[Conjoined twins: prenatal diagnosis, delivery and postnatal outcome]

PURPOSE

The aim of this study was to analyze conjoined twins in terms of antenatal, delivery and postnatal aspects.

METHODS

A retrospective descriptive analysis of prenatally diagnosed conjoined twins. Prenatal ultrasound and echocardiography, delivery details, postnatal follow-up, surgical separation and post mortem data were reviewed. The twins were classified according to the type of fusion between fetal structures. The following data were analyzed: ultrasound and echocardiographic findings, antenatal lethality and possibility of surgical separation, delivery details and survival rates.

RESULTS

Forty cases of conjoined twins were included in the study. There were 72.5% cases of thoracophagus, 12.5% of paraphagus, 7.5% of omphalo-ischiophagus, 5.0% of omphalophagus, and 2.5% of cephalophagus. Judicial termination of pregnancy was requested in 58.8% of the cases. Cesarean section was performed in all cases in which pregnancy was not terminated. The mean gestational age at delivery was 35 weeks; all twins were live births with a mean birth weight of 3,860 g and 88% died postnatally. Ten percent of the live borns were submitted to surgical separation with a 60% survival rate. The total survival rate was 7.5% and postnatal survival was 12%. Antenatal evaluation of lethality and possibility of surgical separation were precise. There were no maternal complications related to delivery.

CONCLUSION

Conjoined twins present a dismal prognosis mainly related to the complex cardiac fusion present in the majority of cases with thoracic sharing. At referring centers, prenatal ultrasound and echocardiographic evaluation accurately delineate fetal prognosis and the possibility of postnatal surgical separation.

First-trimester maternal serum activin A in pre-eclampsia and fetal growth restriction

OBJECTIVE

To investigate whether the reported increase in maternal serum activin A concentration in pre-eclampsia is evident from the first trimester.

DESIGN

This was a case-control study carried out in antenatal clinics among singleton pregnancies at 10-14 weeks of gestation.

METHODS

Activin A concentration was measured in stored maternal serum samples obtained at 11-14 weeks of gestation from 131 women who subsequently developed pre-eclampsia, 77 who developed non-proteinuric pregnancy-induced hypertension, 141 with fetal growth restriction in the absence of hypertensive complications and from 494 normotensive controls.

RESULTS

Compared to the median activin A level in the control group (1.00 MoM), the median MoM in the patients who subsequently developed pre-eclampsia and pregnancy-induced hypertension (1.49 MoM and 1.32 MoM, respectively) was significantly increased (p < 0.001), and in patients with fetal growth restriction (1.02 MoM) it was not significantly different (p = 0.57). In the pre-eclampsia group (n = 131) the disease was considered to be sufficiently severe to necessitate iatrogenic delivery before 35 weeks in 25 patients, and in this group the median MoM was 1.92.

CONCLUSION

Maternal serum activin A concentration at 12 weeks of gestation in pregnancies which subsequently develop hypertensive disease is increased, whereas in those complicated by fetal growth restriction it is normal.

[Fetal abnormalities and prognosis associated with increased nuchal translucency and abnormal karyotype]

OBJECTIVES

This study aimed to evaluate the incidence of chromosomal abnormalities in fetuses with increased nuchal translucency (NT) measurement. Incidence of structural abnormalities and pregnancy outcome was also described in fetuses with increased NT and abnormal karyotype.

METHODS

This was a retrospective study involving 246 fetuses with increased NT and known karyotype followed at the Fetal Medicine Unit, Hospital das Clínicas, São Paulo University Medical School.

RESULTS

Fetal karyotype was abnormal in 14.2% of the cases. Ultrasound anomaly scan and specialized echocardiographic studies in these cases showed fetal structural abnormalities in 80.8% and cardiac defects were found in 61.5% of the fetuses. Pregnancy outcome was abnormal in 76.5% of these women.

CONCLUSION

Increased NT measurement at 11 to 13 weeks and 6 days is an important marker for fetal chromosomal and structural abnormalities, mainly fetal cardiac defects. This finding also indicates increased risk of spontaneous fetal and neonatal death.

Selective fetoscopic laser photocoagulation of superficial placental anastomoses for the treatment of severe twin-twin transfusion syndrome

OBJECTIVE

To report our initial institutional experience with fetoscopic laser photocoagulation of placental anastomoses in severe twin-twin transfusion syndrome using a 1.0 mm endoscope.

