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Placental insufficiency

Placental insufficiency (or uteroplacental vascular insufficiency) is a complication of pregnancy when the placenta is unable to deliver an adequate supply of nutrients and oxygen to the fetus, and, thus, cannot fully support the developing baby. Placental insufficiency occurs when the placenta either does not develop properly or because it has been damaged. It is commonly defined as a reduction in the maternal blood supply (reduced uterine artery blood flow). However, we define placental insufficiency to include reduction in maternal blood supply AND/OR the failure of the maternal blood supply to increase or adapt appropriately by mid-pregnancy. Placental insufficiency can result pregnancy complications, including fetal growth restriction, pre-eclampsia and others, all of which are described below. The management of placental insufficiency is dependent upon additional tests and the unique characteristics of each patient. Factors considered during management of complicated pregnancies are maternal medical and obstetrical history, weight, ethnicity, and blood pressure.

Contents

Findings of placental insufficiency on placental function testing

Management of pregnancies characterized by placental insufficiency

Disorders of placental insufficiency: 

 


 

Findings of placental insufficiency on placental function testing

The following diagram outlines the list of abnormal findings which signal utero-placental vascular insufficiency (UPVI), as assessed by the following placental function tests: umbilical artery Doppler (baby’s blood flow to the placenta), maternal biochemistry, placental morphology, and uterine artery Doppler (mother’s blood flow to the placenta).

  © Leslie Proctor, 2009

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Management of placental insufficiency

Once placental insufficiency has been diagnosed, the next steps depend on when in pregnancy the diagnosis is made. 
 

Management before the developing baby is viable (<24 weeks):

By offering women a program of serial testing at 12, 16 and 20 weeks, the diagnosis of placental insufficiency is typically made before any ill effects on the mother (pre-eclampsia) or the developing baby (growth restriction) are evident. Rarely, one or both may be seen before 20 weeks, and, if so, the outcome is often poor, unfortunately. Although most women and their developing babies with multiple test abnormalities before 24 weeks are healthy at that point, showing early signs of pre-eclampsia and growth restriction increases the risk of preterm delivery (<32 weeks), with a chance of it happening being 30%.

The management approach of these patients is as follows:

  • Provide co-care with the referring obstetrician/family doctor/midwife, or assume full care, if requested: since the risk of preterm delivery is high, maintaining an ongoing relationship with the regional high-risk pregnancy unit is essential; this permits a smooth transfer of care as needed;
  • Educate the woman about pre-eclampsia so she can self-monitor at home: this prevents late diagnosis when severe uncontrolled hypertension may result in earlier delivery (than if the blood pressure was found early and treated carefully) and can sometimes cause injury to the mother or her developing baby; 
  • Provide a plan of fetal monitoring using ultrasound so that IUGR is recognized and monitored carefully;
  • Integrate this plan with regular visits (standard antenatal care).

 

Management after the developing baby is viable (>24 weeks):

If placental insufficiency is diagnosed in later stages of pregnancy, the disease can either remain sub-clinical (not be expressed as IUGR and/or pre-eclampsia), or one or more of several issues develop:

  • Excess maternal weight gain, leg swelling, headaches (signs of pre-eclampsia
  • The mother's stomach measures small, the baby is not moving very well (signs of IUGR)
  • The baby has not moved for two days and no fetal heart beat can be found in the Clinic using a Doptone (signs of stillbirth) 
  • Some vaginal bleeding and/or contractions develop (signs of preterm labour with placental separation, or abruption)

 

The following steps will be taken if any of the above mentioned conditions are noted:

  • If a degree of either pre-eclampsia or IUGR develops, then visit frequency is increased from bi-weekly to every week, then to twice a week and ultimately hospital admission for daily monitoring;   
  • If a concern about the need for delivery arises before 32 weeks, then the mother will be offered a course of steroids (2 intra-muscular [thigh] injections). These steroids diffuse across the placenta to strengthen the developing baby's lungs, helping the fetus prepare in the event that an early delivery is indicated;  
  • If pre-eclampsia and/or IUGR are more severe and are likely to require delivery before 32 weeks, then a high-risk Obstetrician or Maternal-Fetal Medicine specialist takes over to provide intensive outpatient or inpatient care. 

 

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