Ultrasound assessment of the prognosis in triplet pregnancies

Prognostic Value of Doppler Ultrasound in Triplets Conceived by In Vitro Fertilization: A Case Report and Review of the Literature

Umbilical artery Doppler ultrasound-which informs on maternal-fetal-placental blood flow-may be the most valuable surveillance tool in triplet pregnancies, crucial to diagnose early fetal growth restriction. To illustrate the prognostic value of Doppler ultrasound and launch a discussion of its role in multiple gestational, high-risk pregnancy, we present the case of a 42-year-old woman with trichorionic triamniotic triplet pregnancy conceived by in vitro fertilization, who showed early signs of poor outcome for one of the triplets via umbilical artery Doppler by the 23rd week and middle cerebral artery Doppler by the 29th week of gestation.

Reliability of sonographic fetal weight estimation in triplet pregnancies: a retrospective cohort study

PURPOSE

To review our experience in ultrasound fetal weight estimation in our large population of triplet pregnancies.

METHODS

Ninety-seven triplet pregnancies were retrospectively included between January 2003 and January 2017. Sonographic fetal weight estimation using Hadlock's and Schild's formulas was compared to actual birth weight in a tertiary-care center in Vienna, Austria. Statistical analyses were performed using a stepwise linear regression model and crosstabs.

RESULTS

The median discrepancy between the sonographically estimated fetal weight by Hadlock's formula and the actual birth weight was 106 g (IQR 56-190). The percentage error and its standard deviation were - 2.5 ± 12.1%, and the median percentage error was - 3.6%. Concerning the use of Hadlock's formula, estimated fetal weight was the most important factor predictive of actual birth weight with an estimate of 0.920 (p < 0.001). Female neonates had been overestimated by a mean of 50.473 g per fetus. The sonographic prediction of small-for-gestational-age neonates was significantly reliable (p < 0.001), with positive and negative predictive values ranging from 81.3 to 100.0%. Similar results were obtained for Schild's formula.

CONCLUSION

Even if sonographically estimated fetal weight in triplet pregnancies has a high overall accuracy of fetal weight estimation, there are some limitations in prediction of intrauterine growth restrictions, especially in female fetuses.

Accuracy of Prenatal Ultrasound in Detecting Growth Abnormalities in Triplets: A Retrospective Cohort Study

Significant management decisions in triplet pregnancies are made based mainly on ultrasound measurements of fetal growth, although there is a paucity of data examining the accuracy of fetal weight measurements in these gestations. To evaluate accuracy of prenatal ultrasound to diagnose growth abnormalities (intrauterine growth restriction, severe growth discordance) in triplet pregnancies, a retrospective cohort study of 78 triplet pregnancies (234 fetuses) delivered at a single tertiary hospital from January 2004 to May 2015 was performed. Growth percentiles from the last ultrasound were derived from estimated fetal weight using Hadlock's formula for each triplet. Growth discordance was calculated for each triplet set using the formula {(estimated fetal weight largest triplet - estimated fetal weight smallest)/estimated fetal weight largest}. These estimations were compared to birth weights. Sensitivity of ultrasound to predict ≥1 growth restricted fetus in a triplet set was 55.6% [95% CI 35.3, 74.5]; specificity was 100% [95% CI 93.0, 100]; positive predictive value (PPV) 100% [95% CI 74.7, 100]; negative predictive value (NPV) 81.0% [95% CI 73.2, 85.7%]. Sensitivity of ultrasound to detect fetal growth discordance >25% in a triplet set was 80.0% [95% CI 44.4, 97.5], specificity 94.1% [95% CI 85.6, 98.4]; PPV 66.7% [95% CI 42.4, 84.5]; NPV 97.0% [95% CI 90.2, 99.1]. Prenatal ultrasound currently remains the most reliable tool to screen for growth anomalies in triplet pregnancies; however, it appears to have less than ideal sensitivity, missing a number of cases of intra-uterine growth restriction and significant growth discordance.

Prediction of perinatal mortality in triplet pregnancies

PURPOSE

To investigate predictors of perinatal mortality in triplet pregnancies.

METHODS

Retrospective cohort managed in a tertiary teaching hospital (1998-2012) including all pregnancies with tree live fetuses at the first ultrasound examination, performed after 11 weeks of gestation. Primary end-point was defined as the number of children alive at hospital discharge. Ordinal stepwise regression analysis examined the association with maternal age, parity, pregnancy chorionicity, gestational age at our first ultrasound evaluation, presence of maternal clinical, obstetrical and fetal complications and gestational age at delivery.

RESULTS

Sixty-seven triplet pregnancies were first seen at 18.5 ± 6.8 weeks, 33 (49.3 %) were trichorionic, obstetric complications occurred in 34 (50.7 %) and fetal complications were diagnosed in 17 (25.4 %). Perinatal mortality rate was 249 ‰ (95 % CI 189-317) and 138 (73 %) children were discharged alive from hospital (11 pregnancies with no survivors; single and double survival in ten cases each; all children alive in 36). Regression analysis showed that presence of fetal complications (OR 0.10, 95 % CI 0.03-0.36) and gestational age at delivery (OR 1.55, 95 % CI 1.31-1.85) are significant predictors of outcome (p < 0.001).

CONCLUSIONS

Perinatal mortality in non-selected triplet pregnancies is high and is related to the presence of fetal complications and gestational age at delivery.

Three-dimensional sonograph of a monochorionic diamniotic triplet pregnancy

A monochorionic diamniotic triplet pregnancy was diagnosed by sonographic scan at 9 weeks of gestation. The three embryos appeared to share the same trophoblast, with two of them sharing the same amniotic sac. The two amniotic sacs were divided by a thin membrane, with no chorionic projection within it, and each amniotic sac presented a single yolk sac. Only few cases of nontrichorionic-triamniotic triplets have been reported in the literature. Although the diagnosis was reached using the two-dimensional ultrasound, the complementary use of three-dimensional ultrasound helped in confirming the diagnosis, and in offering the couple an adequate counseling.