Renal Colic

Definition: Renal colic is a sharp, sudden, and intense pain, usually located in the lumbar region or flank (the side of the back, below the ribs), which may radiate to the lower abdomen, groin, and genitals. It is caused by an obstruction of urine flow, most commonly due to a kidney stone that moves from the kidney and becomes lodged in the ureter (the thin tube that carries urine from the kidney to the bladder).

Mechanism of Pain: The pain of renal colic results from two main factors:

• Distension (increased pressure) of the renal pelvis and renal capsule due to the accumulation of urine above the point of obstruction.
• The muscle spasms of the ureter, which attempts to “push” the stone forward.

Differentiation: It is important to distinguish renal colic from other lower back pains or “kidney pains,” which may have other causes (such as kidney infections without obstruction, muscle problems, etc.). Renal colic has very particular characteristics, especially its intensity and radiation pattern.

Kidney Stones (Urinary Lithiasis): They are by far the most common cause of renal colic.

• Calculation Setup: Kidney stones form when urine becomes excessively concentrated (supersaturated) with certain minerals and salts (such as calcium, oxalate, phosphate, uric acid, or cystine). These components can crystallize and clump together, forming solid masses (the stones) within the kidneys.
• Triggering Colic: Renal colic occurs when one of these stones dislodges from the kidney and enters the ureter. If the stone is large enough to obstruct or hinder the passage of urine through the ureter, intense pain and other associated symptoms are triggered.

Sudden and Excruciating Pain:

• Initial Location: Typically, the pain begins abruptly in the flank (the area between the ribs and the hip) or in the lower back, on one side.
• Pain Radiation: As the stone descends through the ureter, the pain may change location, radiating to the lower and anterior part of the abdomen, the inguinal region (groin), and may extend to the genitalia (testicles in men, labia majora in women) or the inner thigh on the same side.
• The Nature of Pain: The pain is classically described as colicky, meaning it comes in waves of increasing and decreasing intensity, but it can also be constant with flare-ups. It is often a deep, stabbing, and very severe pain.

Restlessness and Psychomotor Agitation: A person with renal colic usually cannot find a position that relieves the pain, constantly moving and writhing (“pain that won’t let you stay still”).

Nausea and Vomiting: These are very common symptoms, triggered by the intensity of the pain and the stimulation of nerves shared between the urinary tract and the gastrointestinal system.

Hematuria (Blood in the Urine): Urine may take on a pink, red, or brownish color (macroscopic hematuria) due to small lesions caused by the passage of a kidney stone. Often, blood in the urine is only detectable through blood tests (microscopic hematuria).

Associated Urinary Symptoms (Dysuria):

• Dysuria (pain or burning sensation when urinating).
• Pollakiuria (frequent urination, usually in small amounts).
• Urinary urgency (a sudden and strong urge to urinate that is difficult to control).

Fever and chills: These are WARNING SIGNS! If renal colic is accompanied by fever (temperature > 38°C) and/or chills, it may indicate the presence of a urinary tract infection associated with obstruction (obstructive pyelonephritis). This is a serious situation that constitutes a urological emergency and requires immediate treatment.

Other Possible Symptoms: Paleness, cold sweats, increased heart rate (tachycardia).

Seek Immediate Medical Assistance: It is crucial to seek emergency hospital care, especially if:

• For the first episode of renal colic.
• The pain is unbearable and doesn’t ease with common painkillers.
• If you have a fever or chills.
• If persistent vomiting prevents hydration or the intake of oral medication.
• I heard that he only has one functioning kidney.
• If you are pregnant.

Avoiding Overhydration During an Acute Flare: Contrary to popular belief that “drinking lots of water will help expel the stone,” during a severe pain crisis, excessive fluid intake can worsen the pain if there is a significant obstruction, as it increases pressure within the kidney. Hydration will be important afterward, but in the acute phase, pain control is the priority.

Pain relievers: If you have previously been prescribed analgesics or anti-inflammatory drugs for cramps (and have no contraindications), you can take them while awaiting medical evaluation, but be aware that they may be insufficient to control severe pain.

