Ultrasound of the Placenta and Umbilical Cord

Abstract

The placenta and umbilical cord play important roles in the development of the growing fetus. The placenta can be clearly identified by the 14th gestational week and should be evaluated during each obstetric ultrasound examination.This article reviews the formation of the placenta and its expected sonographic appearance throughout gestation along with its normal variants. Expected findings in a singleton pregnancy are primarily addressed. The next portion of the article covers placental abnormalities of clinical consequence, including anomalies of appearance, location, and function.The umbilical cord is also discussed, focusing on the relevance of the location of the umbilical cord's insertion into the placenta.

How is the human umbilical artery regulated?

“…In the vascular bed, the smooth muscle cells (SMC) are the cells responsible for the vascular tonus, responding to several hormonal and hemodynamic stimuli . An excellent source of SMC is the human umbilical artery (HUA) that is involved in fetoplacental circulation . The HUA is a muscular artery of medium caliber that is constituted by three concentric tunics, with different morphologies .…”

“…So, the HUA tonus is modulated by endocrine and paracrine mechanisms that regulate the contractile response of SMC . Moreover, these SMC appear to play an important role in the control of fetoplacental blood flow . Whereby it is important to perform cultures of these cells, to investigate molecular and genetic questions related with its contractility and to know also which are the factors that regulate blood flow in the umbilical circulation.…”

Dynamic modeling of uteroplacental blood flow in IUGR indicates vortices and elevated pressure in the intervillous space – a pilot study

“…It can be expected that the differences between the blood pressure in the IVS and the blood pressure in the fetal capillaries are discrete. Elevated blood pressure in the IVS, as suggested by the models of the present study, could thus be able to reduce fetal capillary diameters and increase fetal vascular resistance with the full 4th degree exponential power of diameter changes in this context32. Pressure peaks or constant pressure above a critical value in the IVS would tend (i) to compress these capillaries, preferably during the low-pressure phases of the fetal heart cycle, (ii) to substantially compromise fetal blood flow, and (iii) could possibly be the cause of umbilical reverse Doppler flow in the third trimester of gestation in pregnancies affected by severe IUGR.…”

Discriminative learning for automatic staging of placental maturity via multi-layer fisher vector

“…Experimental results show that the proposed method with the dense FV has achieved an area under the receiver of characteristics (AUC) of 96.77%, sensitivity and specificity of 98.04% and 93.75% for the placental maturity staging, respectively. Our experimental results also demonstrate that the dense feature outperforms the traditional sparse feature for placental maturity staging.Over the past decade, ultrasound (US) imaging has been extensively applied in prenatal diagnosis and prognosis since it is radiation-free, direct-use, and low-cost [1][2][3][4][5][6][7] …”

“…Over the past decade, ultrasound (US) imaging has been extensively applied in prenatal diagnosis and prognosis since it is radiation-free, direct-use, and low-cost [1][2][3][4][5][6][7] …”