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Managing acute renal colic in primary care

A diagnosis of acute renal colic usually leaves GPs with little option but to admit immediately. Here urology GPSI Dr Jonathan Rees explains how patients can be managed at home with good analgesia.

A diagnosis of acute renal colic usually leaves GPs with little option but to admit immediately. Here urology GPSI Dr Jonathan Rees explains how patients can be managed at home with good analgesia.

Renal colic is a common – often recurrent – condition, with an estimated annual incidence of one or two cases per 1,000, and a lifetime risk of 10-20% for men and 3-5% for women. The diagnosis has often left GPs with little choice but to admit acutely for analgesia and to confirm the diagnosis and plan management. But it is often possible for patients to be managed at home, as long as appropriate analgesia is provided and urgent investigation and outpatient follow-up can be arranged.

Making the diagnosis

Typical history is of pain originating in the loin or flank, radiating to the labia majora in women or to the groin or testicle in men .

Pain is usually a strong ache with episodic severe exacerbations of a colicky nature, with the patient unable to find a comfortable position – unlike in peritonitis, where patients typically lie still and resist moving. Men often say it is the worst pain they have ever experienced. Women liken it to labour pain in terms of severity.

A past history of renal colic would increase the likelihood of the same diagnosis on this occasion.

Consider other causes of the pain, particularly appendicitis (if right-sided), diverticulitis (if left-sided), pyelonephritis or salpingitis in females. Beware left-sided ruptured aortic aneurysm, as this can sometimes mimic left-sided ureteric colic. This carries a lower threshold for admission and investigation in high-risk groups, such as men over 60 with left-sided pain.

In males with pain referred into the external genitalia, the testes must be examined to exclude torsion, especially in high-risk age groups.

Examination and investigations

Examine the patient to exclude other causes and in particular to exclude urinary sepsis. All patients with renal colic and fever should be admitted as they may have infection proximal to the stone that can rapidly cause irreversible kidney damage. An obstructed, infected kidney is a very serious emergency.

Signs that should raise concern include marked tenderness in the loin. Renal colic does not usually present with tenderness unless there is associated obstruction or infection. Be concerned also about a high temperature or a patient who looks unwell.

Urine dipstick testing should be performed where possible on all patients with suspected renal colic. Haematuria will be found in about 80% of renal colic patients. Remember, though, that a negative result does not exclude the diagnosis. The prevalence of dipstick haematuria decreases with time, dropping to 65% on third or fourth day.

Dipstick testing is more sensitive than microscopy as red blood cells lyse and disappear if urine is not examined within a few hours. So the old advice of checking all cases of dipstick haematuria with urine microscopy is incorrect, as a positive dipstick is the most reliable test.

Immediate management

With such severe pain it is crucial to see the patient urgently. A target of assessment – by home visit or in surgery – in 30 minutes is recommended for those in severe pain. If urgent assessment is not possible, patients may be advised to call an ambulance.

Recommended first-line analgesia is intramuscular diclofenac 75mg or rectal diclofenac 100mg, unless NSAIDs are contraindicated – in which case an intra-muscular opiate plus anti-emetic should be used. Oral tramadol is an alternative.

Many urologists believe rectal diclofenac is the most effective and there is evidence that patients receiving NSAIDs achieve greater reductions in pain scores and are less likely to require further analgesia in the short term than those receiving opioids.

Remember to provide a supply of oral or rectal analgesia for ongoing pain relief.

If treating with opioids, tramadol may be the most appropriate oral analgesic. When used for renal colic with a dose of 100mg it has proven as effective as pethidine 50mg.

Some studies have shown local warming of the abdomen and lower back can provide significant analgesia and anxiolysis.

Acupuncture is used effectively in China and Taiwan and has a rapid analgesic effect in studies – more rapid than conventional analgesia – so this may be an option for patients who are not admitted to hospital.

Alternative drugs could be considered for those whose pain is not fully controlled. Isosorbide dinitrate has been shown to augment the effect of NSAIDs, and glyceryl trinitrate patches have also been used with some effect on pain. Calcium channel blockers or a-blockers, when used regularly, may decrease analgesic requirements and promote spontaneous stone passage.

Continuing management

Following immediate pain relief, the GP should reassess the patient – by telephone if necessary – after about an hour to check the response to analgesia.

Inadequate response requires either further analgesia or admission to hospital.

Advise patients to maintain a normal fluid intake. Excess intake can increase the degree of hydronephrosis, making ureteric peristalsis less efficient and decreasing the chance of spontaneous stone passage.

If possible, patients should void into a container or through a tea strainer to try to catch any identifiable calculus, as this will help in future management.

If you are not acutely admitting the patient, consider arranging an MSU (to look for leucocytes, crystals and to exclude infection), serum urea, electrolytes and creatinine to assess renal function and calcium, phosphate and urate as part of a metabolic screen to assess the cause.

Investigation and referral

41187232All those with suspected renal colic require an urgent CT scan (CT KUB) or intravenous urogram within a week. This may require a discussion with radiology to ensure priority.

Urgent referral for outpatient assessment is required – ideally within 14 days – if a calculus is identified.

Management will depend on the size of the stone – 90% of ureteric stones of less than 4mm will pass spontaneously over one to three weeks, and conservative management is preferred where possible.

This rate of stone passage is reduced to about 50% with stones measuring 4-6mm, whereas stones larger than 6mm are likely to need surgical intervention, as fewer than 10% will pass spontaneously. Open surgery is uncommon as most stones will respond to extracorporeal shockwave lithotripsy or extraction with the ureteroscope.

Dr Jonathan Rees is a GPSI in urology at the Backwell and Nailsea Medical Group

Competing interests: None declared

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