Norm of Obstetric Ultrasonography (Obstetric Echogram, Obstetric Ultrasound)
Fetus(es) and sac are of normal size for gestational date. No fetal abnormality detected.
Usage of Obstetric Ultrasonography (Obstetric Echogram, Obstetric Ultrasound)
Evaluate amniotic fluid volume, fetal age, position, size, or viability for proper timing of induced or cesarean delivery; fetal abnormality detection; and multiple gestation determination. Helps diagnose abruptio placentae, ectopic tubal pregnancy, endometriosis, fetal death, molar pregnancy, ovarian size, ovarian torsion, pelvic inflammatory disease, placenta previa, uterine size or rupture; provides guidance for amniocentesis, cervical cerclage placement, fetoscopy, or intrauterine procedures. Used for tumor detection, localization, characterization, and staging; can identify Down syndrome structural markers (duodenal atresia, cardiac abnormalities, brachycephaly, mild ventriculomegaly, macroglossia, abnormal facies, nuchal edema, echogenic or hyperechoic bowel, pyelectasis, and shortening of the limbs), indicating the need for genetic karyotyping.
Description of Obstetric Ultrasonography (Obstetric Echogram, Obstetric Ultrasound)
Evaluation of size, status, and location of fetus, fetal sac, and pelvic organs by the creation of an oscilloscopic picture from the echoes of high-frequency sound waves passing over the pregnant abdomen (acoustic imaging). The time required for the ultrasonic beam to be reflected back to the transducer from differing densities of tissue is converted by a computer to an electrical impulse displayed on an oscilloscopic screen to create a three-dimensional picture of the pelvic contents. Two-dimensional ultrasound has been found to be superior to the three-dimensional technology for evaluation of both healthy and malformed fetuses.
Professional Considerations of Obstetric Ultrasonography (Obstetric Echogram, Obstetric Ultrasound)
Consent form IS required. Although the procedure does not pose physical risks, informed consent information should include the diagnostic accuracy of this procedure for detecting fetal abnormalities.
- This test should be performed before intestinal barium tests or else after the barium is cleared from the system.
- The client should disrobe below the waist or wear a gown.
- Obtain water-soluble gel, a transducer for the ultrasound machine, a camera, and videotape, with or without an oscilloscope.
- See Client and Family Teaching.
- The client is positioned supine.
- The pelvic and abdominal areas are coated with water-soluble gel.
- A lubricated transducer is passed slowly and firmly over the abdominal and pelvic areas at a variety of angles.
- Photographs are taken of the images transmitted to the oscilloscopic screen.
- The procedure should take approximately 30–60 minutes.
- Wipe the gel off the abdominal and pelvic areas.
- Instruct the client to empty her bladder immediately.
Client and Family Teaching
- The client should drink 1 quart of water 1 hour before the procedure because a full bladder is needed to define pelvic organs by serving as an acoustic window for transmission of the sound waves. The full bladder also properly positions the uterus so that it is perpendicular to the transducer. Do not void until the test is completed.
- Lying supine may cause shortness of breath. This may be relieved by elevation of the upper body or by lying on either side.
Factors That Affect Results
- Miscalculation of the conception date.
- Dehydration interferes with adequate contrast between the organs and body fluids.
- Intestinal barium or gas obscures the results by preventing the proper transmission and deflection of the high-frequency sound waves.
- Although a full bladder is recommended, during the first trimester one that is overfilled may compress the uterus, making it difficult to obtain adequate pictures of the early embryonic and extra-embryonic structures.
- An abnormal echo pattern may indicate a multiple pregnancy.
- This procedure has a 98% accuracy rate for identifying the placental site.
- In the first trimester of pregnancy, a transvaginal approach to ultrasonography may be preferred. This method requires an empty bladder and the passage of a small transducer gently into the vagina. This process eliminates the interference of transverse abdominal tissue, allowing for more detailed visualization.
- A chaperone should be present during transvaginal ultrasonography.