Patient selection and evaluation
From March 2017 to May 2020, 17 patients with parapelvic renal cysts were admitted to Handan First Hospital. This study retrospectively analyzed clinical data from ultrasound-guided flexible ureteroscope in the treatment of parapelvic cyst procedures. The informed consent was obtained throughout the process. All of the patients received Imaging evaluations included plain films of the kidneys, ureters and bladder (KUB), renal ultrasonography and CT scanning and computed tomography urography (CTU) to define the collecting system anatomy.
The standard of inclusion criteria and exclusion criteria was followed：
The inclusion criteria were as follows: (1) patients with a Bosniak classification of CT imaging were grade I and II;(2) presence of parapelvic cyst larger than 3 cm in size; (3) urinary obstruction and hydronephrosis caused by parapelvic cyst compressing the renal calyx or renal pelvis;(4) flank pain, hemorrhage and some other complications caused by parapelvic cyst;(5) secondary renal calculi larger than 5 mm in size.
The exclusion criteria were as follows:(1) patients with a Bosniak classification of CT imaging were grade III and IV;(2) suspicion of severe urinary tract infection;(3) ureteral stricture;(4) history of cardiopulmonary insufficiency
A 6Fr Double-J stent (Laekna, Shanghai, China) was placed two weeks before surgery for the dilation of ureter. Urine test and urinary culture were routinely done, antibiotics treatment was administered to the patients with urinary tract infection findings before surgical treatment. The patient was placed in the lithotomy position and the pre-placed 6Fr Double-J stenting was removed after general anesthesia. Operator cannulated the ureteral orifice with a hydrophilic guidewire (Cook® Medical, Bloomington, IN, USA) into the renal pelvis. Confirming guidewire placement in the renal pelvis by ultrasound, then the rigid ureteroscope (Richard Wolf, Germany) was used to examine the relevant ureter routinely. A ureteral access sheath (Cook® Medical, Bloomington, IN, USA) was inserted into the ureteropelvic junction to facilitate flexible ureteroscopy. The operator surveyed the renal pelvis and calyces sequentially with using flexible ureteroscope (Olympus, Tokyo, Japan) to locate parapelvic cysts wall. In addition, handling the renal stones first if the cyst combined with calculus, the renal stones were fragmented to less than 3 mm with holmium laser (Raykeen, Shanghai, China). The large fragments were removed by a stone basket (Bard, Georgia, USA) to prevent the fragments entering the cystic cavity after the wall was opened.
Generally, the parapelvic cyst appeared transparent with blue areas in ureteroscope vision when we tried to search the cyst wall by direct visualization initially. To avoiding renal pedicle injury, the renal calyces were chosen as the best incision point, and then renal pelvis was the second choice. The holmium laser was used to cut the cyst wall about 2 cm to enable communication with the collecting system.
If the typical blue wall was not found, searching a suspicious wall which protruded into the renal pelvis, the flexible ureteroscope was guided close to the suspicious wall in real time by using ultrasound (SIUI, Guangzhou, China). Before the holmium laser was triggered for drainage, the operator Confirmed that the flexible ureteroscope was pushing against the cyst wall under the ultrasound imaging (Video 1). The incision was performed on an appropriate drainage site and the typical smoking sign was observed in ultrasound (Figure 1). For drainage, the proximal double-J stent was coiled in the cyst cavity which was removed 1-3 months later.
All patients were followed-up 3, 6 and 12 months later in our outpatient department. Ultrasonography or CT examinations were used to detect the recurrence of parapelvic cyst and residual stones, patients with cyst shrinks to half of its original size by imaging examination on 6 months were considered as effective therapy. In addition, clinically insignificant residual stone was defined as less than 4 mm in largest diameter.
SPSS 26.0 software was used to analyse the extracted data. T-test was used for comparing quantitative value and χ2 test was used for qualitative values. p < 0.05 was defined as a statistically significant difference.