Meckel-Gruber syndrome. Importance of prenatal diagnosis.

Prenatal sonographic findings are reported in six fetuses with the Meckel-Gruber syndrome to illustrate the variety of sonographic findings associated with this disorder and to emphasize the importance of prenatal sonography in helping to establish the correct diagnosis. All six fetuses demonstrated evidence of renal cystic dysplasia. In five cases the kidneys were large and echogenic, demonstrating small discrete cysts in the range of 2 to 5 mm. The remaining fetus demonstrated unilateral renal cystic dysplasia and contralateral renal agenesis. Oligohydramnios was noted in all cases and was evident as early as 14 weeks. An occipital cephalocele was demonstrated on sonography in each case although the size and contents of the cephalocele varied significantly. Two fetuses, both in the same family, also demonstrated a cystic mass in the posterior fossa and partial absence of the cerebellum consistent with a Dandy-Walker variant or cerebellar hypoplasia. The concurrence of marked oligohydramnios and bilateral severe renal anomalies should initiate a search for anomalies of the central nervous system indicative of the Meckel-Gruber syndrome. Recurrence of Meckel-Gruber syndrome may be evaluated as soon as 14 weeks, but it may not be reliably excluded until 20 weeks.

Translabial ultrasound of the third-trimester uterine cervix. Correlation with digital examination.

This prospective blinded study compared translabial ultrasound (TLU) and digital palpation of the cervix among women whose cervix could not be visualized adequately or at all with transabdominal ultrasound during the third trimester of pregnancy. The cervical canal and internal cervical os were adequately visualized during 109 of 113 TLUs (96%). The TLU was well tolerated by the patients; only two patients refused the TLU pending discussion of the technique with their obstetrician. Among 43 examinations of patients without clinical cervical effacement, TLU showed a cervical length of 2.5 to 4.2 cm (mean, 2.9 cm). An excellent correlation (R = 0.90) was noted between cervical length on TLU and percentage of cervical effacement on digital examination. The correlation between amount of cervical dilatation on TLU and on digital examination was not high (R = 0.58). We conclude that the measurements of cervical length on TLU correlate well with the amount of cervical effacement on digital examination and that TLU provides a rapid and well-tolerated alternative technique to visualize the third-trimester uterine cervix.

The "stuck twin" phenomenon: ultrasonographic findings, pregnancy outcome, and management with serial amniocenteses.

Thirteen consecutive twin pregnancies affected by the "stuck twin" phenomenon were reviewed to determine the potential benefit of serial amniocenteses. The fetal survival rate for the eight pregnancies that underwent serial amniocenteses was 69% (11 of 16 fetuses). This is significantly improved compared with a fetal survival rate of 20% among the five preceding pregnancies managed without serial amniocenteses at the same institution (p = 0.01). It is also markedly improved compared with a combined fetal survival rate of 16% among 48 previously reported pregnancies with the stuck twin phenomenon managed without serial amniocenteses (p less than 0.0001). Survival correlated with the absence of concomitant pregnancy complications (i.e., maternal hypertension or intractable labor) and with the absence of severe fetal structural abnormalities. Procedural complications occurred in three of eight pregnancies (37.5%) managed with serial amniocenteses and was attributed as a cause of fetal death in one case. Two of 11 survivors (18%) had complications after serial amniocenteses including brain infarction and renal tubular necrosis. Serial amniocenteses may significantly improve the survival rate of twin gestations affected by the stuck twin phenomenon but may be associated with complications among survivors.

Prenatal sonographic findings of Down syndrome: review of 94 cases.

Prenatal ultrasound findings were reviewed in 94 consecutive fetuses with proved Down syndrome (trisomy 21) during a 6-year period at a single institution. One or more abnormalities were found in 31 fetuses (33%), including two of 11 fetuses seen before 14 weeks, 17 of 68 fetuses seen between 14-24 weeks, and 12 of 15 fetuses seen after 24 weeks. Major anomalies detected included cardiac defects (five), duodenal atresia (four), cystic hygromas (four), omphalocele (two), hydrops (two), and hydrothorax (one). Nuchal thickening was observed in five fetuses, including four of 25 second-trimester fetuses evaluated prospectively during the last 2 years of the study. Mild cerebral ventricular dilatation (three) and hyperechogenic bowel (five) are new findings that have not been generally associated with Down syndrome. A variety of prenatal sonographic abnormalities may be associated with Down syndrome, and the frequency of detecting most abnormalities increases with menstrual age. Anomalies more frequently detected before 20 weeks include cystic hygromas, nuchal thickening, and hyperechogenic bowel. Awareness of the sonographic findings associated with Down syndrome should result in improved detection of this disorder.

Mild idiopathic lateral cerebral ventricular dilatation in utero: sonographic evaluation.

