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Biomedical subjects

N J Sebire

Publications and source records attributed to N J Sebire.

At least 127 records · Page 7Linked to original sources
PubMed1997

Maternal serum alpha-fetoprotein in fetal neural tube and abdominal wall defects at 10 to 14 weeks of gestation.

Maternal serum alpha-fetoprotein concentration was determined in nine pregnancies with fetal anencephaly, seven with exomphalos containing liver, two with spina bifida and 100 normal controls at 10 to 14 weeks of gestation. The median alpha-fetoprotein in the group with fetal anencephaly and exomphalos was significantly higher than in normal fetuses but the sensitivity of this test is likely to be only about 30% for a false positive rate of 5%.

Abdominal Muscles↗
PubMed1997

Dichorionic twins discordant for intrauterine growth retardation.

A policy of expectant management until 32 weeks of gestation in 29 dichorionic pregnancies discordant for growth retardation resulted in an overall mortality of 24% (95% CI 13.9-37.2%) and a handicap of 2.2% (95% CI 0-12.0%). None of the normally grown co-twins died or was handicapped as a result of iatrogenic prematurity.

Delivery, Obstetric↗
PubMed1996

Prenatal determination of chorionicity in triplet pregnancy by ultrasonographic examination of the ipsilon zone.

OBJECTIVE: To determine chorionicity in triplet pregnancies by ultrasonographic assessment of the ipsilon zone, the junction of the three interfetal membranes. METHODS: The thickness of the component membranes in the ipsilon zone was studied to determine chorionicity in 28 triplet pregnancies, by retrospective examination of the ultrasonographic images taken at 9-24 weeks' gestation, and in 20 consecutive triplet pregnancies followed prospectively by targeted ultrasonography at 8-21 weeks' gestation. Prenatal ultrasonographic findings were compared with those obtained from the records of the infertility centers or referring hospitals (the number of gestational sacs and live embryos in each sac seen by transvaginal scanning at 6-7 weeks' gestation). RESULTS: Of the 28 triplet pregnancies with appropriate images demonstrating the ipsilon zone, 22 were classified as trichorionic, five dichorionic, and one monochorionic. This classification was correct in all but one trichorionic pregnancy, which was misclassified as dichorionic. In the prospective subset (n = 20) there were 16 trichorionic and four dichorionic triplet pregnancies. The ipsilon zone was not present in one case in which the interfetal membrane did not intersect. In the remaining 19 pregnancies, there was a complete correlation between the findings at the ipsilon zone and transvaginal ultrasonography at 6-7 weeks. CONCLUSION: Ultrasonographic assessment of the ipsilon zone is useful for predicting chorionicity in triplet pregnancies.

Chorion↗
PubMed1996

Single uterine entry for genetic amniocentesis in twin pregnancies.

In 176 diamniotic twin pregnancies at 10-20 weeks of gestation, amniotic fluid for cytogenetic studies was successfully obtained from both sacs by the use of a single uterine entry. There were no cases of discordancy between sex at amniocentesis and birth. There were six pregnancies with fetal unbalanced chromosomal defects; in one pregnancy both fetuses were abnormal and in five pregnancies only one fetus was abnormal. The total fetal loss rate was 5.7% (20 of 352 fetuses), including six (1.7%) terminations or selective fetocides and 14 (4.0%) spontaneous deaths. In the 176 pregnancies there were five (2.8%) with no survivors, including one termination and four (2.3%) spontaneous miscarriages or intrauterine deaths. There are only two (1.1%) pregnancies in which amniocentesis could have contributed directly to the losses and therefore the procedure-related rate of fetal loss may be similar to that in singleton pregnancies. The median gestation at delivery was 37 (range 16-40) weeks and delivery before 32 weeks occurred in 9% of the pregnancies. The birth weight distribution was similar to that reported in singleton pregnancies. This study demonstrates that in twin pregnancies amniotic fluid for cytogenetic studies can be obtained successfully from both sacs by use of a single uterine entry. The risk of fetal loss from this procedure appears to be similar to that in singleton pregnancies.

