The amniotic sac, a crucial component of fetal development, plays an essential role in safeguarding and nurturing the baby while in the womb. Early in pregnancy, the placenta is responsible for producing amniotic fluid, which serves as a protective cushion for the fetus. As the pregnancy progresses and the baby’s kidneys begin to function, this fluid is partly made up of the baby’s urine, and it can also be swallowed by the fetus.
The health, growth, and safety of the baby are closely tied to the amount of amniotic fluid present. Abnormal levels of this fluid—either too much or too little—can be a cause for concern and may indicate potential issues with the pregnancy. When there is less amniotic fluid than expected, a condition known as oligohydramnios can develop that can prompt the need for further examination by fetal medicine specialists.
What causes Oligohydramnios?
Amniotic fluid levels are closely tied to kidney function. A decrease in fluid can occur if there is a rupture of the membrane, leading to fluid leakage, or if the baby’s growth is impeded due to reduced blood flow from the mother. Since blood flow is prioritized to the baby’s brain, less blood reaches the kidneys, potentially diminishing urine production and thereby reducing amniotic fluid. Genetic or chromosomal abnormalities can also contribute to reduced fluid levels.
Diagnosis of Oligohydramnios
To diagnose oligohydramnios, specialists may start with abdominal palpation to suspect low fluid levels. An ultrasound is then used to measure the amount of amniotic fluid accurately. The ultrasound assesses fluid in different quadrants of the uterus: upper, lower, right, and left. The measurements are combined to calculate the amniotic fluid index (AFI). If the AFI is less than 5 cm or if the single deepest pool of fluid is less than 2 cm, it indicates oligohydramnios.
Evaluating the clinical history and conducting detailed ultrasounds are essential steps in diagnosing the root cause of low amniotic fluid and the nature of the complicated pregnancy. Ultrasound can reveal both the structure and function of the kidneys and can help in identifying any genetic conditions that may be present.
Timing of Diagnosis and its Importance
The timing of low amniotic fluid also impacts prognosis. In early pregnancy, insufficient amniotic fluid can lead to severe complications such as pulmonary hypoplasia, where the baby’s lungs do not develop properly. This condition severely affects the baby’s survival prospects. However, if oligohydramnios is detected later in pregnancy, timely intervention and careful monitoring can mitigate risks. If the reduced fluid is associated with slower fetal growth, fetal medicine specialists may consider early delivery based on clinical parameters.
In cases where the membranes rupture or premature labour is imminent, management strategies should be developed. Often, oligohydramnios leads to labour, which may increase the risk of infection for both mother and baby.
Thus, consultations with fetal medicine specialists become crucial for managing the pregnancy and ensuring the best outcomes for both mother and child.