Eberhard Merz

Three-dimensional ultrasonography in prenatal diagnosis.

Within the past five years, 3D ultrasonography has developed to the degree that it offers both the patient and the examiner an entirely new visual experience in prenatal diagnosis. With the system described here (Kretz-technik, Austria), any desired plane can be displayed within the stored volume, and within seconds a high-quality 3D surface or transparent image can be calculated and displayed on the ultrasound monitor without need for an external workstation. All of this can be performed routinely in the clinical setting. Since 1989 we have routinely examined a total of 458 fetuses (242 normal and 216 with anomalies) between 16 and 38 weeks of gestation, supplementing our conventional 2D ultrasound scans with a 3D examination using an abdominal volume transducer. A comparison of the 2D and 3D techniques shows that 3D provides a diagnostic gain in a large percentage of cases (64.2%). The simplest 3D technique of the orthogonal image display provided a diagnostic gain in 46.2% (61/132) of the cases owing to the accurate topographic depiction of the desired image plane. The combined 3D display (orthogonal format plus a 3D surface or transparent view) provided a diagnostic gain in 71.5% (233/326) of the cases. This higher percentage resulted from the additional 3D surface reconstruction, the ability to view and evaluate the fetus from various angles, the ability to determine the exact size of a fetal defect, the depiction of skeletal anatomy in the transparent mode, and the improved delineation of complex malformations. Problems with 3D imaging are encountered in patients with pronounced oligohydramnios, which prevents surface reconstruction, and in the examination of moving objects, which produce motion artifacts.

Prenatal sonographic chest and lung measurements for predicting severe pulmonary hypoplasia

Pulmonary hypoplasia was diagnosed sonographically in 32 fetuses from 20 to 33 weeks of gestation. In addition to standard biometry, transverse thoracic diameter (TTD), sagittal thoracic diameter (TSD), thoracic circumference (TC) and lung diameter (LD) were measured in all cases and compared with known nomograms.

Prenatal diagnosis of infantile neuronal ceroid-lipofuscinosis: a combined electron microscopic and molecular genetic approach.

Based on two unrelated index patients afflicted with INCL, fetal chorion tissues were studied from subsequent pregnancies of the two respective mothers resulting in the prenatal diagnosis of INCL in two of the three pregnancies. Documentation of INCL was based on electron microscopy and DNA studies of the biopsied chorion tissue, later confirmed in the two affected fetuses after termination of their pregnancies by demonstrating INCL-specific lipopigments in post-mortem tissues, in the liver of both aborted fetuses and, additionally, in spleen and skeletal muscle of one of the affected fetuses. The autolysis of the aborted tissues, however, precluded a systematic documentation of all affected cell types and tissues. Thus, prenatal diagnosis of INCL is feasible and reliable for both Finnish and non-Finnish families.

Biometry of the fetal corpus callosum by three-dimensional ultrasound

To construct reference ranges of quantitative characteristics of the fetal corpus callosum.

Familial fatal fetal cardiomyopathy with isolated myocardial calcifications: a new syndrome?

We describe three male sib fetuses with isolated myocardial calcifications resulting in intrauterine fetal death (IUFD) as early as the second trimester. No evidence for an underlying mitochondrial cytopathy, dystrophinopathy or myopathy was found. There were no signs of inflammation or a metabolic disorder, and the mother had no prenatal exposure of teratogenic drugs. Furthermore, no mutation in the Barth syndrome gene (G4.5) could be detected. Because isolated calcification of the heart and IUFD are not typical of any previously described inherited cardiomyopathy, it may represent a new familial fetal cardiomyopathy.

DEGUM Recommendations on Infection Prevention in Ultrasound and Endoscopic Ultrasound

Microbial contamination of ultrasound probes for percutaneous or endoscopic use is common. However, infectious diseases caused by transmission of microorganisms by US procedures have rarely been reported. In Germany, legal regulations address hygiene in ultrasound procedures. Based on these regulations and the available literature, an expert panel of the German Society of Ultrasound in Medicine (DEGUM) has formulated sophisticated recommendations on hygienic measures in percutaneous and endoscopic US, including US-guided interventions.

EP11.09: Are femur and humerus lengths measured exactly by 3D ultrasound reliable parameters for the detection of Trisomy 21 in the second trimester?: Electronic Poster Abstracts

Conclusions: The key concern of this study was to obtain high-quality 3D images from US/MRI and to compare them. The 3D evaluation should be used as a complementary tool since it adds valuable information to the educational training of specialists as well as to the emotional control of parents. However, these 3D imaging modalities do not appear to be absolute for the diagnosis and evaluation of fetal prognosis.