METHODS

Between July 2006 and June 2008, 19 monochorionic diamniotic twin pregnancies complicated by severe TTTS (Quintero stages III and IV) underwent fetoscopic laser therapy. Perinatal data were prospectively collected and compared according to the Quintero stages.

RESULTS

Nine patients were classified as stage III and ten as stage IV. The Mean gestational ages at diagnosis and procedure were 20 (range: 17-25) and 22.0 (range: 19.0-26.0) weeks, respectively, with no statistical difference between the two groups. Preterm premature rupture of the membranes occurred in two cases (10.5%), and spontaneous preterm delivery in eight (42.1%). Overall mean gestational age at delivery was 32.1 (range: 26.0-38.0) weeks. Prematurity was more severe in stage IV patients (p<0.01). Among all cases, the overall survival rate was 52.6%, and the percentages of pregnancies with survival of both babies and at least one twin were 26.3% and 78.9%, respectively. In the case of stage III patients, the overall survival rate was 61.1%. Of the stage III pregnancies, 33.3% resulted in both babies surviving, and 88.9% of these pregnancies resulted in at least one surviving twin. For stage IV, as the corresponding statistics were 45.0%, 20.0% and 70.0% respectively.

CONCLUSIONS

Our initial institutional experience with 1.0 mm fetoscopic laser therapy for severe TTTS showed results similar to those reported in the literature for larger endoscopes.

Ductus venosus blood flow assessment at 11 to 14 weeks of gestation and fetal outcome

OBJECTIVE

To evaluate the association between abnormal ductus venosus (DV) at 11-14 weeks' gestation and chromosomal abnormalities, structural defects and fetal outcome.

METHODS

DV flow-velocity waveform (DV-FVW) and nuchal translucency thickness (NT) were prospectively evaluated in 1217 singleton pregnancies.

RESULTS

The DV-FVW was abnormal in 84 fetuses, NT was above the 95th centile in 160 fetuses and both markers were observed in 41 fetuses. Chromosomal defects were diagnosed in 22 fetuses. The sensitivity, specificity and positive and negative predictive values for an abnormal karyotype were 86.4%, 86.9%, 11.9% and 99.7%, respectively, for an increased NT. These values were 68.2%, 96.9%, 31.3% and 99.3%, respectively, for DV-FVW abnormalities and 68.2%, 97.6%, 36.6% and 99.3%, respectively, when both markers were found simultaneously. Regarding structural defects, these values were 43.8%, 92.9%, 8.3% and 99.1% for an abnormal NT, 25.0%, 92.6%, 4.8% and 98.8% for DV-FVW abnormalities and 25.0%, 97.9%, 15.4% and 98.9% for both together. Considering those cases of unexplained fetal demise, the values were 44.4%, 85.9%, 5.0% and 98.9% for NT abnormalities, 22.2%, 92.6%, 4.8% and 98.6% for an abnormal DV-FVW and 22.2%, 98%, 15.4% and 98.7% for both. In cases with increased NT, the percentage of live births with normal karyotype and no major fetal structural defects decreased from 93.8% in normal DV-FVW fetuses to 77.3% in abnormal ones.

CONCLUSION

DV assessment at 11-14 weeks' gestation is useful in screening for fetal chromosomal abnormalities and may help to reduce the false-positive rate when combined with NT measurement. Abnormal DV-FVW is also associated with an increase in adverse perinatal outcome in fetuses with enlarged NT. However, the value of DV-FVW assessment in cases with normal NT is unclear.

Megacystis at 10-14 weeks of gestation: chromosomal defects and outcome according to bladder length

AIMS

To examine the prevalence of chromosomal defects and outcome of fetuses with megacystis at 10-14 weeks of gestation.

METHODS

At the 10-14-week scan fetal megacystis was defined by a longitudinal bladder diameter of 7 mm or more. In 145 such fetuses the fetal karyotype and pregnancy outcome were examined in relation to the longitudinal diameter of the fetal bladder.

RESULTS

Chromosomal defects, mainly trisomies 13 and 18, were present in 30 cases. In the group with longitudinal bladder diameter of 7-15 mm the incidence of chromosomal defects was 23.6% (26/110), whereas in those with bladder diameter > 15 mm the incidence was 11.4% (4/35). The fetal nuchal translucency (NT) was above the 95th centile of the normal range for crown-rump length in a higher proportion of cases with abnormal rather than normal karyotype (76.7% compared to 31.3%; Chi-square P < 0.0001). The expected number of cases of trisomy 21, estimated on the basis of maternal age, gestational age and fetal NT, was 6.2 rather than the observed 2 and the corresponding numbers for trisomies 13 or 18 were 4.2 for expected and 24 for observed. In the chromosomally normal group with longitudinal bladder diameter of 7-15 mm follow-up scans demonstrated spontaneous resolution of the megacystis in 90% of the cases and enlargement of the megacystis and/or the development of echogenic kidneys in 10%. In contrast, none of the cases with bladder diameter > 15 mm demonstrated spontaneous resolution of the megacystis.

