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Biomedical subjects

D H Pretorius

Publications and source records attributed to D H Pretorius.

At least 19 recordsLinked to original sources
PubMed1992

Second-trimester echogenic bowel and chromosomal abnormalities.

OBJECTIVE: Our objective was to examine the outcomes of pregnancies in which echogenic bowel was detected in the second trimester. STUDY DESIGN: Twenty-two cases with a prospective diagnosis of echogenic bowel were reviewed. Karyotypic studies were performed in 19 cases, and 17 families had deoxyribonucleic acid-based risk assessment for cystic fibrosis. The echogenicity of the bowel was retrospectively reviewed and graded as mild or bright. RESULTS: Five cases of trisomy 21 and one case of trisomy 18 were detected; four of these had other ultrasonographic abnormalities. Twenty-seven percent of fetuses with echogenic bowel were aneuploid. Risk was greatest for cases with brightly echogenic bowel. No cystic fibrosis mutations were detected. The diagnosis of echogenic bowel was reproducible. CONCLUSION: Brightly echogenic bowel in the second trimester was found to be associated with a significant risk of fetal aneuploidy.

Chromosome Aberrations↗
PubMed1992

Simple adnexal cysts: the natural history in postmenopausal women.

Transabdominal and transvaginal ultrasound (US) examinations were performed in 184 asymptomatic postmenopausal volunteers to determine prospectively (a) the frequency and natural history of simple adnexal cysts in healthy postmenopausal women and (b) the relationship between cyst activity and both hormone replacement and length of time since menopause. Eighty-three simple adnexal cysts were found in 52 women. Thirty-two of 184 women (17%) had 37 cysts identified at initial examination; 46 new cysts appeared in 31 women (11 of whom previously had cysts). Forty-nine women with 72 cysts were reevaluated with subsequent US scanning over a period of 3-23 months. Thirty-eight of the 72 cysts (53%) disappeared completely, 20 (28%) remained constant in size, eight (11%) enlarged by 3 mm or more, two (3%) decreased in size by 3 mm or more, and four (6%) both increased and decreased in size on repeated examinations. No statistical relationship was found between presence of cysts or cyst activity with respect to the type of hormone replacement or length of time since menopause.

Adnexal Diseases↗
PubMed1992

Spontaneous improvement of intrathoracic masses diagnosed in utero.

The diagnosis and pregnancy outcome for 14 fetuses with sonographically detected chest masses were reviewed retrospectively. Six lesions became smaller or less apparent during gestation or resolved between antenatal and perinatal imaging studies; these included all three types of cystic adenomatoid malformation (CAM), as well as one case of pulmonary sequestration (PS). This information is extremely important in counseling patients in the second trimester who are considering termination of pregnancy. The poor prognosis traditionally assigned to type II and type III CAM needs changing to reflect the phenomenon of improvement with excellent long-term outcomes. Sonographic indicators of poor outcome were polyhydramnios, hydrops or marked cardiac deviation.

Adult↗
PubMed1992

Linear echoes in the fetal cisterna magna.

Linear echoes are seen in the fetal cisterna magna, (CM) on obstetrical sonography. These echoes often are paired, joining as they descend toward the base of the posterior fossa. Histologic correlation suggests that these echoes are most consistent with dural folds, which likely represent the inferior attachment of the falx cerebelli. A prospective series of 322 prenatal studies was performed in which the sonographer was asked to look for the linear echoes in the cisterna magna and image them. Linear echoes were identified in 84% of all fetuses studied. Identification of these echoes was dependent on CM size, in that they were seen less commonly when the CM was less than 3 mm in diameter. However, their identification was not dependent on gestational age. In addition, 18 fetuses with Dandy Walker cyst or Dandy Walker variant were evaluated and in 16 linear echoes were not seen. We conclude that recognition of normal anatomy within the fetal brain, specifically the fetal CM, is helpful for identifying abnormalities in the size of the CM, whether large or small.

