Prenatal diagnosis of rhombencephalosynapsis: neuroimaging features and severity of vermian anomaly

OBJECTIVES

To describe the prenatal neuroimaging spectrum of rhombencephalosynapsis (RES) and criteria for its classification according to the severity of vermian anomaly.

METHODS

In this multicenter retrospective study of fetuses with RES between 2002 and 2020, the medical records and brain ultrasound and magnetic resonance images were evaluated comprehensively to determine the severity of the vermian anomaly and the presence of associated brain findings. RES was classified, according to the pattern of vermian agenesis and the extent of the fusion of the hemispheres, as complete RES (complete absence of the vermis) or partial RES (further classified according to the part of the vermis that was missing and, consequently, the region of hemispheric fusion, as anterior, posterior, severe or mixed RES). Findings were compared between cases with complete and those with partial RES.

RESULTS

Included in the study were 62 fetuses with a gestational age ranging between 12 and 37 weeks. Most had complete absence of the vermis (complete RES, 77.4% of cases), a 'round-shaped' cerebellum on axial views (72.6%) and a transverse cerebellar diameter (TCD) < 3^rd centile (87.1%). Among the 22.6% of cases with partial RES, 6.5% were classified as severe partial, 6.5% as partial anterior, 8.1% as partial mixed and 1.6% as partial posterior. Half of these cases presented with normal or nearly normal cerebellar morphology and 28.5% had a TCD within the normal limits. Infratentorially, the fourth ventricle was abnormal in 88.7% of cases overall, and anomalies of the midbrain and pons were frequent (93.5% and 77.4%, respectively). Ventriculomegaly was observed in 80.6% of all cases, being more severe in cases with complete RES than in those with partial RES, with high rates of parenchymal and septal disruption.

CONCLUSIONS

This study provides prenatal neuroimaging criteria for the diagnosis and classification of RES, and identification of related features, using ultrasound and magnetic resonance imaging. According to our findings, a diagnosis of RES should be considered in fetuses with a small TCD (severe cerebellar hypoplasia) and/or a round-shaped cerebellum on axial views, during the second or third trimester, especially when associated with ventriculomegaly. Partial RES is more common than previously thought, but presents an extreme diagnostic challenge, especially in cases with normal or nearly-normal cerebellar morphobiometric features. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of microcephaly at birth using three reference ranges for fetal head circumference: can we improve prenatal diagnosis?

OBJECTIVE

To evaluate the prediction of microcephaly at birth (micB) using established and two new reference ranges for fetal head circumference (HC) and to assess whether integrating additional parameters can improve prediction.

METHODS

Microcephaly in utero was defined as a fetal HC 3SD below the mean for gestational age according to Jeanty et al.'s reference range. The records of cases with fetal microcephaly (Fmic) were evaluated for medical history, imaging findings, biometry and postnatal examination/autopsy findings. Microcephaly was confirmed at birth (micB) by an occipitofrontal circumference (OFC) or a brain weight at autopsy 2SD below the mean for gestational age. The new INTERGROWTH-21(st) Project and a recent Israeli reference for fetal growth were applied for evaluation of the Fmic positive predictive value (PPV) for diagnosis of micB cases. Optimal HC cut-offs were determined for each of the new references with the aim of detecting all micB cases whilst minimizing the number of false positives found to have a normal HC at birth. We also assessed the difference between the Z-scores of the prenatal HC and the corresponding OFC at birth, the frequency of small-for-gestational age (SGA), decreased HC/abdominal circumference (AC) and HC/femur length (FL) ratios, the prevalence of associated malformations and family history.

RESULTS

Forty-two fetuses were diagnosed as having Fmic according to the Jeanty reference, but micB was confirmed in only 24 (PPV, 57.1%). The optimal INTERGROWTH and Israeli reference HC cut-offs for micB diagnosis were mean - 3SD and mean - 2.3SD, resulting in a statistically non-significant improvement in PPV to 61.5% and 66.7%, respectively. The presence of a family history of microcephaly, SGA, associated malformations and application of stricter HC cut-offs resulted in a higher PPV of micB, although not statistically significant and with a concurrent increase in the number of false-negative results. The deviation of the HC from the mean, by all references, was significantly larger compared with the actual deviation of the OFC at birth, with mean differences between the corresponding Z-scores of -1.15, -1.95 and -0.74 for the Jeanty, INTERGROWTH and Israeli references, respectively.

