Abstract

Background and objectives. Urolithiasis is one of the most common diseases of the urogenital tract. Stones can be asymptomatic, present as renal colic,and predispose to urinary tract infections or chronic kidney disease. ESWL (extracorporeal shock wave lithotripsy) is a minimally invasive option of outpatient treatment for small kidney and ureteric kidney stones. Major complications are uncommon, several sessions per stone can be done. The aim of the study was to assess the efficiacy of ESWL at Tartu University Hospital, its confounding factors, the rate of auxillary surgeries and major complications.

Study design. A retrospective study included a period between January 2013 and April 2018. Data from 785 ESWL sessions and periprocedural radiologic images from Tartu University Clinic inpatient department was collected. Stone density was measured in Hounsfield Units (HU). The efficiency of the procedure was determined as stone disintegration rate. A stone was disintegrated, if residual fragments were ≤ 4 mm or there were no residual fragments at all.

Results. Of all stones 57% (95% CI 53,3%- 61,2%) disintegrated during the first ESWL session, total ESWL efficiacy was 71% (95% CI 67,4%-74,6%). The majority of the stones (71.3%) were smaller than 10 mm. Of all stones 84% were located in a kidney, 16% in a ureter. The efficiency of ESWL depended on stone density, size and location. ESWL was effective for 85% of stones with a density of ≤ 800 HU, for 55% of stones with a density of 801-1199 HU and for 24% of stones with a density of ≥ 1200 HU (p<0,0001). Of all < 10 mm stones 79.3%, of all 10-20 mm stones 53.6% and of all > 20 mm stones 30% disintegrated with ESWL (p<0,0001). Of all ureteric stones 81.8% and of all kidney stones 69% disintegrated with ESWL (p=0,014). Of all non-disintegrated stones 65% were treated surgically, the remaining stones were followed up during the study period. Perirenal hematoma was found in 0.76% of all cases. Inter-rater reliability between visual stone disintegration at the end of an ESWL session and radiologically confirmed disintegration was 55.7%.

Conclusions. ESWL is an effective and safe treatment option in the managment of kidney and ureteric stones. The efficiacy  of ESWL depends on density, size and location of a stone. The majority of stones with smaller density and diameter disintegrate during first ESWL session. Stones with great density and diameter may need several ESWL sessions. Most of the stones, which do not disintegrate during ESWL are treated surgically. Severe complications are uncommon.