Trimester Ultrasonography Research Articles

Pregnancy outcomes with increased nuchal translucency after routine Down syndrome screening

Objectives: The purpose of this study was to evaluate the outcomes of pregnancies with nuchal translucency greater or equal to 3 mm for routine first trimester screening in unselected populations. Methods: A total of 2980 pregnant women for first trimester ultrasonography were routinely offered crown-rump length (CRL) and nuchal translucency (NT) for screening for Down syndrome between 11 and 14 weeks’ gestation. A complete follow-up was obtained in all cases by a review of medical records. Results: Using a cut-off value of 3 mm, the prevalence of increased fetal NT was 0.7% ( n=22). Among the 22 cases, there were five (22.7%) chromosomal abnormalities. Of the 17 chromosomally normal pregnancies, four resulted in fetal demise (spontaneous abortion, intrauterine death or termination of pregnancy due to fetal abnormalities). The remaining 13 pregnancies resulted in live births, including one gestational hypertension and one preterm delivery, respectively. The total incidence of an adverse outcome in the group of increased fetal NT was 45.5%. Conclusions: In a routine population with first-trimester ultrasonography, fetal NT measuring greater than or equal to 3 mm was associated with a poor pregnancy outcome with not only chromosomal abnormalities and congenital cardiac diseases, but also poor maternal and fetal health or adverse pregnancy outcomes. In addition, this study also demonstrated the necessity for fetal assessment and follow-up in cases where the fetal NT is increased in the first trimester.

Genetic Evaluation in the Newborn

After completing this article, readers should be able to: 1. List important factors in the maternal or family history that may suggest the possibility of a genetic disorder in the newborn. 2. List the prenatal factors that may suggest a genetic disorder in the newborn. 3. Describe the most important steps in the initial evaluation of a baby born with dysmorphic features, anomalies, and birth defects of internal organs. 4. Characterize an appropriate genetic evaluation for the newborn who has hypotonia and poor feeding. 5. Delineate the additional tests to be considered in an infant born with congenital heart disease. Approximately 3% of newborns are born with genetic problems such as birth defects. Some anomalies, such as cleft lip, are isolated defects in an otherwise normal, healthy infant and are associated with an excellent prognosis following surgical repair. Other anomalies, when occurring as part of a constellation of dysmorphic features, and other birth defects, may represent a more serious underlying genetic disorder. This article discusses common findings in the newborn that should prompt more in-depth testing and suggests an initial approach to the genetic evaluation of the newborn. A detailed, comprehensive family history is essential. Important clues to possible genetic factors that can be ascertained include: Detailed …

Combined serum and ultrasound screening for detection of fetal aneuploidy

Experience gathered over the last decade from high-risk centers provide strong evidence that mid-trimester sonographic markers are sensitive for Down syndrome prediction. More recent data indicate that combining mid trimester sonography with traditional serum markers significantly improves diagnostic accuracy over either group of markers by themselves.

Second trimester sonography and fetal spina bifida screening

Second trimester sonography and fetal spina bifida screening

P057: Fetal gender determination by first trimester sonography

Objective: To determine the accuracy of first trimester sonography in identifying fetal gender. Materials and methods: This study was carried out prospectively in 250 singleton pregnancies who underwent sonography at 11–14 weeks of gestation (confirmed by CRL or BPD). Fetal genitalia was examined in a midsagittal plane and if the angle of genital tubercle to horizontal line through the lumbosacral skin surface was greater than 30′ the gender was assigned as male and when the genital tubercle was parallel or convergent less than 30′, female. The results were checked after birth. Results: In 22 (8.2%) patients fetal sex was not determined. Genital tubercle was identified in 228 (91.2%) patients. Sex determination was correct in 207 (90.8%) and wrong in 21 (9.2%) of cases. The accuracy of sex determination increase with gestational age from 82.7% at 11 weeks, to 90.9% at 12 weeks, 94.7% at 13 weeks and 94.1% at 14 weeks. Most common mistake was to assign male fetuses as female. Conclusion: Sex determination by sonography at first trimester has an important role in case of X-linked anomalies to avoid invasive procedures in female fetuses. The accuracy of correctly identifying fetal gender by sonography at first trimester was 90.8%.

Is Routine Amniocentesis for Advanced Maternal Age Still Indicated?

