TRANSVAGINAL SONOGRAPHIC IMAGING OF EARLY 2ND-TRIMESTER FETAL ANATOMYASSISTED BY UTERINE FUNDAL PRESSURE

Objective: To assess the advantage of applying uterine fundal pressure to assist transvaginal sonographic imaging of early second-trimester fetal anatomy. Methods: One hundred consecutive patients with singleto n fetuses underwent routine transvaginal sonographic assessment of fet al anatomy between 13 and 17 weeks' gestation. If the entire fetal ana tomy including cardiac outflow tracts was not depicted, uterine fundal pressure was applied with the operator's nonscanning hand in a bimanu al fashion, to facilitate transvaginal imaging. Transabdominal sonogra phy was performed when visualization of the entire fetal anatomy was n ot obtainable with transvaginal or uterine fundal pressure-assisted tr ansvaginal sonography. Observed fetal structures with and without fund al pressure were compared. Factors assessed that may have modified the value of fundal pressure included patient weight, gestational age, fe tal presentation, previous abdominal surgery, and the presence of uter ine fibroids. Statistical analysis included McNemar test, chi(2), Fish er exact test, and t test, with P < .05 considered significant. Result s: Visualization of lower limbs, head (including intracranial structur es), upper limbs, kidneys, spine, gender, feet, hands (digits), face, four-chamber view, and cardiac outflow tracts was significantly enhanc ed by uterine fundal pressure-assisted versus nonassisted transvaginal sonography. Uterine fundal pressure improved transvaginal sonographic imaging in 91% of subjects, and in 51% of all subjects, a complete ex amination was thus obtained. In 20% of all subjects, transabdominal so nography was required to complete the examination. Complete fetal anat omic scanning was unobtainable despite uterine fundal pressure supplem ented by transabdominal sonography in 29% of cases. Completion of the transvaginal sonographic fetal anatomic survey with uterine fundal pre ssure was related to gestational age (P < .02) and maternal weight (P < .05) yet not related to fetal presentation (P = .13), previous abdom inal surgery (P = .06), or uterine fibroids (P = .26). Conclusion: Ute rine fundal pressure applied during early second-trimester transvagina l sonographic evaluation of fetal anatomy significantly improves visua lization of fetal structures otherwise located beyond the effective ra nge of the transvaginal transducer. (C) 1997 by The American College o f Obstetricians and Gynecologists.