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Reproductive/Endocrine Imaging

E3145. Fetal Abdominal Cystic Lesions: Practical Tips for Diagnosis

Shum D. University of California, San Francisco , San Francisco, CA

Address correspondence to D. Shum (dorothy.shum@ucsf.edu)

Background Information: With the advent of early fetal imaging for genetic screening and high-resolution ultrasound, fetal abdominal cystic lesions are being detected with increasing frequency. Cystic structures originate from a variety of organ systems including genitourinary, gastrointestinal, hepatobiliary, or vascular. While many abdominal cysts resolve spontaneously, early recognition of entities such as posterior urethral valves or abdominal teratomas may affect outcomes as in utero treatments are available. Detection of conditions commonly associated with genetic syndromes and chromosomal anomalies such as duodenal atresia with trisomy 21 prompts karyotype evaluation. While precise prenatal diagnosis is not always possible, a systematic approach to optimize diagnostic accuracy of fetal abdominal cystic structures improves patient counseling and facilitates appropriate clinical management.

Educational Goals/Teaching Points: In this exhibit, we provide an algorithm for evaluating cysts that includes determining sex of the fetus, identifying associated findings which aid in diagnosis (ascites, intraperitoneal calcifications, dilated or echogenic bowel, and urinary tract dilation), and a pictorial review of fetal abdominal cystic structures. We will review ovarian cysts, posterior urethral valves in male fetuses, cloacal malformation or hydrometrocolpos in female fetuses, urinoma, multicystic dysplastic kidneys, UPJ obstruction, and urachal cysts, duodenal atresia and obstruction and mimics, enteric duplication cyst, mesenteric cyst, choledochal cyst, hematoma, sacrococcygeal teratoma, and extralobar infradiaphragmatic pulmonary sequestration. Finally, we will provide a brief review of in utero treatments for posterior urethral valves (vesicoamniotic shunts and ablation of valves) and radiofrequency ablation of teratomas.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: This exhibit focuses on recognition of diagnostic imaging features by ultrasound. Examples include daughter cyst (cyst within cyst appearance of fetal ovarian cysts), keyhole sign (dilated posterior urethra in male fetuses with posterior urethral valves), double bubble sign (duodenal atresia or obstruction), anomalous aortic arterial supply to infradiaphragmatic pulmonary sequestration. We will also cover evaluation for associated features of meconium peritonitis (pseudocysts, ascites, dilated or echogenic bowel) and gut signature (seen in some gastrointestinal duplication cysts).

Conclusion: Fetal abdominal cystic structures have a wide variety of implications from benign to significant morbidity. Cystic lesions can be derived from any of the organ systems but are most commonly associated with genitourinary and gastrointestinal systems. Some practical tips such as fetal sex, presence of peritoneal calcifications or ascites, and evaluation of cyst content can help refine the list of potential causes. Accurate fetal diagnosis provides for realistic parental expectations and for appropriate prenatal and postnatal care.