Kidneys & Ureters

The kidneys perform several functions. They filter waste products out of the blood, and turn them into urine. They also produce several important hormones that regulate blood pressure, red blood cell production and calcium.

Urine is full of minerals that are excreted by the kidneys. When there are too many of one of these or there is too little water to dissolve they can crystallize out and turn into stones in the kidneys. Some people are genetically prone to forming stones have underlying medical diseases that can cause them Some people are genetically prone to forming stones ,whilst others can be caused by Dehydration, infection, obstruction of urine and various kidney disorders.

Crystals of salts found normally in the urine aggregate together and gradually enlarge in size to form stones, which may vary greatly in size. Some are as small as a grain of sand whereas others are so big they fill the entire renal pelvis.

There are several different types of stones including: calcium oxalate, calcium phosphate, uric acid, struvite (infection stones), cystine and drug related. Once stones have formed they can either sit in the kidney, or travel down the ureters, sometimes getting stuck. Kidney stones can cause significant symptoms such as pain (colic), blood in the urine, urine infections and nausea and vomiting.

Pain from stones is often described as severe, and may sometimes lead to an emergency attendance to accident and emergency.


Most of the stones which are 5mm can travel down the ureters and pass spontaneously .The passage of the stones could be very painful (renal colic). Strong painkillers are usually prescribed to help with symptoms and to allow patients to go home.

It is important that patients are followed up by a urologist, to ensure that the stone has passed. This is normally done with an x-ray or CT scan. It can take 4-6 weeks for a stone to pass.

In case there is also urine infection, pain is not controllable, there is kidney failure or a single kidney and when the stone is very large, then it is not safe to continue with conservative management and urgent action needed as drainage of the kidney with either a hollow tube internally called a stent, or externally through the back (nephrostomy tube).

Extracorporeal lithotripsy (ESWL):

ESWL can be used as an emergency or as elective treatment treatment for stones that are stuck in the ureter or kidney stones up to 2cm in size. ESWL is regarded as a safe and effective treatment.

It is an outpatient procedure, administered with simple oral analgesia. Treatment lasts for 45 minutes, and it is often necessary to repeat it 2-4 weeks later.

The treatment involves lying on special table called a lithotripter. A cushion is placed against the patients back, and sound waves are focused onto to the stone using either ultrasound or x-rays. The stone is broken up into fine dust that is then passed painlessly out in the urine. It can be uncomfortable during the procedure but this stops as soon the process is finished. About 10% of patients get pain as larger fragments pass through.

Ureteroscopy is an examination or procedure using a ureteroscope.A ureteroscope, is an instrument for examining the inside of the urinary tract. They are used to see beyond the bladder into the ureters, the tubes that carry urine from the kidneys to the bladder. Some ureteroscopes are flexible like a thin, long straw. Others are more rigid and firm. Through the ureteroscope, the doctor can see a stone in the ureter and then remove it with a small basket at the end of a wire inserted through an extra channel in the ureteroscope.

Another way to treat a stone through a ureteroscope is to extend a flexible fiber through the scope up to the stone and then, with a laser beam shone through the fiber, break the stone into smaller pieces that can then pass out of the body in the urine. How and what the doctor will do is determined by the location, size, and composition of the stone.

It is performed under general anaesthesia, but is usually a day case procedure, and the recovery is quick as there are no cuts involved. It is a very safe procedure with few side effects. Occasionally the ureter is tight, and will not allow passage of the ureteroscope. In this situation it is necessary to leave a temporary ureteric stent for 2 weeks. This allows for dilation of the ureter making a subsequent procedure easier.


Percutaneous nephrolithotomy (PCNL) is a minimally-invasive procedure to remove stones from the kidney by a small puncture wound (up to about 1 cm) through the skin. It is most suitable to remove stones of more than 2 cm in size and which are present near the pelvic region.

This is performed under general anaesthesia, and involves a small incision in the back, followed by the passage of a telescope into the kidney to remove stones. Normally entails a 2-day stay in hospital afterwards. It allows for the largest of stones to be removed. There are risks of bleeding and infection afterwards and it should only be performed by an expert in stone surgery.


You may be advised to have some blood and urine tests to investigate why you have formed a stone. There are some medications that can be prescribed to cut down the future risk of another stone.

General advice for preventing stones is:

  • Maintain a high fluid intake (2 litres water a day)
  • Cut down salt intake
  • Low protein diet
  • A normal calcium intake
  • Avoid black tea
  • Reduce intake of oxalate containing foods: chocolate, rhubarb, spinach, nuts, beetroot, tomato juice
  • High intake of citrate (citrus fruits such as oranges and lemons)

Kidney tumours ,also known as renal tumours, are tumours, or growths, on or in the kidney. These growths can be benign or malignant (kidney cancer).

Kidney tumours may be discovered on medical imaging incidentally or may be present in patients as an abdominal mass or kidney cyst, hematuria, abdominal pain, pain in the flank.

The investigation of choice is a CT scan, but you may be asked to have a biopsy or even an ultrasound to help decide whether they are cancerous or not.

Treatment normally involves removal of part or the whole of the affected kidney. This can be done as a keyhole operation. Tumours that form in the collecting system of the kidney (transitional cell cancer) usually present with blood in the urine. Along with a CT scan it is usually necessary to look up into the kidney (ureteroscopy) to confirm the diagnosis. Treatment involves removal of the affected kidney and ureter, although it is sometimes possible to laser tumours at the time of ureteroscopy.