Polymicrogyria in a fetus with human parvovirus B19 infection: a case with radiologic-pathologic correlation.

We report the prenatal magnetic resonance imaging (MRI) appearance of polymicrogyria with pathologic correlation in a fetus with congenital parvovirus B19 infection. Prenatal ultrasound revealed non-immune hydrops, but detected no fetal brain abnormalities. A subsequent fetal MRI scan performed at 23 weeks' gestation demonstrated bilateral polymicrogyria, which was confirmed at autopsy. To our knowledge, prenatal diagnosis of polymicrogyria in association with congenital parvovirus B19 infection has not been previously described. This case provides further evidence for brain abnormalities resulting from congenital parvovirus B19 infection, and suggests that fetal neuroimaging with MRI would be of value in suspected cases of congenital parvovirus infection.

Evaluation of femur length during the second and third trimesters in fetuses with myelomeningocele.

OBJECTIVES: To determine if the femur length of fetuses with myelomeningocele is shorter in the second and third trimesters compared with that of normal fetuses. METHODS: We retrospectively collected measurements of femur length, head circumference, biparietal diameter and abdominal circumference from detailed obstetric ultrasound studies performed during the second and third trimesters in 31 fetuses with myelomeningocele and 43 fetuses with no detectable anomaly. The gestational age predicted by each parameter (based on Hadlock's tables) was compared with the true gestational age (based on last menstrual period), using the ANCOVA test to determine if there was a statistically significant difference between the two groups of fetuses. RESULTS: There was no significant difference in femur length (P = 0.60) or in abdominal circumference (P = 0.85) between fetuses with myelomeningocele and normal fetuses. Fetuses with myelomeningocele did have a significantly lower biparietal diameter and head circumference (P < or = 0.001). CONCLUSIONS: Myelomeningocele is not associated with reduced femur length in the second and third trimesters, suggesting that the known postnatal lower extremity foreshortening in patients with myelomeningocele develops late in gestation or after birth.

The lung-to-head ratio and fetoscopic temporary tracheal occlusion: prediction of survival in severe left congenital diaphragmatic hernia.

OBJECTIVES: To evaluate the reliability of sonographic lung-to-head ratio (LHR) measurement as a predictor of survival in fetuses with congenital diaphragmatic hernia (CDH) and to compare the probability of survival in those with temporary tracheal occlusion (TO) or standard care with respect to the LHR. METHODS: Fifty-six fetuses with left CDH with liver herniated into the thorax at complete prenatal evaluation were included in logistic regression analyses of antenatal predictors of survival to hospital discharge. Sixteen subjects underwent TO and 40 received standard care. RESULTS: LHR was a significant predictor of survival, with probability of survival increasing with increasing LHR (odds ratio (OR) 8.5, P = 0.04). When subjects with anomalies were excluded, the LHR effect was similar after adjustment for TO (OR 7.1, P = 0.11). Linear spline models suggested a plateau in survival at an LHR of 1.0 and all models suggested increased odds of survival with TO. Minimum LHR measurements had a high degree of inter- and intraobserver agreement (intraclass correlation coefficients of 0.70 and 0.80, respectively). CONCLUSIONS: Calculation of the LHR in fetuses with CDH is a reliable and powerful predictor of survival to hospital discharge, although improving odds of survival may plateau at an LHR of 1.0. TO may have an independent benefit on survival to hospital discharge.

Measurement of endometrial thickness at US in multicenter drug trials: value of central quality assurance reading.

PURPOSE: To assess the value of central quality assurance (QA) reading of transvaginal ultrasonographic (US) images obtained to measure endometrial thickness and to assess image quality. MATERIALS AND METHODS: Results of 2,000 US examinations performed in 1,000 subjects during one of two multicenter drug trials were evaluated. Endometrial thickness was measured at the study site; images were then sent to the QA center, where an experienced sonologist evaluated endometrial thickness and image quality. RESULTS: In 360 (18%) of the 2,000 examinations, image quality was insufficient for central QA reading. Repeat examinations were requested, and suggestions for improvement in technique were provided. In 349 (97%) of the 360 examinations, repeat US images were of acceptable quality. In 99 (5%) of the 1,989 examinations in which endometrial thickness was measured, central measurement of thickness differed by more than 2 mm from that of the site. In a group (n = 300) that was followed up for 1 year, requests for repeat US examinations decreased from 24% at baseline to 11% at 1 year. CONCLUSION: Central QA reading provides a consistent evaluation of endometrial thickness on US images obtained in multicenter drug trials and helps to ensure the acquisition of high-quality transvaginal US images. It further leads to demonstrable improvement in site performance.

