Willie Chan, 33 years old
Pettker, MD; James D. Goldberg, MD; and Yasser Y. This document reflects emerging clinical and scientific advances as of the date issued and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed. As soon as data from the last menstrual period, the first accurate ultrasound examination, or both are obtained, the gestational age and the estimated due date EDD should be determined, discussed with the patient, and documented clearly in the medical record. Subsequent changes to the EDD should be reserved for rare circumstances, discussed with the patient, and documented clearly in the medical record. When determined from the methods outlined in this document for estimating the due date, gestational age at delivery represents the best obstetric estimate for the purpose of clinical care and should be recorded on the birth certificate. For the purposes of research and surveillance, the best obstetric estimate, rather than estimates based on the last menstrual period alone, ultrasound dating discrepancies be used as the measure for gestational age.
A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Most dating scans are done with a trans-abdominal transducer and a fullish bladder. If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures. Dating scans are usually recommended if there is doubt about the validity of the last menstrual period. By 6 to 7 weeks gestation the fetus is clearly seen on trans-vaginal ultrasound and the heart beat can be seen at this early stage 90 to beats per minute under 6 to 7 weeks, then to beats per minute as the baby ultrasound dating discrepancies. Ultrasounds performed during the first 12 weeks of pregnancy are generally within 3 - 5 days of accuracy. The most accurate time is between 8 and 11 weeks gestation. This is because the fetus is growing so quickly that there is a big difference in size from week to week.
Name the time in gestation when ultrasound is most accurate 2. Discuss the ACOG recommendations for redating a pregnancy based on trimester. Postgraduate Institute for Medicine PIM requires instructors, planners, managers and other individuals who are in a position to control the content of this activity to disclose any real or apparent conflict of interest COI they may have as related to the content of this activity.
Ultrasound dating discrepancies
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Sonography is very helpful in evaluating pregnancies that are larger than expected based on menstrual dates. The pregnancy can be complicated by polyhydramnios, which can be idiopathic or a result of fetal growth acceleration, maternal diabetes, or fetal malformations. The fetal anomalies most often associated with polyhydramnios include those involving the gastrointestinal tract, central nervous system, thoracic and cardiac anomalies, fetal hydrops isoimmune and nonimmune etiologiessome skeletal defects, chromosomal anomalies, and fetal tumors. When a fetus in the presence of polyhydramnios appears structurally normal sonographically, the outcome is generally excellent. These masses include uterine fibroids and adnexal enlargement such as an ovarian cyst. The evaluation of the patient whose uterine size is larger than dates includes a complete structural survey of the fetus, including an echocardiogram, fetal biometry, and estimated weight assessment, as well as an evaluation of the myometrium and adnexae for possible masses. It is common to find that the size is either too large or too small, thus prompting further evaluation of the pregnancy. Most commonly, the dates are incorrect. Ultrasound dating discrepancies patient may have had some spotting within the first month after she conceived. If she mistook the spotting for a true menstrual period, she would have estimated her dates at 4 weeks less than the actual gestation.
Multivariable linear regression was conducted to determine the extent to which ultrasound GA predicted LMP dating and to correct for systematic misclassification that results after applying standard guidelines to adjudicate differences in these measures. With adjustment for maternal age, smoking, and first-trimester vaginal bleeding, standard guidelines for adjudicating differences in ultrasound and LMP dating underestimated SGA birth by This methodological approach can be applied by researchers using different study populations in similar research contexts. Accurate gestational age GA dating of pregnancies is vital to public health surveillance and research investigating the causes of small-for-gestational-age SGA birth and preterm delivery PTD. Errors in estimating GA can result in misclassification, limiting progress towards identifying vulnerable times of fetal exposure and strategies to prevent adverse pregnancy outcomes. The most widely available approaches for estimating the duration of gestation are last menstrual period LMP dating i. The shortcomings of LMP dating include inaccurate recall, ultrasound dating discrepancies assumption that all menstrual cycles last 28 days, and the possibility of mistaking vaginal bleeding early in pregnancy as a menstrual period 1 — 3.