trocar sheath. It was inflated with normal saline by Toomy syringe to 500-700 ml to create working space. The balloon dissector was deflated and removed. The laparoscope was again inserted. The second 5 mm trocar was inserted under vision through a posterior axillary line roughly posterolateral to the kidney, allowing a grasping forcep to be inserted. The third 10 mm trocar was inserted in the anterior axillary line approximately anterolateral to the kidney; via that trocar a dissecting forcep or clip applier was inserted (Figure 1). The Gerota's fascia was opened, and the kidney was identified. The cyst was dissected and the edge of the cyst was delivered. When aspiration of the cystic fluid was done, if the cystic fluid was bloody, the procedure was converted to open surgery. If the cystic fluid was clear, a suction-irrigation cannula was inserted via the posterior port to remove fluid. The cystic wall was excised with an endoshear (USSC, Norwalk, CT, USA) and the edge was sealed by electrocautery. The base of the cyst was inspected to exclude any tumor growth. The perirenal fat was placed over the base of the cyst. The 18 French Robison tube previously used for the balloon dissector was positioned via a laparoscopic port for drainage. All the ports were removed. The wounds were closed in layers, with 2-0 vicryl for the muscle-fascia, with 4-0 vicryl for the subcuticle, and 3M steri-stripe for the skin.

The GLRA procedure is described as follows (Figure 2): Following endotracheal tube general anesthesia, the patient was placed on the lateral decubitus position. A 3 cm flank muscle-split incision was made, and the wound was deepened into retroperitoneal space. The retroperitoneoscope was introduced via the same wound. Two small Deaver retractors were applied into the retroperitoneum. The surgeons operated under eye vision and TV screen. They could manipulate the instruments through the incision. The surgeons could use laparoscopic and conventional open instruments during the GLRA procedure. A working space was created, the Gerota's fascia was open, and the kidney was identified. The cyst was dissected and aspirated. The cystic wall was pulled outward and excised. The edge of the cystic wall was electrocauterized. An 18 French Robison tube was placed via the same wound. The wound was closed by the same method as in the GR procedure.

The cystic fluid and wall were sent for cytopathologic examination. Intravenous fluid was discontinued and the perirenal drain was removed on postoperative day 1. Regular diet and ambulation were resumed simultaneously. Postoperatively no oral analgesic was given. Meperidine hydrochloride intramuscular injection was provided at patient request. Patients were discharged on postoperative day 3 or 4 if convalescence went well. They were followed up at the outpatient department. Duration of resumption of normal physical activity was recorded. A follow-up sonogram or CT scan of kidney was done three months later, and then at six months intervals. All data are presented as mean +/- standard deviation. For statistical analysis, the assessment was made with Student's t test for continuous variables, and Fisher's exact test for discontinuous variables. A p value less than 0.05 indicates a statistically significant difference.


The GR procedures were completed without anesthetic problems in seven patients. In the GR group, blood loss was minimal, (except in one patient who had a blood loss of about 150 ml), and transfusions were unnecessary. No postoperative complication was encountered in this group. The GLRA unroofings of cysts were performed smoothly in five patients with minimal blood loss. Two patients had blood loss of about 200 ml . Unfortunately, one of them suffered postoperatively from mild urine leakage. He received double-J tube stenting for two weeks, and then the leakage was healed. Cytology of cystic fluid showed negative for malignant cells in all patients. Pathology of the cystic wall revealed simple cysts in 13 patients and a pseudocyst in one. The mean operative time was 104.3 minutes in the GR group, and 52.1 minutes in the GLRA group, a difference which was statistically significant. The duration for resuming oral intake was equal in both groups. The mean parenteral meperidine hydrochloride injection was 21.4 mg in the GR group and 71.4 mg in the GLRA group, again a statistically significant difference. The mean postoperative hospital stay and return to normal activity were 3.7 and 7 days respectively in the GR group. The mean postoperative hospital stay and return to normal activity were 4.6 and 8 days respectively in the GLRA group. All patients' symptoms subsided after operation. One patient who received GR was found to have a 2 cm residual cyst six months postoperatively. Others are free of residual or recurrent cyst.


Simple renal cysts are very rare before 40 years of age. The incidence becomes higher in patients after 40. The prevalence of renal cysts varies in different reports. In Pedersen's series, the prevalence of simple cysts was 1.4 % at age 40 and 5.9% at age 70. In Lauck's series, they occurred in 24% of all individuals older than 40 years and in 50% of those older than 50 years [16,17]. Symptomatic renal cysts are indications for surgical intervention. Traditional open unroofing of renal cysts has been almost abandoned because of invasiveness and high surgical morbidity [3]. Percutaneous aspiration of simple renal cysts is an easy procedure that can be performed safely. However, 50% of patients revealed no change in their cysts [7]. The use of various sclerosing agents, including sodium morrhuate, lipiodol, phenol, bismuth phosphate, CO2, minocycline and alcohol can reduce the recurrence rate [1,5,6,10]. However, the major complication rate of following sclerosing therapy has been reported at 1.4%, and the minor complication rate at 10% [6]. Two cases of severe inflammatory reaction after lipiodol injection have been reported; both resulted in eventual nephrectomy [8]. Radiographic studies and cyst aspiration cytology are useful to exclude malignancy in cysts. There is a 1% to 2% chance of inability to make a diagnosis [6,12]. Percutaneous resection of renal cysts also has been advocated. The long-term result showed a 30% recurrence rate and 20% residual cyst [11]. The transureteral approach using flexible ureteroscopy, although effective, is limited to the treatment of peripelvic cysts [12].