Effect of ultrasound transducer frequency on the appearance of the fetal bowel.

We evaluated how ultrasound transducer frequency affected the appearance of the fetal bowel. One hundred women with singleton pregnancies, who were undergoing routine ultrasonographic examination, were assessed at a single institution. Patients with known fetal anomalies, abnormal biochemical screening results, or a history of cystic fibrosis were excluded. Images of the fetal abdomen were obtained in all patients using a single multi-Hertz transducer, with transducer frequencies set at 5 MHz and 8 MHz. Images were read separately by two radiologists, blinded to patient name and transducer frequency. Observers rated the presence or absence of echogenic bowel, defined as bowel with echogenicity greater than or equal to that of adjacent bone. Using the 8 MHz frequency, the radiologists interpreted 31% of the cases as having echogenic bowel, whereas using the 5 MHz frequency, the radiologists interpreted only 3% of the cases as having echogenic bowel (P<0.0001). A fetus was 10 times as likely to be given a diagnosis of echogenic bowel by both observers when the 8 MHz transducer was used than when the 5 MHz transducer was used by one observer (relative risk 10, 95% CI 3-11). Furthermore, using the 8 MHz frequency transducer, at least one of the radiologists interpreted echogenic bowel in 62% of the cases. We concluded that echogenic fetal bowel is a very common observation when imaging is performed with an 8 MHz transducer, and thus echogenic bowel diagnosed with an 8 MHz transducer is unlikely to reflect underlying abnormality. Identification of echogenic bowel with an 8 MHz transducer should not prompt further testing.

Chorioamniotic separation after second-trimester genetic amniocentesis: importance and frequency.

PURPOSE: To determine the frequency and importance of chorioamniotic separation (CAS) after second-trimester genetic amniocentesis. MATERIALS AND METHODS: In part 1 of the study, ultrasonography (US) databases were reviewed for cases of CAS. In part 2, a study population of 388 women undergoing amniocentesis underwent directed US examination for assessment of CAS 15 minutes and/or 2 weeks after amniocentesis. CAS, when present, was graded. A control population consisted of 363 women undergoing amniocentesis in whom the membranes were not assessed. RESULTS: In part 1, a review of 23,883 records revealed seven cases of complete CAS, with three deaths, two preterm deliveries, and one emergency cesarean section delivery due to fetal distress. In two of these cases, there were extremity deformities at birth. In part 2, CAS was present in 98 (25%) of 388 women at some point. There was no association between CAS and procedural variables. There was no substantial difference in morbidity between patients with and those without CAS, between patients with different grades of CAS, or between the study and control populations. CONCLUSION: Small degrees of CAS are frequently present after amniocentesis but are not detected because the membranes are not specifically evaluated. Complete CAS is less frequent.

The effect of oligohydramnios on detection of fetal anomalies with sonography.

