Prenatal ultrasonographic diagnosis of conditions associated with potential umbilical cord compression.

The objective of this review is to assess the current literature pertaining to prenatal ultrasonographic diagnosis of various conditions that predispose the fetus to potential umbilical cord compression. We performed a MEDLINE search utilizing the terms:umbilical cord compression, nuchal cord, cord entanglement, and true knot. Additional sources were obtained through cross-referencing. Prenatal ultrasound assists in the diagnosis of nuchal cord(s), true knot of the umbilical cord, cord entanglement in monoamniotic twin gestations, and other unusual etiologies that may lead to umbilical cord compression. Supplementary ultrasonographic measures including color Doppler imaging, Doppler flow velocimetry, and possibly three-dimensional ultrasound may further prenatal diagnosis of these conditions. Doppler flow velocimetry may also assist in detecting impaired or deteriorating umbilical artery flow reflecting increasing cord compression prior to the onset of adverse and potentially nonreversible effects upon the fetus. Close fetal surveillance in cases further complicated by decreased fetal movements, decreased amniotic fluid volume, postdates, fetal growth restriction, and impaired umbilical artery Doppler flow velocimetry may assist in the management of such gestations. Although definitive prospective studies investigating neonatal outcome following prenatal ultrasonographic depiction of potential umbilical cord compression are not currently available, review of the literature suggests that increased fetal surveillance may be indicated in certain clinical conditions.