Kidney scanning is a nuclear study performed to assist in diagnosing abnormal blood flow, collecting system defects, and excretory function of the organs. It can also provide information about the size and shape of the kidneys. Flow studies, excretion studies, determination of glomerular filtration rate (GFR), and static imaging reveal the presence of the different types of pathology. Such pathology includes vascular disease, inflammation or infection, obstructive uropathy, masses, congenital anomalies, acute or chronic renal failure, and the effects of trauma or injury. Renography involves the times of uptake and excretion of the radionuclide by the kidneys, which is plotted on a graph and compared with normal parameters of organ function.⁵⁹

Several radiopharmaceuticals administered IV are used in kidney scanning, depending on their distribution in the organs. Technetium 99m administered as technetium Tc 99m DTPA is used to study blood flow and GFR, and technetium Tc 99m dimercaptosuccinic acid (DMSA) or technetium Tc 99m gluceptate is used to assess the parenchyma for structural defects with static imaging; technetium Tc 99m glucoheptonate is the agent of choice for children. Iodine 131 as orthoiodohippurate (OIH) I 131 is administered to study renal plasma flow and tubular secretion. The time schedule for scanning varies with the radiopharmaceutical administered and the information to be obtained. Abnormalities are identified by a delayed, diminished, or absent flow to the affected kidney. A triple renal study can be performed with the administration of two IV injections of radiopharmaceuticals to obtain perfusion, excretion, and structural information.

Another study performed on the genitourinary system involves imaging of the valve action at the ureterovesicular junction to assist in the diagnosis of vesicoureteral reflux. It is performed on adults and children using technetium Tc 99m DTPA instilled into the bladder. This procedure is preferred over voiding cystourethrography because it has a very low radiation exposure to the bladder and surrounding organs.⁶⁰

• Normal size, shape, position, symmetry, perfusion, and function of the kidneys; no renal vascular disease, trauma, infection or inflammation, obstructive uropathy, masses, congenital anomalies, or renal failure

• Inability of client to remain still during the procedure, especially if the client is a child
• Antihypertensives taken within 24 hours of the study

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Indications

• Diagnosing renal artery stenosis resulting from dysplasia or atherosclerosis and causing arterial hypertension and reduced glomerular filtration revealed by a diminished flow to the affected kidney
• Diagnosing renal vein thrombosis resulting from dehydration in infants or obstruction of blood flow resulting from tumors in adults revealed by enlarged kidney and decreased flow
• Diagnosing renal artery embolism or renal infarction causing obstruction as revealed by absent flow and function
• Determining effect of renal trauma such as arterial injury, renal contusion, hematoma, rupture, AV fistula, or urinary extravasation as revealed by decreased or absent flow and an abnormal renal outline
• Detecting renal infection or inflammatory disease such as acute or chronic pyelonephritis, renal abscess, or nephritis as revealed by decreased perfusion in the affected area, decreased kidney size, and scarring
• Determining and locating the cause of obstructive uropathy such as calculi, neoplasm, inflammation, or congenital disorders as revealed by delayed or reduced blood flow to the affected kidney; determining and locating the cause of nonvisualization of the bladder in complete obstruction and nonvisualization of the kidney if the obstruction is of long standing
• Detecting cystic disease such as simple cysts, polycystic disease in children or adults, or medullary sponge kidney or cystic disease in adults as revealed by abnormal renal size and shape, single or multiple cysts, or unperfused or perfused areas, depending on the type of cyst
• Detecting type, position, and number of congenital anomalies such as ectopic kidney, horseshoe kidney, supernumerary kidneys, or agenesis of left kidney as revealed by changes in size, shape, or position of kidney(s)
• Evaluating acute and chronic renal failure as revealed by a reduction in uptake, depending on renal function, and by an absence of uptake in renal insufficiency, indicating a poor prognosis
• Evaluating kidney transplant for acute or chronic rejection as revealed by decreased flow and function early in rejection, acute tubular necrosis within 24 hours of rejection with absence of excretion from the kidney, acute rejection within 5 days postoperatively, and chronic rejection revealed by ongoing decreased flow and function
• Determining vesicoureteral reflux in children as revealed by reflux during bladder filling or micturition, or both, during or after voiding, and calculating the amount of reflux⁶¹

Contraindications

• Pregnancy, unless the benefits of performing the procedure greatly outweigh the risks to the fetus

[Section Outline]

• Indications
• Contraindications

Nursing Care Before the Procedure

Client teaching and physical preparation are the same as for any nuclear scan study (see section under "Brain Scanning").

• Inform the client of the scanning schedule, and explain that the study takes 30 to 60 minutes initially but that an additional 4 hours are needed if special imaging or a renogram is to be performed.
• Ensure that the client has had adequate fluid intake before the study and provide 2 glasses of fluids to drink immediately before the study.
• Advise the client to withhold antihypertensive medications 24 to 48 hours before the test.
• Administer ordered Lugol's solution before the study to reduce uptake of the radionuclide by the thyroid gland.
• Inform the client that additional medications may be administered during the study.
• History should include information about renal-urinary status and results of renal function laboratory tests (blood urea nitrogen, creatinine).

The client is placed on the examining table in a prone, supine, or sitting position depending on the study to be performed. Positions can be changed during the imaging. The client is requested to remain still during the scanning procedure. The radiopharmaceutical for flow studies is administered IV and sequential imaging is performed every 2 seconds for 30 to 60 seconds. Blood pool imaging can also be obtained at this time. Excretion studies are performed after the administration of the appropriate radiopharmaceutical, and one image every minute for 3 minutes at 30-minute intervals is obtained. There is an immediate uptake for flow and excretory studies, with a peak at 3 to 5 minutes, followed by a decline. Renal pelvis and bladder activities can be seen in 3 to 6 minutes. Excretion studies are best performed on the hydrated client, unless the study is performed for hypertension. These are followed by static imaging to reveal the collecting system and delayed static imaging 2 to 3 hours later to reveal cortex abnormalities. In some cases, imaging can be performed 24 hours later, especially in clients with renal failure, because this condition slows the uptake of the radionuclide. All information obtained is stored in a computer for further interpretation and computation. During the flow and static imaging, a loop diuretic such as furosemide (Lasix) can be administered IV to encourage large urinary output, which is then followed by imaging.⁶²

Renogram curves can be plotted concurrently with flow studies in which blood flow is imaged and recorded as it occurs. Information is displayed and a chart recording is made. A curve is plotted based on the amount of radionuclide uptake over a period of time, which results in curve shapes with diagnostic value. The graphed data provide information about vascular, tubular, and excretory phases of radionuclide uptake and removal by the kidneys. Urine and blood laboratory studies are performed after the renogram to correlate findings before diagnosis.⁶³

For a vesicoureteral reflux procedure, the client is requested to void and a catheter is inserted into the bladder. The radiopharmaceutical is instilled into the bladder, and multiple images are obtained during bladder filling. The client is then requested to void after catheter removal or the bladder is emptied with the catheter in place, depending on department policy. Imaging continues during voiding and after voiding is completed. Reflux is determined by calculating the urine volume and counts obtained by imaging. This study is preferred for children who require repeated studies for long-term care for vesicoureteral reflux to avoid the high gonadal radiation exposure that results from x-ray contrast cystourethrography.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any nuclear scan study (see section under "Brain Scanning").