OBJECTIVE: The sonographic examination of fetuses is generally thought to be compromised when oligohydramnios is present because of the subjective impression of less adequate visualization of fetal anatomy. The aim of this study was to evaluate the extent to which oligohydramnios limits our ability to detect major anomalies on sonograms. MATERIALS AND METHODS: Records from the University of California, San Francisco from March 4, 1989 through January 4, 1994, were reviewed to identify all cases of premature rupture of the membranes in patients who then underwent nontargeted sonography. Sonographic results in pregnancies with oligohydramnios and without oligohydramnios (control population) were compared. Follow-up was obtained from a perinatal database, autopsy reports, and medical records. RESULTS: We found 345 patients with a history of premature rupture of the membranes (175 with oligohydramnios, 170 without oligohydramnios). Gestational age of fetuses was 16-38 weeks. Major congenital anomalies, including hydronephrosis, ventriculomegaly, intestinal atresias, hydrops, congenital diaphragmatic hernia, skeletal dysplasias, cloacal malformations, and gastroschisis, were revealed on sonography in 13 of 175 pregnancies with oligohydramnios and in 17 of the 170 pregnancies in the control group. Major anomalies missed in the oligohydramnios group included cardiac anomalies, club foot, small ventral hernia, limb reduction defect, and anal atresia. Major anomalies missed in the control group were club foot, anal atresia, and tracheoesophageal fistula. All of the major anomalies missed in both groups were of the type that are known to be difficult to diagnose before birth and that are frequently missed on sonography. CONCLUSION: Although oligohydramnios subjectively degrades image resolution, sonography still reveals important fetal anatomic landmarks. Major anomalies can be detected on sonography even when the pregnancy has less than the normal amount of amniotic fluid.

Evaluation of a sonographic PACS in clinical practice: analysis of technical and analytical time savings.

The aim of this study was to generate quantitative data regarding technical and analytical time savings obtained by use of an ultrasonographic PACS. Data/time cards were recorded for each patient encountered in an outpatient diagnostic ultrasound facility for a 4 week period immediately before and a 1 year period after installation of a PACS environment. Use of a sonographic PACS resulted in a per case time savings of 293 s in the technical component and 51 to 63 s in the analytical component of an average ultrasonographic examination. We conclude that use of a PACS workstation has the potential to increase productivity for both the sonographer and the radiologist.

Dolichocephaly and oligohydramnios in preterm premature rupture of the membranes.

This study evaluates the association between dolichocephaly and fetal outcome after preterm premature rupture of membranes. Dolichocephaly was more common in preterm fetuses in the breech presentation than those in the cephalic presentation and was more common in fetuses with oligohydramnios of long duration. Of fetuses in the cephalic presentation, 10 of 12 (83%) surviving dolichocephalic fetuses had respiratory distress syndrome compared with 31 of 73 (42%) normocephalic fetuses. However, other outcome parameters did not differ significantly. We conclude that the finding of dolichocephaly is associated with oligohydramnios of long duration. In fetuses with preterm premature rupture of membranes it is associated with respiratory distress syndrome, but not otherwise with a poor neonatal prognosis.

Lateral ventricular effacement as an isolated sonographic finding in premature infants: prevalence and significance.

OBJECTIVE: The sonographic finding of effaced lateral ventricles in premature infants, defined as the absence of visible CSF within the lateral ventricles on both coronal and sagittal sonograms, may be cause to suspect diffuse cerebral edema, especially as published reference standards do not address this phenomenon. This investigation was undertaken to determine the prevalence and significance of effaced lateral ventricles without associated parenchymal abnormality (isolated lateral ventricular effacement, or ILVE) in premature infants. MATERIALS AND METHODS: Sonographic records of 398 consecutive newborns examined from January 1 to December 31, 1993, were reviewed retrospectively to identify those premature infants (< 36 weeks of gestational age) whose initial sonograms showed no evidence of intracranial hemorrhage, ventriculomegaly, structural abnormality, or abnormal parenchymal echogenicity. We identified 142 neonates who met these criteria. Patients were separated into two groups on the basis of whether they had at least one sonographic study in which CSF was not visible within both lateral ventricles on coronal and sagittal images. Medical records were reviewed to assess neurologic outcome. RESULTS: Forty patients (28%) had at least one sonogram demonstrating ILVE, with neurologic follow-up in 33 (representing group A). One hundred two patients (72%) never demonstrated ILVE, with neurologic follow-up established in 86 (representing group B). A comparison of the two groups showed no significant difference in the development of ischemic injury (one patient in each group). ILVE was first detected on the initial sonogram obtained (mean, 4 days) in 30 of the 33 neonates in group A. ILVE was demonstrated beyond the seventh day of life in 30%. Of the 89 patients whose initial sonograms showed CSF in the lateral ventricles (86 in group B and three in group A), three (3%) subsequently had sonograms that showed ILVE; all three were normal at follow-up. CONCLUSION: ILVE in premature infants is common and not associated with neurologic deficits indicative of hypoxic-ischemic encephalopathy. By itself, ILVE is not a significant finding.

