Letters
to the Editor
235
Early sonographic diagnosis of fetal acrania To the Editor
May 21st, 1992
A 31-year-old Chinese woman, gravida 3, para 2, was referred for routine obstetric sonography at 16 weeks of gestational age. Her 2 previous pregnancies were uncomplicated, resulting in 2 term babies. The medical and obstetric history was unremarkable. The abdominal sonography (Aloka SSD-680 3.5 MHz) showed a single viable fetus in vertex presentation. Polyhydramnios was not present. The measurements of abdominal circumference and of femur length were consistent with the gestational age. A normal vertebral column and
Keywords: Acrania; Congenital malformation.
normal facial bones were seen; however, the bony structures above the level of orbits were absent and an attached abundant brain tissue mass floating in the amniotic fluid was found. These characteristics were well demonstrated by vaginal sonography (ALOKA SSD-680 5.0 MHz) (Fig. 1). A maternal serum alpha fetoprotein count of 275 q/ml was obtained. The value was greater than 2.5 multiple of median in our laboratory and was highly suggestive of fetal neural tube defect. After counseling, an elective termination was undertaken with prostaglandin F2a. A dead acranius, weighed 95 g, with no evidence of other abnormality was delivered (Fig. 2). The X-ray examination confirmed the absence of fetal calvaria.
Sagittal view of vaginal sonogram: a large degenerated brain tissue mass surrounded by a thin membrane (arrow) was seen. S, spine; 0. orbital.
Fig. 1.
Int J Obstet Gynecol 39
236
Letters to the Editor
bryologic precursor to anencephaly [2,3]. Associated anomalies such as spina bitida, metatarsus varus, bilateral cleft lip and bilateral absence of the orbital floors have also been found [41. Since the calcification of the cranium was not completed until 11 weeks’ gestation, first trimester diagnosis of this pathologic entity is difficult. Differential diagnosis includes osteogenesis imperfecta, hypophosphatasia, anencephaly and encephalocele. With the presence of high resolution vaginal ultrasound, early diagnosis of fetal acrania would improve. C.P. Chen C.C. Tsai F.M. Chang
Department of Obstetrics and Gynecology National Cheng Kung University Hospital Tainan, Taiwan, China
References
Fig. 2.
Gross appearance of fetal acrania.
Acrania is a rare congenital malformation characterized by partial or complete absence of the calvarium with abnormal development of brain tissue. The etiology of this pathologic entity remains unclear. However, it has been suggested that a failure in normal migration of mesenchyme under the calvarian ectoderm, which occurs at the 4th week, would result in acrania [l]. Some authors reported that fetal acrania is an em-
Int J Obstet Gynecol39
Vergani P, Ghidini A, Sirtari M, Roncagha N: Antenatal diagnosis of fetal acrania. J Ultrasound Med 6: 7 15, 1987. Louise WH, Walter F: Progression of exencephaly to anencephaly in the human fetus - an ultrasound perspective. Prenat Diagn II: 227, 1991. Cox GG, Rosenthal SJ, Holsapple JW: Exencephaly: sonographic findings and radiologic-pathologic correlation. Radiology 155: 755, 1985. Ekici E, Giilmezoglu AM: Sonographic diagnosis of fetal acrania. J Clin Ultrasound 19: 363, 1991.
Correspondenceto: C.-P. Chen Department of Obstetrics and Gynecology National Cheng Kung University Hospital No. 138 Sheng-Li Road 70101 Tainan, Taiwan, China.
to the Editor
235
Early sonographic diagnosis of fetal acrania To the Editor
May 21st, 1992
A 31-year-old Chinese woman, gravida 3, para 2, was referred for routine obstetric sonography at 16 weeks of gestational age. Her 2 previous pregnancies were uncomplicated, resulting in 2 term babies. The medical and obstetric history was unremarkable. The abdominal sonography (Aloka SSD-680 3.5 MHz) showed a single viable fetus in vertex presentation. Polyhydramnios was not present. The measurements of abdominal circumference and of femur length were consistent with the gestational age. A normal vertebral column and
Keywords: Acrania; Congenital malformation.
normal facial bones were seen; however, the bony structures above the level of orbits were absent and an attached abundant brain tissue mass floating in the amniotic fluid was found. These characteristics were well demonstrated by vaginal sonography (ALOKA SSD-680 5.0 MHz) (Fig. 1). A maternal serum alpha fetoprotein count of 275 q/ml was obtained. The value was greater than 2.5 multiple of median in our laboratory and was highly suggestive of fetal neural tube defect. After counseling, an elective termination was undertaken with prostaglandin F2a. A dead acranius, weighed 95 g, with no evidence of other abnormality was delivered (Fig. 2). The X-ray examination confirmed the absence of fetal calvaria.
Sagittal view of vaginal sonogram: a large degenerated brain tissue mass surrounded by a thin membrane (arrow) was seen. S, spine; 0. orbital.
Fig. 1.
Int J Obstet Gynecol 39
236
Letters to the Editor
bryologic precursor to anencephaly [2,3]. Associated anomalies such as spina bitida, metatarsus varus, bilateral cleft lip and bilateral absence of the orbital floors have also been found [41. Since the calcification of the cranium was not completed until 11 weeks’ gestation, first trimester diagnosis of this pathologic entity is difficult. Differential diagnosis includes osteogenesis imperfecta, hypophosphatasia, anencephaly and encephalocele. With the presence of high resolution vaginal ultrasound, early diagnosis of fetal acrania would improve. C.P. Chen C.C. Tsai F.M. Chang
Department of Obstetrics and Gynecology National Cheng Kung University Hospital Tainan, Taiwan, China
References
Fig. 2.
Gross appearance of fetal acrania.
Acrania is a rare congenital malformation characterized by partial or complete absence of the calvarium with abnormal development of brain tissue. The etiology of this pathologic entity remains unclear. However, it has been suggested that a failure in normal migration of mesenchyme under the calvarian ectoderm, which occurs at the 4th week, would result in acrania [l]. Some authors reported that fetal acrania is an em-
Int J Obstet Gynecol39
Vergani P, Ghidini A, Sirtari M, Roncagha N: Antenatal diagnosis of fetal acrania. J Ultrasound Med 6: 7 15, 1987. Louise WH, Walter F: Progression of exencephaly to anencephaly in the human fetus - an ultrasound perspective. Prenat Diagn II: 227, 1991. Cox GG, Rosenthal SJ, Holsapple JW: Exencephaly: sonographic findings and radiologic-pathologic correlation. Radiology 155: 755, 1985. Ekici E, Giilmezoglu AM: Sonographic diagnosis of fetal acrania. J Clin Ultrasound 19: 363, 1991.
Correspondenceto: C.-P. Chen Department of Obstetrics and Gynecology National Cheng Kung University Hospital No. 138 Sheng-Li Road 70101 Tainan, Taiwan, China.
