Renal colic

Definition and clinical significance

Renal colic is an acute pain syndrome caused by a sudden impairment of urine drainage from the renal collecting system or ureter. The most common cause is a ureteral stone.

In emergency practice, the physician's task is not only to relieve pain but also to rule out complicated obstruction, infection, anuria, involvement of a solitary functioning kidney, and other conditions requiring immediate intervention.

Clinical presentation

• Pain typically begins in the lumbar region and radiates along the ureter to the groin, scrotum, or labium.
• The patient is restless and unable to find a comfortable position.
• Associated features include nausea, vomiting, dysuria, and sometimes gross hematuria.
• Fever, rigors, and hypotension are not typical of uncomplicated colic and require an immediate search for infection or another complication.

Initial assessment

Assess the following in parallel:

• blood pressure, pulse, temperature, and oxygen saturation;
• pain severity and urine output;
• high-risk factors: a solitary kidney, bilateral obstruction, pregnancy, immunodeficiency, or a known urinary tract infection.

Required investigations:

• urinalysis (plus culture if infection is suspected);
• complete blood count, creatinine, electrolytes;
• if there is a systemic response: CRP, lactate, and blood cultures.

Imaging

• Ultrasonography is the initial modality: assess hydronephrosis, large stones, and the bladder.
• Low-dose noncontrast CT is the modality of choice when the diagnosis is unclear and to determine stone size and location.
• In pregnancy ultrasonography is preferred, with noncontrast MRI if needed.

Analgesia

• NSAIDs are first-line agents in the absence of contraindications (more effective than opioids; reduce inflammation and intrapelvic pressure).
• If the response is inadequate, use rescue analgesics according to the local protocol.
• Antiemetics as indicated.
• Consider: kidney function, history of peptic ulcer disease, bleeding risk, and cardiovascular status.

Medical expulsive therapy

• An alpha-blocker may be considered in a selected, clinically stable patient with a 5–10 mm distal ureteral stone when safe observation is feasible. Check the approved prescribing information in the Republic of Kazakhstan to establish whether this use is off-label.
• Medical expulsive therapy is not a substitute for drainage in infection, anuria, deteriorating kidney function, uncontrolled pain, or vomiting.

When observation is unacceptable

Urgent intervention is indicated in:

• obstruction with infection;
• anuria;
• bilateral obstruction;
• obstruction of a solitary functioning kidney;
• progressive kidney injury;
• intractable pain or vomiting;
• inability to ensure outpatient follow-up.

In infected obstruction: restore drainage first (stent or nephrostomy) and give antibacterial therapy. Remove the stone after stabilization.

Algorithm

Common errors

• Interpreting fever as a “normal” response to colic.
• Delaying drainage until all investigations are complete.
• Prescribing NSAIDs without assessing kidney function.
• Prolonged observation of a patient with intractable pain.
• Overlooking a solitary kidney or bilateral obstruction.