CONCLUSIONS

The evaluated reference ranges all result in considerable over-diagnosis of fetal microcephaly. The use of the two new HC reference ranges did not significantly improve micB prediction compared with that of Jeanty et al., whilst use of additional characteristics and stricter HC cut-offs could improve the PPV with an increase in false negatives. The postnatal OFC deviates significantly less from the mean compared with the prenatal HC, and we propose that adjustment for this would enable better prediction of the actual OFC deviation at birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Application of a novel prenatal vertical cranial biometric measurement can improve accuracy of microcephaly diagnosis in utero

OBJECTIVE

To construct a reference range for a new vertical measurement of the fetal head and to assess whether its combination with fetal head circumference (HC) can prevent the misdiagnosis of microcephaly in fetuses with an acrocephalic-like head deformation.

METHODS

A new vertical cranial biometric measurement was defined: the foramen magnum-to-cranium distance (FCD), measured between the foramen magnum and the upper inner cranial border along the posterior wall of the brainstem. The measurement was performed in a precise mid-sagittal plane using a three-dimensional multiplanar display of a sagittally acquired sonographic volume of the fetal head. The normal reference range was developed by measuring 396 healthy fetuses of low-risk singleton pregnancies between 15 and 40 gestational weeks. This reference was applied to 25 fetuses with microcephaly diagnosed prenatally (Fmic) based on HC ≥ 3 SD below the mean for gestational age. We determined an optimal FCD cut-off for combination with HC to detect all cases found with microcephaly at birth (micB), while excluding the fetuses with normal head circumference at birth (NHCB), who were described postnatally as having an acrocephalic-like cranial deformation.

RESULTS

In the healthy singleton fetuses, FCD increased with gestational age, with a quadratic equation providing an optimal fit to the data (adjusted R(2) = 0.934). The measurement could be assessed in 95.2% of cases. Of the 25 cases diagnosed with Fmic prenatally, on the basis of HC alone, 14 were micB and 11 were NHCB. We observed FCD below the mean - 2SD for gestational age in all 14 micB cases, but in only four of the 11 NHCB cases (P < 0.003). An acrocephalic-like cranial deformation was described at birth in five of the seven NHCB cases with normal FCD. The mean ± SD FCD Z-score of the micB cases was significantly lower (P < 0.001) than that of the false-positive ones: -3.85 ± 0.96 SD and -1.59 ± 1.45 SD, respectively. Based on HC measurement alone, the positive predictive value (PPV) was 56%. Combination of the HC and FCD criteria raised the PPV to 78%, decreasing the number of false positives from 11 to four, without missing any of the 14 micB cases.

CONCLUSIONS

Fetal vertical cranial biometric assessment in the mid-sagittal plane is feasible and correlates well with gestational age. In our series, a vertical cranial deformation was a frequent cause of a false Fmic diagnosis made on the basis of HC alone. Combination of the new vertical cranial biometric measurement with HC measurement can exclude these cases and thus improve diagnostic accuracy for Fmic. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Congenital periventricular pseudocysts: prenatal sonographic appearance and clinical implications

OBJECTIVE

Periventricular pseudocysts (PVPC) are diagnosed in approximately 1% of premature newborns that undergo brain sonography during the first 24 h of life. These pseudocysts are thought to develop antenatally due to germinal matrix hemorrhage, but have not been described until now in prenatal ultrasound studies. The aim of this study was to report the identification, differential diagnosis, and prognosis of PVPC detected by prenatal ultrasound examination.

DESIGN

Between 1997 and 2001 we made an ultrasound diagnosis of PVPC in 11 fetuses. In nine fetuses the findings were characteristic of PVPC and these patients represent our study group. Fetal magnetic resonance imaging was performed in five patients. Termination of pregnancy was carried out in three patients, in one case intrauterine fetal death occurred at 31 weeks, and one infant died in the neonatal period. The surviving four newborns are being followed in the pediatric neurology clinic.

RESULTS

PVPC were diagnosed by ultrasound scan in fetuses between 16 and 37 weeks of gestation (mean, 29.7 weeks). Magnetic resonance imaging confirmed the presence of PVPC in two cases. In eight cases the pseudocysts were unilateral and in one case bilateral. They were an isolated finding in five patients. Four of these fetuses were delivered at term and have normal neurological development at ages ranging from 6 to 25 months. All fetuses with additional pathologies (coarctation of the aorta, hemimegalencephaly, cytomegalovirus infection, hypoplasia of the vermis with dysmorphism) did not survive.

CONCLUSIONS

The prenatal diagnosis of PVPC warrants an extensive search for possible associated pathological findings. As an isolated finding, antenatal PVPC seem to carry a good prognosis.