Medical History and Physical Examination: The doctor will gather detailed information about the characteristics of the pain, associated symptoms, and personal history of kidney stones or other diseases. The physical examination helps to locate the pain and rule out other possible causes of acute abdominal or lower back pain.

Urine Analysis (Urinalysis / Type II Urinalysis and Urinary Sediment): To detect the presence of blood (hematuria), crystals (which can give clues about the type of stone), and signs of infection (leukocytes, nitrites). If infection is suspected, urine is collected for a urine culture.

Blood Tests: To assess kidney function (urea and creatinine), white blood cell count (which may be elevated in infection or inflammation), C-Reactive Protein (CRP, a marker of inflammation/infection) levels, and sometimes calcium and uric acid levels.

Imaging Tests: They are crucial for diagnosis.

• Abdominal-Pelvic Computed Tomography (CT) Scan, Without Contrast (Helical or Low-Dose): It is the gold standard test for evaluating acute renal colic. It is fast and highly sensitive and specific for detecting urinary stones of almost all types and sizes, their exact location (kidney, ureter, bladder), and for assessing signs of obstruction (such as dilation of the collecting system – hydronephrosis).
• Renal and Bladder Ultrasound (Echocardiography): It is a useful examination for detecting kidney dilation (hydronephrosis), which is a sign of obstruction, and for visualizing stones located within the kidney or bladder. It is the first-line examination in pregnant women and children due to the absence of ionizing radiation. However, ultrasound is less effective for visualizing small stones or those located inside the ureter.
• Plain Abdominal X-ray (KUB – Kidneys, Ureters, Bladder): It can visualize radiopaque stones (most calcium stones). It is less sensitive than CT and may not detect radiolucent stones (such as pure uric acid stones) or small stones, nor provide detailed information about the obstruction.

Pain Relief (Analgesia):It’s the priority.

• Non-steroidal anti-inflammatory drugs (NSAIDs): Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac (which has been shown to be particularly effective in the relief of renal colic), as well as ibuprofen or ketorolac, are generally considered first-line therapy. In addition to providing effective analgesia, these agents reduce inflammation and ureteral spasm. They may be administered orally, rectally (as suppositories), or parenterally via intramuscular or intravenous injection.
• Opioid analgesics (e.g., tramadol, morphine, pethidine):They are used for severe pain that does not respond to NSAIDs, or when NSAIDs are contraindicated (e.g., significant renal insufficiency, active peptic ulcer).
• Antispasmodics (e.g., butylscopolamine):Sometimes used in combination, although the evidence for their effectiveness alone is weaker than that of NSAIDs.

Control of Nausea and Vomiting: With antiemetic medications (e.g., metoclopramide).

Medical Expulsive Therapy (MET):

• For stones located in the distal ureter and of a size associated with a reasonable likelihood of spontaneous passage (generally up to 7–8 mm, although selected cases up to 10 mm may be considered), medical expulsive therapy may be offered using alpha-blockers such as tamsulosin or silodosin. These agents act by relaxing the smooth muscle of the distal ureter, promoting ureteral dilatation and facilitating stone passage, while potentially reducing pain episodes and the need for analgesic medication.

Uncontrollable Pain: Severe pain that does not subside with adequate doses of potent analgesics.

Obstruction with Signs of Urinary Tract Infection (Obstructive Pyelonephritis): Presence of fever (>38°C), chills, and/or deterioration of general condition associated with obstruction. This is an Urological Emergency, which requires immediate drainage of the kidney to prevent progression to sepsis (a potentially fatal systemic infection).

Obstruction in a Single Functioning Kidney or Bilateral Ureteral Obstruction.

Acute Renal Failure: Significant and acute deterioration of renal function due to obstruction.

Persistent and uncontrollable nausea and vomiting: That prevents hydration and the intake of oral medication.

Anuria (Absence of Urine Production): In cases of bilateral obstruction or obstruction affecting only one kidney.

Placement of a Ureteral Catheter (Double J or Stent): A thin, flexible tube is inserted into the ureter (usually via cystoscopy, under anesthesia) to bypass the obstruction and allow urine to flow from the kidney to the bladder. The stone remains in place for later treatment.

Percutaneous Nephrostomy: A small drainage tube is inserted directly into the kidney through the skin in the lumbar region, under ultrasound or radiological guidance. The urine is drained into an external collection bag.