The authors prospectively studied 20 fetuses with mild dilatation of the lateral cerebral ventricles but no other detectable central nervous system abnormality. One case (5%) occurred in a diabetic pregnancy, and three (15%) involved twin pregnancies. Fifteen (75%) fetuses were male, and one (5%) had trisomy 21. Postnatal follow-up at 15-31 months showed a normal outcome in eight cases (40%), an uncertain prognosis in four cases (20%), and death in eight cases (40%). Serial antenatal sonograms were obtained in 17 cases. Among the eight cases with a normal outcome, seven demonstrated no additional sonographic abnormalities and six showed resolution of the ventricular dilatation antenatally. Conversely, all 12 fetuses with demise or an uncertain prognosis demonstrated additional sonographic abnormalities, and six showed stable or progressive ventricular dilatation on follow-up sonograms. Since mild idiopathic lateral ventricular dilatation has a widely variable prognosis, antenatal detection of this finding warrants search for additional findings and follow-up sonography.

Fetal cystic adenomatoid malformation: prenatal diagnosis and natural history.

We studied the natural history and pathophysiology of congenital cystic adenomatoid malformation (CCAM) detected prenatally by ultrasound in twelve fetuses. Two types of fetal CCAM can be distinguished by gross anatomy, ultrasound findings, and prognosis. Microcystic lesions are usually associated with fetal hydrops and have a poor prognosis (five cases with one survivor). Antenatal diagnosis, maternal transport, and immediate thoracotomy after birth allowed the first reported survival of a newborn with a large microcystic CCAM. Macrocystic lesions are not usually associated with hydrops and have a favorable prognosis (five of seven survived). We conclude that fetuses with hydrops are at high risk for fetal or neonatal demise without intervention. Fetuses with CCAM but without hydrops have a good chance for survival with maternal transport, planned delivery, and immediate neonatal resuscitation and surgery.

Infantile polycystic kidney disease: observations from attempts at prenatal diagnosis.

Three successive pregnancies of a couple at risk for infantile polycystic kidney disease were evaluated by sequential ultrasound examinations to attempt prenatal diagnosis of the disorder. The gestational age at which renal sonographic changes were noted varied from 20 to 34 weeks and resulted in both false-positive and false-negative diagnoses.

Intraoperative neurosonography: application and technique.

Intraoperative neurosonography was performed in 44 patients with contact transdural or transgyral scanning technique. Localization of intracranial pathology included primary brain tumors (24), metastatic tumors (11), aneurysms (two), abscesses (two), arteriovenous malformation (one), thrombosed arteriovenous malformations (two), and plasmacytoma (one). Sonographic guidance was used in transdural decompression of three cystic lesions, therapeutic and diagnostic aspiration of two abscesses, and biopsy of three solid lesions. The expertise of the physician-sonographer with sonographic equipment facilitates accurate and expedient intraoperative neurosurgical localization of pathology.

Investigating the efficacy of current quality assurance performance tests in diagnostic ultrasound.

The efficacy of four current quality assurance performance tests in diagnostic ultrasound was investigated. This was done by comparing the ability of the performance tests to detect fluctuations in gray scale, depth of penetration, axial resolution and lateral resolution on a real-time scanner with the ability of sonologists and sonographers to detect the same fluctuations. The performance tests for gray scale, depth of penetration, and axial resolution were found to be efficacious. The lateral resolution test was judged nonefficacious . This suggested a need to revise the protocol for the lateral resolution test with regard to real-time scanners.

Estimating fetal weights less than 2000 g: an accurate and simple method.

An accurate estimated fetal weight in the low-birth-weight infant can provide valuable information for the obstetrician faced with a decision concerning mode and time of delivery. Four existing equations for calculating fetal weight were analyzed and compared with data consisting entirely of infants with birth weights of 500-2000 g. A new formula, birth weight-grams = 10.1 (abdominal circumference-cm X biparietal diameter-cm) - 481, is proposed as a simple yet accurate alternative. This equation has a standard deviation of 99 g/kg.

Observer variability in evaluating extracranial carotid artery stenosis.

One hundred twenty eight cervical carotid arteriograms were twice viewed by three readers for the evaluation of atherosclerotic disease at the carotid bifurcation. Stenoses were estimated using calipers to the nearest 5% and lesions were qualitatively characterized as smooth, irregular, or ulcerated. The intraobserver correlation coefficient between estimates of percent stenosis was .94 overall and .98 for the internal carotid artery. The average intraobserver variability in estimating percent stenosis was 5.23% for all vessels and 6.04% with a standard deviation of 8.09% for the internal carotid artery. The intraobserver percent agreement at a fixed stenosis is defined as the percent of the time one reader on two readings would read at least the fixed percent stenosis among cases that might be read as having the fixed percent stenosis. The intraobserver percent agreement rate for the internal carotid artery was 95.9% at greater than 0% stenosis, 90.4% for 50% or greater stenosis, and 96.8% for 100% stenosis (total occlusion). The interobserver correlation coefficient between readers was .92 overall and .97 for the internal carotid artery. The absolute difference in percent stenosis between readers was 7.21% for all vessels and 8.64% for the internal carotid artery with a standard deviation of 9.5%. The interobserver agreement rate for the internal carotid artery at greater than 0% stenosis was 93.0%, 85.4% for 50% or greater stenosis and 96.8% at 100% stenosis. The addition of oblique views had no statistical effect on estimates of percent stenosis but increased the frequency with which irregularity and ulceration were diagnosed in the internal carotid artery.

