<s>[INST] I am 48 years old and have had kidney stones since I was 19.  I just recently had lithrotripsy to take care of a 14 mm stone.  Sometimes I can feel them pass, sometimes I cannot.  Does this mean my ureters are damaged or scarred?  Also, how many CT scans are too many.  I seem to average about 4 a year.  Also, I have already had a parathyroidectomy and watch my diet.  Any ideas? [/INST] Hello and welcome to Chat Doctor. As a Urologist, let me advise you, that as a stone former, you need CT- scan (plain), once a year. ESL is ideal for kidney stones up to 2.5 CMS size. Stones above 1 cm size or causing pain need treatment. The fragments do no harm to ureter.  If stent is placed, (optional only), it can injure the ureter.  Chat Doctor. You should be more careful after para-thyroidectomy, as small stones need no treatment.  You must have done blood calcium, phosphorus, and uric acid.You're welcome to send a copy of your reports, with last CT, here, in my name, for an expert opinion.  Get well soon. </s>