Kidney stones form when minerals in the urine, most often calcium oxalate, crystallize and grow inside the kidney. A stone can sit quietly for years. The trouble starts when it moves into the ureter, the narrow tube that carries urine to the bladder, and blocks the flow. The pain that follows is not from the stone itself. It comes from the kidney swelling behind the blockage, a condition called hydronephrosis, and it is among the most severe pain in medicine.
At NYMD Center we treat stones with a clear preference: when a stone needs to be broken, we reach for shock wave lithotripsy (ESWL) first in most cases. ESWL focuses sound waves from outside the body onto the stone and fractures it into fragments small enough to pass. There is no incision and no instrument in the urinary tract. The alternative, ureteroscopy, passes a scope up the ureter to laser the stone, and it works well. But it almost always requires a ureteral stent afterward, and stents are the part of stone treatment patients remember. They cause urgency, frequency, bladder spasms, blood in the urine and flank pain for as long as they are in, and removing them means a second procedure. Choosing ESWL first, when the stone is suitable, spares most patients all of that.
We perform ESWL in our own accredited office-based surgery center, about 200 cases a year. Serious complications are uncommon, under 1%, the main one being a bruise on the surface of the kidney (subcapsular hematoma) that usually resolves on its own.
Who it affects and the symptoms that bring people in
Stones are common, men somewhat more often than women, most often between the thirties and fifties. Once you have had one, another is likely. Dehydration, a high-salt or high-animal-protein diet, obesity, certain gut conditions and a family history all raise the risk.
The classic presentation is sudden, severe pain in the flank that comes in waves and may travel toward the groin, often with nausea and vomiting. Blood in the urine is common. As the stone nears the bladder, urgency and burning appear. Some stones cause only a dull ache or are found by chance on a scan done for another reason. Fever with stone pain is different: it suggests infection behind a blockage and is an emergency.
How we evaluate it at NYMD Center
The first step is imaging that tells us exactly what we are dealing with. A non-contrast CT scan is the standard; it shows the stone's size, its location from the kidney down to the ureterovesical junction where the ureter enters the bladder, how much swelling is behind it, and its density in Hounsfield units. Density matters: a stone measuring above about 1,000 Hounsfield units is a strong stone that may not break well with shock waves, and that changes the recommendation. In the office we add a renal ultrasound to gauge hydronephrosis, a urine dip with culture, and blood work to check kidney function and look for the metabolic causes of stone formation. If you pass a stone, bring it; analyzing its composition guides prevention.
Treatment options
Passing the stone with medication
Small stones, generally under 5 millimeters, pass on their own most of the time. We manage pain, prescribe an alpha-blocker such as tamsulosin to relax the ureter and speed passage, and set a time limit. If the stone has not passed within a few weeks, or pain or swelling is not controlled, we intervene rather than letting the kidney sit obstructed.
Shock wave lithotripsy (ESWL)
ESWL is our first choice for stones under about 1.5 centimeters located anywhere from the kidney to the ureterovesical junction. In selected cases we treat stones up to around 2 centimeters, with a frank conversation beforehand that a second session may be needed. The procedure is done under sedation in our surgery center, takes under an hour, and you go home the same day. Fragments pass over the following days to weeks; you may see blood in the urine and feel some flank soreness. Very dense stones, stones in patients with bleeding disorders or during pregnancy, and stones that cannot be targeted are the main exclusions. If ESWL does not clear a stone, nothing has been lost: ureteroscopy and every other option remain available.
Ureteroscopy with laser
A thin scope is passed through the urethra and bladder up the ureter, and a laser breaks the stone, which is then removed in a basket. It is highly effective for a single session and is the better choice for very hard stones, some lower-pole stones, and stones that failed ESWL. The cost is the stent. We place one only when it is truly needed, but after ureteroscopy that is usually the case, and it stays for days to a couple of weeks before a second visit to remove it.
Percutaneous nephrolithotomy (PCNL)
For very large or complex stones, a small tract is made through the back directly into the kidney. It is the most invasive option, requires a hospital stay, and we reserve it for stones that the other methods cannot manage.
A word about stents
We do not stent routinely. A stent is genuinely mandatory with a solitary kidney, or with fever or suspected infection behind an obstructing stone. Outside of those, a stent is a trade-off we make only when the procedure demands it.
Prevention
Every stone patient gets a prevention plan. Drinking enough to produce two to two and a half liters of urine a day is the single most effective step. Stone analysis and a 24-hour urine collection guide the rest: salt, animal protein, oxalate and calcium intake, and sometimes a medication that changes urine chemistry.
What to expect at your visit
If you are in pain, call and we will see you the same day at either office. Bring any imaging on a disc or portal login, and any stone you have passed. If ESWL is planned, you will have blood work and a review of your medications; blood thinners are held beforehand. On the day of the procedure you arrive fasting, are sedated by our anesthesiologist, and are on your way home a couple of hours later with a companion. We see you back with an X-ray or ultrasound to confirm the fragments have cleared. More detail on stone treatment is at nylitho.com.
When to seek care urgently
Fever or chills with flank pain, pain that cannot be controlled, persistent vomiting, or inability to urinate all need immediate care. An infected, obstructed kidney can become life-threatening within hours and must be drained; this is one of the few situations where a stent is placed first and the stone is dealt with later.
Questions patients ask
Why do you prefer shock wave lithotripsy over ureteroscopy?
Because ureteroscopy nearly always means a stent afterward, and stents cause real suffering: urgency, spasms, bleeding and flank pain until a second procedure removes them. ESWL breaks the stone from outside the body with no instrument in the urinary tract and no stent for most patients. When the stone is suitable, that trade is worth making.
Which stones can be treated with ESWL?
Stones under about 1.5 centimeters anywhere from the kidney to the junction where the ureter meets the bladder. In selected cases we treat stones up to about 2 centimeters, with the understanding that a second session may be needed. Very dense stones, above roughly 1,000 Hounsfield units on CT, may not fragment well and may be better served by ureteroscopy.
What happens if ESWL does not break my stone?
Nothing is lost. Ureteroscopy with laser, and for large stones percutaneous nephrolithotomy, remain fully available. Some patients choose a second ESWL session first. Because ESWL leaves no stent and no incision, trying it first does not make the later options harder.
Is the pain from the stone itself?
No. Pain comes from the kidney swelling behind a blocked ureter, a condition called hydronephrosis. That is why a large stone sitting still in the kidney can be painless while a tiny one lodged in the ureter is agonizing. It is also why relieving the obstruction, not just breaking the stone, is the goal.
When is a stent truly necessary?
When you have only one kidney, when there is fever or suspected infection behind an obstructing stone, or when the kidney must be protected without delay. Outside those situations we avoid stents whenever the procedure allows, which is a major reason we choose ESWL first.
How do I keep stones from coming back?
Drink enough to produce two to two and a half liters of urine a day. Beyond that, the plan depends on your stone analysis and a 24-hour urine collection: usually less salt and animal protein, appropriate calcium with meals, moderating high-oxalate foods, and sometimes a medication that adjusts urine chemistry. We review this at your follow-up visit.
Make an appointment
Manhattan (212) 991-9991 · Forest Hills (718) 360-9550 · same-week visits, most major insurance accepted.