This leaflet is to help you understand what Hydrothorax is, what tests you need, and the implication of having been diagnosed with Hydrothorax for your baby and your family. 

What is Hydrothorax?

Hydrothorax is a relatively commonly occurring abnormal finding in the fetus in which there is an abnormal collection of fluid around the lungs. It could occur around one or both lungs and may be the only abnormality found or be one of a number of abnormalities found in the fetus.

How does it happen?

Hydrothorax could be due to a number of causes: If it is isolated, it may be due to a malformation of the duct draining lymph from the abdomen. Hydrothorax may be a component of a condition called hydrops where there is fluid accumulation in two or more body cavities. It may also occur in association with other conditions, which have a high risk of having abnormal chromosomes. Hydrothorax may be severe enough to shift structures from one-half of the chest into the other.

How are chromosomes relevant to Hydrothorax?

There is a high risk of association of hydrothorax with both chromosomal and non-chromosomal syndromes. If there are fetal heart abnormalities or central nervous system abnormalities in addition to hydrothorax, it is likely there are chromosomal abnormalities present. Isolated transient hydrothorax may still be associated with chromosomal anomalies especially Down’s syndrome and Turner syndrome. The long-term outcome is usually good if hydrothorax is isolated and there are no other chromosomal abnormalities.

Should I have more tests done?

There is an association with other abnormalities and other syndromes and because of this. A thorough ultrasound assessment will need to be done by an expert to look for associated abnormalities. Your doctor will likely offer genetic testing to rule out the presence of abnormalities in chromosomes to you.

What are the things to watch for during pregnancy?

The amount of fluid surrounding the lung or lungs will need to be monitored for progression or resolution using serial ultrasound monitoring of the fetus. There may be a displacement of the heart to the other side of the chest if the volume of the fluid in the chest progressively increases. In some cases, if severe, your baby may require an intervention before birth to divert the fluid away from the lungs and into the amniotic fluid surrounding the baby. This procedure involves placement o f a hollow tube into the fluid collection and into the amniotic cavity and is called a “shunt”.

What does it mean for my baby after it is born?

The outcomes depend on the cause of the hydrothorax. Spontaneous resolution of the fluid collection is possible in some cases. If the hydrothorax is due to a more generalized syndrome, hydrops, with fluid collections in multiple places in the baby, from non- identifiable causes, it is less likely to be treatable. The outcome for isolated hydrothorax in the absence of chromosomal abnormalities is usually good.

Will it happen again?

The risk of hydrothorax recurring in subsequent pregnancies depends on the underlying cause of the hydrothorax.

What other questions should I ask?

  • What is the cause of my baby’s hydrothorax?
  • Can I carry this pregnancy to term?
  • Do I have to deliver in a tertiary center?
  • Will my baby need a surgical intervention?
  • Will my next baby also have hydrothorax?


Last updated February 2024