Ureterolithiasis occurs when kidney stones form in the ureters. As the stones obstruct the ureter(s), the patient experiences acute renal colic.
The clinical picture, including the location and quality of pain, is associated with the site of the stone. The degree of obstruction along with ureteral spasms and possibility of infection all contribute to the level of pain experienced by the patient.
When a stone is positioned in the upper urinary tract, the pain radiates to the flank and lumbar region. Right sided cases resemble cholecystitis or cholelithiasis while left-sided events mimic acute pancreatitis.
In cases with a stone in the midureteral region, the pain radiates anteriorly and inferiorly. Right sided pain can be confused with appendicitis and left sided episodes manifest similarly to acute diverticulitis.
If a stone is located at the ureterovesical junction, the patients are likely to experience urinary frequency and dysuria.
With regards to the pain, there are three stages in acute renal colic:
The onset of pain occurs in the morning or at night, often waking the patient. The intensity of the pain may peak as rapid as 30 minutes in some patients while it may take hours for others.
Upon achieving the maximum intensity, the pain persists until medical therapy is initiated or spontaneous abatement occurs.
As the name of this stage suggests, the patient becomes comfortable. This may follow the acute phase at any time.
The main finding on the exam is the profound costovertebral angle (CVA) tenderness. Also, the location of the pain can reflect the migration of the stone.
Abdominal exam is not remarkable as there are no peritoneal signs.
Evaluation of the patient involves a thorough history including the dietary and medicine intake. A physical exam is pertinent to exclude other differentials that may warrant immediate surgery such as acute appendicitis. The workup further includes laboratory studies and imaging.
Urine samples should be obtained to identify any gross or microscopic hematuria, which is observed in almost 85% of patients with stones.
A complete blood count (CBC) is very useful especially in patients with fever or other signs of infection. Other serum measurements include parathyroid hormone (PTH), electrolytes, creatinine, calcium, uric acid, and phosphorous. The results of these tests provide information about the kidney function. The findings can also offer insight on any metabolic abnormalities that predispose these patients to kidney stones.
The European Association of Urology proposes guidelines for evaluation of acute renal colic which are 1) a urine dipstick which can reveal the presence of blood and nitrites (if the latter is positive, a urine culture is warranted) and 2) a plasma creatinine level .
Computed tomography (CT) without contrast of the abdomen and pelvis is the preferred imaging since it is associated with a sensitivity of 95% to 100% and is more specific than an intravenous pyelogram .
Retrograde pyelography provides the most precise assessment and the definitive diagnosis of urinary tract stones.
Ultrasonography of the urinary tract is the chief imaging study in pregnancy .
Evaluation of follow-up patients can be done by both CT imaging and the kidneys-ureters-bladder (KUB) radiograph.
Pain control is pertinent since this disease is one of the most painful ailments experienced by humans . Adequate pain management is typically achieved with narcotics and nonsteroidal anti-inflammatory drugs (NSAIDs) . The route of administration depends on whether the patient is tolerating oral intake.
Once the diagnosis is confirmed, the clinician should assess for possible obstruction and infection. In a case with only obstruction, analgesics and therapies that encourage the migration and excretion of the stone may be initiated. In cases with infection, antibiotics are indicated. Consultation with urology will guide the management more accurately.
If there is no obstruction or infection, pain medications and other medical therapies can be used to guide the small stones (less than 5 to 6mm) to pass. However, stones with larger diameters may require surgical intervention.
Another drug that may significantly improve the pain is desmopressin (DDAVP), which has a rapid onset. DDAVP is not associated with side effects. Another benefit of DDAVP is that it may control the pain without the need for other medications.
The size of the stone determines whether the stone requires surgery or not. For example, if the diameter of the stone is 4mm or below, it is more likely to just pass. Stones greater than 8 mm will typically be removed through a surgical procedure.