Imaging the fetal abdomen: how efficacious are the AIUM/ACR guidelines?

This study was performed to evaluate the efficacy of the American Institute of Ultrasound in Medicine/American College of Radiology guidelines for the detection of fetal abdominal abnormalities. In Part 1 of the study, images from 100 fetuses with sonographically diagnosed abdominal anomalies were masked except for one view of the abdominal circumference, stomach, renal area, bladder, and cord insertion. Ninety-six cases were recognized as abnormal by two sonologists. In Part 2, sonograms of 70 normal fetuses and 30 abnormal fetuses were similarly masked and shown to a sonographer and a fourth year radiology resident. Each identified 29 of 30 abnormal cases. Among fetuses with abdominal anomalies detectable at a prenatal diagnostic center, the majority of abnormal fetuses could be identified by evaluation of the five AIUM/ACR recommended views.

Sonographic detection of inferior vermian agenesis in Dandy-Walker malformations: prognostic implications.

PURPOSE: To compare the prognoses for fetuses with sonographically detected inferior vermian agenesis (IVA) or complete vermian agenesis (CVA). MATERIALS AND METHODS: The sonograms of 65 fetuses with Dandy-Walker malformations were retrospectively reviewed. Fetuses were divided into two groups--those with IVA and those with CVA. RESULTS: Of the 65 fetuses, 37 had IVA; 28, CVA. Thirteen (20%) of the 65-nine (24%) of the 37 with IVA and four (14%) of the 28 with CVA--lived for longer than 1 year. Chromosomal abnormalities were found in 23 (45%) of the 51 fetuses tested for karyotypic abnormalities or clinically thought to have Down syndrome. Seventeen (53%) of the 32 with IVA and six (32%) of the 19 with CVA that were tested for karyotypic abnormalities or clinically thought to have Down syndrome had chromosomal abnormalities (P = .07). Associated morphologic abnormalities were prenatally detected in 49 (75%) of the 65-in 28 (76%) of the 37 with IVA and in 21 (75%) of the 28 with CVA. CONCLUSION: The overall guarded prognosis is similar for fetuses with Dandy-Walker malformations for whom IVA or CVA has been sonographically diagnosed. Fetuses with IVA have a higher prevalence of karyotypic abnormalities.

Gastroschisis: can sonography of the fetal bowel accurately predict postnatal outcome?

To determine whether prenatal sonographic features of the small bowel can accurately predict postnatal outcome in fetuses with gastroschisis, the sonograms of 24 fetuses with prenatally detected gastroschisis were retrospectively reviewed for fetal bowel features including small bowel dilatation and bowel wall thickening. To identify a relationship between the sonographic features and neonatal outcome, each feature was analyzed against eight adverse clinical outcome measures including bowel obstruction or atresia, necrosis, and need for bowel resection, using chi-square analysis and Kendall's taub correlation. When a relationship was identified, the sensitivity and specificity of the sonographic feature for predicting adverse outcome were determined. Only maximum small bowel diameter was related to postnatal bowel complications. Significantly more fetuses with a maximum small bowel diameter of greater than 11 mm (7/12) had bowel complications than did fetuses with MBD 11 mm or less (2/12) P < 0.05). Using a cutoff point of greater than 11 mm for maximum small bowel diameter, the sensitivity was 78%, specificity 66%, and positive predictive value 71% for predicting postnatal bowel complications. However, in only seven of 24 cases did the two observers make the same maximum small bowel diameter measurement, and in 14 of 24 cases their measurements differed by 2 mm or more. The observers varied sufficiently in their measurements to shift three fetuses (13%) between categories (< or = 11 mm or > 11 mm). Although a maximum small bowel diameter of 11 mm stratified our fetuses, this measurement may not be clinically meaningful.

