David Schrimmer

Prophylactic amnioinfusion improves outcome of pregnancy complicated by thick meconium and oligohydramnios

OBJECTIVE The null hypothesis is that the use of intrapartum amnioinfusion in labors complicated by the presence of thick meconium and oligohydramnios will not decrease the incidence of fetal distress, cesarean delivery, meconium aspiration, or meconium aspiration syndrome. STUDY DESIGN One hundred seventy term and postterm patients with thick meconium and oligohydramnios were randomly chosen to receive amnioinfusion or standard obstetric care without amnioinfusion. The frequency of fetal distress, cesarean section, meconium aspiration, and meconium aspiration syndrome were subject to chi 2 analysis, Students t test, or Fishers exact test. RESULTS The rate of fetal distress was significantly reduced in the amnioinfusion group compared with controls (three of 85 vs 19 of 85, relative risk 0.15, 95% confidence interval 0.06 to 0.42). The rate of cesarean section for fetal distress was significantly reduced in the amnioinfusion group (two of 85 vs 17 of 85, relative risk 0.118, confidence interval 0.03 to 0.49). The rates of meconium aspiration (four of 85 vs 33 of 85, relative risk 0.12, confidence interval 0.0449 to 0.327) and meconium aspiration syndrome (0 of 85 vs five of 85, relative risk 0.09, confidence interval 0.009 to 0.872) were significantly reduced by amnioinfusion. CONCLUSIONS Amnioinfusion improves the outcome in pregnancies complicated by thick meconium and oligohydramnios.

Sonographic evaluation of amniotic fluid volume

Over the past 20 years, evaluation of amniotic fluid volume has evolved into a critical component of prenatal care and intrapartum management. Using progressively improving imaging techniques, the practice of amniotic fluid volume assessment has evolved from subjective observations of what appeared to be to too little or too much fluid to an experienced (or inexperienced) practitioner, to more sophisticated techniques for quantifying volume yielding surprisingly reproducible accuracy. As the acceptance and clinical use of various amniotic fluidmeasuring techniques has grown, progressively better correlations between fluid volume and fetal outcome have been obtained. While early work focused on using amniotic fluid volume estimates to predict the likelihood of adverse perinatal events such as fetal distress, meconium passage, and operative delivery, more recent studies have focused on correlating amniotic fluid volume estimates with underlying fetal abnormalities, including growth disturbances and anatomic malformations. Important spin-offs from improved amniotic fluid volume estimation include its inclusion in antepartum testing regimens as an indicator of fetal well-being, as well as the technique of amnioinfusion to improve labor outcome. In pregnancies complicated by oligohydramnios, transcervical and transabdominal amnioinfusion have been shown to be useful in reducing maternal and fetal morbidity during labor, and as a diagnostic tool. Although estimating amniotic fluid volume has become the standard of care in the management of high-risk pregnancies, there is still not universal agreement as to which method of measuring the fluid is most accurate or predictive of perinatal morbidity. The dramatic rise in multiple gestations and their associated problems has also raised the question of how best to quantitate fluid in separate sacs. The advent of threedimensional ultrasound and rapid MRI scanCorrespondence: David B. Schrimmer, MD, Division of Perinatal Medicine, Department of Reproductive Medicine, University of California San Diego, 200 W. Arbor Drive, Mail Code 8433, San Diego, CA 92103. E-mail: trmoore@ucsd.edu PROD. # GRF20401

Current practices in determining amnionicity and chorionicity in multiple gestations

To evaluate the accuracy of amnionicity and chorionicity (A/C) diagnosis of referral physicians and a tertiary care center as compared to histopathologic diagnosis.

The association of inadequate mid-pregnancy weight gain and preterm birth in twin pregnancies.

Objective:To determine whether inadequate gestational weight gain in the second trimester in twin pregnancies is associated with an increased risk of preterm birth (PTB) at <32 weeks.Study Design:Retrospective cohort study including 489 twin pregnancies delivered between 2001 and 2013. Rates of weight gain at different gestational ages were compared with Institute of Medicine guidelines.Result:An inadequate rate of weight gain at <20 weeks was not associated with PTB. Patients with inadequate rates of weight gain at 20 to 28 weeks had a higher risk of PTB at <32 weeks (37.6%) compared to those with adequate weight gain (15.2%) (P<0.001). In multivariate analysis, women with inadequate weight gain at 20 to 28 weeks were 2.8 times more likely to deliver at <32 weeks (95% confidence interval 1.65 to 4.81).Conclusion:Inadequate gestational weight gain at 20 to 28 weeks in twin pregnancies was the strongest predictor of PTB at <32 weeks. This represents an optimal time for interventions to improve weight gain and potentially decrease rates of PTB.

Monoamniotic twin pregnancy: continuous inpatient electronic fetal monitoring—an impossible goal?

