Amniotic fluid surrounds the baby while it is inside the mother's womb in pregnancy. This fluid has important functions, in addition to protecting the baby and cushioning movements, so that alterations in the amount of amniotic fluid can lead to serious complications during pregnancy.
When the amount of amniotic fluid is excessive, it is referred to as polyhydramnios. On the other hand, if the volume of amniotic fluid is reduced, it is called oligohydramnios.
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What is the importance of amniotic fluid?
Amniotic fluid is the yellowish fluid inside the amniotic sac in which the baby floats inside the uterus in pregnancy.
One of the functions of amniotic fluid is to protect the baby by cushioning maternal movements. However, the amniotic fluid also helps maintain a constant temperature and allows the baby to move in the uterus for proper bone and muscle development. In addition, amniotic fluid plays an important role in the development of the baby's lungs.
The amniotic fluid is constantly being renewed: the baby swallows it, but also produces urine that becomes part of the amniotic fluid. Therefore, alterations in amniotic fluid volume may indicate a maternal or fetal problem and may have serious consequences in pregnancy.
How is the amount of amniotic fluid measured?
The amount of amniotic fluid is assessed by ultrasound, using one of two methods:
- Maximum vertical column (MCV): the maximum vertical column of amniotic fluid is determined and measured. Normal MCV values are considered to be between 2 and 8-10 cm (depending on gestational age).
- Amniotic fluid index (AFI): the uterus is divided into 4 quadrants and the maximum vertical columns of amniotic fluid in each of the quadrants are added together, with an AFI between 5 and 24 cm being considered normal.
In general, the method routinely used in low-risk pregnancies to assess the amount of amniotic fluid is CVS. However, if a gestational abnormality is detected, the specialist proceeds to calculate the ALI.
Polyhydramnios
Polyhydramnios is a condition in which the amniotic sac has an excessive amount of amniotic fluid. This disorder occurs in approximately 1-2% of pregnancies.
Polyhydramnios is usually mild. However, if polyhydramnios is severe or if it appears early in pregnancy, there is an increased risk of some complications.
Causes
The main causes of increased amniotic fluid may be related to both the mother and the baby and may include:
- Gestational diabetes.
- Multiple pregnancy.
- Anemia of the baby, such as that caused by Rh incompatibility problems.
- Gastrointestinal, urinary system or nervous system disorders or abnormalities in the infant.
- Fetal infections.
However, the causes remain unknown in about half of the cases of polyhydramnios.
Symptoms
In case of polyhydramnios, although it may be asymptomatic, the woman may notice some symptoms such as shortness of breath or shortness of breath (if the polyhydramnios is severe). This is because the uterus is enlarged, which puts pressure on the diaphragm and other organs of the mother.
In addition, the woman may also feel painful uterine contractions and inflammation or swelling in the legs.
Diagnosis
Although the specialist may suspect the presence of polyhydramnios if the uterus is larger than it should be at the time of gestation, the diagnosis is made by calculating the ILA. To diagnose polyhydramnios, the ILA must be greater than or equal to 25.
Once the diagnosis is established, the woman undergoes any tests that the specialist deems appropriate to try to find out the causes of polyhydramnios (such as a test to rule out gestational diabetes or maternal isoimmunization).
Treatment
The specialist will want to follow the evolution of the polyhydramnios, so the woman will attend frequent check-ups.
Treatment of excess amniotic fluid will depend on the cause of the excess amniotic fluid (if known), the amount of amniotic fluid and the woman's stage of pregnancy.
Therefore, in the event that the cause of polyhydramnios has been identified, appropriate treatment of the polyhydramnios will be carried out.
In some cases, amnio-drainage will be considered (especially if the polyhydramnios is severe or if the mother has severe symptoms). This procedure consists of an aspiration of amniotic fluid in order to reduce its volume.
On the other hand, it is possible to use certain medications to decrease the amount of urine of the baby and, therefore, the volume of amniotic fluid. However, these drugs are used in limited circumstances because of the adverse effects they may have on the baby.
Finally, the specialist will also assess the most appropriate time for delivery.
Oligohydramnios
Oligohydramnios is the medical term for a condition in which the amniotic sac has a decreased volume of amniotic fluid compared to what would be appropriate for the time of gestation.
The consequences of oligohydramnios, i.e. having too little amniotic fluid, can vary depending on the cause, severity and time of pregnancy at which it appears.
Causes
The main causes of decreased amniotic fluid in pregnancy are usually:
- Abnormalities in the fetal urinary system or other fetal alterations.
- Intrauterine growth restriction.
- Fetal cytomegalovirus infection.
- Pregnancy that is prolonged(post-term pregnancy).
- Premature rupture of membranes.
- Problems and dysfunctions in the placenta.
- Arterial hypertension.
- Certain drugs, such as ibuprofen.
However, the causes of oligohydramnios may sometimes be unknown.
Symptoms
Usually, oligohydramnios is asymptomatic and the woman will not notice any symptoms. Occasionally, the woman may perceive slower or fewer fetal movements.