CONCLUSIONS

In fetal megacystis with longitudinal bladder diameter of 7-15 mm there is a risk of about 25% that the fetus will have a chromosomal defect but in the chromosomally normal group there is spontaneous resolution of the megacystis in about 90% of cases. If the bladder diameter is > 15 mm the risk of chromosomal defects is about 10% and in the chromosomally normal group the condition is invariably associated with progressive obstructive uropathy.

Effect of maternal position on cervical length measurement in twin pregnancies

OBJECTIVE

To compare cervical length measurements in twin pregnancies obtained from patients in the recumbent and standing positions.

METHODS

Fifty women with uncomplicated twin pregnancies underwent monthly transvaginal ultrasound examinations for cervical length measurement in the recumbent and standing positions. The correlation between cervical length measurements obtained in the recumbent and standing positions, and between these measurements and gestational age, were examined. The significance of the differences between measurements obtained in the recumbent and standing positions was also analyzed.

RESULTS

Based on data obtained at the first ultrasound examination, there was a significant correlation between cervical length measurements in the recumbent and standing positions (r = 0.77; t = 8.25; P < 0.0001) and both measurements showed a significant inverse correlation with gestational age (recumbent position: r = -0.60, P < 0.0001; standing position: r = -0.46; P = 0.0008). The mean of the differences (standing - recumbent) was -1.8 mm (95% confidence interval = -3.7-0.04; t = -1.96; P = 0.06) and the mean of percentage differences ((standing - recumbent)/recumbent x 100) was -2.9% (95% confidence interval = -8.6-2.7; t = -1.04; P = 0.3). When the data obtained at all examinations were examined by multiple regression analysis, cervical length measurement in the recumbent position was the only parameter that correlated significantly with the percentage difference between cervical length measurements (P < 0.0001).

CONCLUSIONS

Cervical length in twin pregnancies decreases with gestation and there is a good correlation between measurements obtained from women in the recumbent and standing positions. No significant changes in cervical length were observed comparing measurements obtained in the two maternal positions.

Trichorionic triplet pregnancies at 10-14 weeks: outcome after embryo reduction compared to expectant management

OBJECTIVE

To compare the outcome of trichorionic triplet pregnancies managed expectantly with those reduced to twins or singletons.

METHODS

This was a retrospective study of trichorionic triplet pregnancies with three live fetuses at 10-14 (median 12) weeks' gestation referred to our unit for consideration of embryo reduction. Women were counselled as to the available options of either expectant management or embryo reduction. In those choosing reduction, a needle was inserted into the uterus transabdominally and potassium chloride was injected into the fetal heart. Using data derived from this study and from a review of studies reporting on survival and handicap by gestational age in singletons, the effects of embryo reduction on survival and handicap rates were estimated. Main outcome measures were miscarriage before 24 weeks of gestation, preterm delivery before 32 weeks, perinatal death and handicap rates.

RESULTS

In total, there were 280 trichorionic triplet pregnancies and 125 of these were managed expectantly, 133 were reduced to two fetuses and 22 were reduced to one fetus. The rates of miscarriage were 3.2% for those managed expectantly, 8.3% for those reduced to twins and 13.6% for those reduced to singletons. The rates of early preterm delivery in those pregnancies that did not miscarry were 23.1%, 9.8% and 5.3%, respectively. The percentages for pregnancies with at least one survivor were 95.2%, 91.0% and 81.8%, respectively, and the median gestation at delivery was 34 weeks for the non-reduced, 36 weeks for those reduced to twins and 38 weeks for those reduced to singletons. From the published series on early preterm delivery, it was estimated that survival increases from about 27% at 24 weeks to about 98% at 32 weeks, and handicap decreases from 28% at 24 weeks to less than 5% at 32 weeks. From these estimates and the data on triplet pregnancies, it was calculated that, in triplets reduced to twins, compared to those managed expectantly, the chance of survival is similar (90.3% compared to 93.3%), but the risk of handicap may be lower (0.6% compared to 1.5% per fetus).