Spontaneous Passage of the Stone: Many kidney stones, especially smaller ones (less than 5-6 mm), are spontaneously expelled in the urine over days or weeks. During this period, it is important to try filtering the urine (with filter paper or gauze) to try to retrieve the stone. Analyzing its chemical composition is essential to guide future preventative measures.

Urological Medical Follow-up:Regular check-ups with your urologist are essential for:

• Confirm the passage of the stone (usually with a follow-up imaging test, such as ultrasound or plain X-ray).
• Assess the need for further treatment if the stone is not expelled or is too large.

Stone Treatment (if necessary): If the stone is not expelled spontaneously, is too large to pass, or causes persistent symptoms or complications, there are several procedures to remove or fragment it. These include:

• Retrograde Intra-Renal Ureterorenoscopy (RIRS): This is a minimally invasive endoscopic technique that uses a flexible ureteroscope inserted through the urethra into the kidney. It is used to visualize the stone and fragment it directly with a LASER (Holmium or Thulium) into small pieces that are then removed or can be spontaneously expelled. It is a fundamental option for kidney and ureteral stones that do not pass spontaneously. Currently, it is possible to remove stones via this minimally invasive approach, accessing them through natural routes without any incisions, in almost all cases, even very large ones. For large, staghorn stones that occupy the entire kidney, two or even three surgeries may be necessary for complete removal.
• Semirigid ureterorenoscopy (URS): This technique is limited to the treatment of ureteral stones, often with laser fragmentation.
• Percutaneous Nephrolithotomy (PCNL): Percutaneous access is an alternative to RIRS for the surgical treatment of large kidney stones. A puncture is made in the lumbar region, directly into the kidney, and the tract is dilated until a tube can be inserted, allowing access to the inside of the kidney and an instrument that fragments the stones with a laser. It is more invasive than RIRS, but, sometimes even in combination with it, allows the removal of large stone loads.
• Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-invasive treatment that uses focused shock waves (generated outside the body) to fragment kidney or ureteral stones into small pieces that can be expelled naturally. With technological advancements in endourology, it is a technique in decline, mainly due to the lack of control over the expulsion of stone fragments and the potential for damage to the renal parenchyma adjacent to the stones.

Metabolic Study: After an episode of renal colic, especially if it is the first at a young age, if there is a family history of kidney stones, if the stones are recurrent, or if the stone has a particular composition, your urologist may recommend a metabolic study. This study involves blood tests and a 24-hour urine collection to identify possible metabolic changes that favor the formation of kidney stones (e.g., excess calcium, oxalate, or uric acid in the urine; low urine volume; low urinary citrate).

Significant Increase in Fluid Intake: This is the most important and universal preventative measure. It is recommended to drink enough water to produce at least 2 to 2.5 liters of urine per day. The urine should be consistently clear.

Specific Dietary Modifications: Depending on the composition of the stone, dietary changes may be recommended, such as:

• Reducing salt (sodium) consumption.
• Moderation in the consumption of animal protein.
• Controlling the intake of foods high in oxalate (for calcium oxalate stones).
• Reducing intake of foods high in purines (for uric acid stones).

Preventive Medication: In some cases, based on the results of the metabolic study, medications may be prescribed to correct specific alterations and reduce the risk of new stone formation (e.g., potassium citrate to increase urinary citrate and alkalinize urine; thiazide diuretics to reduce urinary calcium; allopurinol to reduce uric acid).

Renal colic is a significant and extremely painful experience that requires prompt and effective medical attention. With rapid diagnosis and appropriate pain management, most episodes can be controlled. After the acute crisis resolves, it is essential to maintain urological follow-up to confirm the resolution of the problem, investigate the cause of stone formation, and implement personalized preventive measures to avoid future colic and protect your kidney health.

If you are experiencing symptoms suggestive of renal colic, especially if accompanied by fever or persistent vomiting, seek immediate emergency medical attention. For the study, treatment, and prevention of urinary lithiasis, or for follow-up after an episode of renal colic, consult an urologist.

We are here to help you overcome this painful condition and work with you to prevent its recurrence. Schedule a consultation for a complete evaluation.