Objective: To evaluate a policy of selective rather than routine use of amniocentesis for advanced maternal age. Method: A consecutive series of 359 pregnant women aged 38–47 underwent nuchal translucency measurement (NTM) at 10–14 weeks, maternal serum screening (MSS) by α-fetoprotein (AFP) and human chorionic gonadotropin (hCG) at 15–17 weeks, and second trimester ultrasound at 21–23 weeks. Women with NTM <3 mm, MSS-derived risk <1/250, and a normal second trimester sonography were considered at low risk and were suggested not to have an amniocentesis. Results: Either the NTM or MSS test was positive in 130 women; 105 (81%) of them elected to have an amniocentesis, versus 122 (53%) of 229 in whom both tests were negative (p < 0.001). Nineteen (5%) of 359 patients had NTM ≧3 mm; all 7 cases of Down’s syndrome were in this group; 122 (34%) of 359 patients had a MSS-derived risk ≧1/250; 6 of the 7 cases of Down’s syndrome were in this group: Ten patients had an abnormal second trimester ultrasound, 1 of which had trisomy 18. Of the 219 patients with MSS-derived risk <1/250, a NTM <3 mm, and a normal second trimester ultrasound, none had a baby with a chromosomal abnormality (95% confidence interval: 0–1.4%). Conclusion: Amniocentesis may be offered on a selective rather than routine basis in women over 38, based upon the results of noninvasive screening tests.

Determination of fetal gender by first trimester ultrasonography

Objective: To assess the accuracy of first trimester ultrasonography in determining fetal sex by orientation of genital tubercle in relation to spine in a midsagittal plane.Material and methods: Between May 2000 and 2001, 110 patients were studied from 11 to 14 weeks of gestation (average 12.1 weeks) at first trimester ultrasonography. The genital region was examined in a midsagittal plane and the fetal gender was assigned as male if the angle of the genital tubercle to a horizontal line through the lumbosacral skin surface was greater than 30° and female when the genital tubercle was parallel or convergent (&lt;30°). All final results were checked after birth.Results: Among 148 patients, only in 16 (10.8%) fetal sex was not determined. In 132 patients (89.2%), genital tubercle was identified and sex was determined. There were 106 (80.3%) hits and 26 mistakes (19.7%).Conclusion: The diagnosis of fetal sex at first trimester has an important role in case of X‐linked anomalies so invasive procedures can be avoided if fetuses are female. Our results are similar to others in literature. The accuracy of gender determination by ultrasonography was 80.3%. Most common mistake was to assign male fetuses as female. We believe that this error is due to the angle variation of the genital tubercle during the exam.

The use of nuchal translucency measurement and second trimester biochemical markers in screening for Down's syndrome.

To assess the effectiveness of antenatal screening for trisomy 21 by first trimester sonography followed by second trimester biochemical screening. Retrospective five-year review. Maternity unit of a university hospital. An unselected group of 7447 pregnant women who had a first trimester scan and nuchal translucency measurement in our unit after January 1995 and had an estimated date of delivery before 1 January 2000. 11.9% were > or = 37 years old. A subgroup (n = 4,864) also had second trimester biochemical testing by alpha-fetoprotein and free beta-human chorionic gonadotrophin. Prenatal and postnatal diagnosis of trisomy 21. Results There were 23 fetuses affected with trisomy 21. The overall prenatal detection rate was 87% (20/23; 95% CI 66% to 97%) and we performed invasive procedures in 8.5% of our population. First trimester sonography identified 74% (95% CI 51.6% to 89.8%) of affected fetuses. Second trimester biochemical screening detected half of the fetuses with trisomy 21 which were missed by first trimester screening, increasing the sensitivity to 90.5% (19/21; 95% CI 69.6% to 98.8%) for an invasive procedure rate of 4.2% performed in screened positive women. However, the positive predictive value of the biochemical test was very low (0.5%). In screen negative women, karyotyping for advanced maternal age did not detect any affected fetuses. First trimester nuchal translucency measurement is an effective screening test for the prenatal detection of fetuses with Down's Syndrome. Although the measurement of biochemical markers in the second trimester can detect additional affected fetuses this may be outweighed by the delay in diagnosis, the extra visits and cost so that the right time for biochemical screening is most likely to be in the first trimester.