CONCLUSIONS

In trichorionic triplet pregnancies, embryo reduction to twins does not improve the chance of survival but may reduce the rate of handicap. Reduction from triplets to singletons may reduce both the survival rate and the handicap rate among survivors.

First-trimester screening for chromosomal abnormalities by fetal nuchal translucency in a Brazilian population

OBJECTIVES

To examine the detection rate of chromosomal abnormalities using nuchal translucency (NT) thickness in a Brazilian population.

METHODS

This was a prospective study of 2996 singleton pregnancies with a live fetus at 10-14 weeks of gestation attending for routine antenatal care in a teaching hospital in Brazil. Fetal crown-rump length (CRL) and NT thickness were measured and the risks for trisomy 21 were calculated by a combination of maternal age and fetal NT with the use of software provided by The Fetal Medicine Foundation. Sensitivity and positive predictive values for different risk cut-offs were calculated.

RESULTS

Chromosomal defects were diagnosed in 22 cases, including 10 cases of trisomy 21. The estimated risk based on maternal age and fetal NT was 1 in 300 or greater in 222 (7.4%) cases and these included nine of 10 (90.0%) pregnancies with trisomy 21 and nine of 12 (75.0%) pregnancies with other chromosomal defects. The NT was above the 95th centile in 5.8% of cases and this group included 70% of the trisomy 21 cases.

CONCLUSION

A combination of maternal age and fetal NT provides an effective method of screening for chromosomal defects. The performance of the test in a Brazilian population is similar to that in Britain.

First-trimester maternal serum levels of placenta growth factor as predictor of preeclampsia and fetal growth restriction

OBJECTIVE

To determine whether the reported decrease in maternal serum placenta growth factor concentration in preeclampsia is evident from the first trimester and before clinical onset of the disease. We also examined levels in pregnancies that subsequently resulted in fetal growth restriction (FGR).

METHODS

Placenta growth factor concentration was measured in stored maternal serum samples obtained at 11-14 weeks of gestation from 131 women who subsequently developed preeclampsia, 137 women who subsequently developed FGR, and 400 randomly selected controls who did not develop preeclampsia or FGR. Preeclampsia was defined as diastolic blood pressure of 90 mmHg or more on two occasions 4 hours apart, accompanied by proteinuria (more than 300 mg of total protein in a 24-hour urine collection or a positive test for albumin on reagent strip) in women with no pre-existing hypertensive or renal disease. Fetal growth restriction was considered present if a woman subsequently delivered a live infant with a birth weight below the fifth centile for gestation.

RESULTS

In the control group, maternal serum placenta growth factor concentration increased with gestation. Compared with the controls (median multiple of the median 0.98, standard deviation [SD] 0.51), levels in the preeclampsia group (median multiple of the median 1.09, SD 0.52) were not significantly different (t = 1.83, P = .07), but in the FGR group (median multiple of the median 1.57, SD 0.74), levels were significantly increased (t = 10.85, P < .001).

CONCLUSION

The previously reported decrease in serum placenta growth factor levels in women with preeclampsia might not precede clinical onset of the disease and is not apparent in the first trimester of pregnancy. Levels are significantly increased in pregnancies resulting in FGR.

Cervical length and funneling at 23 weeks of gestation in the prediction of spontaneous early preterm delivery

OBJECTIVES

To establish the relationship of cervical length at 23 weeks of gestation to the risk of spontaneous delivery before 33 weeks and to determine the possible additional risk if funneling is present.

METHODS

During a 36-month period, 6819 women with singleton pregnancies underwent transvaginal sonographic cervical assessment at 22-24 weeks as a screening test for preterm delivery. The distribution of cervical length and the prevalence of funneling, defined as dilatation of the internal os of > or = 5 mm in width, were established. Women who underwent cervical cerclage, iatrogenic preterm delivery or were lost to follow-up were excluded from further analysis. In the remaining 6334 pregnancies, logistic regression was used to examine the contribution of cervical length and funneling to the risk of spontaneous preterm delivery before 33 weeks.