Prediction of pregnancy-induced hypertension by a combination of rollover test and Doppler flow velocity measurement

Following a rollover test performed in 306 nulliparous women in the 28th gestational week, Doppler flow velocity studies were conducted in all 34 women with positive rollover findings and in 67 women selected at random from those with negative findings. The mean systolic diastolic ratios in both the uterine and the umbilical arteries were significantly higher in women with positive rollover findings than in the control group. A review of the patients' medical records after delivery, indicated that this combined two-stage screening approach--a rollover test followed by a Doppler flow study--improved the predictive value and the sensitivity of the screening procedure from 35% and 39% respectively for the rollover test alone, to 56% and 50% with no decline in specificity. The sensitivity of the Doppler flow test as a single one among the 101 flow-studied women was higher--61%. However, broader studies are needed in order to establish its superiority as a single test for early prediction of pregnancy-induced hypertension.

The use of aspirin to prevent pregnancy-induced hypertension and lower the ratio of thromboxane A2 to prostacyclin in relatively high risk pregnancies

We carried out a prospective, randomized, double-blind, placebo-controlled study to investigate the capacity of aspirin to prevent pregnancy-induced hypertension and to alter prostaglandin metabolism. A total of 791 pregnant women with various risk factors for pre-eclamptic toxemia were screened with use of the rollover test (a comparison of blood pressure before and after the woman rolls from her left side to her back) during week 28 or 29 of gestation. Of 69 women with abnormal results (an increase in blood pressure during the rollover test), 65 entered the study and were treated with a daily dose of either aspirin (100 mg; 34 women) or placebo (31 women) during the third trimester of pregnancy. The number of women in whom pregnancy-induced hypertension developed was significantly lower among the aspirin-treated than among the placebo-treated women (4 [11.8 percent] vs. 11 [35.5 percent]; P = 0.024); the same was true for the incidence of preeclamptic toxemia (1 [2.9 percent] vs 7 [22.6 percent]; P = 0.019). The mean ratio of serum levels of thromboxane A2 to serum levels of prostacyclin metabolites after three weeks of treatment decreased by 34.7 percent in the aspirin-treated group but increased by 51.2 percent in the placebo-treated group. No serious maternal or neonatal side effects of treatment occurred in either group. We conclude that low daily doses of aspirin taken during the third trimester of pregnancy significantly reduce the incidence of pregnancy-induced hypertension and pre-eclamptic toxemia in women at high risk for these disorders, possibly through the correction of an imbalance between levels of thromboxane and prostacyclin.

Pyosalpinx subsequent to tubal ligation

A case of salpingitis with pyosalpinx subsequent to tubal ligation is described. The procedure was performed at the time of cesarean section 7 years earlier. The pyosalpinx included the distal portion of the ligated tube, with no evidence of infection in the proximal segment. Although pelvic peritonitis, salpingitis and tubo-ovarian abscess are rare following tubal ligation, they should be suspected in any patient presenting with lower abdominal pain.

Pathological features and prenatal diagnosis in the newly recognised limb/pelvis-hypoplasia/aplasia syndrome

A second family with the autosomal recessive disorder now referred to as the limb/pelvis-hypoplasia/aplasia syndrome is reported. It is speculated that the gene for this rare skeletal dysplasia may be confined to the Middle East gene pool. The disorder has been shown to be diagnosable prenatally in a pregnancy at risk by using ultrasonography.

Fractional gradients along the outflow tract of the right ventricle in tetralogy of Fallot: anatomic and hemodynamic correlative study

In 16 patients undergoing surgical correction of tetralogy of Fallot, attempts were made to determine where, in the outflow tract, the most critical preoperative obstruction was located. In the open chest, pressures were taken in the right ventricle, proximal conus, distal conus, and pulmonary artery. Pressure gradients between these levels were indicative of stenosis at the infundibular ostium (Ost.), conus (C), and pulmonary valve (PV), respectively. Total delta P = delta P Ost. + delta P C + delta P PV, where delta P is the pressure gradient between the right ventricle and the pulmonary artery. In order to evaluate the contribution of each obstructive segment to the overall obstruction, we introduced a new term, the fractional gradient (FG). The FG is defined by the following formula: FG = (delta P segmental/delta P total). The average total pressure gradient in this series was 7 mm Hg. The average segmental gradients were 15.5, 39.0, and 17.0 mm Hg for the infundibular ostium, conus, and pulmonary valve, respectively. The FGs across segments were 0.20, 0.54, and 0.26, indicating that only 20% of the average obstruction was located in the infundibular ostium. The remaining obstruction is distal and unrelated to the infundibular ostium. Analysis of the FGs in the various types of conus indicated, from an anatomic viewpoint, that in 80% of patients with tetralogy the infundibulectomy does not have to be radical.