Intra-Abdominal Cysts

What is a fetal intra-abdominal cyst?

A fetal intra- abdominal cyst is a fluid filled sac found in the fetal abdomen.

What are the signs of a fetal abdominal cyst?

Fetal cysts are often diagnosed at the twenty-week scan, but may be diagnosed at any stage in pregnancy. Usually they do not cause any problems in pregnancy, however, if they grow very large they can put pressure on the baby’s developing lungs or other organs.
Occasionally large cysts may cause problems such as; polyhydramnios (excess liquor volume), ascites (fluid) or accumulation of fluid in the fetal abdomen) or bowel obstruction (blockage).

Types of intra- abdominal cysts
Cyst type Features Outcome/complications
Ovarian
Most common cyst type found in female fetus.

May be related to pregnancy hormones

May be very large
May be complicated by bleeding or twisting (torsion)
Around half need surgery after birth, the other half will resolve
Will need follow up after birth
Enteric duplication cyst
These form is the gut splits as it is forming during early embryological development.

May be very large
May cause bowel blockage and may need an operation after birth.
Mesenteric cyst
The mesentery attaches to the intestines and carry blood vessels that supply them, these cysts form within the mesentery.
These usually require post-natal surgery
Choledochal cyst
These form from the bile duct in or near the liver.
May require post-natal surgery
Pseudocyst
This is not a true cyst and is caused by a bowel that has ruptured and resealed.
May be complicated by infection
Genito-urinary cyst
These form on the kidney, the ureter or the bladder
Please see section on renal tract anomalies
Hepatic
Liver cyst
Usually uncomplicated

 

How are intra-abdominal cysts monitored during pregnancy?

This is usually done using serial scans (usually every four weeks) and most unborn babies can have a normal vaginal delivery.
Occasionally, if the cyst is very large it may twist upon itself (torsion) or cause pressure effects on other organs, in these cases the doctor may recommend surgery to drain or remove the cyst, before or after birth. After birth, paediatricians will continue to monitor the cyst in the baby.

What causes fetal intra-abdominal cysts?

A fetal abdominal cyst is not a cancer. Most fetal abdominal cysts happen when a difference occurs in the normal growth process makes an extra layer or bubble that fills with fluid. Doctors don’t know why it happens.

How is a fetal abdominal cyst diagnosed?

A routine ultrasound of the unborn baby will diagnose an intra-abdominal cyst. The fetal medicine specialist will study the size, location, contents, blood-flow and movement using ultrasound to try determine the diagnosis.

Occasionally they might recommend a referral to another specialist unit or fMRI to help plan if any treatment and follow up after birth that might be needed

What is the long-term outcome?

Prenatal ultrasound has an overall good diagnostic accuracy of intra-abdominal cysts and they are usually benign.

Clinical symptoms occur in approximately 1/3 of children, about 1/3 of the cysts resolve and about 50% require surgery. In cases which requires surgery the post-operative rate of surgical complication is low.