RESULTS

The median cervical length was 36 mm and in 1.6% of cases the length was < or = 15 mm. There was a significant inverse association between cervical length and percentage rate of spontaneous delivery before 33 weeks. Funneling of the internal os was present in about 4% of pregnancies and the prevalence decreased with increasing cervical length from 98% when the length was < or = 15 mm to about 25% for lengths of 16-30 mm and less than 1% at lengths of > 30 mm. The rate of preterm delivery was 6.9% in those with funneling compared to 0.7% in those without funneling (chi2 = 86.7; P < 0.0001). However, logistic regression analysis demonstrated that funneling did not provide a significant additional contribution to cervical length in the prediction of spontaneous delivery before 33 weeks (odds ratio for short cervix = 24.9, Z = 4.43, P < 0.0001; odds ratio for funneling = 1.8, Z = 0.84, P = 0.40).

CONCLUSION

In the prediction of preterm delivery, funneling does not provide any significant contribution in addition to cervical length.

First trimester maternal serum placenta growth factor (PIGF)concentrations in pregnancies with fetal trisomy 21 or trisomy 18

Placenta growth factor (PIGF), an angiogenic factor belonging to the vascular endothelial growth factor family, pregnancy-associated plasma protein A (PAPP-A) and free beta-human chorionic gonadotrophin (beta-hCG) were measured in maternal serum from 45 pregnancies with trisomy 21, 45 with trisomy 18 and 493 normal controls at 10-13 completed weeks of gestation. In the normal pregnancies maternal serum PIGF levels increased exponentially with gestation. The median multiple of the median (MoM) PIGF concentration in the trisomy 21 group (1.26 MoM) was significantly higher (p<0.0001) than in the control group (1.00 MoM). In the trisomy 18 group the median PIGF was lower (0.889 MoM) but this did not quite reach significance (p=0.064). The corresponding median MoM values for PAPP-A were 1.00 MoM for the controls, 0.49 MoM for trisomy 21 and 0.16 MoM for trisomy 18. The median MoM values for free beta-hCG were 1.00 MoM for the controls, 2.05 MoM for trisomy 21 and 0.38 MoM for trisomy 18. In the control group there was a small but significant correlation of PIGF with free beta-hCG (r=+0.1024) and PAPP-A (r=+0.2288). In the trisomy 18 group there was a significant association between PIGF and free beta-hCG (r=+0.2629) but not with PAPP-A (r=+0.0038). In the trisomy 21 group there was a small but significant association with PAPP-A (r=+0.1028) but not with free beta-hCG (r=+0.0339). The separation of affected and unaffected pregnancies in maternal serum PIGF is small, and therefore it is unlikely that measurement of PIGF would improve screening for these abnormalities provided by the combination of fetal nuchal translucency and maternal serum PAPP-A and free beta-hCG.

First-trimester screening for trisomy 21 in singleton pregnancies achieved by assisted reproduction

BACKGROUND

The possible effect of assisted reproduction on first-trimester screening for trisomy 21 was examined by fetal nuchal translucency thickness (NT), maternal serum free beta-human chorionic gonadotrophin (HCG) and pregnancy-associated plasma protein-A (PAPP-A).

METHODS

Parameters were measured at 11-14 weeks in 411 singleton pregnancies achieved by controlled ovarian stimulation, including 220 that had undergone IVF. Results were compared with 1233 singleton pregnancies conceived spontaneously.

RESULTS

In the IVF pregnancies, the median fetal NT was not significantly different from that in controls, whilst the median free beta-HCG was significantly increased, and PAPP-A was significantly decreased. In the intracytoplasmic sperm injection group, fetal NT and free beta-HCG values were not significantly different from those in controls, but PAPP-A was significantly decreased. In those pregnancies achieved by ovarian stimulation, neither fetal NT, free beta-HCG nor PAPP-A were significantly different from the control group.

CONCLUSIONS

In IVF pregnancies, screening for trisomy 21 by fetal NT, maternal serum free beta-HCG and PAPP-A levels may be associated with a 1.2% higher false-positive rate than in natural conception.

Maternal serum activin A and inhibin A in trisomy 18 pregnancies at 10-14 weeks

In 45 cases of trisomy 18 and 493 control pregnancies at 10-14 weeks of gestation, maternal serum inhibin A, total activin A, free beta-hCG and PAPP-A were measured. In the trisomy 18 pregnancies the median values were 0.74 MoM for inhibin A, 1.23 MoM for activin A, 0.38 MoM for free beta-hCG and 0.16 MoM for PAPP-A. The degree of deviation from normal in the levels of inhibin and activin is small in comparison with free beta-hCG and PAPP-A and they are therefore unlikely to be of value in improving the sensitivity of 90% for a 1% false-positive rate achieved by screening with fetal nuchal translucency and maternal serum free beta-hCG and PAPP-A.