The effect of image size on screen-positive rates for nuchal translucency screening.

It has been shown previously that the absolute measurement of nuchal translucency (NT) thickness, one of the most effective screening tests for fetal Down syndrome, significantly decreases with increasing image size. We undertook a prospective study to assess whether this effect materially alters the NT-derived risk estimation for fetal Down syndrome. In 350 women, NT was measured at both 100 and 200% image sizes. The median NT measurement at 200% was 8% smaller than at 100%. The screen-positive rates at 100 and 200% image sizes were 5.1% (18/350) and 2.3% (8/350), respectively (P= 0.048). Altering the image magnification settings is likely to decrease the sensitivity of NT-derived Down syndrome risk estimation. Further study is required to test the effect of our finding on the sensitivity of NT screening and to assess whether adjustments in gain settings mitigate the effect.

Mid-trimester fetal subdural hemorrhage: prenatal diagnosis.

A routine antenatal ultrasound examination at 20 weeks' gestation revealed a space-occupying lesion in the fetal right cerebral hemisphere. The borders of the mass were indistinct and there was no midline shift. A small collection of echogenic bowel was identified at the right iliac fossa. In an attempt to explain both findings a provisional diagnosis of a fetal blood dyscrasia was made. Fetal cranial magnetic resonance imaging 24 h later confirmed the diagnosis of a subdural hemorrhage. Subsequent fetal blood sampling confirmed severe fetal thrombocytopenia. To our knowledge this is the first report of the antenatal diagnosis of spontaneous mid-trimester fetal subdural hemorrhage.

Laryngeal atresia: antenatal diagnosis in a twin pregnancy.

Congenital laryngeal atresia is a rare malformation almost always incompatible with life. Prenatal sonographic diagnosis of this condition has been described on five occasions and all occurred in singleton pregnancies. To our knowledge, this is the first reported case of prenatal diagnosis of laryngeal atresia in a twin pregnancy. A monochorionic diamniotic twin gestation was noted at a routine ultrasound examination at 18 weeks' gestation. One twin was found to have changes consistent with laryngeal atresia with bilateral enlarged hyperechogenic lungs and hydrops fetalis. The other twin appeared normal. A Cesarean section was performed for worsening pre-eclampsia at 29 weeks' gestation. The abnormal twin died, despite resuscitative measures and autopsy confirmed the diagnosis of laryngeal atresia. The presence of the anomaly in only one twin of a monozygotic gestation supports the theory of a developmental anomaly within the branchial arches. Prenatal diagnosis of laryngeal atresia allows prenatal planning for resuscitation at birth, but its presence in one twin of a twin gestation poses several management dilemmas.

Successful outcome with serial amniocenteses for polyhydramnios complicating cystic adenomatoid malformation of the lung.

Hydrops fetalis secondary to congenital cystic adenomatoid malformation of the fetal lung is almost invariably a lethal condition. This poor prognosis may be attributed to the combined effects of tissue compression from the thoracic space occupying lesion and premature delivery of a hydropic baby following rupture of the membranes in the presence of polyhydramnios. We describe a successful outcome with serial amniocenteses. Partial in utero resolution of the lung lesion with complete return to normal of the aberrant liquor volume was documented, and a live infant was delivered at term.

Disappearing lung echogenicity in fetal bronchopulmonary malformations: a reassuring sign?

Congenital bronchopulmonary malformations detectable on prenatal ultrasound include cystic adenomatoid malformation (CAM), lobar sequestration, and upper airway atresia. We describe three fetuses with prenatally detected intrathoracic lesions in which the associated pulmonary hyperechogenicity disappeared before delivery. In the first case of pulmonary sequestration, the infant was asymptomatic after birth. However, in a case of CAM and another with laryngeal atresia, respiratory distress developed after delivery, despite recent scans showing apparently normal lung fields. This experience suggests that ultrasonic resolution of hyperechogenic lung lesions in utero does not necessarily indicate resolution of the underlying pathology.

Fetal ovarian cysts: diagnostic and therapeutic role for intrauterine aspiration.

Antenatal diagnoses of fetal ovarian cysts have not usually been confirmed until postnatal surgery. We describe 2 cases of hemorrhage into fetal ovarian cysts in which cyst aspiration in utero allowed both confirmation of the diagnosis prenatally and obviated the need for neonatal surgery. In both cases, cytology of the cyst aspirate demonstrated luteinized granulosa cells and biochemistry showed estradiol levels of > 10,000 pmol/l, indicating ovarian etiology. Hemorrhage, which had been suspected on ultrasound, was confirmed by cytology, showing hemosiderin-laden macrophages. There was no evidence of recurrence in either case following aspiration. The described association of fetal hypothyroidism was excluded by testing thyroid function in cord blood and/or cyst aspirate. We suggest that intrauterine aspiration contributes to the management of fetal ovarian cysts by confirming their ovarian origin, demonstrating the presence or absence of hemorrhage and facilitating preservation of ovarian function both by reducing the risk of torsion and the need for neonatal surgery.