A method of gathering information about the body by taking images using high-frequency sound waves.
Also known as sonography or ultrasonography; a diagnostic screening technique that uses high-frequency sound waves to create images of internal body structures. Because ultrasound scanning does not involve exposure to ionizing radiation (as X rays do), it is a safe screening and diagnostic technique that can safely be used in pregnant women and in children. During pregnancy, ultrasound is used to determine the age and rate of growth of the fetus and its position in the uterus. It can also be used to identify multiple pregnancies or a visible birth defect, and to determine the position of the placenta and the amount of amniotic fluid. Ultrasound scanning is also used to guide procedures such as laparoscopy, amniocentesis, chorionic villus sampling, and needle biopsies.
Ultrasound is a diagnostic method involving the transmission of exceptionally high-frequency sound waves into the body. The subsequent analysis of the echoes that bounce back is used to create visual representations of internal organs or a fetus within the uterus. Distinguishing itself from various other imaging methods, ultrasound scanning can generate dynamic, moving images. This procedure is painless and regarded as safe.
Ultrasound scanning’s capability to visualize soft tissues renders it valuable for inspecting fluid-filled or delicate structures within the body. However, ultrasound waves are impeded by bone or gas, consequently restricting their effectiveness in examining regions enclosed by bone (like the adult brain) or those containing gas (such as the lungs or intestines).
One prevalent application of ultrasound involves observing the uterus and fetus at any stage of pregnancy.
Ultrasound allows for the assessment of the fetus’s age, dimensions, and rate of development. When the conception date is known, the scan reveals whether the fetus corresponds to the anticipated size for its gestational age. Conversely, the fetus’s size aids in determining the precise conception date, which in turn assists healthcare professionals in estimating the projected delivery date.
Ultrasound scans can reveal the presence of multiple fetuses. Moreover, they facilitate the identification of specific fetal issues like neural tube defects or congenital heart disease, enabling prompt post-birth treatment for affected infants. Additionally, these scans provide insight into the placenta’s positioning, which serves as the conduit for oxygen and nutrients to the fetus. If the placenta’s placement might hinder a natural delivery, a caesarean section delivery might be required.
Scans are commonly conducted around the 18–20 week mark of pregnancy. In instances where concerns like an ectopic pregnancy (when an embryo is outside the uterus) or an impending miscarriage are suspected, early scans might be performed. Scanning plays a pivotal role in procedures such as amniocentesis (the extraction of amniotic fluid for analysis) and chorionic villus sampling (the removal of placental tissue). It provides visibility into the fetus’s and placenta’s positions, aiding in guiding needles into the uterus. Subsequent scans might be conducted later in pregnancy if there’s a perception of slowed fetal growth, a reduction or increase in fetal movements, or vaginal bleeding in the mother. For pregnancies deemed high-risk or overdue, a scan might be conducted just before delivery to assess fetal size, development, position within the uterus, the quantity of amniotic fluid, and to confirm the placenta’s positioning.
Ultrasound scanning can additionally be employed with newborn infants to inspect the brain by utilizing an opening in the skull, enabling the investigation of anomalies like hydrocephalus, which involves an excessive accumulation of fluid within the skull.
Ultrasound imaging offers clear visibility of the liver, enabling the diagnosis of liver conditions like cirrhosis, cysts, abscesses, or tumors. This method also detects the presence of gallstones in the gallbladder or bile ducts. In cases of jaundice, a scan can determine whether the cause is bile duct obstruction or liver disease. The pancreas can be examined for cysts, tumors, or pancreatitis, while the kidneys can be screened for congenital defects, cysts, tumors, and hydronephrosis (swelling due to urine outflow blockage). Additionally, various other organs can be assessed through ultrasound for purposes such as identifying cysts, solid tumors, or foreign bodies. These organs include the thyroid gland, breasts, bladder, testes, uterus, fallopian tubes, ovaries, spleen, and eyes. Ultrasound can also be utilized to gauge the risk of fracture in suspected cases of osteoporosis.
Echocardiography, a form of ultrasound imaging, is employed to examine the heart. This technique proves especially valuable in the assessment of heart murmurs, congenital heart disease, heart failure, and heart valve disorders.
Ultrasound scanning is additionally employed in needle biopsy procedures, aiding in the precise guidance of a thin hollow needle to a specific location within an organ for the extraction of cells, tissue, or fluid for examination.
This method is an adapted version of ultrasound scanning, employing the Doppler effect (the alteration in pitch when a sound source is in motion relative to the detector) to investigate moving entities. Doppler ultrasound scanning finds utility in assessing the fetal heartbeat and acquiring data about blood flow rates within blood vessels, such as those found in the fetal umbilical cord.
The patient disrobes the area to be examined, ensuring that the skin is exposed. Subsequently, a gel is applied to the skin to promote proper contact between the skin and the transducer, the device responsible for emitting and receiving ultrasonic waves. This transducer is positioned on the skin above the targeted body part and moved in a back-and-forth motion. As tissues meet their boundaries, echoes rebound to the transducer. The transducer converts these sound echoes into electrical signals, which are then sent to a computer for conversion into an image. In cases of early pregnancy or gynecological assessments, an alternative approach involves inserting a transducer into the vagina, referred to as transvaginal ultrasound.
In cases of early pregnancy scans, it’s typically advised for the woman to abstain from urinating for a few hours before the procedure. A full bladder aids in enhancing the view of the uterus by shifting adjacent loops of intestines. Meanwhile, for liver or gallbladder scans, patients are generally requested to refrain from eating for several hours prior to the scan.