[First trimester cystic structures in the fetalabdomen: diagnosis and prognostic value]

To define the major sonographic findings used in the diagnosis and differential diagnosis of fetal abdominal cysts in the first trimester and to establish their clinical relevance to the perinatal outcome.

A prospective longitudinal study of 5 antenatally detected cases of fetal abdominal cysts between 11-14 w.g. was performed in the University Hospital of Obstetrics and Gynecology "Maichin dom" and MC "Markovs", Sofia between Jan 2007 and Aug 2009. In all cases color flow mapping was used to differentiate the cystic structure from the fetal bladder by identifying the two umbilical arteries. All continuing pregnancies were carefully followed up sonographically at 14-16 w.g, 18-22 w.g. and 28-32 w.g., including with fetal echocardiography. Genetic amniocentesis was offered in all cases to exclude associated chromosomal abnormality. Termination of pregnancy was an option in all affected cases. Information about the perinatal outcome was ascertained by the hospital records, the referring physicians and/or the patients themselves.

There were 5 cases of fetal abdominal cysts diagnosed between 11-14 w.g. during the study period (2--megacystis, 3--cystic structures from the gastro-intestinal tract). In one case of megacystis the patients opted for termination of pregnancy at 15 w.g. The second affected case was a male fetus from a twin pregnancy. The patient delivered at term by Cesarean section with a subsequent surgical treatment of the newborn. In one of the remaining three cases of fetal abdominal cysts the patients opted for termination of pregnancy at 12 w.g. The other two were followed up sonographically. Eventually, a complete resolution of the cystic structure was demonstrated. Both newborns had an uneventful perinatal outcome and were delivered at term with no complications in the early neonatal period.

Megacystis is a common fetal abdominal cyst in early pregnancy. Abdominal cysts with other origin often resolve spontaneously or remain small in the second and third trimester. Thus, they usually have a good perinatal outcome. Nevertheless, some first trimester fetal abdominal cysts can be associated with structural abnormalities or other complications from the gastrointestinal tract.