Other important factors determining the need for surgery are pain and the presence of infection and obstruction. In fact, patients with both infection and obstruction are at increased risk for urosepsis and even mortality. Therefore, these cases require urgent surgical intervention with ureteral stent placement or percutaneous nephrostomy.
Percutaneous nephrostomy is a safer and more rapid method in septic or unstable patients. This technique drains the affected kidney.
For stones under 2 cm that impact the upper or middle calyx, the calculi can be removed through the minimally invasive procedure known as extracorporeal shockwave lithotripsy (SWL). Nevertheless, this technique is not performed in pregnant women.
In percutaneous nephrostolithotomy, large calculi are fragmented and removed from the urinary tract. However, this is associated with morbidity and thus is reserved for large (greater than 2 cm) and complex stones especially in cases where SWL and ureteroscopy are unsuccessful.
Note that the passed stone should be collected and submitted for analysis. This can provide insight into the prevention of future episodes.
Most cases of urolithiasis result in good outcomes. Specifically, almost 80% to 85% of urinary tract stones will pass spontaneously. However, about nearly 20% of patients are hospitalized for severe and persistent pain, urinary tract infections, inability to pass the stone, or intolerance to fluid intake.
Life-threatening complications include the co-manifestation of urinary tract obstruction and upper UTI. Other sequelae are pyelonephritis, pyonephrosis, and even urosepsis. These conditions warrant prompt surgical drainage.
Urinary calculi are associated with high recurrence frequency. Furthermore, this rate is typically reported as 50% within five years and at least 70% within a decade. However, these numbers may be lower according to literature.
Kidney stones are formed under the influence of several factors as described below.
Individuals with a personal history of stones, metabolic diseases such as diabetes mellitus, and hereditary disorders such as primary hyperoxaluria, cystinuria, and polycystic kidney disease are at elevated risk to develop stones.
The major environmental factor is low fluid consumption which results in oliguria and subsequently, elevated urinary solutes. Additionally, diet may aid in the growth of kidney stones.
Increased calcium concentration in the urine is considered to be the most prevalent metabolic abnormality in the formation of urinary tract calculi. Hypercalciuria is attributed to 1) increased intestinal calcium absorption, 2) increased bone resorption such as in hyperparathyroidism, and 3) leak of calcium in from the renal tubules. The first cause is associated with higher intake of calcium and hyperactive pathways involved in intestinal absorption.
Hypomagnesuria and hypocitraturia are two other abnormalities. Magnesium and citrate inhibit the development of stones. Hence, a reduction in their levels corresponds to a higher risk of developing stones.
Certain drugs or their resultant metabolites can produce stones once they precipitate in the urine. The main examples are the protease inhibitors indinavir and atazanavir, members of the sulfa family, as well as silicate, guaifenesin, and triamterene   .
In the United States and other industrialized nations, the incidence of urinary tract calculi is 0.2% yearly. Furthermore, kidney stones develop in 5% to 12% of Americans. Additionally, 10% to 15% will have bilateral involvement.
The location of the stones varies in different parts of the world, which is likely due to diet differences. For example, upper urinary tract stones are more prevalent in developed countries whereas bladder stones are more common in developing regions.
Asia demonstrates a 2% to 5% lifetime risk of developing urolithiasis while the probability in the West is 8% to 15%. Furthermore, this disease is rarely observed in Greenland and certain coastal parts of Japan.
With regards to patient demographics, there is a preference for males, who are 3 to 4 times more at risk than females. As for race, this disease occurs more frequently in Asians and white people as opposed to blacks, Native Americans, and individuals native to certain parts of the Mediterranean.
Classification of kidney stones
There are four types of kidney stones according to their composition: calcium, struvite, uric acid and cystine. The cumulative number of etiologies are many.
The most common are the calcium stones, which is responsible for 75% of all renal calculi. The second most prevalent type is struvite as it accounts for 15%. This is linked to chronic urinary tract infections (UTI) secondary to Proteus, Pseudomonas, and Klebsiella species.
