Currently, comparisons of the effects between AS and LD in the treatment of renal cysts were lacking, therefore, we first conducted a meta-analysis on this subject. Statistics in Table 1 show that renal pain would be the primary presenting symptom among patients with renal cysts, renal lump, hypertension and hematuria frequently happen to renal cyst patients as well. Besides, Kim et al. investigated 3,249 patients with renal cysts and they also improved that the occurrence of renal cysts was significantly positively related to that of hypertension, which has the following characteristics: bilateral distribution, number of cyst no less than two and diameter of cyst larger than 1 cm. Although renal cyst is a benign disease in most cases, complicated variations of that still has the connection of renal cell carcinoma, which may urge patients with renal cysts to be more cautious about the importance of regular follow-up.
At present, treatments such as AS and LD are available to renal cyst patients. Relating to AS, it is time-saving, economical, well tolerance and simple technique so that can be performed under local anesthesia and even in the outpatient rooms in most cases. Our meta-analysis also illustrated that treatment time of AS is significantly shorter than LD. As we all know, AS can be conducted under local anesthesia while LD should be operated with general anesthesia. Thus, LD needs more time for therapy. The high heterogeneity of treatment may be caused by different ways of records about these data. Some of included studies collected the entire time of hospital stay, nevertheless, the rest of studies only recorded the operation time.
Studies reported by Ali et al. and Monville et al. evaluated the efficiency of ultrasound-guided percutaneous sclerotherapy among patients with renal cysts, their results showed that the radiological successful rate is up to 98% and 91.6% respectively meanwhile the complication and recurrence leveled off to zero. However, the rates of radiological success reported by Efesoy et al. and Bas et al. are 63.2% and 60% separately, which are presented in Table 2. Ethanol contacting the cyst wall causes protein degeneration, cell death as well as inflammatory fibrosis so that patients should keep 5 to 10 minutes at least in each position according to the cyst size and volume. Therefore, the difference among them may be ascribable to the different treatment procedure, which also was hard to make a standard therapy.
In addition to this, although study reported by Zhong et al. shows no recurrence was observed after AS treatment, in the outcome of our meta-analysis, it is remarkably higher in AS group than LD group in the matter of recurrence. The reason why simple fluid aspiration was ineffective and even promoted the recurrence of cyst is that the renal cyst epithelium was not destroyed by sclerosing agents completely and adhered to each other, thus the remained cyst wall can still secrete fluid.
In terms of LD therapy, it has the advantage in high rate of cure and low rate of recurrence and could be thought as a complete treatment of renal cysts. Nasseh et al. collected the data of renal cyst patients treated with LD in their center and 91.3% patients reached symptomatic and radiological success while only one patient got recurrence, which was consistent with our meta-analysis results. As LD operation preferred to excising the complete cyst including all cyst walls, so the leaved tissues were out of secreting function, which lead high cure rate an low recurrence rate. Hence, LD could be the standard in the management of renal cysts, especially suited for patients failed after aspiration-sclerotherapy.
To enhance the efficiency of LD treatment, Lai and colleagues studied the impacts of perirenal pedicled fat tissue wadding technique (PPFTWT) on the recurrence rate during this surgery operation, they found that LD using PPFTWT can decrease the rate of cyst recurrence. Inserting fat tissue into the cavity of the cyst and fixing it prevented the cyst wall from adhering to the residuary cyst wall or surrounding tissue, and contributed to the secretion drainage and absorption of the remaining cyst wall, thus declined the risk of cyst recurrence. Therefore, laparoscopic de-roofing with PPFTWT may be a better choice in the treatment of renal cysts.
When it comes to complications, our statistics showed there was no significant difference between AS group and LD group, both of which can cause post-treated complications such as fever, infectious, pain, hemorrhage. On account of ethanol as the common sclerosing agents in AS treatment, patients may get alcohol intoxication and lose consciousness even injury femoral nerve due to the rupture of cysts. As for LD therapy, vessels damage and subcutaneous emphysema may happen to patients during the process of cyst ablation and establishing pneumoperitoneum.
The limited included studies in our meta-analysis and the heterogeneity of some date are two main limitations of this study. Due to the lack of researches on the comperation between AS and LD, we included six articles merely and the patients selection bias or difference of provider training/experience could be limitations. Therefore, further studies are expected to confirm our outcomes. As for the heterogeneity, in the study of Bas et al., the difference of treatment techniques may contribute to the heterogeneity in symptomatic successful rate. Besides, in terms of complication rate, the researches of Agarwal et al. and Shao et al. only recorded some severe complications such as port infections so that they might omit some information about comlications after aspiration treatment, which also leaded to the heterogeneity.