What are the absolute and relative contraindications of SWL?

Absolute contraindication of SWL :

1- Acute infection

2- Uncorrected coagulopathy

3- Pregnancy

4- Distal obstruction

Relative contraindication of SWL:

1- Cystine stone

2- Calcium oxalate monohydrate stone

3- Obesity (skin to stone >10 cm)

4- Stone size and location

Note: Cystine stone and calcium oxalate monohydrate stones are relatively contraindicated for SWL because they are extremely hard stones that do not fragment easily with shockwave lithotripsy.

Note: Lower pole stone success rate is lower with SWL especially if infundibulum is long (>10 mm), narrow (<5 mm) or the infundibulopelvic angle is <90o.

How do you diagnose cystine stones?

The presence of cystine stone is suggested by radiolucent filling defect, hexagon crystals on urinalysis, and acidic urine pH. However, cystine stone is diagnosed by positive cyanide nitroprusside test and stone analysis.