Third-trimester Examination Research Articles

Screening for small for gestational age infants in early vs late third-trimester ultrasonography: a randomized trial

Recent studies have demonstrated that a routine third-trimester ultrasound scan may improve the detection of small for gestational age infants when compared with clinically indicated ultrasound scans but with no reported reduction in severe perinatal morbidity. Establishing the optimal gestational age for the third-trimester examination necessitates evaluation of the ability to detect small for gestational age infants and to predict maternal and perinatal outcomes. Intrauterine growth restriction most often corresponds with small for gestational age infants associated with pathologic growth patterns. This study aimed to assess the performance of routine early ultrasound scans vs late ultrasound scans during the third trimester of pregnancy to identify small for gestational age infants and fetuses with intrauterine growth restriction. This was an open-label, randomized, parallel trial conducted in Upper Normandy, France, from 2012 to 2015. The study eligibility criteria were heathy, nulliparous women older than 18 years with gestational age determined using the crown-rump length at the first trimester routine scan and with no fetal malformation or suspected small for gestational age fetus at the routine second trimester scan. Pregnant women were randomly assigned to a third-trimester scan group at 31 weeks gestational age ±6 days (early ultrasound scan) or at 35 weeks gestational age ±6 days (late ultrasound scan). The primary outcome of this trial was the ability of a third trimester scan to predict small for gestational age infants (customized birth weight <10th percentile) and intrauterine growth restriction (customized birth weight <third percentile) using birth weight as the gold standard. The purpose of these adjustments was to optimize the detection of fetal weight associated with pathologic growth patterns. It was calculated that a sample size of 3720 women would be required to obtain 80% power at a 2-sided level of 0.05 with a 15% difference in sensitivity between the 2 intervention group to detect small for gestational age fetuses in favor of the late ultrasound scan group and considering that small for gestational age infants would represent 10% of all live births. Secondary outcomes were maternal and perinatal morbidities with interventions reported. The analysis was based on the intention-to-treat principle. Results from 1853 women assigned to the early ultrasound scan group and 1848 women assigned to the late ultrasound scan group were analyzed. The sensitivity was found to be higher in the late ultrasound scan group than in the early ultrasound scan group, both for identifying small for gestational age infants (27%; 22%-32% vs 17%; 13%-22%; P=.004) and intrauterine growth restriction (44%; 35%-54% vs 18%; 11%-27%; P<.001). There was little difference in the specificity between the late ultrasound scan and early ultrasound scan groups in identifying cases of small for gestational age (97%; 96%-98% and 98%; 97%-99%, respectively; P=.04) and intrauterine growth restriction (96%; 95%-97% and 97%; 96%;-97%, respectively; P=.24). Overall, the maternal and neonatal outcomes were comparable between the early ultrasound scan and late ultrasound scan groups with the exception of additional (at least 1) ultrasound scans performed (25% in the early ultrasound scan group vs 19% in the late ultrasound scan group; P<.001). Rates of perinatal death (0.4% vs 0.8%; P=.12) and adverse perinatal outcomes (1.8% vs 2.7%; P=.08) were comparable between the early ultrasound scan and late ultrasound scan assigned groups, and the overall sensitivity to detect small for gestational age infants and intrauterine growth restriction, including in the last ultrasound scan performed before delivery, were also similar (30%; 25%-36% vs 26%; 21%-31%; P=.23; and 50%; 40%-60% vs 38%; 28%-48%; P=.07). A late ultrasound scan performed in the third trimester increases the probability of detecting small for gestational age infants and intrauterine growth restriction with fewer additional scans reported than for the early ultrasound scan group. The overall perinatal outcome risk was comparable between the 2 groups. However, the overall sensitivity for detecting small for gestational age fetuses and intrauterine growth restriction, including in the last ultrasound scan performed before delivery, remains comparable between the late ultrasound scan and early ultrasound scan groups.

The incidence and distribution of anomalies found in the pregnant women applied to Kayseri City Hospital for obstetric ultrasound in 2019: a retrospective analysis

