To understand the causes of fluid accumulation in an unborn baby’s abdomen, how it is diagnosed during pregnancy, and the available treatment options, we spoke with Dr Shraddha Shinde, Consultant – Foetal Medicine at Ankura Hospital for Women and Children, Pune.
What Is Foetal Ascites?
Foetal ascites is the buildup of fluid inside a baby’s abdominal cavity before birth. Doctors usually detect it during a prenatal ultrasound.The fluid collects around the abdominal organs, such as the intestines and liver. Foetal ascites is a finding, not a disease, so doctors investigate the underlying cause.
Sometimes, fluid is present only in the abdomen. This is called isolated foetal ascites. In other cases, fluid may also collect around the lungs or heart, or under the skin. When fluid builds up in multiple areas, it may indicate a more serious condition called foetal hydrops.
Foetal ascites is a finding that needs further investigation, not a diagnosis that determines a baby’s future. Early evaluation and appropriate multidisciplinary care help identify the underlying cause, guide treatment decisions, and ensure the best possible care for both mother and baby.
What Causes Fluid to Build Up in a Babys Abdomen?
Foetal ascites can develop because of problems affecting the baby’s organs, blood circulation, or fluid drainage.Common causes include:
- Digestive system problems: A bowel blockage or hole in the intestine can let intestinal contents leak into the abdominal cavity, causing inflammation and fluid buildup.
- Urinary tract problems: Blockages in the baby’s urinary tract may cause urine to leak into the abdomen.
- Heart or circulation problems: Certain heart conditions can disrupt normal blood flow and cause fluid buildup.
- Foetal anaemia: A low red blood cell count can affect the baby’s circulation and, in severe cases, lead to fluid buildup.
- Infections: Some infections during pregnancy, including parvovirus B19 and cytomegalovirus, may contribute to fetal ascites.
- Genetic or developmental conditions: Certain chromosomal conditions or abnormalities affecting the baby’s organs and lymphatic system may cause fluid accumulation.
What Are the Signs of Foetal Ascites?
Foetal ascites usually does not cause symptoms that the mother can identify herself. Doctors usually detect it during an ultrasound.Doctors may notice:
- Fluid surrounding the baby’s abdominal organs
- An unusually enlarged or swollen-looking foetal abdomen
- Abnormalities involving the intestines, bladder, kidneys, or other organs
- Additional fluid around the heart or lungs, or beneath the skin, in cases associated with foetal hydrops
How Is Foetal Ascites Diagnosed?
Doctors use ultrasound findings and additional tests to identify the cause and assess the baby’s condition.- Detailed foetal ultrasound: Checks the amount of abdominal fluid and looks for abnormalities involving the digestive, urinary, and other organ systems.
- Foetal Doppler assessment: Evaluates blood flow and may help identify signs of foetal anaemia or circulation problems.
- Foetal echocardiography: A specialised ultrasound that examines the baby’s heart when a cardiac problem is suspected.
- Maternal blood tests: May check for infections, blood group antibodies, and other conditions depending on the suspected cause.
- Genetic testing: Amniocentesis or other appropriate testing may be offered when chromosomal or genetic conditions are suspected.
Can Foetal Ascites Be Treated?
Yes, treatment may be possible, but it depends on the cause of the fluid buildup and how severely it affects the baby.- Regular monitoring: If the fluid is limited to the abdomen and the baby is otherwise stable, doctors may recommend repeat ultrasounds and specialist follow-up.
- Treatment for the underlying cause: If foetal ascites is linked to a condition such as foetal anaemia, doctors may recommend specific treatment during pregnancy.
- Foetal intervention: In selected cases, a specialist may consider an intervention before birth, depending on the underlying problem and the risks involved.
- Treatment after birth: Some babies may need surgery for digestive or urinary tract abnormalities. Others may require treatment for infection or other medical conditions.
When Should You See a Doctor?
If an ultrasound shows fluid in your baby’s abdomen, contact your obstetrician or foetal medicine specialist promptly for further assessment.Your doctor may recommend:
- A detailed ultrasound to look for the cause
- Additional tests based on the findings
- Follow-up scans to monitor the fluid
- Delivery planning at a hospital with appropriate neonatal care, if needed
FAQs on Fluid in a Baby’s Belly Before Birth: Causes, Diagnosis and Treatment
- Does foetal ascites always mean the baby has a birth defect?
No. It can result from several conditions, and not every case involves a birth defect. - Is foetal ascites the same as foetal hydrops?
No. Foetal ascites affects the abdomen, while foetal hydrops involves fluid buildup in at least two areas of the baby’s body. - Can foetal ascites be detected during a routine pregnancy scan?
Yes. Ultrasound can detect abdominal fluid, and further tests may help identify its cause.