154 Prenatal diagnosis of atretic parietal cephalocele: A case report

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Introduction and aims of the study: The term cephalocele refers to the herniation of intracranial structures through a fetal skull defect. The reported incidence of cephaloceles is 0.8-4 per 10000 live births, while atretic cephaloceles account for 4-17% of the total. Our objective is to present the prenatal diagnosis of an atretic parietal cephalocele, highlight the diagnostic pitfalls and discuss post diagnosis dilemmas. Methods: We present the case of a 34-year-old pregnant woman who presented to our Obstetrics Ultrasound Department for the routine second trimester (anomaly) scan. Her medical and family history was uneventful. She was Gravida 1 Para 0 (G1P0). The ultrasound examination revealed a singleton live fetus with a gestational age of 23 weeks. Biparietal diameter, head and abdominal circumference, femur length, estimated fetal weight and amniotic fluid index were within the normal range for the gestational age of the pregnancy. Detailed scanning of the fetal head revealed a posterior protruding sac-like structure, which appeared to originate from the right lambdoid suture. The mass measured 22.6x27x16mm and did not appear to include brain tissue. MRI revealed the apparent elevation of the straight venous sinus, a pathognomonic feature of congenital atretic parietal cephaloceles. Discussion: Theories regarding the origin of cephaloceles have suggested persistence of neural crest remnants or fetal neural blebs. A common sonographic find is the vertical position of the straight sinus. Prognosis determination is challenging as the condition is rare and it depends on the presence of concurrent central nervous system abnormalities. Conclusions: Thorough evaluation of the fetal head during the second trimester anomaly scan is essential for the diagnosis of atretic cephaloceles. The use of MRI facilitates the differential diagnosis of sculp lesions such as sinus pericranii, teratomas, lipomas, sarcomas and cephaloceles. Timely and accurate prenatal detection allows more time for parental counselling and delivery planning.