When does the text say a urinary stone yields to medicine, and when does it call for surgery?

Detailed answer

Verse 19 likens ashmari to thunderbolt, poison, fire and a snake. Verse 17 calls a stone with terrible pain, bloody urine passed with difficulty and ulcers incurable or hard to cure, and verse 18 says a patient with swollen navel and scrotum, blocked urine and extreme pain is to be given up.