Cisterna Magna↗
PubMed1992

3-dimensional sonographic analysis based on color flow Doppler and gray scale image data: a preliminary report.

This paper presents preliminary results of a technique that permits acquisition and display of three-dimensional (3D) anatomy using data collected from color flow Doppler and gray scale image sonography. 3D sonographic image data were acquired as two-dimensional planar images with commercially available equipment. A translational stage permitted the transducer position and orientation to be determined. Color flow sonographic video image data were digitized into a PC-AT computer along with transducer position and orientation information. Color flow velocity and gray scale data were separated, 3D filtered, and thresholded. A surface rendering program was used to define the vessel blood-lumen interface. Planar slices of arbitrary orientation and volume rendered images were displayed interactively on a graphics workstation. The technique was demonstrated in a lamb kidney in vitro and for the carotid artery at the bifurcation in vivo. Our results demonstrate the potential of 3D sonography as a technique for visualization of anatomy. Color flow data offer direct access to the vascular system, facilitating 3D analysis and display. 3D sonography offers potential advantages over existing diagnostic studies in that it is noninvasive, requires no intravenous contrast material, offers arbitrary plane extraction and review after the patient has completed the examination, and permits vascular anatomy to be visualized clearly via rendered images.

Animals↗
PubMed1992

Sonographic evaluation of pregnancies with maternal varicella infection.

We reviewed 37 cases of mothers who had varicella-zoster virus (VZV) infection during early pregnancy, who subsequently underwent fetal sonography in the 13th to 37th week of gestation. Of the five infants later shown to have congenital varicella infection at postnatal examination (1 case) or autopsy (4 cases), all showed ultrasonographic abnormalities suggesting infection, and all died by 4 months of age. None of the 32 unaffected infants demonstrated in utero ultrasonographic abnormalities. No statements about relative risk of being affected by the virus can be made from this data.

Chickenpox↗
PubMed1992

Abnormal spinal curvature in the fetus.

We reviewed 20 cases of sonographically detected abnormal fetal spinal curvature to help determine the significance of this finding. Both marked (13 cases) and mild (7 cases) curves were diagnosed sonographically. Sonography showed associated anomalies in 19 fetuses, including neural tube and ventral wall defects. Outcomes were poor, with only three infants surviving. Isolated scoliosis was identified prenatally in one neurologically normal infant with hemivertebrae. We conclude that abnormal spinal curvature in the fetus is a significant finding, whether mild or severe. Even as an isolated finding, it is significant, as prenatal detection assists postnatal management.

Female↗
PubMed1991

Prevalence of simple adnexal cysts in postmenopausal women.

This prospective study was performed with ultrasound (US) to determine the prevalence of unilocular, nonseptated adnexal cysts ("simple cysts") in healthy postmenopausal women and the relationship between cyst occurrence and both hormone replacement and length of time since onset of menopause. Transabdominal and transvaginal US were performed on 149 volunteers aged 50 years or older. Patients were classified according to hormone regimens (no hormones, unopposed estrogen, continuous daily estrogen and progesterone, and sequential estrogen and progesterone) and time since onset of menopause (less than 5 years, 5-10 years, and greater than 10 years). Simple adnexal cysts were found in 22 women with the aid of transvaginal and/or transabdominal US, yielding a relative frequency of 14.8% +/- 5.7% and a prevalence of 14,800 patients with cysts per 100,000 patients. No statistical relationship was found between cyst frequency and type of hormone replacement or length of time since onset of menopause.

Aged↗
PubMed1991

Endometrial thickness after menopause: effect of hormone replacement.

