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Original Research |
1 Department of Radiology, Kaohsiung Veterans General Hospital, 386 Ta-Chung
First Rd., Kaohsiung, Taiwan 813, ROC.
2 National Yang-Ming University, Taipei, Taiwan.
3 Department of Internal Medicine, Kaohsiung Veterans General Hospital,
Kaohsiung, Taiwan.
Received August 2, 2004;
accepted after revision November 12, 2004.
Supported by a grant from Kaohsiung Veterans General Hospital
(VGHKS90-60).
Abstract
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MATERIALS AND METHODS. We retrospectively reviewed 36 renal cysts in 33 patients treated by ethanol sclerotherapy with a single-session single-injection technique during the past 6 years. After complete aspiration of the cystic fluid, 95% ethanol was injected into the cyst and was retained for 4 hr in 14 cysts (group 1) and for 2 hr in 22 cysts (group 2). The average maximal diameter and aspirated volume of the cysts were 8.3 cm and 223 mL in group 1 patients and 7.9 cm and 167 mL in group 2, respectively. The ablated cysts were followed up regularly by sonography, CT, or both at 3- to 6-month intervals for at least 1 year. The nonparametric Mann-Whitney U test was used to compare differences in characteristics, treatment results, and laboratory data of the subjects in the two groups. The level of statistical significance was set at a p value of less than 0.05.
RESULTS. Technically, all the patients tolerated the procedures. One patient had gross hematuria 10 days after the procedure. She underwent surgical deroofing treatment and was excluded in the later statistical analysis. After sclerotherapy, 14 cysts disappeared completely and 16 cysts showed marked regression with residual maximal diameter of less than 3 cm. The overall volume reduction rate was 97.6% in all 35 cysts. The mean residual longest diameters and average volume reduction rates of the treated cysts were 1.9 cm and 97.9% in group 1 patients and 1.1 cm and 97.3% in group 2 patients, respectively, which showed no statistical significance of volume reduction rate with a p value 0.149.
CONCLUSION. The single-session prolonged ethanol-retention technique is safe and efficacious for the treatment of renal cysts. There is no statistical difference in therapeutic efficacy between 2- and 4-hr ethanol-retention techniques.
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Recently, several studies compared the therapeutic effects of a single session with that of multiple sessions of ethanol injection, with encouraging results for the latter [1, 6–8]. The investigators performed two or three sessions with a 12- to 48-hr interval between each session. Gasparini et al. [9] injected a small volume of ethanol and repeated the procedure twice a day for 5 days [9]. They retained the ethanol in the cyst for 90 min. Other authors performed single-session multiple-injection sclerotherapy [10] or single-session sclerotherapy followed by 24–48 hr of tube drainage [11]. Although those researchers reported favorable therapeutic outcomes by varying the sclerosing technique, the optimal technique of treating renal cysts with reasonable cost-effectiveness has not yet been established. On the basis of statements of Bean [3]—that ethanol was rapidly coagulating the cell lining of the cyst (1–3 min) but was slowly penetrating the fibrous capsule (4–12 hr)—we developed a novel technique of single-session prolonged alcohol-retention sclerotherapy for renal cysts and compared the efficacy of 2- and 4-hr retention techniques.
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The largest diameter of the renal cysts on the initial images obtained
before the procedures was 4.2–12.0 cm (mean, 8.1 cm). Of the eight
patients with hydronephrosis, seven patients had a peripelvic cyst (range in
diameter, 4.2–8 cm; average diameter, 5.6 cm), whereas the eighth
patient had a cortical cyst that was 9 cm in diameter. We calculated the
volume (V) of a cyst using the following equation:
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Technique
With the patient in the prone position, the selected puncture site was
infiltrated with 2% lidocaine. Using sonographic and fluoroscopic guidance,
the operator punctured the cyst with an 18-gauge needle and placed a
0.035-inch guidewire (hydrophylic guidewire, Terumo) in the cyst. The needle
was then removed, and an 8-French pigtail drainage catheter (Angiomed, Bard)
was inserted into the cyst after dilation of the percutaneous route with an
8-French dilator. Cystic fluid was aspirated as completely as possible through
the catheter. The volume of the fluid aspirated was recorded, and some fluid
was collected for bacteriologic, cytologic, and biochemical tests.