Adult↗
PubMed1996

Intrauterine lethality of trisomy 21 fetuses with increased nuchal translucency thickness.

This study investigates whether first-trimester screening for trisomy 21 by fetal nuchal translucency thickness preferentially identifies those fetuses destined to die in utero and examines the potential impact of such a method of screening on the live birth incidence of trisomy 21. In 70 pregnancies, trisomy 21 was diagnosed at 12 (range 11-14) weeks of gestation and the parents opted for elective termination which was carried out at 14 (12-20) weeks. In all cases, viability was established by ultrasound scan at the time of chorion villus sampling (CVS) and just before termination of pregnancy. Eight (11.4%) fetuses died in the interval between CVS and termination of pregnancy and this rate of lethality was higher than the 6.9% estimated rate for an unselected population of trisomy 21 fetuses. This 4.5% increase may, in part, be attributed to the effects of CVS and may also be due to patient selection on the basis of increased nuchal translucency. The rate of lethality increased with translucency thickness from 5.3% for those with translucency of 1-3 mm to 23.5% for translucency of > 7 mm. In trisomy 21, the rate of intrauterine lethality is associated with nuchal translucency thickness. Nevertheless, a policy of screening by maternal age and fetal nuchal translucency followed by selective termination of affected fetuses would still result in a more than 70% reduction in the live birth incidence of trisomy 21.

Down Syndrome↗
PubMed1996

The lambda sign at 10-14 weeks of gestation as a predictor of chorionicity in twin pregnancies.

Chorionicity was prospectively determined in 369 twin pregnancies by ultrasound at 10-14 weeks of gestation. Pregnancies were classified as monochorionic if there was a single placental mass in the absence of the lambda sign at the inter-twin membrane-placental junction, and dichorionic if there was a single placental mass but the lambda sign was present, or the placentas were not adjacent to each other. In 81 (22%) cases, the pregnancies were classified as monochorionic and in 288 (78%) as dichorionic. Pregnancy outcome was available in 279 cases and all 63 of these pregnancies classified as monochorionic resulted in the delivery of same-sex twins. Similarly, all 100 different-sex pairs were correctly classified as dichorionic. These findings demonstrate the high reliability of ultrasound examination at 10-14 weeks of gestation in determining chorionicity in twin pregnancies.

Adult↗
PubMed1996

Fetal megacystis at 10-14 weeks of gestation.

During the study period, 24,492 pregnant women attended the Harris Birthright Research Centre at 10-14 weeks of gestation, at which time, in addition to the measurements of nuchal translucency thickness and crown-rump length (CRL), data on fetal abnormalities were recorded onto a computer database. Cases of megacystis were identified and the records were reviewed. Additionally, the relationship of the longitudinal bladder diameter with the CRL and the bladder diameter/CRL ratio (expressed as a percentage) were examined with the use of data from 300 normal fetuses at 10-14 weeks. Megacystis was present in 15 of the 24,492 pregnancies (1 in 1,633) and in these cases the minimum longitudinal bladder diameter was 8 mm and the minimum bladder diameter/CRL ratio was 13%. In the 300 control fetuses the bladder was visualized in 278 (92.7%) of the cases and the longitudinal bladder diameter increased with the CRL (bladder diameter = 0.065 x CRL - 0.69; r = 0.47, p < 0.001), none of the measurements was more than 6 mm and the median bladder diameter/CRL ratio was 5.4% (range 0-10.4%) which did not change significantly with gestation (r = 0.1, p = 0.09). The bladder was visible in all cases with a minimum CRL of 67 mm. In three of the 15 cases with megacystis, there were chromosomal abnormalities. In the chromosomally normal group, there were seven cases with spontaneous resolution, whereas in four cases there was progression to severe obstructive uropathy. The bladder diameter was 8-12 mm and the bladder diameter/CRL ratio 13-22% in all cases with resolution and in one case with progressive megacystis; in the other three cases with progressive obstruction, the bladder length was more than 16 mm and the bladder diameter/CRL ratio was more than 28%.

Crown-Rump Length↗
PubMed1996

Maternal serum concentrations of pregnancy associated placental protein A and pregnancy specific beta-1-glycoprotein in multifetal pregnancies before and after fetal reduction.