Objective Our aim is to determine the incidence and distribution of anomalies found in the pregnant women referred to the first obstetric radiology outpatient clinic of our hospital for ultrasound (US) examination in 2019. Methods A total of 5661 obstetric US examinations were performed in 4018 pregnant women, 588 of whom were foreigners, for routine control, follow-up and screening purposes between January 1 and December 31, 2019, and their results were analyzed retrospectively after obtaining the approval of ethics committee. All US examinations were conducted by a single radiologist (ŞT) with Canon Aplio 500 ultrasound device (Canon Medical Systems Corporation, Tokyo, Japan) using 3.5 Mhz convex probe. The results of the cases with anomalies were accessed and grouped systematically, and their incidence and distribution were reviewed by comparing with the literature. Results As a result of the reviewed obstetric US examinations, a total of 62 fetuses with anomalies, 17 of whom were from the foreign pregnant women, were found to have anomalies. Of these anomalies, 29 were craniospinal, 10 were genitourinary, 6 were cardiac, 6 were skeletal, 3 were gastrointestinal, 2 were thoracic and 6 were unclassified. The pregnant women were between 17 and 43 (27.5±7.21) years old and their weeks of gestation were varying between 11 and 39 (22.3±8.63) weeks. There were 8 (13%) pregnant women younger than 20 years old, 43 (69%) pregnant women between 20 and 35 years old, and 11 (18%) pregnant women older than 35 years old. Anomaly diagnosis was established during first trimester in 14 (22.5%) fetuses, 26 (42%) fetuses during second trimester, and 22 (35.5%) fetuses during third trimester. Conclusion We found in our study that the incidence of fetuses with congenital anomaly was 1.54% in total, 2.89% in foreigners and 1.31% in Turkish citizens. The most common anomaly is acrania with 7 (0.15%) cases, and the diagnosis was established during first trimester in six of them. Detailed fetal screening during first trimester is very important for the detection of non-chromosomal anomalies. However, second- and third-trimester examinations are also important for the accurate diagnosis in pregnancies without follow-up.

Agenesis of the ductus venosus: three-dimensional power Doppler reconstruction

The ductus venosus (DV) is an important fetal vascular structure that connects the umbilical venous system to the inferior vena cava (IVC) near its insertion point into the right atrium1. It allows 20–30% of the umbilical blood to bypass the liver in utero and reach the heart rapidly, thus increasing the flow of well-oxygenated blood to the cephalic and coronary circulation. The DV therefore plays a key role in increasing the shunt of oxygenated blood to the heart and decreasing placental return during hypoxemia and hypovolemia1,2. For several years, improvements in ultrasound techniques, such as two-dimensional (2D) and threedimensional (3D) ultrasound reconstruction, have made it possible to identify numerous malformations that were previously undetectable antenatally, including agenesis of the DV3, which is associated with various morphological and cytogenetic abnormalities. Examination of the DV has been used in referral centers to refine diagnoses involving cardiac, extracardiac and chromosomal anomalies2 as well as in first-trimester screening for Down syndrome in the high-risk population4. The DV pulsatility index for veins can be used as a continuous variable, in combination with nuchal translucency (NT) measurement, to increase specificity in the identification of congenital heart defects5. We report here the case of a 31-year-old primigravida, referred at 35 weeks of gestation to our prenatal center after the abnormal finding at third-trimester ultrasound of a highly dilated IVC (4.1 mm) and umbilical vein. Firstand second-trimester findings had been unremarkable. Combined marker screening in the first trimester indicated a 1/554 risk for Down syndrome, with NT on the 60th percentile. The only morphological abnormalities found during the third-trimester examination were the dilated IVC and umbilical vein. Suspecting agenesis of the DV, we performed a color Doppler ultrasound examination. Looking for an abnormal course or flow in the umbilical vein, we found that it was connected directly to the IVC and the flow velocity was high. To clarify the situation, 3D volume datasets were acquired with transverse and sagittal sweeps over the abdominal region. The umbilical vein and IVC were reconstructed using the glass-body rendering (angiographic) mode to optimize examination of these vessels. To highlight their abnormal connection, we then used the Magicut postprocessing application (Figure 1). This 3D power Doppler reconstruction demonstrated the anomalous course of the dilated umbilical vein, which was connected directly to the dilated subdiaphragmatic IVC and bypassed the liver. Fetal echocardiography showed substantial disproportion in the diameters of the IVC and superior vena cava at the points of insertion into the heart: 4.1 mm vs 1.2 mm. No features of cardiac decompensation or morphological abnormality were seen. The patient was offered amniocentesis for karyotype determination because agenesis of the DV is associated with a high rate (17%) of chromosomal abnormalities2; the karyotype was normal. The remainder of the pregnancy and delivery were uneventful, and the child appeared healthy. Little is known about the consequences and clinical implications of agenesis of the DV6. This anomaly affects approximately 6/1000 fetuses in a high-risk population. The few reports in the literature of an absent DV are associated with three different abnormal patterns: the umbilical vein may bypass the liver and then connect to the subdiaphragmatic IVC or to the iliac or renal veins, it may connect directly to the right or left atrium, or it may connect directly to the portal vein without giving rise to the DV2,7. DV agenesis is associated with congenital morphological abnormalities in approximately 65% of cases and with cytogenetic abnormalities in 17%2,8. The cardiac anomalies associated with DV agenesis, which occur in 48% of cases, include atrial and ventricular septal defects, tricuspid atresia, double outlet right ventricle, pulmonary atresia and transposition of the great arteries7,9. Other common associated anomalies involve the gastrointestinal system (duodenal atresia and tracheoesophageal fistula), the genitourinary system (bilateral hydronephrosis and ectopic kidney) and the musculoskeletal system

