Acute kidney pain is considered as a potential diagnosis if the patient is experiencing a sudden onset of nauseating pain ranging from the loin to the groin, indicating that the pain is situated in the renal tract. The patient is often in agony as a consequence.
If the patient’s pain is caused by kidney stones, the pain is due to stones obstructing flow in the ureter which results in an increase in pressure within the ureter, causing pain. This pain can be episodic and once an episode has passed, that does not mean the stones have also passed although passage of the stones from the ureter to the bladder may reduce the pain. Thus, the patient requires further investigations and follow-up procedures to ensure all the kidney stones are flushed before receiving the all-clear.
In such patients, it is important that the Emergency Department makes the correct diagnosis of renal tract stones as there are other red flag conditions also associated with pain in the renal area e.g. pancreatitis or appendicitis. Therefore, it is vital to ascertain whether this patient’s state is an emergency, or if the patient can be safely discharged for investigations and a follow-up. To do this effectively, the following procedures recommended by the Royal College of Emergency Medicine should be performed.
The key investigation in determining whether there are kidney stones is the CT KUB (kidney, ureter and bladder) that measures the size of any calculi found and assesses the degree of urinary obstruction within the patient. CT KUB may also alert the clinicians to alternative diagnoses such as appendicitis. However, there are limitations to this investigation. CT KUB takes time to undertake and report, and the patient may have become pain-free whilst in the Emergency Department and is expecting discharge.
A urine dipstick test is also performed on arrival to identify haematuria. If the patient genuinely has renal or ureteric colic, they will have blood in their urine. Unfortunately patients who present with pain who are trying to receive opiate analgesia may even add blood to their normal urine in order to receive these painkillers so the Emergency Medicine clinician should be aware of this possible problem and use non steroid anti inflammatory drugs which are effective for renal colic due to stones in preference to using opiates
Blood tests especially looking for evidence of renal impairment are important as these results may influence whether the patient can be safely discharged from the Emergency Department for out patient follow up in clinic or if they need to be admitted for urgent treatment under the urology team. Other blood tests that may help to conform the composition of the stones are unlikely ot influence the treatment in the Emergency Department but may prevent multiple blood sampling by the specialist teams and so should be undertaken with the routine urea and electrolyte tests.
There are some centres that will discharge the patient form the Emergency Department without a CT KUB particularly if they have had a previous history of small stones and no evidence of renal impairment but most would not discharge a patient until they are painfree and have radiological evidence of small stones and no renal impairment.
It is important to prevent recurrent episodes that may in the longer term lead to gradual renal impairment that such patients are not simply discharged back to the Primary care service but are followed up in a hospital out-patient service especially if the imaging finds evidence of stones in the kidneys that may lead to future episodes of pain and Emergency Department attendances