The Burden of Perinatal Practice of Finding Normal Variants on Fetal Ultrasound.

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OBJECTIVE: A number of prenatal ultrasound (U/S) findings initially classified as anomalies are now being considered as “normal variants” (NV) in the low-risk population. Because many of these women may not require counselling, we examined the proportion of NV among all fetal sonographic findings (SF) that were detected in a referral U/S unit in order to determine their potential impact. STUDY DESIGN: Our unit serves a widespread geographical area and is a referral center for prenatal U/S. In addition to following American Institute of U/S in Medicine guidelines, all our exams also routinely target: face/neck (including nuchal fold thickness), cardiac (4 chamber views and outflow tracts, aortic and ductal arches), all extremities and long bones (including hands/feet) and genitalia. From 1997-99, all identified fetal SF were prospectively recorded. These were classified into organ systems: cranial, face/neck, thoracic, cardiac, spine, abdomen, abdominal wall, stomach, renal, bladder, umbilical cord and extremities. From the cranial, cardiac, abdominal and renal systems, fetal SF were further divided into significant abnormalities or NV. RESULTS: Of 47,972 U/S exams performed, a total of 3,392 separate fetal SF were detected. Of these, 52% (n = 1755) were comprised of these NV: choroid plexus cysts (CPC), echogenic intracardiac foci (EIF), hyperechoic bowel (HB) and pyelectasis (PY). Some patients may have had > 1 U/S exams, and fetuses may have had > 1 SF. The table depicts the total number of fetal SF in 4 organ systems and the proportion that were NV. CONCLUSION: In a large referral U/S unit, ≥ 65% of all fetal cranial, cardiac and renal SF consist of NV rather than significant abnormalities and may not necessarily require counselling in the context of low-risk patients. This high frequency demonstrates the impact and potential burden in an U/S unit and suggests that familiarity with their implications is imperative.


Obstetrics and Gynecology


Department of Obstetrics and Gynecology, Department of Obstetrics and Gynecology Faculty

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