Renal colic, also called kidney colic, is sudden, extremely severe pain in the loin (the side of the lower back) that occurs when the drainage of urine from the kidney is suddenly blocked. The most common cause is a stone that has left the kidney and become stuck in the ureter – the thin tube leading to the bladder.
The pain is among the most severe a person can experience, but in itself it is not dangerous – the complications are: infection in the blocked kidney and damage to its function if the blockage lasts a long time. That is why it is important to know what to do in the first few hours and when you should not wait.
What is renal colic?
When a stone blocks the ureter, the urine has nowhere to drain. The pressure in the renal pelvis rises, the capsule of the kidney is stretched, and the ureter contracts in spasms trying to push out the obstruction – hence the wave-like pain with short periods of relief.
Where the pain is felt suggests where the stone is: high in the ureter, the pain is in the loin and flank; as the stone moves down, the pain shifts towards the abdomen and groin; with a stone right next to the bladder, frequent, urgent needs to pass urine appear. The kidney above the obstruction becomes dilated – a condition known as hydronephrosis.
Symptoms
- sudden, sharp pain in the loin on one side, spreading forwards and down towards the groin and genitals;
- waves in which the pain builds up until it is unbearable and then partly eases;
- restlessness, paleness, cold sweats;
- nausea and vomiting;
- blood in the urine – visible or found only on testing;
- frequent urges and burning when passing urine, when the stone is low down.
Some signs require the emergency department or a call to 112 (the European emergency number) instead of a booked appointment: a temperature above 38 °C or shivering, much less urine or none at all, an attack in a single or transplanted kidney, pregnancy, constant vomiting, and pain that does not ease after a painkiller. A blocked and infected kidney can lead to a severe generalised infection within hours.
Causes and risk factors
The most common cause is kidney stones – a fragment that has broken off travels down the ureter and gets stuck at one of its natural narrow points. Less often the ureter is blocked by a blood clot, compressed from outside, or narrowed from birth where it joins the renal pelvis.
The risk is higher if you have had a stone before, if you drink little and in hot weather, with a diet high in salt and animal protein, with excess weight, gout, diabetes, frequent urinary infections and kidney stones in the family.
Diagnosis
In the acute phase, diagnosis most often begins in an emergency department: a urine test, blood tests for kidney function and inflammation, an ultrasound that shows the dilated kidney and often the stone itself, and, if needed, a low-dose CT scan without contrast, which determines the size and position of the stone most accurately.
Pain in the back can also be caused by appendicitis, gynaecological conditions, a gallbladder attack or a problem with the blood vessels, so tests are essential. Once the acute pain is under control, Dr Penev carries out a kidney stone consultation with ultrasound at his practice in Plovdiv, assesses whether the stone can pass on its own and draws up a plan for treatment and follow-up.
Treatment
What you can do at home
If the attack has already been diagnosed and there are no urgent signs, the first step is pain relief. The most effective are non-steroidal anti-inflammatory drugs (NSAIDs), which also reduce the swelling of the ureter; if you have a stomach ulcer, kidney disease, an allergy or are pregnant, the choice is paracetamol. A hot-water bottle on the back or a warm shower relaxes the muscles. Do not force yourself to drink lots of water while the pain is at its peak – this raises the pressure above the stone and makes the pain worse; drink normally, in small amounts. You will find detailed steps in the advice on first aid for renal colic.
What the urologist does
If the stone is smaller than 5–6 mm, is in the lower part of the ureter, and there is no infection or reduced kidney function, Dr Penev usually recommends waiting with the help of medication – painkillers and an alpha-blocker, which relaxes the ureter. Follow-up with ultrasound continues for up to several weeks; if the stone does not move on, it is removed.
Emergency unblocking of the kidney
If the blocked kidney is infected, if no urine is being produced, or if the pain cannot be controlled, the first task is not the stone but restoring drainage. At the Department of Urology at Kaspela University Hospital (UMBAL Kaspela), Plovdiv, this is done with a thin ureteric stent or a nephrostomy – a drain through the skin of the back. Antibiotics are given at the same time, and the stone is removed at a second stage, once the infection is under control.
Removing the stone
When the stone is large, does not move or causes repeated attacks, the method of choice is ureteroscopy – endoscopic stone treatment, in which the stone is reached through the natural passages, broken up with a laser and removed. For stones high in the ureter, shock wave lithotripsy (breaking up the stone from outside the body) is an alternative. After the procedure a stent is often left in place for one to several weeks and is then removed as an outpatient.
When to see a urologist
Every attack of renal colic deserves a check-up, even when the pain has passed – the stone may still be in the ureter and silently blocking the kidney. Book an appointment as soon as possible if the pain comes back, if there is blood in your urine, or if you know of a stone that has not passed within two to four weeks.
Prevention
The surest way to avoid a second attack is not to form a new stone: enough fluids throughout the day, less salt and processed meat, more fruit and vegetables, and weight control. Analysis of the passed stone and tests of your metabolism allow Dr Penev to recommend individual measures and, if needed, medicines.
Renal colic is frightening, but with timely and correct action it passes in most cases without lasting consequences for the kidney. If you have had an attack or have a stone that is yet to pass, book an appointment with Dr Penev in Plovdiv or Karlovo for a consultation, an ultrasound and a treatment plan.
Frequently asked questions
Can I drive and go to work after an attack of renal colic?
Yes, once the pain has settled and you are not taking strong painkillers. Bear in mind that an alpha-blocker can make you dizzy when you stand up suddenly, which is why it is taken in the evening. Carry the prescribed painkiller with you in case the attack comes back.
Why do I still feel a dull ache in my back after the attack?
The stretched renal pelvis and the swelling of the ureter take a day or two to return to normal, so a mild feeling of heaviness is common. If the pain lasts more than a few days, comes back in waves or you develop a fever, have a follow-up ultrasound – the stone may still be in the ureter.
What is different about renal colic during pregnancy?
The diagnosis is made with ultrasound, CT is avoided, and non-steroidal anti-inflammatory drugs are not used in the later months. If the kidney needs to be unblocked, a stent is more often placed, and treatment is coordinated with the obstetrician. Pregnant women with renal colic should be monitored in hospital.
Do antispasmodics help with renal colic?
Antispasmodics are widely used, but they work less well than non-steroidal anti-inflammatory drugs and do not replace them, although they can be added to them. Do not start an antibiotic on your own – it is needed only for a proven infection and is prescribed by a doctor.
The information on this website is for general education and does not replace an examination and consultation with a doctor. If you have urgent symptoms, seek medical help immediately or call 112.