Supine Position Yields Better ESWL Results

Extracorporeal shockwave lithotripsy (ESWL) is more effective for treating distal ureteral stones if patients are placed in a supine rather a prone position, according to a new review and meta-analysis.

Tao Li, MD, and colleagues from West China Hospital, Sichauan University, in Chengdu, China, pooled data from 4 randomized and case-control trials of 647 patients. (Patients with multiple stones were excluded.)  

According to results published online ahead of print by Urologia Internationalis, supine ESWL was associated with more than 4 times the stone-free rate of prone ESWL at the first treatment session and triple the rate at the final session. The researchers found no significant differences between the supine and prone procedures in the average number of shocks per ESWL session, percentage of power used in the first session, or the average number of sessions per patient.

“In the supine position, the lithotripter treatment head is in contact with the patient's posterior abdomen and shockwaves entering the body traverse homogenous muscle tissues, reaching the stone with attenuation of only 20% of its power; however, in the prone position, shockwaves entering the body would be significantly decreased because they traverse the air-filled bowel,” the researchers explained. The distance between the skin and stone is also greater in the prone position. 

No major complications were reported. Most patients experienced transient hematuria and skin reddening; colic developed in 6 patients, and urinary tract infection with fever developed in 3 patients. 

The researchers acknowledged that certain factors may have affected the comparison, such as the size and location of ureteral calculi, ureteral tube diameter, and surgeon experience.

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