Ultrasound, Thyroid and Parathyroid

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Ultrasound, Thyroid and Parathyroid

Synonym/acronym: Parathyroid sonography, thyroid echo, thyroid sonography.

Common use

To visualize and assess the thyroid and parathyroid glands for tumor, cancer, and cyst. Also used to stage cancer, guide biopsies, and monitor the effectiveness of therapeutic interventions.

Area of application

Anterior neck region, parathyroid, thyroid.

Contrast

Done without contrast.

Description

Ultrasound (US) procedures are diagnostic, non-invasive, and relatively inexpensive. They take a short time to complete, do not use radiation, and cause no harm to the patient. High-frequency sound waves of various intensities are delivered by a transducer, a flashlight-shaped device, pressed against the skin. The waves are bounced back off internal anatomical structures and fluids, converted to electrical energy, amplified by the transducer, and displayed as images on a monitor. US is often used as a diagnostic and therapeutic tool for guiding minimally invasive procedures such as needle biopsies and fluid aspiration. The contraindications and complications for biopsy and fluid aspiration are discussed in detail in the individual monographs.

Thyroid and parathyroid US is used to determine the position, size, shape, weight, and presence of masses of the thyroid gland; enlargement of the parathyroid glands; and other abnormalities of the thyroid and parathyroid glands and surrounding tissues. The primary purpose of this procedure is to determine whether a nodule is a fluid-filled cyst (usually benign) or a solid tumor (possibly malignant). This procedure is useful in evaluating the glands’ response to medical treatment or assessing the remaining tissue after surgical resection. US is clearly the procedure of choice when examining the glands of pregnant patients. This procedure is usually done in combination with nuclear medicine imaging procedures and computed tomography (CT) of the neck. Despite the advantages of the procedure, in some cases it may not detect small nodules and lesions (less than 1 cm), leading to false-negative findings.

This procedure is contraindicated for

    N/A

Indications

  • Assist in determining the presence of a tumor, as evidenced by an irregular border and shadowing at the distal edge, peripheral echoes, or high- and low-amplitude echoes, depending on the density of the tumor mass; and diagnosing tumor type (e.g., benign, adenoma, carcinoma)
  • Assist in diagnosing the presence of a cyst, as evidenced by a smoothly outlined, echo-free amplitude except at the far borders of the mass
  • Assist in diagnosis in the presence of a parathyroid enlargement indicating a tumor or hyperplasia, as evidenced by an echo pattern of lower amplitude than that for a thyroid tumor
  • Determine the need for surgical biopsy of a tumor or fine-needle biopsy of a cyst
  • Differentiate among a nodule, solid tumor, or fluid-filled cyst
  • Evaluate the effect of a therapeutic regimen for a thyroid mass or Graves’ disease by determining the size and weight of the gland
  • Evaluate thyroid abnormalities during pregnancy (mother or baby)

Potential diagnosis

Normal findings

  • Normal size, position, contour, and structure of the thyroid and parathyroid glands with uniform echo patterns throughout the glands; no evidence of tumor cysts or nodules in the glands

Abnormal findings related to

  • Glandular enlargement
  • Goiter
  • Graves’ disease
  • Parathyroid tumor or hyperplasia
  • Thyroid cysts
  • Thyroid tumors (benign or malignant)

Critical findings

    N/A

Interfering factors

  • Factors that may impair clear imaging

    • Attenuation of the sound waves by the ribs, which can impair clear imaging of the right lobe of the parathyroid
    • Incorrect placement of the transducer over the desired test site; quality of the US study is very dependent upon the skill of the ultrasonographer
    • Metallic objects (e.g., jewelry, body rings) within the examination field, which may inhibit organ visualization and cause unclear images
    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status
  • Other considerations

    • Nodules less than 1 cm in diameter may not be detected.
    • Nonthyroid cysts may appear the same as thyroid cysts.

Nursing Implications and Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in assessing thyroid and parathyroid gland function.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s endocrine system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results (i.e., barium procedures, surgery, or biopsy). There should be 24 hr between administration of barium and this test.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Address concerns about pain related to the procedure and explain that some pain may be experienced during the test, and there may be moments of discomfort. Inform the patient that the procedure is performed in a US department by a health-care provider (HCP), with support staff, and takes approximately 30 to 60 min.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure that the patient has removed all external metallic objects from the area to be examined prior to the procedure.
  • Instruct the patient to void and change into the gown, robe, and foot coverings provided.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Ask the patient to remain still throughout the procedure because movement produces unreliable results.
  • Place the patient in the supine position on an examination table; other positions may be used during the examination.
  • Expose the neck and chest area and drape the patient.
  • Hyperextend the neck, and place a pillow under the patient’s shoulders to maintain a comfortable position. (An alternative method of imaging includes the use of a bag filled with water or gel placed over the neck area.)
  • Conductive gel is applied to the skin, and a transducer is moved over the skin to obtain images of the area of interest.
  • Ask the patient to breathe normally during the examination. If necessary for better organ visualization, ask the patient to inhale deeply and hold his or her breath.

Post-Test

  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • When the study is completed, remove the gel from the skin.
  • Recognize anxiety related to test results. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include antibodies antithyroglobulin, biopsy thyroid, chest x-ray, CT thorax, MRI chest, newborn screening, PTH, parathyroid scan, radioactive iodine uptake, thyroid-binding inhibitory immunoglobulin, thyroglobulin, thyroid scan, TSH, thyroxine free, thyroxine total, triiodothyronine free, and triiodothyronine total.
  • Refer to the Endocrine System table at the end of the book for related tests by body system.