The use of nuchal translucency measurement and second trimester biochemical markers in screening for Down's Syndrome

Objective To assess the effectiveness of antenatal screening for trisomy 21 by first trimester sonography followed by second trimester biochemical screening. Design Retrospective five-year review. Setting Maternity unit of a university hospital. Population An unselected group of 7447 pregnant women who had a first trimester scan and nuchal translucency measurement in our unit after January 1995 and had an estimated date of delivery before 1 January 2000. 11.9% were ≥ 37 years old. A subgroup ( n=4864) also had second trimester biochemical testing by alpha-fetoprotein and free β-human chorionic gonadotrophin. Main outcome measures Prenatal and postnatal diagnosis of trisomy 21. Results There were 23 fetuses affected with trisomy 21. The overall prenatal detection rate was 87% (20/23; 95% CI 66% to 97%) and we performed invasive procedures in 8.5% of our population. First trimester sonography identified 74% (95% CI 51.6% to 89.8%) of affected fetuses. Second trimester biochemical screening detected half of the fetuses with trisomy 21 which were missed by first trimester screening, increasing the sensitivity to 90.5% (19/21; 95% CI 69.6% to 98.8%) for an invasive procedure rate of 4.2% performed in screened positive women. However, the positive predictive value of the biochemical test was very low (0.5%). In screen negative women, karyotyping for advanced maternal age did not detect any affected fetuses. Conclusion First trimester nuchal translucency measurement is an effective screening test for the prenatal detection of fetuses with Down's Syndrome. Although the measurement of biochemical markers in the second trimester can detect additional affected fetuses this may be outweighed by the delay in diagnosis, the extra visits and cost so that the right time for biochemical screening is most likely to be in the first trimester.

Training in obstetric sonography for radiology residents and fellows in the United States.

The purpose of our study was to assess the current experience of radiology residents and fellows in obstetric sonography. Written surveys were sent to the directors of 206 accredited radiology residency programs and 85 fellowship programs in the United States. The surveys encompassed obstetric sonographic experience during routine working hours and after hours, the level of supervision, the types of scanning performed, and the extent of formal lectures available during training. Additional questions concerned the relative knowledge of laboratory accreditation processes and training of faculty covering obstetric sonography. Sixty (29%) of 206 accredited radiology residency programs and 24 (28%) of 85 fellowship programs returned surveys. The experience among residency programs was similar, providing fewer than 4 weeks per year of obstetric sonography, usually within their own department of radiology. Residents were more likely to be sent to outside departments for second or third trimester sonography experience. A decrease in scanning assistance was reported for examinations performed after hours, more so for second or third trimester studies. Lecture topics revealed similar deficiencies for residency and fellowship programs. Greater emphasis on the performance of prenatal sonographic examinations may be warranted during formal sonography rotations. Current levels of experience in obstetric sonography may not be providing sufficient experience to allow residents to appropriately manage call cases or for practicing radiologists to provide such services after their training is completed.

Limited sonography in collaborative midwifery practice

In 1996, the American College of Nurse Midwives published guidelines for midwives who wish to incorporate limited third trimester sonography into their practices. First, however, certain didactic and clinical content needs to be disseminated through basic and continuing midwifery education. To assist the busy practitioner, information is offered related to recommended methods of obtaining learning validation and continuing competency in limited sonography. This article discusses various clinical situations in which the assessment and management of a patient’s condition might be improved by having ultrasonographic information immediately available. In addition, selected data obtained by limited sonography that may necessitate physician collaboration are described through clinical case presentations. The pitfalls of limited sonography are also discussed by use of case descriptions detailing some of the risks inherent in performing a limited ultrasonogram. The recommendation of performing a complete uterine survey with each limited ultrasonogram is emphasized. Finally, some of the controversies surrounding routine sonography in pregnancy and sonograms for entertainment are addressed.

WS16: Early pregnancy WS16‐01The value of first trimester sonography for the diagnosis of structural and chromosomal abnormalities

ObjectivesTo assess the value of first trimester scanning for the diagnosis of structural and chromosomal abnormalities.Population/methodsAn unselected group of 7447 pregnant women who had a first trimester scan in our unit. In all the cases an anatomical survey was performed and the nuchal translucency was measured. Four thousand and 84 women also had second trimester biochemical screening. We assessed the performance of first trimester scanning in the detection of structural and chromosomal abnormalities.ResultsThe incidence of anomalous fetuses was 1.4%, including 43 chromosomal abnormalities. The detection rate for structural abnormalities was 59% (37/63). Seventy‐eight percent of chromosomal abnormalities were diagnosed at 11–14 weeks either because of a nuchal translucency measurement above the 99th centile or due to the presence of structural abnormalities. Second trimester biochemical screening detected half of the fetuses with trisomy 21 which were missed by first trimester screening, increasing the sensitivity to 90.5% (19/21; 95%C.I. 69.6% to 98.8%). However, the positive predictive value of the biochemical test was very low (0.5%).ConclusionFirst trimester NT measurement is an effective screening test for the prenatal detection of fetuses with structural and chromosomal abnormalities. Although the measurement of biochemical markers in the second trimester can detect additional affected fetuses this may be out‐weighted by the delay in diagnosis, the extra visits and cost so that the right time for biochemical screening still needs to be determined. Second trimester anomaly scanning should continue to be an essential part of a prenatal screening programme.

