Oligohydramnios causes, risk factors, symptoms, signs

Oligohydramnios (Low Amniotic Fluid):

Amniotic fluid is the fluid that surrounds and protects the baby in the womb. Initially it is made with water from the mother, but over time the fetus is made with urine. Oligohydramnios occurs when the volume of fluid in the amniotic sac is too small. About 4% of pregnant women have oligohydramnios.

Causes of oligohydramnios

Oligohydramnios can occur at any time during pregnancy, but it is usually diagnosed in the third trimester.

Oligohydramnios is usually caused by:

1. Placental problems: If the placenta does not provide enough nutrients to the baby, the baby may stop recycling fluid, thus reducing the amniotic fluid.
2. Birth defects: Some birth defects cause problems in the urinary tract and fetal kidneys, and insufficient urination.
3. Premature rupture of PROM membranes: When the water breaks before labor begins.
4. Amniotic fluid leak: A tear in the membrane causes a gush or leak of amniotic fluid.
5. Pregnancy after date: There is a risk of oligohydramnios after 42 weeks of pregnancy, as the amniotic fluid is reduced by half after this time. Additionally, a study of 3,050 complicated singleton pregnancies between 40 and 41.6 weeks’ gestation found that 11% had oligohydramnios.
6. Obstetric problems: maternal conditions such as diabetes, dehydration, hypertension, and pre-eclampsia can affect amniotic fluid levels.

Risk factors for oligohydramnios:

In some cases, women who develop oligohydramnios do not have significant risk factors. For this reason, it is important for doctors to monitor amniotic fluid levels during pregnancy. However, there are risk factors for oligohydramnios in most pregnant women.

Risk factors for oligohydramnios:

1. Maternal hypertension / preeclampsia
2. Gestational diabetes
3. Maternal dehydration
4. Obstetric hypoxia
5. Placental problems

Oligohydramnios signs and symptoms:

Some common signs and symptoms of reduced amniotic fluid volume.

1. Amniotic fluid leak
2. Less amniotic fluid on ultrasound
3. Measurements of size smaller than normal for gestational age.
4. Little maternal weight gain
5. Excision of membranes
6. Abdominal discomfort
7. Sudden decrease in fetal heart rate
8. Fetal movements or fetal movements are not reduced.
9. Abnormal fetal monitoring results, including fetal distress.

Diagnosis:

1. Ultrasound measurement of the amniotic fluid volume.
2. Complete ultrasound examination, including evaluation of fetal defects.
3. Tests to detect clinically suspicious maternal causes.

Oligohydramnios may be suspected if the size of the uterus is smaller than expected for the dates or if fetal movements are reduced; It can also be suspected based on random ultrasound findings. However, qualitative estimates of amniotic fluid volume are subjective. If oligohydramnios is suspected, the amniotic fluid should be evaluated quantitatively using the amniotic fluid index (AFI).

Except during cesarean delivery, the volume of amniotic fluid cannot be directly measured with certainty. Therefore, excess fluid is defined indirectly using ultrasound standards, usually AFI. AFI is the sum of the vertical depths of fluid measured in each quadrant of the uterus. The typical AFI ranges from> 5 to <24 cm, with values ​​denoting oligohydramnios ≤ 5 cm.

Treatment for Oligohydramnios:

1. Serial ultrasound to determine AFI and monitor fetal growth.
2. Test at rest or biophysical profile.

Ultrasound should be done once every 4 weeks (every 2 weeks if growth is limited) to monitor fetal growth. The AFI should be measured at least once a week. Most experts recommend fetal monitoring at least weekly with a resting test or biophysical profile and isolated oligohydramnios, otherwise it is administered at 36 to 37 weeks / 6 days (1). However, this approach has not been shown to prevent fetal death.

Also, the exact time of delivery can be controversial and can vary depending on the patient’s symptoms and fetal problems.

How are oligohydramnios maintained after birth?

Your pediatrician will design a management plan tailored to your child’s specific needs. The details of the plan depend on why we think your baby’s amniotic fluid is low.

1. If your amniotic fluid is low because your membranes are ruptured, you will be hospitalized so we can monitor you for signs of preterm labor. You can also take antibiotics to prevent infection and stimulate your labor depending on how far along you are in your pregnancy.
2. If the amniotic fluid is low due to the baby’s placenta not working properly, a test will often be scheduled, perhaps including a Doppler ultrasound. We will take a closer look at how your baby is doing and how the placenta is working. Sometimes mothers need to be hospitalized for this follow-up. Also, you may be given medicine to prepare your baby’s lungs for the possibility of premature delivery. In some cases, babies with a poorly functioning placenta must be born early to prevent fetal distress or delivery.
3. If your baby’s amniotic fluid is low due to an anatomical problem with the baby’s kidneys, bladder, or bladder, your baby’s management plan will depend on the specific birth defect. We will try to identify any critical factors that may require additional treatment or consultation. That way, we can be ready to care for your baby during and after delivery. We will also help you make appointments with pediatric urologists or nephrologists (kidney specialists) who will advise you on any surgery or other special care your baby may need after birth. In some cases, such as lower urinary tract obstruction (LUTO), we may even provide prenatal intervention.
4. If you are concerned that your baby is not having adequate lung development due to prolonged oligohydramnios in early pregnancy, we will work with your family, your pediatric neonatologist, and your palliative care specialist to manage the treatment and care you need. Before and after the baby is born.