Placental function in multifetal pregnancies before and after embryo reduction was investigated by measuring maternal serum concentrations of pregnancy associated placental protein-A (PAPP-A) and pregnancy specific beta-1-glycoprotein (SP-1). Three groups of pregnant women were studied following assisted reproduction; groups 1 and 2, were 12 singleton and 12 twin pregnancies respectively, and group 3 comprised 12 women with multifetal pregnancies undergoing embryo reduction. PAPP-A and SP-1 were measured serially at 8-21 weeks gestation. In all pregnancies, maternal serum PAPP-A and SP-1 increased with gestation. In twin pregnancies the mean concentrations of SP-1 were significantly higher than in singletons at all gestations, whereas for PAPP-A, concentrations were similar between these groups. In multifetal pregnancies before embryo reduction, the serum concentrations of both proteins were significantly higher than in twin pregnancies. Following reduction, the concentrations of PAPP-A remained significantly higher than for twins throughout, whereas the concentrations of SP-1 gradually converged towards those of twins; by 19 weeks there was no difference between the means of the two groups. These findings suggest that circulating concentrations of SP-1 reflect total placental mass, which is proportional to the number of live fetuses, whereas the pattern of PAPP-A changes suggests that this protein is produced by the placenta, decidua and other tissues.

Female↗
PubMed1996

Screening for trisomy 21 in twin pregnancies by maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation.

OBJECTIVE: To determine the prevalence of increased fetal nuchal translucency thickness in twin pregnancies and to evaluate screening for trisomy 21 by a combination of translucency thickness and maternal age. DESIGN: Prospective screening study at 10 to 14 weeks of gestation. SETTING: Fetal Medicine Centre. POPULATION: 22,518 self-selected pregnant women at 10 to 14 weeks of gestation, including 21,477 singleton and 448 twin pregnancies with live fetuses. METHODS: Fetal nuchal translucency thickness was measured by ultrasound examination at 10-14 weeks. Sensitivity and false positive rates of screening for trisomy 21 by a combination of fetal nuchal translucency thickness and maternal age were calculated. MAIN OUTCOME MEASURES: Prevalence of increased nuchal translucency thickness and detection of trisomy 21. RESULTS: In the 448 twin pregnancies the nuchal translucency thickness was above the 95th centile of the normal range (for crown-rump length in singletons) in 65/896 fetuses (7.3%), including 7/8 (88%) with trisomy 21. Increased translucency was also present in four fetuses with other chromosomal abnormalities. In the chromosomally normal twin pregnancies the prevalence of increased nuchal translucency was higher in fetuses from monochorionic (8.4%; 16/190) than in those with dichorionic pregnancies (5.4%; 37/688). The minimum estimated risk for trisomy 21, based on maternal age and fetal nuchal translucency thickness, was 1 in 300 in 19.5% (175/896) of the twins including all eight of those with trisomy 21. CONCLUSIONS: In twin pregnancies the sensitivity of fetal nuchal translucency thickness in screening for trisomy 21 is similar to that in singleton pregnancies, but the specificity is lower because translucency is also increased in chromosomally normal monochorionic twin pregnancies.

Adult↗
PubMed1996

Fetal karyotyping in twin pregnancies: selection of technique by measurement of fetal nuchal translucency.

OBJECTIVE: To examine the usefulness of selecting the appropriate technique for fetal karyotyping in twin pregnancies by using maternal age and fetal nuchal translucency thickness to determine risk for chromosomal defects in each fetus. SETTING: Fetal Medicine Centre, London, United Kingdom. SUBJECTS: Sixty-seven twin pregnancies identified at the time of an ultrasound scan for determination of fetal nuchal translucency thickness, where the parents requested karyotyping. INTERVENTION: The risk for chromosomal defects in each fetus was calculated from the maternal age and fetal nuchal translucency thickness at 10 to 14 weeks of gestation. If the estimated risk for either fetus was 1 in 50 or greater, chorion villus sampling was the method of choice, whereas if the risk was less than 1 in 50 second trimester amniocentesis was performed. RESULTS: The estimated risk for trisomies was more than 1 in 50 in 34 pregnancies and 23.5% of these fetuses were found to be chromosomally abnormal. In contrast, in the 33 low risk pregnancies chromosomal abnormalities were found in only 1.5% of the fetuses. CONCLUSIONS: In twin pregnancies the technique for fetal karyotyping may by selected by calculating the risk for chromosomal abnormality based on maternal age and fetal nuchal translucency thickness.