Prevalence of ventriculomegaly in association with myelomeningocele: correlation with gestational age and severity of posterior fossa deformity.

PURPOSE: To investigate the relationship of ventriculomegaly (VM) with gestational age (GA) and the severity of the associated Chiari II malformation. MATERIALS AND METHODS: The sonograms of 51 fetuses with myelomeningoceles were retrospectively reviewed. VM was judged to be present when the transverse ventricular atrial diameter was greater than 10 mm. The severity of the posterior fossa (PF) deformity was subjectively graded as mild, moderate, or severe. Thirty-four fetuses were scanned at < or = 24 weeks GA, and 17 were scanned at > 24 weeks GA. RESULTS: The prevalence of VM was 61%. However, only 44% of fetuses < or = 24 weeks GA had VM, whereas 94% of fetuses > 24 weeks GA had VM. When compared with fetuses with mild PF deformities, fetuses with moderate or severe deformities had a higher prevalence of VM and the largest ventricles. CONCLUSION: The prevalence of VM in fetuses with myelomeningoceles varies with both GA and the severity of the associated PF deformity. These observations may provide additional prognostic information once a myelomeningocele is detected at sonography.

Growth retardation in prenatally diagnosed cases of gastroschisis.

Gastroschisis is a rare congenital anomaly characterized by the herniation of fetal intestines directly through an abdominal wall defect. It is associated infrequently with chromosomal or other nonbowel defects and can be treated surgically after delivery, with survival rates reported to be between 87 and 100%. We reviewed 21 cases of prenatally diagnosed gastroschisis to ascertain the effect of fetal growth retardation on perinatal outcome. Ten of the 21 fetuses (48%) were identified prenatally as growth retarded, although only seven of these ten truly had birth weights less than the 10th percentile. Three additional fetuses that had not been identified prenatally as growth retarded did, in fact, have birth weights less than the 10th percentile, for a total frequency of growth retardation at birth of 48% (10/21 fetuses). When compared to non-growth-retarded fetuses with gastroschisis, fetuses who were growth retarded, although more likely to have been delivered by emergency cesarean section, had shorter hospitalization times, were more likely to have undergone primary closure on the first day of life, and had fewer major complications. We conclude that growth retardation is common in fetuses with gastroschisis and the postnatal outcome in gastroschisis is not poorer for fetuses who are growth retarded.

Sonographically detected testicular microlithiasis and testicular carcinoma.

Testicular microlithiasis is an uncommon abnormality that produces the characteristic sonographic appearance of diffuse, punctate, hyperechoic foci throughout the testicular parenchyma. We have detected this distinctive sonographic pattern in 4 patients during a seven-year period. Three of the patients had proven concurrent testicular carcinoma. We describe our experience and review previous reports of testicular microlithiasis. We conclude that testicular microlithiasis may be associated with testicular neoplasia, and advocate particularly careful evaluation and follow-up of the testes when this abnormality is detected.

Elevated levels of amniotic fluid alpha-fetoprotein: sonographic evaluation.

From 1978 to 1990, 263 fetuses with an elevated level of amniotic fluid alpha-fetoprotein (AF-AFP) (> 2.0 multiples of the median) were examined with targeted fetal sonography. All cases of AF-AFP elevation among 22,355 genetic amniocenteses were represented. Sonography correctly showed 32 open neural-tube defects, including 20 myelomeningoceles, and depicted 94% (63 of 67) of the anomalous fetuses. Two of five anomalous fetuses with normal sonograms, however, had extremely high AF-AFP levels leading to prospectively correct diagnoses of congenital nephrosis. Therefore, programmatically, 97% (65 of 67) of the anomalous fetuses were recognized. The three programmatic misdiagnoses were all detected in the neonatal period and surgically corrected; subsequent development was normal. The combination of an elevated AF-AFP level and a detailed sonogram allowed distinction between a normal and an anomalous fetus in 99% of cases. When elevated levels are noted, AF-AFP analysis followed by detailed sonography is highly successful for the detection and characterization of anomalous fetuses and the recognition of normal fetuses with physiologic increases of this protein in the amniotic fluid.