MULTISCAN--a Scandinavian multicenter second trimester obstetric ultrasound and serum screening study.

AIM: To study the detection rates of second trimester ultrasound screening for neural tube defects (NTD), abdominal wall defects (AWD) and Down's syndrome (DS) in low risk populations at tertiary centers, and to compare the ultrasound screening detection rates with those that were obtainable by biochemical serum screening (double test: alpha-fetoprotein/human chorion gonadotrophin/age test). STUDY DESIGN: Prospective multicenter study with a three year inclusion period: 1/1/1989-31/12/1991. SUBJECTS: 27,844 low-risk women at 18-34 years of age who had a second trimester ultrasound screening examination. Of these, 10,264 also had a serum test. METHODS: An ultrasound malformation scan and a serum test were carried out at 17-19 weeks of gestation. Risk calculations regarding DS were based on alpha-fetoprotein, human chorion gonadotrophin and maternal age; performed retrospectively for the first two years. RESULTS: In total 73 cases were identified in the study population: NTD (n=34), AWD (n=7) and DS (n=32). The detection rates, (%, with 95% confidence interval) for ultrasound screening were: NTD: 79.4 (62.1-91.3); AWD: 85.7 (42.1-99.6); DS: 6.3 (0.8-20.8). In the subgroup of women who had both tests, the detection rates for ultrasound screening vs double test were: NTD: 62.5 (24.5-91.5) vs 75.0 (34.9-96.8); AWD: 66.7 (9.4-99.2) vs 100 (29.2-100.0); DS: 7.7 (0.2-36.0) vs 46.2 (19.2-74.9). The false positive rates (%) for ultrasound screening vs double test were: NTD: 0.01/3.3; AWD: 0.01/3.3; DS: 0.1/4.0. CONCLUSION: Second trimester ultrasound screening in a low risk population gave a low detection rate for fetal DS (6.3%) and an acceptable detection rate for NTD (79.4%) and AWD (85.7%). In the subgroup of women who had both tests, serum screening performed better than ultrasound as applied in the present study, especially regarding DS.

Intrauterine growth curves based on ultrasonically estimated foetal weights.

Available standard intrauterine growth curves based on birthweights underestimate foetal growth in preterm period. New growth curves are presented based on data from four Scandinavian centres for 759 ultrasonically estimated foetal weights in 86 uncomplicated pregnancies. Mean weight of boys exceeded that of girls by 2-3%. A uniform SD value of 12% of the mean weight was adopted for the standard curves as the true SD varied non-systematically between 9.1 and 12.4%. Applied to an unselected population of 8663 singleton births, before 210 days of gestation, 32% of birthweights were classified as small-for-gestational age (SGA; i.e. below mean - 2 SD); the corresponding figures were 11.1% for gestational ages between 210 and 258 days, and 2.6% for ages of 259 days or longer. The new growth curves reveal better the true distribution of SGA foetuses and neonates, and are suggested for use in perinatological practice.

Fetal and uteroplacental blood flow in prolonged pregnancies. A clinical study.

In a prospective study during 1 year, 102 women with prolonged pregnancies (more than 294 completed gestational days) were followed with serial pulsed Doppler blood flow examinations every 2nd day, either to spontaneous onset of labor (n = 82) or to induction of labor due to subsequently occurring complications (n = 20). Mean aortic blood velocity did not change significantly with gestational age beyond 294 days either in fetuses with normal outcome or in fetuses that developed asphyxia at birth. The flow velocity waveforms in the descending aorta, the umbilical artery, the common carotid artery and the uterine artery did not change significantly compared to the values at term. Abnormal flow velocity waveforms in the fetal descending aorta, umbilical artery or uterine artery had no significant relationship to fetal asphyxia. Absence of diastolic flow velocities was not found in any of the vessels examined, indicating that the fetuses did not suffer from chronic hypoxia in utero and that aging of the placenta did not alter fetal and uteroplacental blood flow. Notching of the aortic flow velocity waveform was a common finding among prolonged pregnancies. The hemodynamic implications and consequences of this phenomenon are discussed.

Ultrasonic imaging in the differential diagnosis of diffuse thyroid disorders in children.

