Smellie W. Treatise on the Theory and Practice of Midwifery. In: McClintock A. London: The New Syndenham Society; Denman T. London: J. Johnson; An Introduction to the Practice of Midwifery.
Scammon R. Minneapolis: University of Minnesota Press; Reece L. Morphometry of the Human fetus. Crichton D. Ball R. Donald I. A method of measuring the biparietal diameter of the fetus in utero by pulsed ultrasound. Willocks J. Fetal Biparietal diameter measurement by ultrasound. Chitty L. Charts of fetal size: 2. Head measurements. Campbell S, Newman G. Growth of the fetal biparietal diameter during normal pregnancy. J Obstet Gynaecol Br Commonw. Kurtz A.
B, Wapner R. Analysis of biparietal diameter as an accurate indicator of gestational age. Clin Ultrasound. Hadlock R. Fetal biparietal diameter: A critical re-evaluation of the relation to menstrual age by means of real time ultrasound. Ultrasound Med. Kankeow K. Charts of fetal biometries at Sukhothai Hospital. J Med assoc Thai. Support Center Support Center. Measurement technique The BPD should be measured on an axial plane that traverses the thalami, and cavum septum pellucidum.
The calipers should be placed at the: outer edge of the near calvarial wall inner edge of the far calvarial wall The cerebellar hemispheres should not be in the plane of the image.
Interpretation BPD has been shown to be accurate in predicting gestational age from 14 to 20 weeks 2. Quiz questions. Callen PW. Ultrasonography in Obstetrics and Gynecology. Elsevier Health Sciences. Read it at Google Books - Find it at Amazon.
Related articles: Pathology: Genitourinary. Promoted articles advertising. If it is at least 2 cm deep, then true oligohydramnios is not considered present. Some sonographers and clinicians find this definition too restrictive and will measure the largest pocket in two diameters. Using the AFI, the deepest pocket of fluid in each of four uterine quadrants is measured. The four measurements are added to each other. If the sum is less than 7. If more than While these measurements are commonly used, there is considerable subjectivity involved in obtaining them.
Further, the amount of amniotic fluid present varies, depending to some extent on the state of maternal hydration. Placental Location In most cases, the exact location of the placenta is of little clinical consequence. In a few cases such as 2nd and 3rd trimester bleeding, placenta previa, low-lying placenta , the location of the placental is very important. It is usually relatively simple to perform, readily available, and relatively inexpensive.
More detailed scanning Level II, or targeted scan requires higher resolution more expensive equipment and sonographic skills that are more limited in their availablity and significantly more expensive. Indications for a Level II scan may include:. Suspicious findings on a Level I scan History of prior congenital anomaly Insulin dependent diabetes or other medical problem that increases the risk of anomaly.
History of seizure disorder, particularly if being treated with medications known to increase the risk of anomaly. As a practical matter, ultrasound scanning has proven to be so popular with patients and their obstetricians, that almost everyone receiving regular prenatal care ends up with at least one scan anyway.
For this reason, the focus of the debate has more recently shifted to when and under what circumstances should patients have ultrasound scans. Those favoring frequent, routine scans, do so on the basis that incorrect gestational age assessments can be corrected, many congenital anomalies can be detected, growth abnormalities can be identified and treated, and multiple gestations identified early, when intervention is more likely to improve results.
Those opposed to routine scanning point to the lack of significant improvement in outcome identified to date in large studies or routinely-scanned patients. The debate continues. Umbilical Cord in Cross Section Doppler Flow Studies Using the Doppler principle, blood flow through structures such as the umbilical cord can be identified and quantified.
As placental resistance to flow increases, the amount of diastolic flow through the umbilical artery decreases, although systolic flow rates are usually unchanged. As the resistance increases further, diastolic flow into the placenta ceases. In the most severe form of placental resistance, the diastolic flow reverses. Doppler flow studies can be useful in determining fetal status in the second trimester fetus who is too small for traditional fetal monitoring techniques to be useful.
Racial differences in fetal morphometry in Singapore. Ann Acad Med Singapore ; Neonatal anthropometry: The thin-fat Indian baby. The Pune Maternal Nutrition Study. Sabbagha RE, Hughey M. Standardization of sonar cephalometry and gestational age.
Obstet Gynecol ; Campbell S. The prediction of fetal maturity by ultrasonic measurement of the biparietal diameter. J Obstet Gynaecol Br Commonw ; Sonar biparietal diameter. Analysis of percentile growth differences in two normal populations using same methodology.
Am J Obstet Gynecol ; Tolerance intervals for standards in ultrasound measurements: Determination of BPD standards. Ultrasound fetal growth parameters. J Obstet Gynecol India ; Ultrasonic biparietal diameter in Indian women.
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