What is renal colic?

Renal colic is not an independent disease but rather severe persistent or paroxysmal pain in the lower back or flank caused by smooth muscle spasms in the renal collecting system (renal calyces and pelvis) or ureter due to various conditions (typically urinary tract issues, especially ureteral stones).

It often occurs suddenly without warning and may radiate along the ureter to the groin, inner thigh, or, in males, the scrotum, and in females, the labia majora. It is one of the common surgical emergencies.

What are the causes of renal colic?

1. The most common cause is ureteral obstruction, often due to urinary stones (especially ureteral stones) or other factors such as ureteral polyps, blood clots, necrotic tissue, renal tumors, or renal tuberculosis. These block the ureter, causing acute obstruction, rapid pressure buildup in the upper urinary tract, acute dilation, smooth muscle spasms, and the release of inflammatory mediators, leading to severe pain in the flank or abdomen.
2. Infarction or thrombosis of the renal arteries, veins, or their branches.
3. Floating kidney or nephroptosis: May lead to Dietl's crisis (manifested as acute renal colic, nausea, vomiting, pallor, collapse, and hematuria).
4. Vesicoureteral reflux.
5. After extracorporeal shock wave lithotripsy, fragmented stone particles entering the ureter; complications like renal injury may also cause pain.
6. Chyluria irritating the renal pelvis or ureter.

Points 2–6 can cause similar pain and are also classified as "renal colic." Therefore, clinical diagnosis must identify the underlying cause.

Who is commonly affected by renal colic?

It frequently occurs in individuals with a history of urinary stones, ureteral strictures, or polyps; it is more common in young adults (more often in males than females), those with low water intake, and people who lack physical activity.

What are the common symptoms of renal colic?

Patients suddenly experience severe, persistent, or intermittent pain in the renal region, usually unilateral. The pain often starts at the costovertebral angle on the affected side and radiates along the ureter to the lower abdomen, inner thigh, and perineum. The colic may last minutes to hours, then turn into dull pain or disappear suddenly.

Patients often appear restless, with nausea, vomiting, sweating, pallor, or even a weak, rapid pulse and low blood pressure. Severe cases may lead to shock. Urinary irritation symptoms (frequency, urgency, dysuria) may occur, and hematuria is common after the colic subsides.

How is renal colic diagnosed?

1. Diagnosis is straightforward based on a history of stones, hematuria, or chyluria, combined with typical symptoms and physical examination of accompanying symptoms and radiation patterns.
2. Physical examination reveals tenderness and percussion pain in the affected kidney area and tenderness along the ureter.
3. Red blood cells in urinalysis often indicate obstructive renal colic due to stones. Common diagnostic tools include ultrasound (simple, convenient, and inexpensive, often the first choice during an episode), abdominal X-ray, intravenous urography, and spiral CT.

How is renal colic treated?

Emergency management of renal colic varies between home and hospital settings:

At home:

1. During an acute episode, the priority is pain control, typically with NSAIDs like ibuprofen.
2. Seek medical attention. If alone and in severe pain, call emergency services (e.g., 120).

In the hospital:

1. Initial treatment focuses on symptom relief using analgesics, sedatives, or antispasmodics (e.g., NSAIDs, opioid agonists, M-cholinergic blockers). Increased water intake and moderate exercise may help.
2. Fluid replacement is important, and antibiotics are used if infection is present.
3. After pain relief, address the underlying cause:

• For stones: Treatments include expulsion therapy, extracorporeal shock wave lithotripsy, ureteroscopic lithotripsy, or percutaneous nephrolithotomy.
• Stones >6 mm may require surgical options like shock wave lithotripsy, ureteroscopic lithotripsy, ureteral stent placement, or percutaneous nephrostomy.
• Congenital urinary anomalies, renal tuberculosis, or ureteral strictures may necessitate surgery.

What is the prognosis for renal colic?

Renal colic has a sudden onset, but once the spasm or obstruction is resolved, the pain quickly subsides. Identifying and treating the underlying cause generally leads to a good prognosis.

How to prevent renal colic? What should patients pay attention to?

• Those with a history of renal colic should drink plenty of water and regularly check for hematuria via urinalysis.
• Adjust diet based on stone composition; medication may be necessary.
• Exercise regularly and stay active.