In 22 patients with suspected diffuse goiter, the diagnostic accuracy of ultrasonography was compared with that of aspiration biopsy cytology and thyroid antibody testing. Ultrasonography was abnormal in 100% (10/10) of the patients with autoimmune thyroid disease, only 90% (9/10) of whom were identified with antibody testing. All patients with diffuse colloid goiter had normal echo patterns on ultrasound imaging, whereas 29% (2/7) of them had positive results on antibody testing. Whether these are 'false positives' or represent focal thyroiditis remains unclear. Thus, ultrasound imaging stands out as a valuable diagnostic tool for the differential diagnosis of diffuse thyroid disorders in children.

Ultrasonic measurement of fetal blood velocity wave form as a secondary diagnostic test in screening for intrauterine growth retardation.

Based on routine fetometry screening at 32 weeks of gestation, 80 out of 3226 singleton pregnancies were suspected of intrauterine growth retardation (IUGR) and 72 of them were subjected to repeated fetal blood flow measurements by Doppler ultrasound for evaluation of the fetal condition. The maximum blood velocity wave form recorded from the fetal descending aorta and umbilical artery was classified as normal or abnormal depending on the presence or absence of positive end-diastolic blood flow. Compared to the pregnancies with normal fetal blood flow, the group of 30 pregnancies with abnormal blood flow patterns had significantly more pregnancy complications and more operative deliveries for fetal distress. In the latter group, all newborns but one were small-for-gestational age and had low 1-min Apgar scores more frequently. Fetal blood flow measurements have a good capacity for predicting unfavorable fetal outcomes and can be recommended for clinical use. The combination of ultrasound screening and Doppler blood flow measurement has reduced the number of pregnancies requiring intensive surveillance.

Ultrasound measurement of fetal blood flow in predicting fetal outcome.

The efficacy of fetal blood flow assessment in predicting fetal outcome was evaluated in 159 pregnancies suspected of intrauterine growth retardation (IUGR). Blood flow in the fetal aorta and umbilical vein was measured with imaging and pulsed Doppler ultrasound. Volume blood flow values and variables describing the waveform of the maximum aortic blood velocity were checked for relations to subsequent fetal outcome. A new semi-quantitative velocity waveform variable, blood flow class (BFC), was designed and tested. The occurrence of IUGR, imminent fetal distress, a low Apgar score at 1 and 5 min, and a low pH in the umbilical artery and vein were adopted to characterize fetal outcome. Receiver operating characteristic curves were used to demonstrate the sensitivity and false positive rate, and the Cohen's Kappa index was used to compare the predictive capacity of the various blood flow variables. BFC, describing the blood velocity waveform with emphasis on its end-diastolic part, was found to be the most powerful marker of imminent fetal asphyxia (Kappa = 0.66) and of intrauterine growth retardation (Kappa = 0.48).

Fetal blood flow in pregnancies complicated by intrauterine growth retardation.

A noninvasive pulsed Doppler ultrasound technique was used to characterize blood flow in the descending thoracic aorta and the intra-abdominal part of the umbilical vein in 159 fetuses suspected of intrauterine growth retardation (IUGR) on the basis of ultrasound fetometry. From this group, 74 infants with IUGR (defined as gestational age-related birth weight of 2 standard deviations [SD] or more below the population mean) were born. The blood flow results were not available to the clinicians managing the pregnancies. Blood flow mean velocity in the fetal aorta was lower, pulsatility index and rising slope higher, and umbilical volume flow and umbilical flow per 100 g placental tissue were lower in the pregnancies with IUGR than in 21 normal pregnancies. The waveform of the maximum aortic velocity envelope was related to operative delivery for fetal distress, Apgar score, and umbilical cord blood pH. The pulsatility index and the configurational assessment of the diastolic part of the waveform were combined to form a new concept, the blood flow class. The blood flow class was abnormal in 57% of the fetuses classified as having IUGR at birth and in 93% of those growth-retarded fetuses who subsequently developed signs of fetal distress requiring operative delivery. Waveform analysis, in terms of blood flow class, seems to be a useful tool in the surveillance of fetuses when IUGR is suspected. Abnormal blood flow class is a marker of fetal distress and probably gives an earlier indication than antenatal nonstressed cardiotocography. The results of this study point to a strong association between IUGR and impaired fetal blood flow. The aortic volume blood flow, unlike waveform analysis, does not seem to be a variable sensitive enough to predict fetal outcome in the individual pregnancy.