However, if premature rupture of membranes has occurred, the woman will be able to observe a loss of amniotic fluid.
Diagnosis
It is true that oligohydramnios may be suspected if the uterus is smaller than what corresponds to gestational age. However, for the diagnosis of oligohydramnios, ILA measurement by ultrasound is performed.
The diagnosis of oligohydramnios is established with an ILA of less than 5 cm, which leads the specialist to request a series of tests to the pregnant woman to try to find out the possible causes.
Treatment
After the diagnosis of oligohydramnios, ultrasounds will be performed frequently to monitor the baby's development and ILA, as well as tests to assess the baby's heart rate (resting cardiotocography). However, it will be important to treat the cause, if known.
In addition, the pregnant woman may be advised to rest and increase fluid intake.
On the other hand, the specialist will also assess the best time for delivery, depending on the particular situation.
FAQs from users
What recommendations should a woman with oligohydramnios follow?
Oligohydramnios occurs when the volume of amniotic fluid is decreased during gestation. The diagnosis is ultrasound, measuring the amount of amniotic fluid by ultrasound.
We can divide the causes of Oligohydramnios into three main groups:
- Fetal causes: restricted intrauterine growth (RIC), chronologically prolonged gestation (CPG), fetal infection or alterations of the fetal urinary tract.
- Placental-membrane causes: premature rupture of membranes (PROM) accounts for most cases.
- Maternal causes: maternal medication.
Depending on the cause of Oligohydramnios and the time of pregnancy, your obstetrician will give you recommendations.
What happens when there is a lot of amniotic fluid?
When there is an excess of amniotic fluid in pregnancy, known as polyhydramnios, some complications may appear such as:
- Difficulty breathing in the mother.
- Premature rupture of membranes.
- Placental abruption.
- Premature delivery.
- Cesarean delivery.
- Prolapse of the umbilical cord.
For this reason, in the case of a diagnosis of polyhydramnios, the specialist will carry out an exhaustive control of the pregnancy.
What are the consequences of moderate or severe oligohydramnios?
The lack of amniotic fluid for a prolonged period of time can affect the organogenesis and growth of the fetus, especially the maturation of the lungs, leading to pulmonary hypoplasia.
At the time of delivery, oligohydramnios can also lead to complications such as fetal distress or meconium aspiration syndrome (MAS), leading to emergency cesarean section.
Suggested for you
If you want to read more about the effect of being overweight on male fertility, we recommend you enter the following article: Polyhydramnios: excess amniotic fluid.
On the other hand, if you want to know more about oligohydramnios, you can visit this article: Oligohydramnios: causes, diagnosis and treatment in pregnancy.
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References
Capone V, Persico N, Berrettini A, Decramer S, De Marco EA, De Palma D, Familiari A, Feitz W, Herthelius M, Kazlauskas V, Liebau M, Manzoni G, Maternik M, Mosiello G, Schanstra JP, Vande Walle J, Wühl E, Ylinen E, Zurowska A, Schaefer F, Montini G. Definition, diagnosis and management of fetal lower urinary tract obstruction: consensus of the ERKNet CAKUT-Obstructive Uropathy Work Group. Nat Rev Urol. 2022 May;19(5):295-303. (View)
Cheung KW, Morris RK, Kilby MD. Congenital urinary tract obstruction. Best Pract Res Clin Obstet Gynaecol. 2019 Jul;58:78-92. (View)
Khan IU, Aslam N, Anis FM, Mirza S, AlOwayed A, Aljuaid RM, Bakr RM. Amniotic Fluid Classification and Artificial Intelligence: Challenges and Opportunities. Sensors (Basel). 2022 Jun 17;22(12):4570. (View)
Kunochová Ivana, Gábor Martin, Jr Križko Marián, Alföldi Martin, Totka Adrián, Ferianec Vladimír. Fetal lower urinary tract obstruction: a current overview of intrauterine diagnosis and treatment. Ceska Gynekol. 2021;86(2):133-139. English. (View)
Matěcha J, Nováčková M. Idiopathic polyhydramnios. Ceska Gynekol. 2020 Winter;85(6):417-421. English. (View)
Morris RK, Meller CH, Tamblyn J, Malin GM, Riley RD, Kilby MD, Robson SC, Khan KS. Association and prediction of amniotic fluid measurements for adverse pregnancy outcome: systematic review and meta-analysis. BJOG. 2014 May;121(6):686-99. (View)
Pagan M, Eads L, Sward L, Manning N, Hunzicker A, Magann EF. Umbilical Cord Prolapse: A Review of the Literature. Obstet Gynecol Surv. 2020 Aug;75(8):510-518. (View)
Wax JR, Pinette MG. The amniotic fluid index and oligohydramnios: a deeper dive into the shallow end. Am J Obstet Gynecol. 2022 Sep;227(3):462-470. (View)
FAQs from users: 'What recommendations should a woman with oligohydramnios follow?', 'What happens when there is a lot of amniotic fluid?' and 'What are the consequences of moderate or severe oligohydramnios?'.
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