The routine or screening obstetrical ultrasound examination.
The debate concerning the value of routine screening ultrasound in the low-risk patient continues. The most likely benefits are obstetrical, with confirmation of dates, detection of multiple gestation, baseline growth data, and location of the placenta being primary advantages gained from such an examination. The detection of the unexpected major fetal malformation has always been the least likely benefit of routine ultrasound. Furthermore, the majority of reports have been retrospective, uncontrolled, and too small to resolve the question. The RADIUS study was intended to solve these problems, but suffered from such intense selection that the final population for study had little need for medical care at all and little relevance to the average population. The rate of adverse outcomes among the control group was so low that few interventions would appear useful. Furthermore, the analysis of the RADIUS data appeared to suggest bias by underestimating the diagnostic sensitivity of ultrasound for major anomalies, and de-emphasizing those statistically significant obstetrical benefits that were recorded. An attempt at cost-benefit analysis by the RADIUS study misrepresented the cost of routine ultrasound by overestimating the size of the low-risk population, arbitrarily costing out two scans instead of one, and therefore overestimated the cost savings of omitting these examinations. Diagnostic sensitivity of the screening obstetrical ultrasound examination appears to be highest in high-risk patients examined by highly specialized ad experienced personnel that may be of limited availability. diagnostic sensitivity may be quite good, however, even in low-risk patients with a basic or routine examination if recognized guidelines for content are followed and referral to experienced referral resources for unclear or suspicious images is liberally practiced. Optimal service and minimum liability exposure will result if the following guidelines are followed: 1. The obstetric population should be carefully screened for historical or clinical risk factors that might indicate increased probability of fetal abnormality. Identification of such increased risk should cause consideration of referral. 2. The screening ultrasound examination should be methodical and complete and include examination of each of several recommended scanplane views to maximize diagnostic sensitivity. 3. The performance of a complete and methodical examination should be carefully documented with both descriptive text and image records to show that a standard of care service was provided. 4. Referral for second opinion should be easily considered and easily obtained in the case of any suspicious finding. Should every obstetrical patient have an ultrasound examination? Only if it is competently performed, properly recorded, and if the patient is aware of appropriate goals and limitations. The ideal gestational age is between 18 and 22 completed weeks.