OBJECTIVE We sought to determine the effectiveness of continuous fetal monitoring in monoamniotic twins and assess the percentage of successful monitoring across gestation. STUDY DESIGN This was a single-center retrospective cohort analysis of monoamniotic twins. Each subjects entire electronic fetal heart tracing was reviewed. The primary outcome measure was the percentage of time that 0, 1, and 2 fetuses were successfully monitored. To compare the effectiveness of monitoring across gestation, these data were stratified by gestational age (<27, 27-30, and >30 weeks). RESULTS A total of 10,402 hours of fetal monitoring were reviewed for 17 monoamniotic twin pairs. Successful monitoring of 0, 1, and 2 fetuses occurred 21.2%, 27.1%, and 51.6% of the time, respectively. Successful monitoring of both fetuses was positively correlated with gestational age (<27 weeks 37%; 27-30 weeks 51%; >30 weeks 57%; P < .007). CONCLUSION Successful monitoring of both fetuses occurred 51.6% of the time. Continuous monitoring efficiency improved with advancing gestational age.

Maternal and neonatal outcomes in women with twin pregnancies with excessive gestational weight gain

Abstract Objective: To determine if an excessive rate of gestational weight gain (GWG) in twin pregnancies is associated with adverse obstetric outcomes. Methods: Retrospective cohort study of twin pregnancies delivered at the University of California, San Diego 2001–2014. Women were included if they had adequate or excessive rates of GWG as determined by Institute of Medicine guidelines. Demographic and outcome variables were collected by chart review. Results: Four hundred and eighty-nine twin pregnancies met inclusion criteria. Of which, 40.5% had adequate rates of GWG and 41.5% had excessive rates of GWG. The rates of preterm birth and gestational diabetes were similar between the two groups. Gestational hypertension and preeclampsia were more common in women with excessive GWG (37.9% versus 19.7%; p < 0.01). This finding persisted in multivariate analysis. The mean birth weight percentiles were higher in the excessive GWG group and these women were also less likely to have an infant with a birth weight <10th percentile (21.4% versus 35.9%, p < 0.01). Conclusions: Excessive GWG is associated with a higher risk for gestational hypertension and preeclampsia, but no other adverse perinatal outcomes. Infants born to mothers with excessive GWG are less likely to be small for gestational age than those born to women with adequate GWG.

Monochorionic twins misclassified as dichorionic: Was there an empty tent?

To the Editor: A small (but not insignificant) percentage of twins have a sonographic misclassification of chorionicity, which is more likely to occur in direct proportion to the gestational age at diagnosis. This problem was well documented several years ago in a study by Wan et al1 and was again confirmed in a recent article by Blumenfeld et al,2 who found no apparent differences in other maternal or sonographic factors associated with misclassification of chorionicity. Thus, this critical clinical determination remains problematic. Dichorionic twins misclassified as monochorionic are less worrisome than the converse, since these dichorionic twins would be monitored more closely than otherwise. The main concern is for monochorionic twins that are assumed to be dichorionic. They would have less frequent monitoring; thus, the rapid onset of twin-twin transfusion syndrome or other adverse events may not be discovered until it is too late to intervene. The sonographic parameters used to determine chorionicity are well known. However, some, such as membrane thickness, are somewhat subjective and susceptible to imaging artifacts. Probably the most useful parameter is the “twin peak” sign, but this too may be misinterpreted. For example, in some cases of monochorionic placentation, the two adjacent amniotic membranes will separate and form a similarly shaped twin peak as they attach to the placenta. The only difference in this case is the absence of placental tissue within these tented amniotic membranes, thus forming an anechoic pseudo twin peak that looks like the opening of an empty tent (Figure 1). Such distinctions may not have been known by the sonographers whose chorionicity determinations were in error. It would be of great interest to review the images of those cases that were not properly classified. Although there were 545 twin cases in the study by Blumenfeld et al,2 only 17 of 90 monochorionic twins were misclassified as dichorionic. Did the authors make any attempt to contact the physicians at the centers where these 17 cases were seen and try to get access to the sonograms from the scans that were used to determine chorionicity? Sonogram availability may be limited, since the study was a secondary analysis based on data obtained from a previous study published in 2007.3 Nevertheless, many centers have electronically stored images on either CDs or hard drives going back many years. A review of those images, even if available on only a limited number of the 17 cases, may provide useful lessons for physicians and sonographers. It may not be too late or too onerous to try to obtain the sonographic reports and their associated images from at least some of the 17 cases.

OP19.06: How accurate are we in determining the placental cord insertion site in multiple gestations?

L. E. Romine1, M. Hwang5, N. Trivedi2, J. Wan4, Y. LaCoursiere2, P. Do4, K. Benirschke3, D. Schrimmer2, D. H. Pretorius1 1Radiology, University of California, San Diego, CA, USA; 2Reproductive Medicine, University of California, San Diego, CA, USA; 3Pathology, University of California, San Diego, CA, USA; 4School of Medicine, University of California, San Diego, CA, USA; 5School of Medicine, Vanderbilt University, Nashville, TN, USA