OBJECTIVE: The management of lower pole stones remains to be controversial because of the limited success of extracorporeal shockwave lithotripsy (ESWL) in terms of stone clearance. Various interventions have been attempted to improve lower pole stone clearance after ESWL; however, none of these methods have gained widespread acceptance. This study evaluates the degree of clearance of lower pole stones among Filipino patients who underwent inversion maneuver during ESWL.
MATERIALS AND METHODS: This study used a prospective cohort design which included patients who underwent ESWL with documented lower pole stones noted on ultrasound or x-ray from January 2005 and July 2005 in a stone treatment center. Those with history of urologic surgery or metabolic disease such as hyperparathyroidism were excluded from the study. There were two comparison groups. One group underwent the inversion maneuver during ESWL while the other group did not. The inversion maneuver was undertaken by positioning the patient supine and in a 30 degree angle during ESWL session. Patients were then followed up for 3 months to check for residual stones. Data analysis included computation of frequency and chi-square statistics.
RESULTS: A total of 145 subjects were included in the study. Subjects had a mean age of 40 years. A total of 57 (39.3 percent) patients underwent the inversion maneuver. Twenty-five of these (43.9 percent) had opaque stones while 32 (56.1 percent) had lucent stones. On the other hand, there were 88 (60.7 percent) subjects who did not undergo the maneuver; 33 of which (37.5 percent) had opaque stones while 55 (62.5 percent) had lucent stones. Among the 57 patients who underwent the maneuver, 47 (82.4 percent) were stone free at the end of three months while only 28 of the 88 patients (31.8 percent) who did not undergo the maneuver (31.8 percent) were stone free at the end of the observation period. This pattern was observed for both opaque and lucent stones.
CONCLUSION: This study showed a possible relationship between the use of the inversion maneuver during ESWL among patients with lower pole stones and clearance of stones after 3 months. (Author)