Depth of brain fissures in normal fetuses by prenatal ultrasound between 19 and 30 weeks of gestation

To establish normal reference ranges for the depth of the insula and Sylvian (SF), parieto-occipital (POF) and calcarine (CF) fissures on prenatal ultrasound between 19 and 30 weeks of gestation. This was a prospective study of 15 consecutive normal fetuses per gestational week between 19 + 0 and 30 + 6 weeks. We measured the depth of the insula and SF in a standard transventricular axial plane of the fetal head; the depth of the POF in a plane above and parallel to that used for the insula; and the depth of the CF in a coronal view of the posterior fossa. All measurements were done transabdominally during the routine second- or third-trimester examination. Reproducibility for each of the parameters was assessed by two operators using stored images from 30 cases. The depth of the four structures increased with increasing gestational age. The insula and SF could be seen in all cases from 19 weeks onwards, while the POF and CF could be identified in 93.3% and 6.6% of cases, respectively, at 19 weeks. From 20 weeks onwards, the POF could be seen in all examinations, as could the CF from 24 weeks. Intra- and interobserver reproducibility analysis showed good results. Assessment of the insula, SF, POF and CF is feasible during prenatal ultrasound examination using standard views of the fetal head. Since the normal ranges increase with gestational age, they could be used to estimate brain development. It is possible that this assessment might be incorporated into the neurosonogram to identify fetuses at risk of maturation disorders or as a complement to other standard evaluations.

Acoustic Output as Measured by Mechanical and Thermal Indices During Routine Obstetric Ultrasound Examinations

The purpose of this study was to quantify the acoustic output of clinical ultrasound instruments, as expressed by the thermal index (TI) and mechanical index (MI), during routine obstetric examinations. A prospective, observational study was conducted. Sonographers were unaware of the data being sought. Data were collected regarding duration of the examination and specific duration spent at each MI and TI. A total of 11 first-trimester, 14 second-trimester, and 12 third-trimester examinations were evaluated. The mean duration of the first-trimester examination was 8.9 minutes. The mean MI was 0.73 (range, 0.3-1.3), and the mean TI was 0.34 (0.1-1.7). The mean duration of the second-trimester examination was 31.8 minutes. The mean MI was 1.04 (0.5-1.5), and the mean TI was 0.28 (0.1-2.4). The mean duration of the third-trimester examination was 16.3 minutes. The mean MI was 1.06 (0.2-1.5), and the mean TI was 0.32 (0.1-2.4). Statistical significance existed across trimesters with regard to examination durations and MI (P < .001). However, no statistical significance existed in the TI across trimesters. During the third trimester, 3.5% of the examinations had a TI of greater than 1.0. Of these, 2.4% were between 1.0 and 1.49 and 1.1% were greater than 1.5. These changes (of TI > or = 1) were brief (mean +/- SD, 0.17 +/- 0.08 minutes) and were observed during the short periods of color Doppler imaging. Output levels during routine obstetric ultrasound examinations, as expressed by the MI and TI, are generally low. However, higher output levels, particularly TI levels of greater than 1.5, can be achieved, although they account for only a very small proportion of examination time.

The natural history of pelvic organ support in pregnancy.

Little is known about the anatomic and physiologic changes in the pelvic floor that occur during pregnancy. The purpose of this study was to prospectively document pelvic organ support throughout pregnancy using the standardized system of the International Continence Society, also known as the Pelvic Organ Prolapse Quantification (POPQ) Staging System. Pelvic organ support evaluations were performed in nulliparous pregnant women presenting for routine obstetric care during each trimester. POPQ stage assignments and POPQ component measurements were compared for first-, second- and third-trimester examinations. Overall POPQ stage was significantly higher in the third trimester than in the first (P=0.001). Individual POPQ points which showed significant differences between the first and third trimesters include Aa, PB, Ap, Ba, Bp, TVL and GH. These findings probably represent normal physiologic changes of the pelvic floor during pregnancy, but suggest that significant changes may be objectively demonstrated prior to delivery.

