Prenatal ultrasonographic morphologic assessment of the umbilical cord: a review. Part I.

Our objective was to review current data pertaining to prenatal ultrasonographic morphology of the umbilical cord. To this goal we identified studies published in the English language regarding prenatal ultrasonographic morphology of this structure. The studies were obtained from a MEDLINE search from 1966 through May 1997; additional sources were identified through cross-referencing. All published reports, case studies, and articles regarding ultrasonographic morphology of the umbilical cord were reviewed. Data pertaining to Doppler flow velocimetry in association with umbilical cord structural anomalies and umbilical cord compression, were also included. Review of the literature supports that prenatal ultrasound may outline normal anatomy or alternatively depict various congenital abnormalities of the umbilical cord including: cysts; pseudocysts; umbilical vein varix; persistent right umbilical vein; hemangiomas; umbilical vessel aneurysm (arterial or venous); single, hypoplastic, or fused umbilical artery; hematomas (spontaneous or iatrogenic); velamentous insertion; and vasa previa. The umbilical cord coiling index, an additional ultrasonographic morphologic feature may identify patients at risk for adverse perinatal outcome. Conditions of potential fetal compromise due to umbilical cord compression including nuchal cords, true knots, occult prolapse, cord presentation, fetal grasping, and cord entanglement in monoamniotic twins, may be detected prenatally and impaired umbilical flow confirmed with Doppler flow velocimetry. Ultrasound has been widely applied to guide invasive diagnostic and therapeutic procedures involving access to umbilical circulation. In conclusion, precise prenatal ultrasonographic depiction of the morphology of the umbilical cord may enhance perinatal management.