Uric acid stones compose 5% of stones. This type develops with acidic urine (pH below 5.5), malignancy, or excessive consumption of foods with purine such as legume, fish, and organ meats. Furthermore, almost 25% of cases with uric acid renal calculi exhibit gout.
The remaining 2% of kidney stones is comprised of cystine, which forms secondary to a metabolic defect that inhibits the tubular reabsorption of cystine, ornithine, and other amino acids. The elevated urine levels of cystine lead to the crystal deposition.
Pathogenesis of urolithiasis
There are two mechanisms thought to contribute to the pathogenesis of urolithiasis:
When the urine becomes heavily concentrated with calcium, oxalate, and uric acid, these ions crystallize. As these stones become lodged in the ureter, the patient experiences symptoms.
The second mechanism is described by the stone deposits on Randall plaques, which are comprised of calcium phosphate. The basis of this mechanism emerges from corroborating studies .
Acute renal colic
Renal colic is caused by obstruction, the subsequent dilation and stretching of the ureter, and spasms. The obstruction site is marked by inflammation and edema which may account for the initial pain. The exacerbation of the pain can be attributed to the peristalsis, movement of the stone, or twisting of the calculi which causes further blockage.
Preventative measures include modification of diet, supplements, and certain medications. With regards to food, some data indicates that low protein and low salt are better than low calcium for prevention of further episodes .
In ureterolithiasis, the renal calculi are lodged into one or both ureters. The stones initially develop in the kidneys, but can grow further once they are positioned in the ureter. The ensuing clinical picture, renal colic, is regarded as one of the most painful situations rivaling events such as childbirth and surgery.
There are four chemical types of urinary tract stones according to their composition: calcium, struvite, uric acid and cystine. There are more than 20 underlying etiologies for kidney stones. Additionally, there are risk factors for stone formation. For example, a previous or family history of kidney stones, renal disease, anatomical anomalies of the urinary tract and metabolic disorders can contribute to the development of calculi.
The symptoms consist of excruciating pain that typically originates in the flank and radiates to the groin. Furthermore, the location of pain corresponds to the site of the stone in the ureter. The acute renal colic attack is also associated with nausea, vomiting and possibly hematuria.
The assessment includes components such as a detailed history, physical exam, blood and urinary tests, and imaging. It is important to identify whether there is a presence of obstruction and/or infection. One or both of these manifestations will guide the therapeutic approach.
Achieving pain control is the initial goal in the management of these patients. Surgical intervention is reserved for patients with larger stones and critically ill patients. Additionally, antibiotics therapy is indicated in cases complicated by infection. Finally, consultation with urology is pertinent for treatment and prevention of future episodes.
Kidney stones can lodge in the ureters, which are the long muscular tubes that join the kidneys to the bladder. When the stones block the ureters, the result is renal colic, which is a condition so painful that it is compared to childbirth.
There are different types of kidney stones and many causes. Some of the causes are related to problems with the metabolism that produce large levels of calcium in the urine. Additionally, certain disorders like diabetes mellitus, polycystic kidney disease, and hyperparathyroidism can influence the formation of stones.
Patients with a personal history of stones can have recurrent episodes. Also, there are medications such as certain diuretics and calcium based antacids that can develop kidney stones.
The symptoms include very severe pain in the flank (lower back), which moves towards the groin as the stone travels towards the bladder. Patients usually experience nausea, vomiting and blood in the urine. Also, they may have urgency and frequent urination. Some patients will develop an infection and exhibit signs such as a fever and chills.
To reach the diagnosis, the clinician will obtain a full history, physical exam, blood and urine studies, and imaging.
The main component in the treatment of these patients is pain control. Also, the patient may be prescribed medication that helps the stone pass through the urine. In large stones greater than 8mm, surgery may be needed to remove the stone. Finally, the patient should follow up with a urologist to help prevent further episodes.