Second trimester ultrasonography may identify 77 to 97% of fetuses with trisomy 18.

Between 1990 and 1999, 30 second trimester fetuses with trisomy 18 and 2000 control fetuses underwent real-time and color Doppler ultrasonographic examination followed by genetic amniocentesis. Abnormal fetal anatomy was present in 97% of fetuses with trisomy 18, with a false-positive rate of 15.7%. Logistic regression identified six markers (choroid plexus cysts, central nervous system malformations, an abnormal nuchal skin fold, ventricular septal defect, outflow tract abnormalities of the heart, and right-to-left chamber disproportion of the heart) and one interaction between markers (right-to-left chamber disproportion and outflow tract abnormalities) to significantly contribute to the identification of 93% of fetuses with trisomy 18, with a false-positive rate of 8.9%. Noncardiovascular markers (choroid plexus cysts, central nervous system malformations, and abnormal nuchal skin fold) identified 77% of fetuses with trisomy 18, with a false-positive rate of 3.9%. Combining right-to-left chamber disproportion of the heart with choroid plexus cysts, central nervous system malformations, and nuchal skin folds identified 83% of fetuses with trisomy 18, with a false-positive rate of 4.4%.

The current clinical presentation of complete molar pregnancy.

To study the current clinical presentation of complete molar pregnancy. Retrospective study of the clinical and ultrasonographic records of 41 patients with complete hydatidiform mole. 17 (41%) patients were asymptomatic. 24 patients (58%) presented with vaginal bleeding, 6 (15%) had excessive uterine size, 1 (2%) had anemia and 1 (2%) had hyperemesis. Non of the patients had any other systemic manifestation. Pre-evacuation ultrasound was performed in all cases and molar pregnancy was diagnosed in 36 (88%). Currently with routine first trimester ultrasonography a significant proportion of patients with molar pregnancy are asymptomatic at the time of diagnosis.

Abdominal circumference vs. estimated weight to predict large for gestational age birth weight in diabetic pregnancy

Early third trimester fetal abdominal circumference and sonographic fetal weight estimates were compared to predict large for gestational age birth weight in diabetic pregnancy. Both parameters have similar sensitivity, specificity, and predictive values. However, the optimal percentile cutoff values differ. Choice of birth weight standard significantly influences test characteristics. Negative prediction of large birth weight is more accurate than positive prediction. At third trimester sonography with maternal diabetes, the abdominal circumference percentile is potentially useful and should be routinely reported.

Prenatal detection of trisomy 21: combined experience of two British hospitals.

A retrospective study was performed to determine the detection rate of trisomy 21 in two British hospitals using a combination of: (1) second trimester serum screening with maternal age, alphaFP and hCG; (2) karyotyping for raised maternal age and high background risk of aneuploidy; and (3) second trimester fetal anomaly ultrasonography at 18-22 week gestation. 36-410 women with a median age of 27 years were studied. Trisomy 21 detected by the combination of methods in both hospitals was compared with the actual number of pregnancies affected by trisomy 21, to determine the detection rate. Serum screening as the backbone of the service detected 31/48 (65%) trisomy 21 affected pregnancies. Karyotyping for maternal age and previous aneuploidy detected eight trisomy 21 affected pregnancies, and second trimester ultrasound a further six, giving a total detection rate of 45/56 (80%). Thus, the detection rate of trisomy 21 in our population is 65% by serum screening alone. This is similar to demonstration projects, but the addition of second trimester ultrasonography and karyotyping for maternal age and prior risk, contributes further to improve the overall sensitivity to 80%. The invasive procedure rate was 4.8% of all women.

Apolipoprotein E genotype and the risk of gallbladder disease in pregnancy

The E4 allele of apolipoprotein E (apoE4) has previously been associated with symptomatic gallstone disease. The aim of this study was to determine if apoE4 is associated with the development of gallbladder sludge and/or stones during pregnancy. We conducted a nested case-control study based on an ongoing cohort study of gallbladder disease in pregnancy. Women in this study receive gallbladder ultrasounds in each trimester of pregnancy. Cases (n = 52) were defined as women with incident gallbladder sludge or stones diagnosed at the third trimester ultrasound. Controls (n = 104) were defined as women without gallbladder sludge or stones on any of 3 study ultrasounds. ApoE genotyping was performed from stored white blood cell pellets. Data were analyzed by stratified analysis and multivariate logistic regression. Cases and controls were similar in baseline characteristics. Forty-two women had sludge, 6 had gallstones, and 4 had both sludge and stones. After adjusting for risk factors such as age, parity, and body mass index, the odds ratio (OR) for the association between heterozygosity or homozygosity for the apoE4 allele and incident gallbladder sludge or stones was 0.91 (95% confidence interval [CI], 0.41-2.02). Further adjustment for family medical history and serum lipid levels did not substantially change these results (OR, 0.73; 95% CI, 0.29-1.82). In conclusion, apoE4 appears to have little or no overall association with the development of new gallbladder sludge or stones in pregnancy. However, an effect could not be ruled out in certain subgroups, such as blacks or women who are homozygous for apoE4.