Ultrasound (US) images of the pelvis were evaluated in 112 asymptomatic postmenopausal women to investigate the normal range of endometrial thickness (double-layer measurement) and the effect of hormone replacement on these measurements. Twenty-one patients (19%) had endometrial thickness greater than 0.8 cm. One patient, with an endometrial thickness of 2.5 cm, had endometrial carcinoma. Consideration of the known actions of estrogen and progestogen on the endometrium led the authors to believe that the clinical significance of an endometrium measuring more than 0.8 cm depends on the patient's hormonal status. Among asymptomatic postmenopausal women with an endometrial thickness between 0.8 and 1.5 cm, those receiving unopposed estrogen or continuous estrogen and progestogen need to undergo dilatation and curettage (D&C) or biopsy and those receiving no hormones or receiving sequential estrogen and progestogen should be encouraged to undergo D&C or biopsy. If a patient in one of the latter two groups is unwilling to undergo an invasive procedure, then US examination at 3-month intervals is acceptable. Any patient with endometrial thickness of at least 1.5 cm should undergo histologic diagnosis, regardless of symptoms or hormone status.

Biopsy↗
PubMed1991

Ossification of the fetal spine.

The neural arch ossification centers in the distal fetal spine were evaluated with ultrasound (US) during the second trimester of pregnancy in 239 fetuses. Ossification of the neural arch centers occurred in a predictable pattern and in a caudal direction. An additional vertebral level became ossified every 2-3 weeks from L-5 through S-5 after 16 weeks gestational age; by 22 weeks, S-2 was ossified in all fetuses studied. Radiographic and histologic correlation was performed in one fetus, and the method of establishing vertebral level with US proved accurate. In addition, the origin of the echoes at US corresponded to the histologic ossification centers. In 95% of the fetuses, S-1 was at the top of the iliac wing. Therefore, the level of ossification in the distal fetal spine could be rapidly assessed. Ossification to S-2 by 22 weeks, with a normal transverse configuration, normal overlying integument, and normal cranial structures, should lead to reassurance in excluding neural tube defects, except for distal sacral lesions.

Female↗
PubMed1991

Significance of nonvisualization of the fetal urinary bladder.

The fetal urinary bladder was visualized sonographically in 1254 (94%) of 1335 consecutive fetuses of 14 weeks of development or older, but it could not be seen in 81 cases (6%). Five of these cases were lost to follow-up and were excluded from the study. Of the remaining 76 cases, 69 (91%) of the pregnancies progressed to term, and the infants were normal at birth and at 6 week perinatal follow-up. Seven (9%) of the fetuses had a variety of associated obstetrical abnormalities that resulted in fetal demise or termination of the pregnancy (oligohydramnios, hydrops, intrauterine growth retardation [IUGR], ventriculomegaly, diaphragmatic hernia, cystic hygroma, and triploidy). Notably, none of these were renal tract anomalies. We concluded that (1) nonvisualization of the fetal urinary bladder with an otherwise normal sonogram, including normal volume of amniotic fluid and normal renal areas, is of no clinical concern and does not require follow-up, and (2) nonvisualization of the fetal urinary bladder in the setting of associated obstetrical abnormalities may be secondary to renal tract anomalies or may only be a consequence of the associated abnormalities.

Female↗
PubMed1990

Device for the calibration of flow-velocity-measuring Doppler ultrasound equipment.

A new device is described for verifying the calibration accuracy of flow-velocity Doppler ultrasound (US) equipment. A rotating circular disk whose circumferential velocity may be fixed or modulated provides a strong signal source suitable for calibrating clinical Doppler US instruments. Circumferential edge velocity, derived from the disk angular frequency, is used to verify the accuracy of Doppler instrument calibration. A limited survey of routinely used Doppler US instruments demonstrates that calibration accuracy generally is satisfactory for clinical purposes, with minimal variation between instruments. Factors that affect measurements include transducer type, scale range, and display size. All transducers used on a specific piece of equipment need to be tested because the transducer design is an important part of the instrument operation. Variations were observed in reported velocities obtained from different transducers on the same equipment and for the same transducer with different scale ranges. In particular, some scales were more accurate than others, suggesting that individual scales should be tested when performing clinical Doppler US instrument calibration. Other measures of performance including scale display range, sample depth, aliasing, and transducer selection may be studied to identify their effect on measurement accuracy. Temporal modulation of angular velocity produces waveforms that may be used to simulate pulsatile velocity characteristics. The device is simple to construct and use, and it provides a convenient way to verify high-quality instrument performance.

