the gradual decrease in the magnitude or intensity of a sound wave as it passes through its medium; in the case of ultrasound this is caused by a combination of energy absorption by the medium as heat and sound wave scattering
class II device
Class II devices are those for which general controls alone are insufficient to assure safety and effectiveness, and existing methods are available to provide such assurances. In addition to complying with general controls, Class II devices are also subject to special controls. Examples of Class II devices include powered wheelchairs, infusion pumps, surgical drapes, and fetal dopplers.
continuous wave doppler
This type of Doppler ultrasound uses the change in pitch of the sound waves to provide information about blood flow through a blood vessel. The doctor listens to the sounds produced by the transducer to evaluate the blood flow through an area that may be blocked or narrowed. This type of ultrasound can be done at the bedside in the hospital to provide a rapid estimate of the extent of blood vessel damage or disease.
This is the type of ultrasound used by your hand-held fetal ultrasound doppler.
a unitless term of measure that expresses a value as a fraction or multiple of a standard unity value. Decibel notation allows an extremely wide dynamic range to be represented by a much smaller data set.
A special form of ultrasound that uses sound waves to measure the velocity of blood flow. Doppler ultrasound can be used to listen to the fetal heart beat, examine the fetal heart for defects, and estimate placental blood flow.
electronic fetal monitor
An electronic device that is used to monitor the heart rate of the fetus before delivery. The electronic fetal monitor is usually used in labor and can identify fetal problems before delivery. There is some evidence that monitoring the fetal heart rate electronically may increase the rate of cesarean delivery. Most obstetricians believe that it identifies serious fetal problems earlier than other methods, thus improving outcome. Another method for monitoring the fetus' health during labor is listening to the fetal heart beat with a special fetal stethoscope or fetal ultrasound doppler device at regular intervals. There are two types of fetal monitors: 1) external, which are attached to the mother's abdomen and 2) internal, which attach to the infant's scalp inside the uterus.
Fetal Heart Rate
Monitoring of the baby before birth. This usually refers to monitoring of the fetal heart beat. There are two ways to do this. Before the mother's membranes have ruptured (water has broken) a belt containing a receiver similar to an fetal ultrasound doppler can be strapped to her abdomen and used to monitor the fetal heart rate and uterine contractions. After the membranes have ruptured and the cervix has dilated, an internal monitor can be attached directly to the baby's scalp. There are other tests that can be used to monitor the fetus during and before labor such as ultrasound , scalp pH measurements, and others.
fetal heartbeat sounds
A galloping horse is what your baby's heartbeat will sound like and will be about twice as fast as the mother's heart rate. An average normal fetal heart rate is between 120-180 BPM (Beats Per Minute). Where as an average adult heart rate at rest is between 60-100 BPM
fetal ultrasonic monitor
is a device designed to transmit and receive ultrasonic energy into and from the pregnant woman, usually by means of continuous wave (doppler) echoscopy. The device is used to represent some physiological condition or characteristic in a measured value over a period of time (e.g., perinatal monitoring during labor) or in an immediately perceptible form (e.g., use of the ultrasonic stethoscope). This generic type of device may include the following accessories: signal analysis and display equipment, electronic interfaces for other equipment, patient and equipment supports, and component parts. This generic type of device does not include devices used to image some relatively unchanging physiological structure or interpret a physiological condition, but does include devices which may be set to alarm automatically at a predetermined threshold value.
This is a special type of stethoscope used for listening to a baby. There are many types of fetoscopes available, and a regular stethoscope works as well. This can usually be used after about 18 weeks.
the rate at which oscillations governed by a sine wave occur in a given property, measured in cycles per second. A cycle is the process of shifting from minimum value up to a maximum value and then back down to the initial minimum value.
Pregnancies at high risk of fetal or maternal complications. There are many factors that contribute to complications during pregnancy and delivery. Chronic medical problems in the mother, past history of repeated preterm delivery, and abnormalities of the fetus or placenta all increase the risk of complications. Women with high-risk pregnancies should be seen and treated by someone who is experienced in caring for complicated pregnancies. Usually, this is an obstetrician or a perinatologist, an obstetrician with additional training in treating high-risk pregnancy problems. In some cases a consultation with neonatologist (specialist in the care of sick newborns) can prepare you for what to expect if your baby has problems. Some hospitals have high-risk pregnancy units, where mothers stay during part of their pregnancy to receive the care they need. This is one of those conditions that is best treated by a hospital that has a high volume of these types of patients.
