Placental insufficiency is a pregnancy complication where the placenta cannot adequately deliver oxygen and nutrients to the developing fetus. As the lifeline between mother and baby, the placenta transfers necessary elements for growth while removing waste products. This organ attaches to the uterine wall and connects to the baby via the umbilical cord, and when its function is compromised, fetal development can be hindered.
Causes of Placental Dysfunction
The origins of placental insufficiency are linked to problems with blood flow from the mother to the placenta. Certain maternal health conditions are associated with this complication. Chronic high blood pressure and pregnancy-induced hypertension, like preeclampsia, can constrict blood vessels and reduce placental blood supply. Conditions such as diabetes and blood-clotting disorders can also affect the vascular integrity of the placenta.
Lifestyle choices, such as smoking or using substances like cocaine, can impair placental function. The issue can also stem from structural problems with the uterus or the placenta failing to attach properly. In some cases, the placenta may be abnormally shaped or smaller than average, limiting its capacity. Despite these known associations, a specific cause for the dysfunction cannot always be identified.
Identifying Insufficiency on an Ultrasound
An ultrasound examination is the primary tool for identifying placental insufficiency. It allows for an indirect assessment of placental health by observing its effects on the fetus and uterine environment. Clinicians look for specific signs that indicate the placenta is underperforming.
Fetal Growth Measurement
A primary indicator of placental insufficiency is slowed fetal growth, known as Intrauterine Growth Restriction (IUGR). During an ultrasound, a sonographer measures the baby’s head, abdomen, and femur length. These measurements are compared to standard growth charts for the gestational age. A fetus measuring significantly smaller than expected or whose growth tapers off suggests an inadequate supply of nutrients.
Amniotic Fluid Volume
The volume of amniotic fluid is another marker. The fetus produces this fluid through urination, which depends on receiving adequate blood flow from the placenta. An ultrasound measures fluid pockets to calculate the Amniotic Fluid Index (AFI). Low levels of amniotic fluid, called oligohydramnios, can indicate the placenta is underperforming.
Doppler Flow Studies
Doppler flow studies, a specialized ultrasound, directly examine blood circulation efficiency. This technology creates a visual representation of blood moving through vessels. A sonographer assesses flow through the umbilical artery, which carries waste from the fetus to the placenta. With placental insufficiency, increased resistance can slow, stop, or even reverse blood flow in this artery, which is a direct sign of compromise.
The Physical Appearance of an Insufficient Placenta
After delivery, a physical examination of the placenta can confirm issues suspected during pregnancy. An insufficient placenta is often smaller and thinner than a healthy one, which weighs between one and two pounds at term. Its color may also appear pale, reflecting poor blood perfusion.
The placental surface might show distinct areas of damage. Infarcts, which are sections of dead tissue from a lack of blood supply, appear as firm, pale patches. Another finding is calcifications, which are small, hard, white spots. While some calcification is normal late in pregnancy, excessive amounts suggest parts of the placenta have aged prematurely and are no longer functioning.
Monitoring and Management Protocols
Once placental insufficiency is suspected, care shifts to intensive monitoring to track the baby’s well-being. This involves more frequent prenatal visits and specialized tests. Regular non-stress tests monitor the baby’s heart rate for patterns indicating good oxygenation. Biophysical profiles combine a non-stress test with an ultrasound assessment of:
- Fetal movement
- Muscle tone
- Breathing efforts
- Amniotic fluid levels
Repeated growth scans are scheduled every few weeks to track the baby’s growth and assess Doppler blood flow. Management also includes addressing underlying maternal health conditions, like controlling high blood pressure or diabetes. This surveillance helps determine the optimal time for delivery, balancing the risks of prematurity against those of a compromised uterine environment.
An early delivery is recommended if monitoring reveals stalled growth, signs of fetal distress, or severely abnormal blood flow. The goal is to deliver the baby before the placental support fails completely. This decision weighs the fetus’s gestational age against the severity of the compromise.