An ultrasound-guided biopsy is a minimally invasive diagnostic procedure that combines real-time imaging with the collection of a tissue sample. It uses harmless, high-frequency sound waves to create live images of internal structures. This allows a specialist, typically a radiologist, to visually track the biopsy needle’s path as it enters the body. The purpose of this technique is to obtain small specimens from an area of concern, such as a suspicious lump or lesion, for microscopic examination by a pathologist. This collection of tissue is important for determining a definitive diagnosis.
Indications for Guided Biopsy
Ultrasound guidance is selected for tissue sampling due to its advantages over other imaging methods. Unlike CT or X-ray, ultrasound does not use ionizing radiation, making it a safer option for repeated use and for populations such as pregnant women. The technology provides excellent visualization of soft tissues and fluid-filled structures, often yielding clearer images of masses within organs like the thyroid, breast, and liver. Real-time visualization enables continuous monitoring of the needle tip to ensure accurate placement within the target lesion. This precision maximizes the diagnostic yield and prevents sampling healthy surrounding tissue. The technique is commonly employed to investigate abnormalities in accessible sites, including lymph nodes, breast lumps, and thyroid nodules.
Patient Preparation and Consent
Patients receive specific instructions regarding preparation. A key requirement is the temporary modification of medication, particularly blood thinners like aspirin or anticoagulants, which increase the risk of bleeding at the biopsy site. Patients must consult their physician several days in advance to determine when to safely stop or adjust these medications. Fasting is not always necessary but may be required depending on the biopsy site, such as with certain abdominal procedures. Prior to the biopsy, the informed consent process is completed, where the specialist explains the steps, risks, and benefits. Patients are advised to arrange for someone to drive them home afterward, especially if a sedative is administered.
Navigating the Procedure
The procedure begins with the patient positioned comfortably on an examination table to allow the specialist easy access to the target area. A sterile gel is applied to the skin, and an ultrasound transducer is placed over the area to visualize the lesion on a monitor. The skin is cleaned with an antiseptic solution before a local anesthetic is injected to numb the biopsy site. Once numb, a tiny incision is created to allow the biopsy needle to pass through the skin. The specialist then carefully inserts the specialized needle, guiding its path continuously with the ultrasound image until the tip is precisely positioned within the target lesion. Two common methods are used:
- Fine-needle aspiration (FNA) collects a small sample of cells or fluid.
- Core needle biopsy (CNB) uses a larger needle to extract a small cylinder of tissue.
Several samples, or passes, may be taken to ensure an adequate specimen is collected for the pathologist. Following the collection, a small metallic marker may be placed at the biopsy site, especially in breast tissue, to mark the exact location for future reference.
Recovery and Pathology
Immediately after the needle is withdrawn, firm pressure is applied to the biopsy site for several minutes to stop bleeding and minimize bruising. A small sterile dressing is then applied over the puncture site. Patients are typically monitored for a short observation period, often between 30 minutes to a couple of hours, before being discharged to ensure there are no immediate complications. Minor bruising, swelling, and mild soreness at the biopsy site are common side effects that usually resolve within several days. At-home care instructions include keeping the area dry for 24 to 48 hours and avoiding strenuous activities for a day or two. The collected tissue samples are transported to a pathology laboratory for detailed analysis by a pathologist. The pathologist examines the tissue under a microscope to identify cellular structure and determine the nature of the lesion. Results are typically finalized and sent to the referring physician within three to seven working days. The physician then contacts the patient to discuss the findings and plan the next steps for care.