Amniotic fluid issues

Amniotic fluid is a specialized liquid that surrounds the baby as the baby grows inside the uterus. Is produced from the placenta, the membranes and the babies secretions themselves. It plays an important role in the mechanics of the development of the baby. For example, it is breathed in and out as the baby's lungs are developing, allowing them to expand as they grow. Moreover, it cushions the umbilical cord which is the vital link between mother and baby for the circulation of blood. Problems with the amniotic fluid can lead to problems with pregnancy. The reverse is also true. Sometimes we can pinpoint the cause of overly low or high fluid but much of the time we cannot. In these pages you will get a feeling for the important role that amniotic fluid plays and consequences when it is not normal.

Polyhydramnios (high fluid) 

Polyhydramnios means too much amniotic fluid. We measure amniotic fluid several ways, One common way is called the amniotic fliud index. When a patient is pregnant near term, normal amniotic fluid index might be between 6 cm and 22 cm. This amniotic fluid index is obtained when ultrasonographers measures the largest pocket of empty fluid in each of the four quadrants of the pregnancy and adds them up. It is a useful but approximate measurement. 

Causes of polyhydramnios : 

• The number one cause of polyhydramnios is unknown.
• Diabetes, either pre-existing or gestational, is a common cause of polyhydramnios
•  Rh disease can be associated with polyhydramnios
• Infections like syphilis can be associated with polyhydramnios

Effects of polyhydramnios

• Polyhydramnios over distends the uterus. It also puts pressure on the placenta. For this reason we see the following effects : 
• Uterine irritability and threatened preterm labor
• Abdominal pain
• Difficulty breathing
• Increased risk of premature placental separation, also known as abruption.
• Increased incidence of malpresentation such as transverse or breech presentation, simply because the baby has so much room

Management of polyhydramnios

• Management of polyhydramnios centers on increased surveillance  for the conditions listed above, most notably preterm labor and abruption. It turns out that there is nothing that we can directly do to reduce the amount of fluid the pregnancy produces. Efforts to remove fluid are only met with the reproduction of the fluid volume in a short period time.
• Patients with polyhydramnios require frequent monitoring in the form of nonstress tests. They also require frequent ultrasound to ascertain fluid levels and determine the position of the baby.

Oligohydramnios (low fluid) 

Oligohydramnios is defined as amniotic fluid index of 5 cm or less. It is easier to understand the reasons behind oligohydramnios than it is to understand the reasons behind polyhydramnios. Since amniotic fluid is, in some ways, a marker for bloodflow to the pregnancy,  anything that interferes with this can reduce fluid volume. It is interesting to note that the risk factors for oligohydramnios are similar, if not identical to those for fetal growth restriction.

Risk factors for oligohydramnios

Maternal medical conditions

• Pregestational diabetes mellitus
• Renal insufficiency
• Autoimmune disease (eg, systemic lupus erythematosus)
• Cyanotic cardiac disease
• Pregnancy-related hypertensive diseases of pregnancy (eg, chronic hypertension, gestational hypertension, or preeclampsia)
• Antiphospholipid antibody syndrome 
• Substance use and abuse (eg, tobacco, alcohol, cocaine, or narcotics) 
• Multiple gestation 
• Teratogen exposure (eg, cyclophosphamide, valproic acid, or antithrombotic drugs) 
• Infectious diseases (eg, malaria, cytomegalovirus,
• rubella, toxoplasmosis, or syphilis) 
• Genetic and structural disorders (eg, trisomy 13,
• trisomy 18, congenital heart disease, or gastroschisis) 
• Placental disorders and umbilical cord abnormalities

reference : ACOG Practice Bulletin, Fetal growth restriction, Number 134, May 2013

Effects of oligohydramnios

• Oligohydramnios present in very early in just station can make it difficult for the funeral lungs and limbs to grow
• Oligohydramnios present later in gestation makes it more likely that the umbilical cord will be compressed, possibly compromising fetal growth and well-being.
• Oligohydramnios present during labor we'll make it more likely that the umbilical cord will be compressed and that the baby will not tolerate labor.

Management of oligohydramnios

• Management of oligohydramnios centers on addressing the underlying conditions which produced it in the first place.
• Reduced physical activity together with excellent hydration and nutrition are commonly utilized.
• Patients with oligohydramnios require frequent monitoring in the form of nonstress tests, serial ultrasounds with measurement of amniotic fluid, and oftentimes Doppler umbilical cord flow measurements.