Intervillous blood flow in the third trimester gravid rhesus monkey (Macaca mulatta): Use of sonographic contrast agent and harmonic imaging

A properly implanted and functioning placenta is essential for the normal outcome of pregnancy. As pregnancy advances, an increasing supply of maternal blood, which reaches the intervillous space of the placenta via the spiral arteries, is necessary for continued growth and development of the fetus. Presumably, deficient blood flow to the intervillous space can lead to placental ischaemia and an unfavourable outcome, such as pre-eclampsia. In this study, we used a primate model, where echocontrast-enhanced harmonic imaging was utilized to demonstrate placental intervillous blood flow without visualization of fetal blood circulation within the chorionic villi. We propose that this technique, which requires further assessment of efficacy and safety prior to use in humans, is a potentially useful non-invasive clinical tool for assessing intervillous blood flow in the third trimester of pregnancy.