Placental insufficiency · What is it, Causes, Symptoms, Treatment, and More

Placental insufficiency, also known as placental dysfunction, refers to a medical condition in which oxygen and nutrients are not sufficiently transferred to the fetus via the placenta during pregnancy. In placental insufficiency, the placental vascular remodeling (i.e., transformation of the small spiral uterine arteries to large placental vessels in order to secure adequate blood supply of the placenta) is affected. As a result, placental functioning progressively deteriorates. This process affects the placental blood flow, leading to fetal hypoxemia, or low levels of oxygen in the blood, and restriction of fetal growth. 

The underlying causes of placental insufficiency are typically a result of disturbances to the perfusion, or blood supply, of the placenta. Any restrictions in the placental blood flow can lead to hypoxemia, which activates proteins involved in the clotting of blood (i.e., coagulation factors) and promotes the deposition of fibrin (i.e protein circulating in the blood responsible for controlling bleeding) within the placenta. Under those circumstances, the transfer of nutrients to the developing fetus is minimized. 

Furthermore, reduction in the amount of surface area of the placenta that becomes integrated in the uterine walls can also be associated with placental insufficiency. In placental abruption, (i.e. the early separation of the placenta from the uterus before labor) where the placental surface area is significantly reduced, serious pregnancy complications can follow. Excessive hemorrhage, or bleeding, and insufficient nutrition of the baby are some of the common complications of placental abruption. 

Placentation (i.e., the formation of the placenta within the uterus) can be negatively affected by lateralization (i.e., when placentation favors one side instead of implanted centrally) as blood is not equally distributed, thereby affecting the distribution of the necessary nutrients to the fetus.

The diagnosis of placental insufficiency requires a thorough review of the individual’s medical history and a very detailed physical examination. There are currently no standardized diagnostic methods yet to be established; however, Doppler ultrasounds to measure the amount of blood flowing in vessels have proven to be very useful in evaluating fetal and placental circulations. Notably, measuring the blood flow of the uterine artery during Doppler screening has proven to be very sensitive in detecting severe IUGR and preeclampsia. In order to reduce fetal risk, especially in high-risk pregnancies, regular screening with Doppler ultrasound should be performed to increase the chances of early diagnosis. 

Additional imaging, like MRIs, can also provide further information when ultrasound imaging is inconclusive. In certain MRI sequences (e.g., T2-weighted), placental insufficiency can be easily diagnosed. Loss of signal in a vessel where blood typically flows vigorously, like the vessels between the placenta and the uterus, can indicate insufficient blood supply. An additional feature of MRI imaging is the detailed illustration of soft tissues. Therefore, any placental malformations, including hemorrhages and infarctions (i.e., obstruction of blood supply) of which indicate a higher risk for the development of placental insufficiency, can be detected.