Renal Caliectasis and Pyelectasis: What They Mean in an Ultrasound Report

You open your kidney ultrasound report and see an unfamiliar word: caliectasis, pyelectasis, or pyelocaliectasis. These terms all describe the same thing — dilatation of the cavities of the kidney where urine collects. Let us calmly explain what this means and whether it is dangerous.

What renal caliectasis and pyelectasis are

The kidney is internally organized as a system of cavities: urine from tiny structures, the nephrons, collects into the calyces, which drain into the renal pelvis, from where it passes through the ureter to the bladder. Caliectasis is dilatation of the calyces. Renal pyelectasis is dilatation of the renal pelvis. Both words describe that the outflow of urine is obstructed somewhere, and the cavities stretch. When both the calyces and the pelvis are dilated, this is called pyelocaliectasis. Essentially this is the picture of hydronephrosis — a condition in which the kidney swells from accumulated urine. Hydronephrosis occurs in 0.6–4.5% of the population depending on age.

Pyelocaliectasis: how it differs from pyelectasis

Pyelectasis is dilatation of the renal pelvis only. Pyelocaliectasis is dilatation of the renal pelvis together with the calyces, meaning more cavities are involved. The doctor describes the stage: in the first, only the pelvis is dilated, and kidney function is unchanged or mildly impaired. In the second, the kidney is enlarged by 15–20%, the pelvis is significantly dilated, the wall is thinned, and function is reduced by 20–40%. In the third, the kidney is enlarged 1.5–2 times, the calyces and pelvis are severely dilated, and function is reduced by 60–80% or absent.

Why the renal pelvis becomes dilated

The cause is almost always the same — something prevents urine from draining. Causes include: kidney stones, pregnancy, an enlarged prostate, urinary tract infections, trauma or surgery on the ureters, a blood clot, a tumor. In a fetus, hydronephrosis is often found on ultrasound screening; it is usually mild due to increased urine production, and in most cases no treatment is needed.

How dilatation of the calyceal-pelvic system manifests

Symptoms of hydronephrosis: pain in the lower back, in the side or in the abdomen, frequent urges to urinate, difficulty urinating, cloudy urine, blood in the urine, high fever, a feeling of heat, cold or chills. In young children there may be abdominal enlargement, vomiting, restlessness, and signs of urinary tract infection. In a pregnant woman and the fetus there are usually no symptoms.

How caliectasis and pyelectasis are detected

The basis of diagnosis is ultrasound, as well as excretory urography and renography. The doctor may order blood and urine tests for infection, a digital rectal examination to check the prostate, and X-ray or CT to find an obstruction in the path of urine. In a fetus, the degree is assessed by the size of the renal pelvis on ultrasound.

When to see a urologist or nephrologist

With dilatation of the kidney cavities, one should see a urologist or nephrologist. An appointment is needed if you see these words in your ultrasound report, if your side or back hurts, if your urine is cloudy or contains blood, or if your temperature rises. These signs should be checked as soon as possible to determine the cause.

• Pain in the lower back, in the side or in the abdomen
• Cloudy urine or blood in the urine
• High fever, chills
• Frequent or difficult urination

Dilatation of the kidney cavities by itself is not a reason to call an ambulance. 103/112 — if the condition is life-threatening or has sharply worsened, for example, with sudden loss of consciousness or inability to help oneself independently.

This material is for reference. What your ultrasound picture means and whether treatment is needed is decided by a doctor at an appointment.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer