Amnioreduction is an ultrasound-guided procedure that removes excess amniotic fluid through a needle. It may be considered when severe polyhydramnios causes significant maternal discomfort or breathing difficulty, contributes to threatened preterm birth, or forms part of management for a specific fetal or twin complication.
The procedure reduces fluid volume; it does not automatically correct the process that produced the fluid. This distinction is essential in counselling.
Why fluid may be high
Polyhydramnios has many causes, including maternal diabetes, impaired fetal swallowing, gastrointestinal obstruction, fetal anaemia, infection, neurological or muscular disorders, and complications of monochorionic twins. Sometimes no cause is identified.
Before drainage, ultrasound assesses fetal anatomy, growth, placental findings, cervical length, fluid severity, and signs of hydrops. Maternal history, glucose testing, infection or genetic evaluation, and fetal echocardiography may be relevant depending on the pattern.
During and after the procedure
Under sterile conditions and continuous ultrasound guidance, a needle is passed into an amniotic-fluid pocket away from the fetus and important placental structures. The planned volume and stopping point depend on symptoms, gestation, uterine response, fetal status, and local protocol.
Risks can include fluid leakage, membrane rupture, contractions, preterm birth, bleeding, infection, placental abruption, fetal injury, or pregnancy loss. Fluid may accumulate again, particularly when the underlying mechanism continues, and repeat procedures may be discussed.
Amnioreduction in TTTS
In twin-to-twin transfusion syndrome, amnioreduction can relieve polyhydramnios but does not ablate the placental vascular connections that drive the syndrome. The role of drainage must therefore be considered against gestational age, TTTS stage, cervical findings, availability and appropriateness of fetoscopic laser, and the whole clinical picture.
Questions to ask
Ask what is causing the excess fluid, what the procedure is intended to achieve, what alternatives exist, how recurrence will be monitored, which symptoms require urgent contact, and whether the diagnosis changes delivery or neonatal planning.
The essential distinctions
Where fluid collects helps explain the finding.
Fluid around the baby and fluid inside the baby are different findings. The underlying cause determines the options.
- Find the cause
Imaging and selected tests assess the placenta, heart, blood, genetics, and infection.
- Locate the fluid
Chest, abdominal, or skin fluid needs a different interpretation from excess amniotic fluid.
- Choose the response
Observation, treatment of the cause, drainage, or birth may be discussed according to the complete picture.