Deep vein scanning, or fibrinogen uptake study, is a nuclear study performed to assist in diagnosing thrombi in the lower extremity veins. It allows detection of newly formed as well as old clots. The radionuclide iodine 125 (125I) as fibrinogen I 125 is administered IV followed by immediate and delayed scanning. Increased uptake of the radionuclide indicates an abnormality because fibrinogen is involved in blood clotting and appears at the clot site. This study can be continued on a daily basis for up to 1 week after the injection in clients at risk for formation of deep venous thrombosis (DVT), that is, in postoperative, postpartum, and immobile clients.⁵⁴

• Normal structure of veins of lower extremities and venous patency; no formation or presence of DVT

• Inability of client to remain still during the procedure
• Other abnormalities in the extremity, such as infection, edema, or phlebitis, that cause fibrinogen concentration

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Indications

• Detecting DVT in its earliest stages, especially in immobilized clients, as revealed by steadily increased counts over 1 to 2 weeks
• Diagnosing and identifying the area of clot formation revealed by increased counts when compared with the opposite extremity
• Diagnosing DVT in clients who are too ill for radiographic venography or who are sensitive to the contrast media used

Contraindications

• Allergy to iodine, unless a steroid or antihistamine is administered before the study
• Need for diagnosis of DVT immediately or sooner than 24 hours
• Lymphedema, cellulitis, superficial phlebitis, or active arthritis⁵⁵

[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 that a radiation Geiger-type detector is the device used for scanning and that the study takes 1 hour.
• Administer potassium iodide before and during the procedure to prevent uptake of the radionuclide by the thyroid gland, which would affect uptake in the areas to be examined.
• History should include chronic disorders of the vascular system of the extremities; allergies to iodine; and signs, symptoms, and risks for DVT.

The areas on the extremity to be scanned are marked, and the radiopharmaceutical is administered IV. The client is requested to remain still, and the marked areas (calf and thigh) are scanned 10 minutes after the injection. A Geiger-type device is used to detect and count radiation levels. This provides a baseline for later comparisons when scanning is performed in 24 hours. In some cases, scanning is performed daily for 7 or more days after the injection of the radiopharmaceutical because it takes that long for the radionuclide to concentrate in possible thrombi. Subsequent scanning of the marked areas in 24 hours is compared with the amount of uptake in the opposite extremity. A reading of 15 times greater than the baseline or the opposite extremity reading indicates DVT.⁵⁶

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").