First trimester ultrasonography of multiple gestations: a review.

The objective was to review current literature pertaining to first trimester ultrasonography of multiple gestations. To this goal, all manuscripts published in the English language regarding this topic were selected and reviewed in a MEDLINE search from 1966 through May 1998. Additional sources were identified through cross-referencing. Current widespread application of first trimester ultrasonography and especially transvaginal sonography has introduced a new dimension in both diagnostic and management aspects of multiple gestations. Application of first trimester ultrasonography in multiple gestations enables an earlier and more precise depiction of important anatomical details regarding fetal viability, chorionicity, pregnancy outcome, structural abnormalities, pathophysiology of developmental disorders (such as twin reverse arterial perfusion [TRAP] sequence), early sonographic signs associated with fetal aneuploidy (nuchal translucency and abnormal crown-rump length), and potential fetal growth discordancy. First trimester ultrasonography also assists in guiding operative procedures including: amniocentesis, chorionic villus sampling, and selective fetal reduction. Enhanced information obtained with high-resolution, first trimester transvaginal ultrasonography is rapidly becoming a standard for establishing critical information that will assist clinicians to stratify management of multiple gestations. Given the increasing incidence of multiple gestations because of various assisted reproductive technology modalities, it is important that obstetricians become aware of the potential advantages of first trimester ultrasonography in clinical management of multiple gestations.

"Appearing twin": undercounting of multiple gestations on early first trimester sonograms.

An important role of first trimester sonography is to determine whether a pregnancy is a singleton, twin, or higher order multiple gestation. We assessed how frequently sonography at 5.0-5.9 weeks undercounts multiple gestations. We identified all pregnancies at our institution since 1988 in which (1) an initial sonogram obtained at 5.0-5.9 weeks demonstrated at least a singleton intrauterine pregnancy and (2) a subsequent sonogram at 6.0 weeks or beyond demonstrated a living multiple gestation. Twenty-four (11%) of 213 dichorionic twin gestations were initially undercounted as singletons, as were six (86%) of seven monochorionic twin gestations. Among 105 higher order multiples, 17 (16%) were undercounted initially. All but one of the undercounted cases were scanned transvaginally. Undercounting occurred in both natural and assisted conceptions, and it occurred more frequently on sonograms obtained at 5.0-5.4 weeks than at 5.5-5.9 weeks (P = 0.02, Fisher's exact test). Prognosis for undercounted multiple gestations was similar to that of correctly counted ones with respect to several measures of pregnancy outcome, including the likelihood that all fetuses would be delivered liveborn, gestational age at birth, and birth weight (P > 0.20, all comparisons). In conclusion, transvaginal sonography at 5.0-5.9 weeks frequently undercounts multiple gestations. Initially undercounted multiple gestations and those correctly counted have similar pregnancy outcomes.

First trimester sonographic detection of chromosomal abnormalities in an unselected population.

To investigate the role of first trimester sonography in detecting chromosomal abnormalities in an unselected obstetric population. 2281 women (mean maternal age 30 years [range 16-47]; mean gestational age 12(+3) weeks [range 11-14]) underwent transabdominal scanning to assess fetal structure and, if anatomical survey was considered to be incomplete (31% of cases), transvaginal sonography was also performed. Measurement of nuchal translucency was included and karyotyping performed as considered appropriate. There were 16 chromosomal abnormalities; 13 (81%) were diagnosed at 11-14 weeks either because of a nuchal translucency greater than or equal to the 99th centile for gestational age (7/16; 44% [95% CI 25-63]) or due to the presence of structural abnormalities (6/16; 38% [95% CI 14.2-61.8]). Seventy-five percent of cases of trisomy 21 were also diagnosed either because of having a nuchal translucency greater than or equal to the 99th centile (5/8; 63%) or due to the presence of a structural abnormality (1/8; 13%). A significant proportion of fetal chromosomal abnormalities can be detected by first trimester sonographic screening to assess fetal structural appearance. The sensitivity of detection can be improved by combining measurement of nuchal translucency with detailed examination of fetal anatomy.