The efficacy of biochemical assays in assessing an IUGR risk-group, preselected with ultrasound fetometry.

Dehydroepiandrosterone sulphate, progesterone, estradiol, estriol and human placental lactogen (hPL) were biochemically assayed in a group of 92 pregnancies in which intra-uterine growth retardation was suspected. The group was selected with ultrasound fetometry at 32 weeks of gestation, and maternal blood was sampled at 33, 35, 37 and 39 weeks of gestation. The IUGR group consisted of 30 pregnancies resulting in the birth of an infant with a birthweight of 2 standard deviations or more below the mean for gestational age in the Malmö population. Intra-uterine growth trends were defined by serial ultrasound fetometry performed every second week. Both serum hormone and hPL content were examined in relation to birth-weight, occurrence of imminent asphyxia at delivery, Apgar score, and pH in the umbilical vein. Neither dehydroepiandrosterone sulphate, nor progesterone nor estradiol values correlated to any of the outcome variables. To some extent estriol values distinguished IUGR from non-IUGR fetuses but not until the 39th gestational week, whereas hPL was effective in this respect in all weeks studied. An hPL value below 4 mg/l predicted IUGR with a sensitivity ranging from 52% to 74%, and a specificity ranging from 85% to 78%. HPL correlated well with the subsequent intra-uterine growth rate, but not with the outcome variables studied.

Thyroglobulin in cord blood. The influence of the mode of delivery and the smoking habits of the mother.

The cord thyroglobulin (Tg) concentration was estimated in 160 full-term newborns of whom 103 were delivered normally, 26 by elective Cesarean section and 31 by vacuum extraction. There was no correlation between the median cord Tg concentration and gestational age at delivery (37-43 weeks), birth weight or sex of the child or the median cord TSH concentration. The median cord Tg concentration was significantly higher in the children born by Cesarean section than in those delivered by vacuum extraction (P less than 0.001). The same tendency was found when smokers and non-smokers were compared separately. Mechanical force on the thyroid gland during labour and delivery therefore does not seem to increase the cord Tg concentration. The influence of maternal cigarette smoking on the cord Tg concentration was studied also. Forty-five mothers were smokers. The median cord Tg concentration in the children of these women was significantly higher than in the children of non-smoking mothers (130 micrograms/l vs 100 micrograms/l, P less than 0.001), whereas the median cord TSH concentration did not differ between these groups. It therefore seems possible that components of cigarette smoke, e.g. thiocyanate, may have a direct effect on the thyroid gland of the fetus.

Perinatal outcome in growth retarded pregnancies dated by ultrasound.

To analyse the incidence of fetal growth retardation and its impact on perinatal mortality and neonatal morbidity, pregnancies complicated by intra-uterine growth retardation (IUGR) were compared with matched non-IUGR pregnancies. The IUGR group included all infants born in the city of Malmö during the study period and having a birthweight of 2 standard deviations or more below the mean birthweight for gestational age. The gestational age of all pregnancies was assessed with ultrasound in the first half of pregnancy. The IUGR fetuses were more vulnerable during delivery, and emergency cesarean section due to imminent fetal asphyxia was performed more frequently, but Apgar scores were similar in both groups. The frequency of respiratory disorders was lower in the IUGR group than in the non-IUGR group when corticosteroid-treated pregnancies were excluded. The IUGR group required slightly longer care on the neonatal ward than the non-IUGR group, but not more intervention. The IUGR group as a whole had an unexpectedly low neonatal complication rate, such complications as did occur being related to preterm birth rather than to growth retardation.

The effect of bedrest in hospital on fetal outcome in pregnancies complicated by intra-uterine growth retardation.

A prospective study was made to evaluate whether bedrest in hospital is beneficial in pregnancies where intra-uterine growth retardation (IUGR) was suspected. Diagnosis was based on routine fetometry at 32 weeks of gestation, in conjunction with general ultrasound screening. 107 patients with suspected IUGR-pregnancies were divided into two groups, 49 in a hospital bedrest group and 58 in an 'out-patient' group. Fifteen women in the bedrest group refused hospitalization, and 8 women in the out-patient group had to be hospitalized for medical reasons other than suspected growth retardation, leaving 79% of the women in their allocated group. The women in the bedrest group were hospitalized for a mean duration of 29.2 days (range 5-54). The results suggest that bedrest in hospital is not beneficial, either to fetal growth or to pregnancy outcome.

