Ultrasonography of percutaneous nephrostomy tube

A nephrostomy or percutaneous nephrostomy is an artificial opening created between 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 ...

and the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

which allows for the urinary diversion directly from the upper part of the urinary system ( renal pelvis). It is an

interventional radiology Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as Fluoroscopy, x-ray fluoroscopy, CT scan, computed tomography, magnetic resonance imaging, or ultraso ...

surgical procedure Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

in which the renal pelvis is punctured whilst using imaging as guidance. Images are obtained once an antegrade pyelogram (an injection of contrast), with a fine needle, has been performed. A nephrostomy tube may then be placed to allow drainage. An urostomy is a related procedure performed more distally along the urinary system to provide urinary diversion.

Uses

A nephrostomy is performed whenever a blockage keeps urine from passing from the kidneys, through the ureter and into the

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

. Without another way for urine to drain, pressure would rise within the urinary system and the kidneys would be damaged. The most common cause of blockage necessitating a nephrostomy is

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

, especially ovarian cancer and colon cancer. Nephrostomies may also be required to treat pyonephrosis, hydronephrosis and kidney stones.

Diagnosis

Percutaneous nephrostomy is used in Whitaker test to differentiate recurrent obstruction or permanent dilatation after an operative surgery that corrects the cause of obstruction. This procedure is also used for antegrade pyelography to visualize the upper urinary tract system.

Treatment

Percutaneous nephrostomy is also used to treat hydronephrosis caused by kidney stones, pregnancy, stricture of the urinary tract, urinary tract/cervical/prostate tumours. Besides, infections such as urosepsis and pyonephrosis can also be drained by nephrostomy tube insertion. Percutaneous nephrostomy is also useful in divert urine away from diseased site to enhance healing. Examples of conditions that can be treated with such method are malignant/traumatic/inflammatory

fistula In anatomy, a fistula (: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") is an abnormal connection (i.e. tube) joining two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other h ...

, and haemorrhagic cystitis. Percutaneous nephrostomy is also used to provide access for chemotherapy/antibiotic/antifungal therapy, antegrade urethral stent placement, stone retrieval, and endopyelotomy (endoscopic surgery for the enlargement of the junction of renal pelvis and ureter). Ureteral stents may be placed during the procedure for patients who are expected to need long-term decompression of the renal system, such as those with malignant obstructions. A recent meta-analysis has shown that ureteral stenting is a safe alternative to traditional percutaneous nephrostomy. Stenting may help to improve patient quality of life by reducing need for frequent tube exchanges and a lower risk of tube displacement.

Process

Nephrostomies are created either by

surgeon In medicine, a surgeon is a medical doctor who performs surgery. Even though there are different traditions in different times and places, a modern surgeon is a licensed physician and received the same medical training as physicians before spec ...

s or interventional radiologists. Under interventional radiology, the subject either lies down on the side or in a prone position. An area is selected below the 12th rib, bounded laterally by the posterior axillary line and the muscles of the spine and from below by the pelvic bone. The exact area is then located by ultrasound. Local anesthetic infiltration is used to numb the area. Then a needle would pass through to make the puncture on the kidney. Then, urine from the kidney is aspirated and check for its contents. If the urine is clear, dye will be injected to delineate the renal pelvis and renal calyx. If the urine is turbid, it means the urine is infected. Dye injection is avoided in case of turbid urine to prevent the spread of infection to other parts of the urinary system. Then, a guidewire is inserted into the through the needle and parked within the upper renal calyx or within the ureter under

fluoroscopy Fluoroscopy (), informally referred to as "fluoro", is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a surgeon to see t ...

guidance. Then the puncture tract is dilated using a dilator. Various types of catheters such as pigtail catheter or Malecot catheter (a catheter that has a special mechanism for preventing blockage in case of thick pus in pyonephrosis and not easily dislodged when compared to pigtail catheter) can be used. The catheter is inserted through the guidewire and is secured in place by suturing it to the skin. The other end of the catheter is attached to a urine bag for drainage of urine from the kidney.

Risks

Percutaneous nephrostomy is overall a very safe procedure. Risks and complications include: * Malposition * Intra- peritoneal leakage, causing ascites *

Hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, ...

Infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

. This can generally be treated with

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy ...

. Although pneumothorax and colonic injury are more common on subcostal needle insertion, these are rare complications. Blood in urine usually clears up after 48 to 72 hours. Bleeding longer than this period may signifies more serious bleeding complication. About 2–4% of percutaneous nephrostomy cases require blood transfusion. Arteriovenous fistula is a rare complication. The BMJ has published original research of this condition and its treatment, * Malignant ureteric obstruction (MUO) in the context of metastatic cancer indicates a poor prognosis. * Nephrostomy is commonly used for renal decompression in these cases but rarely confers survival benefit. * Living with a nephrostomy is associated with complications and a reduced quality of life. * The extremely poor mortality ... displayed in this study will aid clinicians in being more selective when offering patients nephrostomy when presenting with MUO. BMJ report "High early mortality following percutaneous nephrostomy in metastatic cancer: a national analysis of outcomes"; Amandeep Dosanjh1, Benjamin Coupland, Jemma Mytton, Stephen King, Harriet Mintz, Anna Lock, Veronica Nanton, Param Mariappan, Nigel Trudgill and Prashant Pate

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References

External links

Cardiovascular and Interventional Radiological Society of Europe
{{Urologic surgical and other procedures Urologic surgery Interventional radiology Nephrology