Home uterine monitoring
Measurement of uterine activity at a patient's home. Women wear a special belt that identifies uterine contractions and either notifies the woman directly or transmits the information to the doctor. It can be especially helpful in monitoring women with premature labor. Use of this technique puts patients in daily contact with their health care provider. The contractions are transmitted by telephone to a center so the doctor can evaluate them on a computer. This can be an alternative to hospitalization
The fetal doppler itself may have some background noise, static, popping etc. When the fetal doppler probe is moved on the abdomen, louder popping noises may result. Sometimes, the movements of your baby in later pregnancy also produce louder noises. Ultrasound gel use is integral on cutting down on much of the static produced when positioning the fetal dopplers trasducer during an exam.
internal fetal monitoring
It is an internal monitoring with an electrode attached to the baby's head to record heart tones, and a pressure catheter to record contractions. This is also used during labor and birth, however, it is not used intermittently
You may also hear sounds of your own heart or blood flow. A major artery runs through your abdomen and the swish of your blood through it is sometimes picked up by the fetal doppler. This sound is heard by the baby later in pregnancy and has been recorded and used to calm upset babies after birth.
A specialist in the medical and surgical problems associated with women's reproductive system. These doctors receive at least four years of specialty training to prepare them to assist women with pregnancy, delivery, postnatal care and other women's health issues. Many OB-GYN serve as primary care physicians for their patients and are viewed as such by insurance plans. During pregnancy, a strong doctor-patient relationship often develops. This relationship can be a source of confidence and trust in dealing with other health issues. Surveys have shown that women often continue to receive care from the same OB-GYN for many years.
A-Mode - is a one-dimensional display of sound waves. Each time a sound wave hits a structure, a spike is formed on the examiner's screen. The height and spacing between each of the echoes provides the examiner with valuable information. A-Mode scans are now mostly obsolete in medical imaging.
B-Scan - is used to create a two-dimensional, cross-section view. Multiple sound waves are emitted from the probe allowing the examiner to visualize structures.
2D - Traditionally fetal ultrasounds are 2D, providing a two dimensional image. These images are made up of image slices of which only one at a time is visible and creates a flat looking image. A 2D fetal ultrasound can display up to 100 images per second.
3D - Recently, three dimensional fetal ultrasounds have become more and more common but due to there high expense ($250,000) haven't made there way into all hospitals. The 3D fetal ultrasound takes thousands of slices and digitally stores and shades them to emulate a more life like image of the baby.
4D - A Four dimensional fetal ultrasound simply means that the images can be seen in real time, allowing for the study of fetal behavior.
Ultrasounds allow imaging of body parts using sound waves. Ultrasound uses sound waves that are above the range of human hearing to create an image of organs within the body. Sound waves are reflected off internal body structures and back to the ultrasound machine. The reflected sound waves are analyzed by computer and turned into pictures. This method of imaging results in less clearpictures than X-rays, CAT scans or MRI. However, there is no radiation risk with ultrasound and no confirmed adverse effects on the fetus or mother from diagnostic ultrasound examinations in pregnancy.
There are different types of ultrasound exams. They are differentiated by the purpose for which they are done and the level of detail obtained.
- Limited exams are focused studies used to answer specific questions about the fetus, mother, or both. This exam is often used when you go to your doctor or the hospital with an urgent problem related to your pregnancy.
- Basic exams are performed to survey for obvious malformations of the fetus and to estimate fetal age, the amount of amniotic fluid present, location of the placenta, and for other concerns. These are the kind of exams that you would likely receive in your doctor's office or in the hospital as a routine evaluation. They are typically performed at 18-20 weeks of pregnancy.
- Comprehensive exams are a more in-depth look at the fetus when there is reason to suspect something is wrong with the fetus or mother. They include a detailed examination that is often done as a response to an abnormal screening test such as the alpha-fetoprotein (AFP) screen. In some areas of the country this is called a Level II or Level III ultrasound. Technical difficulties and the need to image many different areas of the fetus may extend the length of this exam to 30 or more minutes.
Ultrasound can measure fetal size, the amount of amniotic fluid, estimate fetal gestational age, identify multiple fetuses, some fetal abnormalities such as microcephaly or Down Syndrome, and locate the location of the placenta. Although an ultrasound can usually determine gender of your baby, many families do not want to know this information before delivery and some ultrasound centers have a policy of not revealing the gender
Ultrasound gel is specially formulated to act as a coupling agent and reduce static that is often caused when using a fetal doppler. To get optimal use and sound out of a fetal doppler monitor use plenty of ultrasound gel. Do not use colored gels or lotions. Any oil based substance used with a fetal doppler will cause excess static and can damage the fetal doppler probe.