Ultrasound screening for detection of intra-uterine growth retardation.

Intra-uterine growth retardation (IUGR) is a major problem in contemporary obstetrics. Early antenatal diagnosis is important if morbidity and mortality are to be minimized. We present the results of one years ultrasound fetometric screening for IUGR of the pregnant population in the city of Malmö. All pregnancies were dated by early biparietal diameter (BPD) measurement. From findings at 32 weeks of gestation, an IUGR risk-group (n = 436) was selected on the basis of predicted birthweight deviations with reference to standard curves, established at the Department, for BPD, abdominal diameter, femur length, and intra-uterine weight, all plotted against gestational age. The risk-group, which included 60 (77%) of the 78 IUGR infants eventually born, was subjected to additional fetometry examinations at 34, 36 and 38 weeks of gestation, in the total pregnant population of 2,068, each pregnancy was the subject of 2.3 examinations. Other fetometry variables were evaluated for their efficacy as IUGR markers, but were not found to be superior to the current screening procedure in which BPD and abdominal diameter are combined in a simple formula to assess intra-uterine growth. Overall, the screening procedure currently used at Malmö had a sensitivity of 64.1% and a specificity of 96.5%, the prevalence for IUGR being 3.8%.

Prenatal diagnosis of urinary tract abnormalities by ultrasound.

The capacity of a general ultrasound screening program to detect fetal malformations affecting the urinary tract was evaluated in an epidemiologic study. A total of 11,986 pregnant women, representing 97% of the pregnant population in Malmö, Sweden, from April 1978 through August 1983 were examined. On routine examinations performed by midwives in the 17th and 33rd gestational weeks, the fetal anatomy was carefully surveyed. The overall frequency of fetal malformations was 0.5%, with urinary tract abnormalities representing approximately 50% of the total number. In 20 of 33 cases, the ultrasound findings were those of hydronephrosis or hydroureter. In ten cases, a cystic renal malformation was found, and the remaining three cases represented double renal pelvis, Potter syndrome, and posterior urethral valve. A total of 28 abnormalities were unilateral and five bilateral. No case of unilateral absence of renal tissue was noted prenatally. Prenatal diagnosis of urinary tract abnormalities known to precipitate neonatal urosepsis and subsequent renal scarring and other complications makes it possible to start an early antibiotic prophylaxis regimen. A complete workup of the infants can be started early and before life-threatening complications occur.

Hip joint instability in breech pregnancy.

222 consecutive fetuses found by ultrasound to be in breech presentation in the 33rd gestational week were followed with repeated examinations in weeks 35 and 38. Ninety-one of these fetuses persisted in breech presentation until delivery, while cephalic version occurred in 131. The frequency of hip joint instability was 21% in the breech delivered group and 1.5% in the vertex delivered group. The position of the fetal legs was established at each ultrasound examination. The intrauterine fetal attitude was classified as extended when the fetuses had extended knees and maximally flexed hips at all ultrasound examinations. This occurred in 30 breech delivered fetuses, 47% of which developed hip joint instability. Only 8% of the breech born infants with flexed legs in utero developed hip joint instability. It is concluded that instability of the hip joint is a consequence of the intrauterine attitude, rather than of the breech delivery per se.

Role of asphyxia and slow intrauterine growth in morbidity among breech delivered infants.

The outcome of breech delivery was evaluated by a neonatal neurological score and a follow-up examination at 18 months of age. The subjects were 132 children identified by ultrasound to be in breech presentation in the 33rd gestational week. 62 were born in breech presentation, while 70 turned to vertex presentation. During the early neonatal period, a neurological score was obtained based on the results of 29 items concerning posture, muscle tone, reflexes and reactions. Although there was no difference, in neurological score or in general development when the entire breech and vertex groups were compared, the SGA (small-for-gestational age) infants and the infants with low Apgar scores of the breech group had the poorest neurological scores. The contribution of certain maternal and fetal factors to postnatal condition was evaluated by a multiple linear regression analysis. Within the breech group, relationships were found between the neurological score and the variables intrauterine growth, fetal sex, and low Apgar score. A major part (66%) of the variation in neurological score was explained by the combination of these variables. These factors should therefore be taken into consideration when deciding on the mode of delivery in breech presentation.