Fetal intra-abdominal cysts: accuracy and predictive value of prenatal ultrasound

The finding of a fetal intra-abdominal cyst is relatively common and it can be due to a wide variety of clinical conditions. The aims of this study were to determine the accuracy of the prenatal ultrasound (US) in identifying the etiology of fetal intra-abdominal cysts and to describe the neonatal outcomes.

All cases of fetal intra-abdominal cystic lesion referred to our center between 2004 and 2012 were reviewed. Cysts of urinary system origin were excluded. Prenatal and postnatal data were collected. Our cohort was divided into subgroups according to the prenatal suspected origin of the lesion (ovarian, mesenteric, gastro-intestinal and other locations). For each subgroup, sensitivity, specificity, positive predictive value, false-positive rate and accuracy of fetal US were calculated.

In total 47 fetuses (10/37 M/F) were identified. The mean gestational age at the time of diagnosis was 33 ± 4.9 weeks. Our cohort comprised of 25 ovarian cysts (10 simplex and 15 complex), 3 GI duplication, 6 mesenteric lesions, 4 meconium pseudocyst and 9 lesions of other origin. Surgery was performed in 38 cases (81%) at birth. The prenatally established diagnosis was exactly concordant with post-natal findings in 34 cases (72.3%). Sensitivity, specificity, positive predictive value and false-positive rate of US were 88.1%, 95.5%, 71% and 5.4%, respectively. Long-term outcome was good in almost 90% of the cases.

The etiology of fetal intra-abdominal cysts can be prenatally diagnosed in about 70% cases. Despite the high risk of surgery at birth, the long-term outcome was good in most of the cases.