Chromosome Aberrations↗
PubMed1995

Fetal exomphalos and chromosomal defects: relationship to maternal age and gestation.

In an ultrasound screening study involving 15,726 viable, singleton pregnancies at 11-14 weeks of gestation, exomphalos was diagnosed in 0.11% of the cases and, in those with exomphalos, the frequency of trisomy 18, trisomy 13 or triploidy was 61%. The corresponding frequencies of exomphalos of fetuses with these chromosomal defects were 22.5%, 9.1% and 12.5%, respectively. The median maternal age of the screened population was 33 (range 15-48) years, which is higher than in all pregnancies in England and Wales. Expected prevalences of trisomy 18, trisomy 13 and triploidy in the total population were derived on the basis of the age distribution of all deliveries in England and Wales and maternal and gestational age-specific risks for these chromosomal defects. From these numbers and the observed frequencies of exomphalos in association with the various chromosomal defects, it was estimated that the prevalence of exomphalos in a population with the maternal age distribution of all deliveries in England and Wales was 7.4 per 10,000 at 12 weeks of gestation, and this decreased to 3.5 at 20 weeks and 2.9 in live births. The estimated frequency of chromosomal defects in fetuses with exomphalos decreased from 39.4% at 12 weeks of gestation to 27.5% at 20 weeks and 14.4% in live births. The prevalence of chromosomal defects in 153 fetuses with exomphalos referred to our center at 16-26 (median 20) weeks of gestation was not significantly different from that predicted in an unselected population. However, the reported frequency of chromosomal defects in a total of 299 neonates with exomphalos (9.3%) was significantly lower than expected in an unselected population. This study demonstrates that the prevalence of a fetal abnormality and the frequency of associated chromosomal defects depends on the maternal age and gestational age distributions of the populations examined.

Adult↗
PubMed1995

Prevalence of fetal facial cleft at different stages of pregnancy.

During a 7-year period (1988-94), we diagnosed 102 fetuses with trisomy 18, and 54 with trisomy 13; in 6.9% of the trisomy 18 and in 40.7% of the trisomy 13 fetuses, there was a facial cleft. On the basis of (1) these frequencies of facial cleft in trisomic fetuses; (2) the reported prevalence of facial cleft in mid-trimester fetuses; and (3) estimates of the prevalence of trisomies 18 and 13 at 20 weeks of gestation in a population with the maternal age distribution of all deliveries in England and Wales, it was calculated that 6.5% of fetuses with a facial cleft would have trisomy 18 or 13. This estimated frequency of trisomies was significantly lower than the 26% observed in 111 fetuses with a facial cleft that were referred to our unit for fetal karyotyping. These findings suggest that the patients with a facial cleft examined in a referral center are preselected in favor of those with multiple abnormalities, and therefore a higher frequency of associated chromosomal defects. In the future, with improving quality of ultrasound equipment and standards of scanning, it is likely that more cases of isolated facial cleft will be identified and, consequently, the observed frequency of chromosomal defects should decrease.

Adolescent↗
PubMedDate not supplied

Preterm prelabour amniorrhexis: relation to histological chorioamnionitis.

Infection-mediated inflammation may be responsible for premature delivery in cases of preterm prelabour amniorrhexis. Histological examination of the cord and placenta was performed in 54 such pregnancies, in addition to amniocentesis and cordocentesis at presentation. Histological chorioamnionitis was more likely in those with positive amniotic fluid and/or fetal blood cultures, and in those cases with histological evidence of inflammation, the interval to delivery was short regardless of the culture results. Inflammation rather than infection per se may be the best indicator of preterm delivery in preterm prelabour amniorrhexis.

Amniocentesis↗