Ultrasound of the urinary tract involves the use of an

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

probe to image parts of the

urinary tract The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressu ...

. The urinary tract is the path that

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

follows after it is formed within the

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

s, and involves a left and right

ureter The ureters are tubes composed of smooth muscle that transport urine from the kidneys to the urinary bladder. In an adult human, the ureters typically measure 20 to 30 centimeters in length and about 3 to 4 millimeters in diameter. They are lin ...

, the

bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...

, and the

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

Procedure

Ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

involves a probe that is placed near a structure and uses the transmission of ultrasound waves through a structure to produce images, after computer processing. Ultrasound of the urinary tract is performed by a probe placed on the abdominal wall, called a transducer. This occurs while a person is lying down. It is then moved around to better visualise different parts of the urinary tract. Gel is used on the abdominal wall, allowing smooth movement and improve sound conduction. The images are usually taken by a trained ultrasonographer, and then reported by a specialist radiologist. Prior to the test, a medical practitioner will have conducted a medical history to evaluate for symptoms that may relate to the urinary tract. Before the exam, the person will need to drink three glasses of water (about 500 ml) at least one hour before the exam. If the person is on

fluid restriction diet A fluid restriction diet is a diet which limits the amount of daily fluid consumption. Besides beverages, many foods also include fluids which needs to be taken into consideration. A fluid-restrictive diet assists in preventing the build-up of fluid ...

(due to heart, liver or kidney problems), then he can ignore the instruction. If there is a

urinary catheter The human urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pr ...

, the catheter should be clamped immediately after drinking the water. The person should not pass any urine until the scan is over. If the urinary bladder is the subject of interest, a person will be asked to pass urine and the amount of urine left in the bladder may be recorded.

Uses

For imaging of the urinary tract it may involve: * Assessment of the urinary tract for abnormalities such as blockage or narrowing, the presence of

kidney stone Kidney stone disease (known as nephrolithiasis, renal calculus disease, or urolithiasis) is a crystallopathy and occurs when there are too many minerals in the urine and not enough liquid or hydration. This imbalance causes tiny pieces of cr ...

s, or tumours. * Use of

duplex ultrasound Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of a ...

to determine if there is backward flow of urine, for example in

vesicoureteric reflux Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one directi ...

. * Determination of how much urine is in the bladder, for example to assess for

urinary retention Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include urinary incont ...

. * To look for evidence and the cause of chronic kidney disease, for example shrunken kidneys. * To assist with an interventional procedure, such as the taking of a biopsy, or draining of an abscess or cyst. * To monitor a kidney transplant. The symptoms that a person may experience that cause the test to be requested may be blood in the urine, abdominal pain, abnormal kidney function tests, and frequent

urinary tract infection A urinary tract infection (UTI) is an infection that affects a part of the urinary tract. Lower urinary tract infections may involve the bladder (cystitis) or urethra (urethritis) while upper urinary tract infections affect the kidney (pyel ...

s (of which symptoms may include the need to pass urine frequently, pain on urination, and worsening urinary incontinence).

Risks

Ultrasound is non-invasive and does not involve radiation, unlike some methods of imaging of the urinary tract such as

X-rays An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

CT scans A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

. It is usually painless. It is safe in pregnancy. Risks specific to the scan involve: * Discomfort from the abdominal probe * Distress related to results that are reported *

Financial risk Financial risk is any of various types of risk associated with financing, including financial transactions that include company loans in risk of default. Often it is understood to include only downside risk, meaning the potential for financi ...

s related to the scan, especially if it produces an indeterminate result * Risks entailed with treatment or further investigations required following the results. Abdominal obesity, gas within the colon, and barium within the intestines can all impact the accuracy of the test.

Other tests

Other tests are available to image the urinary tract. These include

MRI scan Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ra ...

References

{{Medical imaging Ultrasound Urologic imaging