The presence of extravasation or of a connection with the renal collecting system was evaluated under fluoroscopy by injecting diluted contrast medium in a volume equal to that of the estimated injected volume. For peripelvic cysts, caution should be taken not to puncture directly into the renal sinus to prevent penetration through a large vessel or an artificial connection of the cyst with the collecting system. This can be accomplished safely by puncturing through peripheral renal parenchyma into the periphery of the peripelvic cyst under sonographic guidance. Usually, we inject more contrast medium into the collapsed peripelvic cysts after aspiration to high-light small contrast extravasation and exclude any communication with the urinary tract.
After aspiration of the testing contrast medium in the cyst, 95% ethanol in a quantity of 30–50% of the aspirated volume, based on patient tolerance, was injected into the cyst. The injection was discontinued if the patient complained of intolerable pain during ethanol instillation. The maximal amount of ethanol injected was limited to 150 mL for a large cyst. The patient was rolled into supine, prone, and lateral decubitus positions at 10- to 15-min intervals during the procedure to increase contact between all surfaces of the cyst and ethanol. The patient's vital signs were monitored every 10–15 min at our observation room during the procedure. Afterward, residual fluid in the cyst was aspirated and the pigtail catheter was removed immediately. Ethanol was retained in the cyst for 4 hr for 14 cysts in 12 patients (group 1) from June 1997 to July 2000 and 2 hr for 22 cysts in 21 patients (group 2) from September 2000 to April 2003. The basic characteristics of the patients in groups 1 and 2 are summarized in Table 1. Blood ethanol concentration also was measured at 1, 2, 3, 4, and 5 hr after ethanol injection for the first four patients in group 1; however, because the blood ethanol concentration levels were low, we discontinued these measurements for subsequent patients.
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No sedatives or prophylactic antibiotics were used in this study. All the procedures were performed on an in-patient basis. Patients had stayed in the hospital for overnight observation. Analgesics or antiemetics were prescribed for patients after the procedure, if necessary, for 1–3 days. Informed consent was obtained from each patient and his or her family. This study had been approved by the ethics committee of our hospital.
After sclerotherapy, the residual sizes of the ablated cysts were followed
by sonographic images, CT images, or both at 3- to 6-month intervals for at
least 1 year. Biochemical renal function tests (i.e., blood urea nitrogen and
creatinine) were also checked both before and after (3–6 months) the
procedure. The volume reduction (VR) rate was calculated as follows:
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Statistical Analysis
Commercially available statistical software (SPSS version 10.0, Statistical
Package for the Social Sciences) was used for analyzing patient data. Data are
presented as mean ± SD. The laboratory data before ethanol injection
were compared with the laboratory data after sclerotherapy. The nonparametric
Mann-Whitney U test was used to compare differences in
characteristics, treatment results, and laboratory data of the subjects for
the two groups (4- and 2-hr ethanol-retention groups). The level of
statistical significance was set at a p value of less than 0.05.
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Cytology results revealed unremarkable findings in all patients. Most patients complained of mild to moderate tenderness, nausea, causalgia, or transient drunkenness. These symptoms subsided gradually by 1–2 hr after ethanol injection.
One patient in group 2 who had an 11-cm-diameter cyst in the left kidney developed gross hematuria 10 days after the procedure. A sonography study revealed residual cyst with a diameter of 7 cm and showed internal echogenicity of the ablated cyst (Fig. 1A). IV pyelography revealed normal excretory function but with a mass effect compressing the renal calyx of the left kidney (Fig. 1B). Retrograde pyelography showed contrast opacification of the ablated cyst (Fig. 1C). The patient then underwent deroofing surgery, and a small communication hole between the ablated cyst and a renal calyx was noted, which was then sutured. This patient was excluded in the later statistical analysis of group 2 patients.
Three of 14 cysts in group 1 and 11 of 21 cysts in group 2 after treatment had disappeared completely (Figs. 2A, 2B, 2C, 3A, 3B, 3C, and 3D), and eight cysts in each group had residual maximal diameter of less than 3 cm. The overall volume reduction rate was 97.6% in all 35 cysts. The other five cysts with residual diameter of more than 3 cm (3.2–4.9 cm) had achieved volume reduction of 97.5%, 96.7%, 96.1%, 86.2%, and 63.7%. The mean residual maximal diameters and average volume reduction rates of the treated cysts were 1.9 cm (range, 0–4.9 cm) and 97.9% ± 3.6% (SD) (range, 86.2–100%) in group 1 patients and 1.1 cm (range, 0–4.3 cm) and 97.3% ± 7.9% (range, 63.7–100%) in group 2 patients. The p value of the volume reduction rate between group 1 and group 2 patients was 0.149, which is of no statistical significance.
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All patients had a follow-up period of at least 12 months except two patients who died of unrelated causes 8 and 10 months after the procedure. The average follow-up time was 28.1 months (range, 6–67 months) in group 1 and 23.5 months (range, 8–39 months) in group 2.
The highest blood ethanol concentration measured in the first four patients
was 42 mg/dL. The data of blood ethanol concentrations at 1, 2, 3, 4, and 5 hr
are listed in Table 2. Before
treatment, four patients (one patient in group 1 and three patients in group
2) had an abnormal creatinine level that ranged from 1.3 to 2.1 mg/dL (normal,
1.2 mg/dL). None of the patients showed abnormal or worsening renal
function at 3–6 months after sclerotherapy.
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Hanna and Dahniya [1] reported the recurrence rate (regrowth to the original size) to be 80% in cysts treated with aspiration only and 32% in cysts after a single ethanol injection. Okeke et al. [5] described failure of single-session ethanol sclerotherapy for the treatment of renal cysts in all of their six selected patients in whom symptoms recurred. Thereafter, those researchers abandoned sclerotherapy for the treatment of symptomatic renal cysts and used laparoscopic deroofing surgery, for which a 90% success rate has been reported [15]. The recurrence of renal cysts after sclerotherapy is attributed to incomplete ablation of the cyst wall [3], and it is likely that the longer time of contact between ethanol and the renal cyst epithelium may cause higher success rates [7].
In two comparison studies of single- and multiple-session ethanol injections, Hanna and Dahniya [1] found no recurrence (regrowth to the original size) of cysts in the patient group (13 patients) treated with two injections over a 48-hr interval. They attributed the improved results to longer ethanol retention, which results in damage and nonviability for more epithelial cells lining the cyst. Chung et al. [7] reported an overall success rate of 57% in patients who underwent single-session sclerotherapy and of 95% in those who received two or three injections with a 12-hr interval for each session. Delakas et al. [8] also performed two repeated ethanol injections with a 24-hr interval and reported complete regression of the renal cysts in 83.8% and partial regression in 11.8%. They defined partial regression as greater than 50% reduction in diameter. However, the therapeutic success of partial regression (> 50% diameter reduction) may be disputed by urologists in renal cysts with an initial diameter of 12 cm being reduced to 6 cm in diameter after sclerotherapy (volume reduction, 87%). Recently, Gasparini et al. [9] reported that only three cysts with residual diameter of less than 2 cm persisted after 12 months of follow-up in 17 cysts. Using their technique, they retained the ethanol for 90 min in each session and repeated the sclerosing procedure eight times within 5 days.
The investigations described confirm that sclerotherapy with a longer time of ethanol retention does achieve a satisfactory therapeutic effect. A shorter retention time may preclude full contact of the ethanol with the epithelial cells of the cyst due to infolding of the cyst wall and formation of temporary loculations. Because the ethanol is being diluted by residual cystic fluid, especially during the first injection, most investigators consider multiple-session injection mandatory for the prolonged ethanol-retention technique. Several disadvantages of using a multiple-session technique exist: It is time-consuming to perform repeated aspiration and injection procedures with 12- to 48-hr interval for each session, adds to patient discomfort and inconvenience, and the risk of ethanol leakage is also of concern during the second or later injections if they are not performed under fluoroscopy [5].
