ESWL for Distal Ureteric Stone: Supine Versus Prone

Extracorporeal shockwave lithotripsy (ESWL) for urinary stone is common and widespread nowadays. Approximately 80% of urinary stones are treated by ESWL. Traditionally distal ureteric stones are treated with ESWL in the prone position. However, as some patients cannot tolerate lying in the prone due to medical illness such as chronic obstructive pulmonary disease (COPD), some authors have reported using the supine approach of ESWL for treatment of distal ureter stones. No serious complications had developed in the patients who underwent supine approach. Only minor complications such as self-limiting blood in the urine, painful passage of urine, or local pain that had responded to oral painkillers. There were no serious complications encountered in children as well. In the most recent retrospective review by Tolley et al, they had revealed that patients who had underwent supine ESWL for distal ureteric stones had an improved stone-free rate compared with the traditional prone approach.

Patient with radio-opaque distal ureteric stones (stones below the sacroiliac joint) on KUB X-ray, who have opted for ESWL treatment, are randomized into two groups: one undergoing ESWL in the supine position and the other undergoing ESWL in the prone position. Patients will be observed for two hours after ESWL before being discharged. Oral painkillers as necessary will be provided to the patient. The patients will have a KUB Xray at 2 weeks post-ESWL, and then monthly afterwards if required. If there are residual stones at the 2-week follow-up, the patient will be offered ESWL again. Patients are free to withdraw from the study at any time and will continue to be managed as per usual.

The investigators aim to have 130 patients, with 65 patients in each group with an interim analyses to be performed when 66 patients have been recruited (33 patients in each group).

Previous authors have reported using the greater and lesser sciatic foramina as a pathway for the shockwaves to reach the distal ureter. No serious complications had developed in the patients who underwent transgluteal approach. Only minor complications such as self-limiting hematuria, dysuria, or pain that had responded to oral analgesics. There were no serious complications encountered in children as well. In the most recent retrospective review by Tolley et al, they had revealed that patients who had underwent transgluteal ESWL for distal ureteric stones had an improved stone-free rate of 78% in the transgluteal group versus 40% in the prone group after one session of shockwave lithotripsy and a stone-free rate of 92% versus 63% respectively after two sessions of shockwave lithotripsy. This has been speculated to be due to the presence of bowel gas attenuating the shockwaves as well as a long skin-to-stone distance in the prone position.

Eligibility Criteria:
Inclusion Criteria:

* All patients, over 18 years of age, with distal ureteric stones with stone size of ≥3mm on kidney-ureter-bladder (KUB) X-ray who opted for ESWL treatment

Exclusion Criteria:

* Patients who are unable to provide consent
* radiolucent stones
* active urinary tract infections
* pregnancy
* uncontrolled hypertension
* uncontrolled bleeding tendencies
* severe skeletal malformations
* arterial aneurysms within the vicinity of the stone (such as iliac artery aneurysms)
* unable to assume the appropriate position (prone or supine) for ESWL
* solitary kidneys
* transplanted kidneys
* presence of ureteric stents