True or false umbilical cord knot? Differentiation via 3D/4D color Doppler ultrasound

True umbilical cord knots are actual knots in the umbilical cord formed during pregnancy, while a false umbilical cord knot is a bulge in the umbilical cord due to twisting of the vein around the arteries or around an overlap of umbilical cord loops lying against one another. True umbilical cord knots are relatively rare. Based on births, an incidence of 0.3 – 1.2 % is specified [1, 2]. Various factors are associated with the occurrence of an umbilical cord knot: grandmultiparity, chronic hypertension, diabetes, a long umbilical cord, a small fetus, a male fetus, monoamniotic twins, and patients who had undergone amniocentesis [2– 7]. While the risk of intrauterine death is 4 times higher in the case of true umbilical cord knots [2], there is no risk to the fetus in the case of false umbilical cord knots. However, even in the case of a true umbilical cord knot, there is no risk to the fetus as long as the knot is loose and blood circulation is not restricted. Wharton’s jelly provides a significant protective layer in this case. True umbilical cord knots typically appear in the form of a single knot. However, up to four true knots in one umbilical cord have been described [8]. It is assumed that umbilical cord knots are formed between 9 and 12 gestational weeks [2]. At this time there is significant amniotic fluid and fetal movement so that the fetus can slip through a loop of the umbilical cord during corresponding movements and gyrations. It is difficult to detect a true umbilical cord knot via 2 D ultrasound since it is a three-dimensional structure. In a retrospective study including 18 cases in which a true umbilical cord knot was found at the time of birth, Sepulveda et al. [1] were able to show that an umbilical cord knot was not detected during routine second-trimester ultrasound examination in any of these cases. Bohîlea et al. [9] specify a prenatal detection rate of 12%. Sonographic differentiation between a true and a false umbilical cord knot is even more difficult. Individual sonographic signs of a true umbilical cord knot have been described in the literature: umbilical cord in the form a four-leaf clover [10], an unusual multicolor umbilical cord pattern [4], or the “hanging noose” sign [11]. All of these signs can be indications of a true umbilical cord knot but do not provide definitive proof. Already in 2010, Guzikowski et al. [7] noted the advantages of 3D/4D color Doppler ultrasound for verifying an umbilical cord knot. Given the current quality of 3D/ 4D color Doppler ultrasound, it is now possible to more clearly verify a true umbilical cord knot on the basis of the three-dimensional image and to determine the degree of constriction (▶ Fig. 1). Differentiation from a false umbilical cord knot is also possible. In the case of an overlap of the umbilical cord simulating an umbilical cord knot, the false umbilical cord knot can be detected by rotating the volume and visualizing the umbilical cord (▶ Fig. 2a) from a different angle (▶ Fig. 2b). When detecting a true umbilical cord knot, blood flow measurements on Dop▶ Fig. 1 3D image of a true umbilical cord knot in an umbilical cord with a single umbilical artery (3D HDlive power Doppler). There is no compression of the two umbilical vessels.

Advantages of 3D ultrasound in the assessment of fetal abnormalities

Abstract Three-/four-dimensional (3D/4D) imaging enables a more detailed survey of the embryo and the fetus compared to two-dimensional (2D) ultrasound. The availability of several display modes and standardized examinations permits the demonstration of both the normal and abnormal fetal anatomy in controlled planes and rendered images from different angles. This allows the demonstration of even subtle fetal defects in an ideal sectional plane in a precisely rendered surface or transparent image viewed from an optimal angle. When counseling the parents, the rendered images can help them understand the severity of an existing malformation or, conversely, ensure them of the absence of any fetal abnormality. This is particularly useful in cases with an increased recurrence risk of a specific fetal malformation.

Normal Doppler Reference Values of the Pericallosal Artery.

PURPOSE To provide the normal reference values of the Doppler flow of the pericallosal artery in relation to gestational age from 18 to 41 weeks of gestation. MATERIALS AND METHODS The pericallosal artery (PCA) was studied in 466 normal pregnancies. The pulsed Doppler evaluation of the pericallosal artery was done in A3 and A4 segments, and records from PI, RI and Vmax were studied. RESULTS The resistance index of the pericallosal artery in A3/A4 segments exhibits a plateau from 18 to 31 weeks of gestation. After 31 weeks, a marked decrease becomes apparent. The pulsatility index of the pericallosal artery in A3/A4 segments shows a plateau until 36 weeks of gestation. During the final weeks of gestation, there is a decrease in the pulsatility index. Vmax exhibits a plateau for the maximal flow velocity in A3/A4 segments of the pericallosal artery from 18 to 28 weeks of gestation. After 28 weeks of gestation, there is a slight increase in Vmax. CONCLUSION Normal reference values of the pericallosal artery might have an impact on clinical judgment during adaptive hemodynamic changes and regarding the progression of the fetal deterioration occurring in the presence of fetal hypoxia.