Randomised comparison of amoxycillin and erythromycin in treatment of genital chlamydial infection in pregnancy

SummaryErythromycin, the standard treatment for chlamydial infection in pregnant women, commonly causes side-effects, which limits its efficacy. In a randomised, double-blind study, we compared amoxycillin with erythromycin in this setting. 210 pregnant women with Chlamydia trachomatis infection were randomly assigned 7 days' treatment with amoxycillin (500 mg three times daily) or erythromycin (500 mg four times daily). Control cultures were obtained 21 days after treatment, during late pregnancy, and from the infant within a week of birth. Treatment was judged a failure if any post-treatment culture was positive or if the patient had to stop therapy because of severe side-effects.11 women (5·2%) were lost to follow-up. 1 (of 100) amoxycillin-treated women had to stop treatment because of severe side-effects compared with 12 (of 99) erythromycin-treated women (p=0·002). 1 woman in the amoxycillin group had a positive culture at the third-trimester examination. No positive post-treatment culture was found in the erythromycin group. Severe gastrointestinal side-effects were more common in women who received erythromycin (31 vs 6%, p<0·001). The overall failure rate was therefore 2% in the amoxycillin group and 12% in the erythromycin group (p=0·005). These results suggest that amoxycillin is an acceptable alternative to erythromycin for C trachomatis infection in pregnant women.

Computed estimates of maximum temperature elevations in fetal tissues during transabdominal pulsed Doppler examinations

Measured characteristics of ultrasonic fields were obtained in submissions from manufacturers of diagnostic ultrasound equipment for devices operating in pulsed Doppler mode. Simple formulae were used with these data to generate upper limits to fetal temperature elevations, ΔT lim, during a transabdominal pulsed Doppler examination. A total of 236 items were analyzed, each item being a console/transducer/operating-mode/intended-use combination, for which the spatial-peak temporal-average intensity, I SPTA, was greater than 500 mW cm −2. The largest calculated ΔT lim, values were approximately 1.5, 7.1 and 8.7°C for first-, second- and third-trimester examinations, respectively. The vast majority of items yielded ΔT lim, values which were less than 1 °C in the first trimester. For second- and third-trimester examinations, where heating of fetal bone determines ΔT lim, most ΔT lim, values were less than 4°C. The clinical significance of the results is discussed.

Doppler ultrasonography in early pregnancy does not predict adverse pregnancy outcome.

A transvaginal color and pulsed Doppler study was performed on 330 pregnancies at 7-16 weeks of gestation. Blood flow velocity waveforms were recorded from the main uterine arteries and their branches (arcuate and trophoblastic vessels) and from the umbilical arteries. The systolic/diastolic velocity ratio and the pulsatility index were calculated as indices of vascular resistance, respectively, at uterine and umbilical levels. A total of 282 patients had an uneventful pregnancy outcome, 19 developed an early pregnancy failure (missed abortion, n = 8; anembryonic pregnancy, n = 11) and 29 developed later complications such us hypertension (n = 10), fetal growth retardation (n = 13) or both n = 6). In normal pregnancies, Doppler-measured vascular resistances significantly decreased with advancing gestation at the level of both uterine and umbilical circulations. When the Doppler indices of the patients with early pregnancy failure or with later complications were compared to those of normal pregnancies, no evident differences were found in either of the vascular districts considered. However, in the patients who developed hypertension and/or fetal growth retardation, abnormal velocity waveforms were frequently present in uterine and umbilical arteries during second- or third-trimester examinations. Our results suggest a limited clinical value of Doppler velocimetry in early pregnancy.

Increased frequency of detection of human papillomavirus deoxyribonucleic acid in exfoliated cervical cells during pregnancy

Exfoliated cells of the uterine cervix obtained from women during pregnancy and at the time of their first postpartum examination were used to monitor the prevalence of human papillomavirus infections in this population and to study the natural fluctuations in viral expression. When deoxyribonucleic acid hybridization analysis alone was used to monitor the presence of human papillomavirus infection, 20.9% of our study population had results that were positive for human papillomavirus deoxyribonucleic acid during their first-trimester examinations. A dramatic increase in the percentage of women with positive results for human papillomavirus deoxyribonucleic acid was observed at the time of the patients' third-trimester examinations (46%). The overall increase in human papillomavirus-positive patients was a combination of a small number of patients who had positive results on their first examination and negative results on their second examination, and a larger number of patients who had negative results on their first-trimester examination and positive results for human papillomavirus deoxyribonucleic acid in the exfoliated cervical cells at the time of their third-trimester examination. The total percentage of patients with positive results for human papillomavirus deoxyribonucleic acid in their cervical cells at one or both assay points during pregnancy was 52.5%. Samples obtained at the postpartum examination demonstrated a dramatic decrease in the number of samples positive for human papillomavirus deoxyribonucleic acid (17.5%). This result was a combination of a large decrease in human papillomavirus-positive patients coupled with a small increase in detectable levels of human papillomavirus deoxyribonucleic acid in cervical samples from patients who had negative results on their previous examination. This study demonstrates a very high level of detectable human papillomavirus deoxyribonucleic acid in exfoliated cervical cells obtained during pregnancy and shows that the detectable levels of human papillomavirus deoxyribonucleic acid fluctuate during pregnancy.