Intracranial hemorrhage in premature infants: accuracy in sonographic evaluation.

The real-time high resolution mechanical sonographic sector scanner is a convenient and useful instrument for the detection of intracranial hemorrhage in premature infants. Experience with 27 infants with intracranial hemorrhage detected by sonography and confirmed by computed tomography (CT) or by autopsy is analyzed. The severity of the hemorrhage shown by those methods was graded by an accepted classification for standardized reporting. The extent of intraparenchymal and intraventricular hemorrhage was accurately assessed by sonography in all cases except for small amounts of blood in normal sized ventricles in five of 12 instances. Sonography also failed to detect subarachnoid hemorrhage in each of 13 cases. There were no known false-positive sonograms. From this experience the authors believe sonographic sector scanning should be the initial examination in all infants at high risk for intracranial hemorrhage. When the ventricles are of normal size, CT scanning is recommended to search for small intraventricular hemorrhage that may not be detected by sonography. For subarachnoid bleeding, CT is preferable to sonography.

Real-time sonography of pleural opacities.

Fifty patients with radiographic pleural or pleural-based opacities were examined with high resolution real-time sonographic sector scanning. In 90% of cases selected for thoracentesis, fluid sufficient for diagnosis was obtained. Complex, septated pleural loculations contained an exudative effusion in 74% of the patients, while anechoic areas yielded exudative and transudative effusions with almost equal frequency. The use of real-time scanning is stressed because of greater flexibility and shorter examination time compared to compound scanning, and its utility for portable scanning on critically ill patients.

Aortic and lower extremity arterial aneurysms.

A sonographic survey of 100 patients with suspected abdominal aortic, femoral, or popliteal arterial aneurysms was conducted over a period of 2 yr. Patients referred for suspected abdominal aortic aneurysms had a low incidence of associated lower extremity arterial aneurysms. Those patients referred for possible femoral or popliteal artery aneurysms frequently had multiple other peripheral arterial aneurysms. The authors recommend a survey scanning protocol in this subgroup with lower extremity aneurysms to rule out the presence of other aneurysms.

Correlation of arteriographic findings and symptoms in cerebrovascular disease.

The arteriograms of 109 patients with symptomatic cerebral ischemia were analyzed to determine the distribution of extracranial and intracranial vascular abnormalities. In the 66 patients with transient hemispheric or ocular ischemia, potentially embolic lesions were more common than hemodynamically significant lesions (84% versus 50%). In the 29 patients with fixed neurologic deficits, 25% had occlusion of the internal carotid artery on the appropriate side; ulcerated lesions were again more common in the remaining patent arteries than were hemodynamically significant lesions. The major difference between the transient group and the fixed group was the 29% incidence of intracerebral disease or anomaly in the transient group, with similar lesions in 90% of the group with fixed neurologic deficit. Symptoms of cerebral ischemia are more likely to be related to ulceration than to hemodynamically significant lesions. The risk of stroke seems greatest when there is also intracerebral siphon disease or anatomic anomaly of the circle of Willis.

Detection of carotid occlusive disease by ultrasonic imaging and pulsed Doppler spectrum analysis.

Ultrasonic imaging of the cervical carotid arteries by ultrasonic arteriography and duplex scanning combined with pulsed Doppler spectrum analysis were investigated in a series of patients undergoing arteriography. By using the ultrasonic image as a guide for precise placement of the pulsed Doppler sample volume, the characteristics of blood flow at points of interest in the carotid arteries could be determined. Audible analysis of the Doppler signal permitted correct diagnosis of 23 of 26 (88%) high-grade stenoses or occlusions with ultrasonic arteriography and 24 of 26 (92%) with duplex scanning. Spectrum analysis of Doppler signals obtained with the duplex scanner detected all of the 22 high-grade stenoses. Spectral abnormalities of a lesser degree also were detected in 18 of 23 vessels (78%) with atherosclerotic plaques which should not have reduced cerebral blood flow. These techniques permit the accurate detection of and the distinction between high-grade stenoses and occlusion, as well as the identification of many plaques which are not large enough to affect intracranial hemodynamics.