romancing the stone

ROMANCING THE STONE

THIRTY YEARS OF PROGRESS IN THE DIAGNOSIS, PREVENTION AND

MANAGEMENT OF URINARY CALCULI

WHY STONES?

• Lifetime prevalence 13%• Stone belt phenomenon• Global warming• American diet• Sedentary lifestyles

DIAGNOSIS

• Symptoms – flank pain• Physical exam• Urinalysis • Radiographic

RADIOLOGY - 1982

• KUB• IVP

PROBLEMS WITH IVP

• Some stones are radiolucent• Contrast allergy• Contrast nephropathy• Radiation exposure

RADIOLOGY - 2012

• Rarely contrast studies (CT, IVP) • Non-contrast CT scanning

ADVANTAGES

• No contrast• Fast• Only indinavir stones and some matrix stones

are “radiolucent” for the CT• ? Other pathology found

DISADVANTAGES

• Radiation exposure• Expense

MEDICAL MANAGEMENT - 1982

• Taught no need to investigate first stone• Water• Thiazides

WHAT HAVE WE LEARNED?

• If you have first stone, you are going to have another

• Medical management works• Oxalate restriction• Importance of uric acid in calcium stone

formation (protein restriction)• Importance of citrate as inhibitor• Importance of limiting salt intake

INTERVENTION - 1982

• If stone is < 5 mm, let it pass• Still good advice but can be morbid and

patient may be unproductive during that time (shouldn’t drive if taking pain meds)

• Can we predict better who will pass their stone?

PREDICTION OF SPONTANEOUS URETERAL CALCULUS PASSAGE WITH AN ARTIFICIAL NEURAL NETWORK

James M. CummingsSeth D. IzenbergDavid Kitchens

Rupa KothandapaniUniversity of South Alabama

Mobile, Alabama

AUA 1999, JUrol 2000

Results

• 125 patients used to train neural network• 55 patients in test set (25 with spontaneous

passage, 30 required intervention)• Network prediction was correct in 42

patients (76%)• Network prediction was 100% correct in the

subgroup passing their stones

Influences on network predictions

Symptom duration*Hydronephrosis grade

PositionNausea/vomitingObstruction grade

*Most influential in neural network by far

INTERVENTION - 1982

• Blind stone basketing• Open surgery

INTERVENTION - 2012

• Ureteroscopy (URS)• Percutaneous nephrostolithotomy (PCNL)• Extracorporeal shock wave lithotripsy (ESWL)

Ureteroscopy

• Performed transurethrally• Good for ureteral stones• Stone free rate 95% for distal ureteral stones• Flexible and rigid scopes• Variety of baskets, small lithotriptors and

lasers

PCNL

• Scope passed into kidney through small incision in flank

• Stone visualized and broken up and extracted• Used mainly for very large staghorn type

stones

EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY

(ESWL)

ESWL

• Discovered as a result of research into stress on airplane wings passing through air

• Thousands of shock waves passed through body to strike stone

• Stone breaks into small pieces and pass• Best used with renal and upper ureteral

stones < 2.5 cm in size

Complications / Morbidity

• Hematuria (gross or microscopic): 100%• Pain: 60-70%• Renal colic in 5-10%• Hematoma / perirenal hemorrhage

(clinically significant): <1%• Sepsis <1%• Steinstrasse

Complications / Morbidity

• Renal trauma (hemorrhage, endothelial cell damage, glomerular atrophy & sclerosis, & interstitial fibrosis)– 22% decrease in GFR after ESWL in solitary kidneys;

29% decrease after PCNL• Hypertension (inconclusive)• Bowel perforation: 3 reports.

Efficacy

Opell & Pahira. Contemp Urol; 12-27, October 2000

Efficacy

• Stone-free rate using HM-3 for stones < 2 cm is 91.3% at 3 months

• Only 50-70% stone-free rate with 2-3 cm stones

• In general, stone-free rate is inversely related to stone size

CONCLUSIONS – IN 30 YEARS

• Diagnosis has moved from contrast studies to noncontrast CT

• Prevention is used over a broader range of sufferers

• Intervention is minimally invasive with scopes and shockwaves – no longer open surgery or blind efforts