A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine. Urinary stones are typically classified by their location in the kidney (nephrolithiasis), ureter (ureterolithiasis), or bladder (cystolithiasis), or by their chemical composition (calcium-containing, struvite, uric acid, or other compounds). About 80% of those with kidney stones are men. Men most commonly experience their first episode between 30 and 40 years of age, while for women the age at first presentation is somewhat later.
Signs and symptoms
The hallmark of stones that obstruct the ureter or renal pelvis is excruciating, intermittent pain that radiates from the flank to the groin or to the genital area and inner thigh. This particular type of pain, known as renal colic, is often described as one of the strongest pain sensations known. Renal colic caused by kidney stones is commonly accompanied by urinary urgency, restlessness, hematuria, sweating, nausea, and vomiting. It typically comes in waves lasting 20 to 60 minutes caused by peristaltic contractions of the ureter as it attempts to expel the stone. The embryological link between the urinary tract, the genital system, and the gastrointestinal tract is the basis of the radiation of pain to the gonads, as well as the nausea and vomiting that are also common in urolithiasis. Postrenal azotemia and hydronephrosis can be observed following the obstruction of urine flow through one or both ureters.
Dietary factors that increase the risk of stone formation include low fluid intake and high dietary intake of animal protein, sodium, refined sugars, fructose and high fructose corn syrup, oxalate, grapefruit juice, apple juice, and cola drinks.
Investigation for kidney stones
Kidney Function Test:
Kidney function tests are a collective term for a variety of individual tests and procedures that can be done to evaluate how well the kidneys are functioning. A doctor who orders kidney function tests and uses the results to assess the functioning of the kidneys is called a nephrologist. Kidney function tests help to determine if the kidneys are performing their tasks adequately.
Urine Routine & Microscopy:
A urinalysis (UA), also known as Routine and Microscopy (R&M), is an array of tests performed on urine, and one of the most common methods of medical diagnosis. When a doctor orders a urinalysis they will request either a routine urinalysis or an R&M urinalysis. The difference being a routine urinalysis is everything but the microscopy or culture, whereas the R&M is Routine and Microscopy urinalysis.
- Urine test strip: A urine test strip can quantify parameters such as:
- Leukocytes: with presence in urine known as leukocyturia
- Nitrite: with presence in urine known as Nitrituria
- Protein: with presence in urine known as Proteinuria also see Albuminuria and Microalbuminuria
- Blood: with presence in urine known as Hematuria
- Specific gravity
A urine sample is about to be examined under a phase-contrast microscope using a Neubauer counting chamber. The urine is under the cover slide, in the upper segment formed by the H-shaped grooves. The numbers and types of cells and/or material such as urinary casts can yield a great detail of information and may suggest a specific diagnosis.
- Hoematuria: associated with kidney stones, infections, tumors and other conditions
- Pyuria: associated with urinary infections
- Eosinophiluria: associated with allergic interstitial nephritis, atheroembolic disease
- Red blood cell casts: associated with glomerulonephritis, vasculitis, malignant hypertension
- White blood cell casts: associated with acute interstitial nephritis, exudative glomerulonephritis, severe pyelonephritis
- (heme) granular casts: associated with acute tubular necrosis
- Crystalluria: associated with acute urate nephropathy
- Calcium oxalatin: associated with ethylene glycol toxicity
Ultrasound Whole Abdomen with Kidney, Ureter & Bladder (KUB):
Abdominal ultrasound is an imaging procedure used to examine the internal organs of the abdomen, including the liver, gallbladder, spleen, pancreas, and kidneys. The blood vessels that lead to some of these organs can also be looked at with ultrasound. An ultrasound machine creates images that allow various organs in the body to be examined. The machine sends out high-frequency sound waves, which reflect off body structures to create a picture. A computer receives these reflected waves and uses them to create a picture. Unlike with x-rays or CT scans, there is no ionizing radiation exposure with this test.
Intravenous Pyelogram (IVP):
An intravenous pyelogram (IVP) is an X-ray test that provides pictures of the kidneys, the bladder, the ureters, and the urethra (urinary tract). An IVP can show the size, shape, and position of the urinary tract, and it can evaluate the collecting system inside the kidneys. IVP is commonly done to identify diseases of the urinary tract, such as kidney stones, tumors, or infection. See a picture of an IVP showing a kidney stone. It is also used to look for problems with the structure of the urinary tract that were present from birth (congenital).