Our series showed that there is no statistical difference between the 4- and 2-hr ethanol-retention techniques for sclerotherapy of renal cysts. The volume reduction rates and residual maximal cyst diameter in both techniques were 97.9% versus 97.3% and 1.9 versus 1.1 cm, respectively. The reasons may be attributed to, first, nearly all the epithelial cells on the cyst had been destroyed after 2 hr of ethanol retention or, second, the concentration of ethanol in the cyst after 2-hr retention had been diluted to below the level of the coagulating effect for cyst epithelium (or both). Although no data on the ethanol concentration versus retention time in renal cysts are available to our knowledge, from our present study, at most 2-hr retention in a single session is adequate to achieve a satisfactory chemical ablation of renal cysts.
Dominicis et al. [11] performed a single-session technique with ethanol retention for 45–60 min followed by continuous tube drainage for 24–48 hr. They reported cysts in 29 (76%) of 38 patients had complete regression or the diameter of the residual cyst was less than 3 cm, cysts in eight patients developed a small liquid layer of 3–4 cm, and the cyst recurred in one patient. In our series, 30 (86%) of 35 cysts showed complete regression or the diameter of the residual cyst was less than 3 cm in diameter and only five cysts had residual cyst diameter of 3–5 cm. It seemed that the therapeutic efficacy of longer retention time (2 hr) was at least comparable or superior to that of 60-min retention followed by tube drainage in the series reported by Dominicis et al.
The ethanol blood concentrations measured in our first four patients in group 1 were low. This may be attributed to, first, ethanol penetrates slowly (4–12 hr) through the fibrous capsule of the renal cyst [3], so it is removed before being absorbed into the systemic circulation; or, second, part of the ethanol is directly excreted into the collecting system rather than into the systemic circulation (or both). Paananen et al. [10] reported that the ethanol concentration in urine (< 0.27 g/L) was not greater than that in systemic blood (< 0.3 g/L) after repeated ethanol injection in their series. Although we did not measure the ethanol concentrations in patients' urine, we expect that the urine ethanol concentrations in our series were also low. None of our patients showed abnormal or worsening renal function during 3–6 months of follow-up after sclerotherapy.
One of our patients in group 2 had gross hematuria 10 days after sclerotherapy due to a communication hole between the ablated cyst and the renal calyx. Because this complication had not been reported in the literature to our knowledge and there was no evidence of any communication between the cyst and collecting system during the contrast pretesting procedure or evidence of structural damage of the collecting system or functional impairment of renal excretion on the later imaging study (IV pyelography and retrograde pyelography), we postulate that the communication hole may have been caused by extension of the necrotic cystic wall to caliceal mucosa or associated with a minor trauma injury of the patient.
Peripelvic renal cysts have been excluded for sclerosing therapy by some investigators [8, 15] because of a prior report of extravasation of the sclerosing substance into the peripelvic tissue with resulting fibrosis of the ureteropelvic junction [16]. In our series, seven patients with peripelvic renal cysts underwent ethanol sclerotherapy with no procedure-related complications encountered. All but one patient with peripelvic cysts had achieved a satisfactory therapeutic result. Thereafter, we considered peripelvic renal cyst not a contraindication for ethanol sclerotherapy if meticulous needle puncture and ethanol instillation were performed under sonographic and fluoroscopic guidance.
In conclusion, our technique of single-session prolonged ethanol retention for the treatment of renal cysts is efficacious, is easy to perform, offers low morbidity, and has a relatively low cost. There is no statistical difference in the therapeutic results between the 2- and 4-hr retention techniques, both of which had a comparable efficacy as compared with those of multiple-session sclerotherapies and laparoscopic deroofing surgery.
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