In brief — the direct answer
Amnioreduction removes some amniotic fluid through an ultrasound-guided needle. It may be considered when severe polyhydramnios causes substantial maternal discomfort or difficulty breathing. It can relieve pressure but does not treat every underlying cause or guarantee that preterm birth will be prevented. The team first investigates why the fluid is increased.
What is Amnioreduction?
The procedure is similar to an amniocentesis but on a larger scale.
While an amniocentesis takes only 20ml of fluid for testing, an amnioreduction can remove anywhere from 1 to 3 liters of fluid. We use a vacuum-seal system or a controlled pump to ensure the fluid is removed at a steady pace, preventing sudden changes in pressure that could distress the baby.
Who is at risk?
Specialist assessment considers the severity of symptoms and fluid excess, gestation, fetal findings and the cause. Mild, asymptomatic polyhydramnios is not itself an indication for drainage. TTTS requires a separate fetal-therapy assessment; fluid drainage does not correct the shared placental vessel connections.
How we diagnose it
Before the procedure, we perform a detailed fluid assessment:
- Amniotic Fluid Index (AFI): Measuring the fluid in all four quadrants of the uterus.
- Deepest Vertical Pocket (DVP): A pocket over 8-10cm is usually considered significant.
- Fetal Anatomy Scan: Checking for any reasons why the baby might not be swallowing correctly (a common cause of extra fluid).
What does management involve?
The procedure is performed under local anesthesia in a comfortable setting:
- Continuous Monitoring: We watch the baby's heart rate and movements throughout the process.
- Needle Guidance: A thin needle is guided into a large pocket of fluid away from the baby.
- Controlled Drainage: Fluid is slowly drawn out into specialized containers. This usually takes between 30 and 60 minutes.
- Immediate Relief: Mothers often feel an instant reduction in pressure and find it much easier to breathe before they even leave the procedure room.
What are the outcomes?
Symptoms may improve after drainage, but fluid can reaccumulate and repeat procedures may be needed. Evidence does not establish a predictable number of extra weeks of pregnancy caused by the procedure. Risks include membrane rupture, contractions or preterm birth, infection, bleeding and placental abruption. The clinician should explain an individual risk estimate and alternatives rather than a universal percentage.
When to see a subspecialist
Arrange MFM review for severe fluid excess or significant discomfort. New breathlessness, pain, contractions, fluid leakage or reduced fetal movements needs prompt maternity assessment rather than waiting for an outpatient appointment. After drainage, follow the written aftercare and contact instructions.