A kidney, ureter, and bladder (KUB) x-ray study is an abdominal x ray. The KUB study is a diagnostic test used to detect kidney stones and to diagnose some gastrointestinal disorders. The KUB is also used as a follow-up procedure after the placement of devices such as ureteral stents and nasogastric or nasointestinal tubes (feeding tubes) to verify proper positioning.
Spiral CT plain and contrast:
CT scanning, sometimes called CAT scanning is a noninvasive medical test that helps physicians diagnose and treat medical conditions. CT scanning combines special x-ray equipment with sophisticated computers to produce multiple images or pictures of the inside of the body. These cross-sectional images of the area being studied can then be examined on a computer monitor, printed or transferred to a CD. It is often the best method for detecting many different cancers, including lung, liver, kidney and pancreatic cancer, since the image allows a physician to confirm the presence of a tumor and measure its size, precise location and the extent of the tumor’s involvement with other nearby tissue.
Treatments for Kidney Stones
Extracorporeal Shock Wave Lithotrispy (ESWL):
Extracorporeal shockwave lithotripsy is the most commonly prescribed treatment for kidney stones. The technique uses shockwaves to break up stones so that they can easily pass through the urinary tract. Most people can resume normal activities within a few days. Complications of extracorporeal shockwave lithotripsy include blood in the urine, bruising, and minor discomfort in the back or abdomen. In extracorporeal shockwave lithotripsy, shockwaves that are created outside the body travel through the skin and body tissues until they hit the denser kidney stones. After the stones have been hit, they will break down into sand-like particles that are easily passed through the urinary tract in the urine.
Percutaneous Nephrostolithotomy (PCNL):
A common surgical treatment of kidney stones is PCNL. It requires having a tube placed into the kidney through the back by a radiologist (a nephrostomy tube). Then at a later time in the operating room we can place instruments through this tube and into the kidney to remove the stones. Often this procedure can be done the same day that the nephrostomy tube is placed. PCNL is most appropriate for very large, complex stones, or in patients who already have a nephrostomy tube in the kidney, or in patients who have special anatomic problems in their urinary tract. PCNL is the most aggressive and has the greatest chance of making you stone-free with one trip to the operating room. It is the treatment of choice for large complex stones in the kidney. In most cases the nephrostomy tube can be converted to an internal urtereral stent (a plastic tube positioned in the kidney, ureter and bladder). This may be done at the time of PCNL or sometime after surgery by a radiologist. Usually after the internal stent is placed the nephrostomy tube can be removed. PCNL usually requires 1-2 days in the hospital.
URS (ureteroscopy) is the most versatile form of stone therapy. Virtually any stone can be reached using URS. Special laser fibers can be deployed through the utereroscope to fragment the stone. Special baskets can be deployed through the ureteroscope to retrieve any stone fragments. URS is usually the technology of choice for stones in the ureter, especially the lower ureter. Large renal stones can be treated with URS, ESWL, and/or PCNL. Some complex stones may require a combination of two or more treatment modalities. Routine URS can be performed as an outpatient surgery.
RIRS (Retrograde Intrarenal Surgery) with Holmium Laser:
Retrograde Intrarenal Surgery (RIRS) allows the surgeon to do surgery inside the kidney without making an incision. The instrument for RIRS enters through the body’s natural opening, through the bladder and the ureter, into the kidney. RIRS is used for patients with stones in the kidney, narrowing of the outlet of the kidney or within the kidney (strictures) and tumors in the kidney. The RIRS is an outpatient procedure using local, intravenous or general anesthesia. RIRS is used for difficult-to-treat cases, such as:
- Failed previous treatment attempts
- Stones too large for ESWL (lithotripsy)
- Stones in children
- Patients with bleeding disorders
- Patients with gross obesity
Since the advent of extracorporeal shockwave lithotripsy (ESWL) and percutaneous nephropyelolithotomy (PCN), pyelolithotomy is becoming an uncommon surgery in most developing countries. However, before these newer technologies, pyelolithotomy was the procedure of choice for stones within the renal pelvis, including stones that demonstrated minimal invasion into calyces and infundibulum. Pyelolithotomy continues to have a role in the management of renal pelvic stones in areas where ESWL and PNL are not feasible because of the lack of equipment or expertise. Pyelolithotomy is also indicated when the patient’s condition does not permit transfer.
Indications for pyelolithotomy include minimally branched staghorn stones in the renal pelvis of complex collecting systems and excessive morbid obesity. Pyelolithotomy is also appropriate in patients who are undergoing major open abdominal or retroperitoneal surgical procedures for other indications; the most common concomitant procedure is open pyeloplasty for ureteropelvic junction (UPJ) obstruction.