Oligohydramnios

What Is Amniotic Fluid?

A woman becomes pregnant when her ovum is fertilized and when this fertilized ovum becomes firmly implanted within the uterus. The embryo draws upon nutrients and oxygen supplied by the mother’s body. It will continue to depend on the mother’s body for all its needs throughout its gestation period of roughly nine months after which it is ready to be born.

The developing fetus’s body communicates directly with the mother’s through a set of vital structures, namely the placenta and the umbilical cord. During gestation, the fetus floats in sac full of fluid. This structure is known as the amniotic sac and the liquid it contains is called amniotic fluid.

What Does It Do?

This clear, slightly yellowish fluid helps to keep the baby safe from mechanical shocks. It also helps to maintain a stable thermal environment around your baby, protecting it from fluctuations in temperature. As the baby floats in this liquid medium, it inhales and even gulps down some fluid which then passes through its system and back out into the amniotic sac. This can be considered practice for actual breathing which will be initiated as soon its head emerges from the birth canal.

Antibodies present in the fluid also help to protect the fetus from infections. This fluid also gives the growing baby freedom to move about and practice various movements. Since the umbilical cord is free to float in the liquid, it is less likely to become compressed or constricted.

The composition of the fluid changes as pregnancy progresses but it generally contains variable quantities of water, antibodies, electrolytes, nutrients, hormones, fetal wastes and even some foetal cells. The amniotic sac develops a few days after conception and safely encases the fetus until it is ready to be born. When the baby is ready to be born, the amniotic sac ruptures and releases its liquid contents. This is what is referred to as ‘water breaking’.

What Is Oligohydramnios?

At around the beginning of the second trimester, that is one-third of the way into the pregnancy, there would be around 50ml of liquid within the amniotic sac. As the pregnancy progresses and the fetus grows larger, the volume of this liquid increases. Normally, at its maximum, there will be between 800 to 1000ml of liquid within the amniotic sac. This tends to drop slightly at the end of the third-trimester approaches. Having the right quantity of amniotic fluid is vital for ensuring normal and healthy development of the baby and preventing complications.

Sometimes, there can be problems with the amniotic sac and fluid prior to completion of the pregnancy. Small amounts of the fluid may leak out or there may be too much of it. When there is too much amniotic fluid, this is known as polyhydramnios. On the other hand, if there is too little of it, the condition is known as oligohydramnios. Oligohydramnios is detected in nearly 4% of all pregnancies.

Why Does This Happen?

There can be a few different reasons for oligohydramnios. For instance, if the mother is pregnant with multiple fetuses simultaneously, as in the case of twins or triplets, she may develop oligohydramnios. A good portion of the amniotic fluid is actually composed of fetal urine. Therefore, if the fetus has any kidney-related problem or lack of renal development, their volume of amniotic fluid may be significantly diminished.Here are some known risk factors for having too little amniotic fluid:

• Rupture of amniotic membranes, allowing the fluid to leak out.
• Placental insufficiency.
• Multiple pregnancies. In other words, being pregnant with more than one fetus at a time.
• Renal problems in the fetus.
• Certain chromosomal abnormalities in the fetus.
• Medications such as certain non-steroidal anti-inflammatory drugs.
• Post-term pregnancy.

If the mother has any of the following conditions, she might have a higher than normal risk for developing oligohydramnios:

• Dehydration.
• Diabetes or gestational diabetes.
• High blood pressure.
• Infections in the uterus.
• Preeclampsia.
• Systemic lupus erythematosus.

Will There Be Any Noticeable Symptoms?

Most probably not. If you have too little fluid in your amniotic sac, it is not very likely for you to become aware of this unless tests are conducted. In case there is a rupture in your amniotic sac and the fluid is leaking out, you may notice a wetness between your legs. Sometimes, it is also possible to tell from the size of the pregnant woman’s belly. If her belly is significantly smaller than expected during the third trimester, this may be an indication of oligohydramnios. However, this is only a very rough and somewhat arbitrary guideline and cannot serve as conclusive proof. The best way to find out for sure is to schedule a visit with your doctor and undergo tests that will help both you and your doctor monitor the progress of your pregnancy.

What Are Some Possible Complications Of Having Too Little Amniotic Fluid?

This problem can develop during any stage of the pregnancy but it is often observed in instances of pregnancies extending beyond the expected due date. Oligohydramnios carries a risk of long-term deficits and pregnancy complications, especially if this remains unrelieved through the final trimester. The general observation is that the sooner in the pregnancy that oligohydramnios sets in, the poorer is the eventual outlook.

Here are some probable critical outcomes:

• Miscarriage.
• Impaired fetal growth.
• Pregnancy complications. In order to ensure the best possible outcome, the mother may be advised to undergo delivery via Caesarean section.
• The baby may be born too early. This is known as pre-term birth or premature birth.
• It is also possible for stillbirth to occur.
• Alternatively, the baby may be born with congenital defects and abnormalities.

How Is This Detected?

The quantity of amniotic fluid is expressed by a value known as the amniotic fluid index or AFI. Mainly, abnormalities during pregnancy are detected through ultrasound tests. This will also reveal whether fetal development is normal and proceeding ‘on course’. If abnormalities are found, additional procedures such as amniocentesis (extracting a small sample of the amniotic fluid for testing) may be conducted. Normal tests during pregnancy will also examine the mother for signs of complications such as gestational diabetes or hypertension. Additionally, if the doctor suspects that the mother is suffering from an undiagnosed problem like lupus, specialized tests can help to confirm this.

Treatment and prevention

Once it has been identified that a pregnant woman has too little amniotic fluid, she will continue to be monitored from then on until the completion of her pregnancy. The treatment method will be determined based on the cause for the problem. In case the mother is dehydrated, this can be effectively remedied by drinking more water. It is also possible to temporarily boost the volume of the fluid by means of a procedure known as amnioinfusion. This involves actually injecting saline liquid into the amniotic sac. However, if oligohydramnios is detected close to the time of delivery, the best solution might actually be to deliver the baby. Often, this is done via Caesarean section, in order to avoid further risks.

The best option to treat low amniotic fluid in a 36 to 37-week pregnant female is by delivering the baby. In case the pregnancy is less than 36 weeks, the healthcare provider evaluates the health of the fetus and the pregnancy is monitored with fetal ultrasounds. Additionally, the pregnant female is advised to drink more fluids in order to prevent dehydration. Low amniotic fluid during labor can be treated by placing fluid in the amniotic sac- a procedure known as amnioinfusion. A catheter is placed in the cervix during labor and saline is infused into the amniotic sac.

Prevention of oligohydramnios is mainly by evaluating the development of the fetus regularly (so as to diagnose fetus health issues at an early stage) and maintaining a healthy lifestyle and diet. Keeping a check on the pregnant female’s health conditions is equally important.

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