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.
Yeo, L. Smulian, J. C., Donoghue, E. A., Guzman, E. R., Walters, C. Vintzileos, A. M. (2003, February). The Burden of Perinatal Practice of Finding Normal Variants on Fetal Ultrasound. Am J Obstet Gynecol 2003;187(S192):Abstract #-489. Poster Presented at: The Society for Maternal-Fetal Medicine. San Francisco, California.