Blood Flow Velocity↗
PubMed1989

Dandy-Walker syndrome: a review of fifteen cases evaluated by prenatal sonography.

Fifteen cases of the Dandy-Walker syndrome evaluated by prenatal sonography were reviewed retrospectively. A posterior fossa cyst communicating with the fourth ventricle was a feature in each case. Hydrocephalus was present in 53% of fetuses. Extracranial congenital malformations were documented in 60% of cases. Cardiac, genitourinary, gastrointestinal, and skeletal anomalies were noted. Of 12 available karyotypes, 4 (33%) were abnormal, including two cases of trisomy 18. Excluding terminated pregnancies, there was an overall mortality of 55%. Associated congenital defects contributed to 83% of the postnatal deaths. The Dandy-Walker syndrome can be accurately diagnosed in utero by sonographic demonstration of characteristic morphologic changes in the fetal posterior fossa. The prenatal examination should include an evaluation of associated supratentorial and extracranial defects. Coexisting structural and chromosomal anomalies occur frequently and adversely affect survival.

Abnormalities, Multiple↗
PubMed1989

Disparity of amniotic fluid volume and fetal size: problem of the stuck twin--US studies.

The "stuck twin" phenomenon in monochorionic diamniotic (MCDA) pregnancies is characterized by marked disparity in both fluid volume and fetal size between the twin gestations. To determine the prevalence, sonographic characteristics, and clinical outcome of this phenomenon, discharge summaries, placental pathologic reports, and prenatal sonograms from 307 twin pregnancies were reviewed. Of 52 cases of MCDA pregnancies, 18 (35%) demonstrated marked disparity in amniotic fluid volume. In 16 of these 18 cases there was discordant twin growth, further suggesting the diagnosis of twin transfusion syndrome. All 16 cases and an additional nine cases supplied by another center demonstrated a small, morphologically normal fetus in an oligohydramniotic sac suspended anteriorly (72%) or laterally (28%) in the uterus. The amniotic membrane separating this twin from the larger twin in the polyhydramniotic sac was thin, closely applied to the smaller fetus, and difficult to detect. Perinatal morbidity was 100% for all twin pairs, and premature labor occurred in all cases. Perinatal mortality ranged from 88% for the larger/poly twin to 96% for the small/oligo twin.

Adult↗
PubMed1989

Fetal omphalocele: prenatal US detection of concurrent anomalies and other predictors of outcome.

Forty-six consecutive fetuses with an identified omphalocele were examined with prenatal ultrasound (US) to determine the accuracy of detecting concurrent malformations and to evaluate other possible indicators of fetal outcome. In 43 fetuses with adequate follow-up, 29 (67%) had additional malformations, including 23 with major malformations and six with minor malformations. Thirty-six fetuses (78%) died at termination of pregnancy (n = 23) or spontaneously (n = 13). With the exclusion of pregnancy terminations, fetal mortality was strongly associated with the presence of concurrent malformations, (P less than .001). In 10 surviving fetuses, only three had concurrent malformations, and all were minor. Fetal mortality was also found to be statistically associated with anomalies detected at US (P = .01) and abnormal amniotic fluid volume but was not associated with fetal ascites (P = .64) or omphalocele size (P = .65). Chromosome abnormalities correlated with the absence of liver in the omphalocele sac (P less than .001) and with abnormal amniotic fluid volume (P = .02). Prenatal US can help predict the outcome in fetuses with an omphalocele.

Abnormalities, Multiple↗