Laparoscopy has become widespread in urology in recent years. Laparoscopic unroofing of a simple renal cyst is attractive and effective [1,2,13,14]. Laparoscopic access to retroperitoneal structures is usually obtained via a transperitoneal approach. This provides a large working space under the pneumoperitoneum. In case of bowel adhesion from previous abdominal surgery, redundant sigmoid colon, hepatomegaly or splenomegaly, access to the retroperitoneum is quite difficult. Additionally, the ipsilateral colon and/or part of the duodenum must be mobilized before the retroperitoneum can be entered. This increases the total operative time significantly [14]. In 1992 Dr. Gaur reported a laparoscopic operative retroperitoneoscopy by the use of a balloon dissector [18]. This created an adequate pneumoretroperitoneum for direct approach to the adrenal gland, kidney and ureter. It is much more simple than the transperitoneal laparoscopic approach. Reduced risk of hypercarbia, hypothermia, postoperative ileus, inadvertent intra-abdominal organ injury and hernia formation were reported [19].

There are three methods for entry into the retroperitoneum: (1) to make a small skin incision [18]; (2) to make a blind Veress needle puncture [20]; (3) to use sonography to facilitate placement of the Veress needle into a safe area below the inferior pole of the kidney [14]. Our division had used optic urethrotomy for establishment of a tract into the kidney to treat renal stones for more than 10 years [21]. From that experience, it was learned that the Visiport optic trocar, a device like the optic urethrotome, makes access to the retroperitoneum more convenient. It avoids unfit skin incisions which cause CO2 leakage during surgery. It also reduces the possiblity of inadvertent colon or kidney injury under blind Veress needle puncture. Using a sonography guide for Veress needle placement is tenuous. The direct Visiport optic trocar puncture was found to be a simple and safe method for introducing into the retroperitoneum.

One of the disadvantages of GR unroofing of cysts is that it is time-consuming: it needs time to master. Much time is used to create a working space and gain access to cysts, especially in cases of retroperitoneal adhesion. Although the pneumoretroperitoneum caused less hemodynamic changes than the pneumoperitoneum, changes were observed when the unilateral pneumoretroperitoneum was maintained at 15 mmHg for two hours [22]. This was caused by tension of the pneumoretroperitoneum for the long duration of anesthesia, or by peritoneal tears with tension. In comparison with GR, GLRA unroofing of a cyst is a time-saving, easily performed procedure without the risk of hypercarbia. However, the GLRA unroofing group required more meperidine hydrochloride injection than the GR group. Rapid postoperative convalescence was noted in both groups. Follow-up revealed one patient in the GR group with a 2 cm cyst adjacent to the site of the excised cyst.

In our previous sclerosing therapy experience, sonoguided percutaneous aspirations followed by injection of lipiodol was performed in 25 patients over a 6-year period. During the mean three years follow-up period, there was an 8% success rate (cyst size reduced more than 75%), a 52% improved rate (cyst size reduced > 50%) and a 40% rate of unchanged or slightly reduced cyst size. Flank pain was improved in 64%. Poor operative risk patients (ASA III, IV, or V) [15] can not tolerate the laparoscopic procedure under general anesthesia. Although sonoguide aspiration with sclerotherapy is not satisfactory, it remains the first choice of treatment because of its minimal invasiveness and lack of anesthesia risk. Repeated sonoguide aspiration with sclerotherapy could be performed if a recurrent cyst is noted. In good-risk patients (ASA I or II) with symptomatic renal cysts, sonoguide aspiration with sclerotherapy can be considered first, if the patient prefers the procedure. In patients with a single renal cyst, GR unroofing of the cyst was performed. In good-risk patients with multiple or complex cysts, GLRA unroofing is recommended as the first choice, and GR unroofing as another option. Accordingly, the authors design an algorithm by which the symptomatic renal cyst can be treated step by step (Figure 3). GLRA unroofing is suggested in good-risk patients with recurrent cysts after GR unroofing or aspiration with sclerotherapy. Open surgery is done only when GLRA unroofing of renal cysts has been performed twice, with recurrence. All patients should be regularly followed up (Figure 3).


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Copyright: 1997, Chinese Medical Association (Taipei)