Computed Tomography (CT) Scan - Nursing Responsibilities

A CT scan (computed tomography, also called computerized axial tomography or CAT) is a painless, noninvasive imaging study that produces cross-sectional images of tissue that a plain X-ray cannot show clearly. Your job runs the whole length of the study: history, consent, prep, education, and watching for contrast reactions.

CT may be done with or without contrast. Contrast is an iodine-based or barium-sulfate compound given orally, rectally, or intravenously to sharpen specific tissues, organs, or vessels. Scan time depends on the area imaged.

Procedure

Protocols vary by area, but the sequence is generally:

1. Position the patient on an adjustable table inside the encircling scanner (gantry); straps and pillows help hold position.
2. Instruct the patient to hold the breath during scanning.
3. Take and record a series of transverse radiographs.
4. The computer reconstructs the data and selected images are photographed.
5. After review, IV contrast may be ordered and additional images obtained.
6. Assess the patient carefully for adverse reaction to the contrast.

Types

Abdominal and pelvic. Works up unexplained abdominal or pelvic pain and disease of the bladder, uterus, liver, colon, small bowel, and other internal organs.

Bone and skeletal. Assesses severity of bone disease: fractures, cancer, infection.

Brain. Also called cranial CT or head CT. Details head injury, stroke, brain tumors, and other brain disease.

Cardiac calcium scoring. Detects coronary artery disease (CAD) early in people at risk who have no symptoms yet. Most often suggested for males aged 45 years or older and females aged 55 and over.

Ear. Diagnoses chronic otitis media, ear infection, cholesteatoma, conductive hearing loss, mastoiditis, and evaluates cochlear implants.

Liver and biliary tract. Detailed look at the liver, gallbladder, bile ducts, and related structures.

Orbital. Details the eye sockets, eyes, and adjacent bone.

Pancreas. Helps diagnose pancreatic cancer and pancreatitis and differentiates pancreatic problems from retroperitoneal disorders.

Renal. Examines structural and functional abnormality of the kidney: tumors, obstructions, lesions.

Spinal. Images the vertebrae and spinal structures to detect spinal injury and disease.

Thoracic. Works up unexplained cough, fever, dyspnea, chest pain, and other respiratory symptoms; used to screen for lung cancer at an early, curable stage.

Contraindications

• Pregnancy (absolute contraindication)
• Known iodine allergy
• Claustrophobia
• Renal impairment, unless benefits outweigh risks
• Hyperthyroidism or toxic goiter (can induce thyrotoxic crisis)
• Complications after previous contrast administration
• Severe obesity (usually more than 300 pounds)

Interfering factors

• Retained oral or IV contrast from prior studies can degrade image visibility.
• Metal objects: eyeglasses, dentures, jewelry, hairpins.

Nursing responsibilities

Before the procedure

• Consent. Obtain a properly signed informed consent.
• Allergies. Assess for allergy to iodinated dye or shellfish if contrast will be used.
• History. Ask about recent illness, other conditions, and current medications. The scan type drives whether oral or IV contrast is needed.
• NPO. Hold food and drink for the ordered window, especially when contrast will be used.
• Clothing. Have the patient wear comfortable, loose-fitting clothing.
• Contrast warning. Tell the patient to expect mild transient pain at the needle stick and a flushed sensation from IV contrast.
• Stay still. During the scan the patient must stay still and report itching, difficulty breathing or swallowing, nausea, vomiting, dizziness, or headache immediately.
• Duration. The study takes 5 minutes to 1 hour depending on scan type and how well the patient relaxes and holds still.

After the procedure

• Diet. Resume usual diet and activity unless otherwise ordered.
• Fluids. If contrast was given, push fluids to flush the dye.

Normal results

• The specific scan type shows normal findings for that area.
• On a CT, bone (densest tissue) reads white. Tissue densities show as shades of gray, fat as black or dark gray. Cerebrospinal fluid reads black. Air also reads black, darker than fat.

Abnormal results

Abnormal findings vary by the area studied.