Diffuse brain damage caused by acute twin-twin transfusion during late pregnancy

Ultrasound Imaging of Fetal Brain Abnormalities

Prenatal ultrasound evaluation of the fetal brain requires documentation of specific structures according to guidelines set by the American College of Radiology and the American Institute of Ultrasound in Medicine. Among these required structures are: cerebellum, cisterna magna, lateral cerebral ventricles, choroid plexus, midline falx, and cavum septum pellucidum. All these structures can be visualized in three crucial planes of imaging that include cisterna magna/cerebellum, cavum septum pellucidum, and ventricular atria. A systematic approach can be achieved by instituting a protocol that includes these three basic levels of imaging of the fetal head. These anatomical levels should be incorporated in daily routine for complete obstetric ultrasound evaluation.

Management of Multiple Pregnancy

Over the past 20 years, the number and rate of multiple births have dramatically increased in the United States. The rise in multiple births is mainly attributable to the increased use of ovulation-inducing drugs and the newly developed assisted reproductive technologies such as in vitro fertilization. Multifetal gestation is associated with an increased risk of perinatal morbidity and mortality. Multiple births account for an increasing percentage of low-birth-weight infants, preterm births, and infant mortality. In this article, the unique complications of multiple gestation and their management are reviewed. Also, selective termination and multifetal reduction in multiple gestation are discussed.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe the effects of the rising rate of multiple pregnancies on perinatal morbidity and mortality, to recall the complications of diagnosing and treating abnormalities of multiple pregnancies, to list the multiple severe complications associated with multiple gestations, and to describe the difficulty in managing these complications.

Perinatal outcomes in monoamniotic gestations

OBJECTIVE

A comprehensive review of monoamniotic twin gestations reported between 1990 and 2002 was performed to estimate current perinatal mortality and morbidity rates, as well as the predictive value of an antenatal diagnosis of cord entanglement for poor obstetric outcomes.

METHOD

A Medline literature review using the search term 'monoamniotic' and limited to articles published in the English language between 1990 and 2002 was performed.

RESULTS

A total of 133 continuing, non-conjoined twin monoamniotic pregnancies with delivery information were identified. Perinatal loss per 2-week interval was relatively constant at 2-4% from 15 to 32 weeks. However, of the 131 fetuses reaching 33 weeks, the percentage loss significantly increased to 11.0% at 33-35 weeks and 21.9% at 36-38 weeks compared to that at 30-32 weeks. Overall perinatal mortality was 23.3%. Of all losses, 61.2% involved both twins and 38.8% involved only one fetus. Cord entanglements were documented antenatally in 22.6% of reports. There was a statistically significant decrease in the average number of neonatal intensive care unit days for non-anomalous neonates (10.6 +/- 7.7 vs. 32.6 +/- 32.0), average gestational age at the time of delivery (30.4 +/- 7.6 vs. 32.6 +/- 4.1), as well as a decrease in the prevalence of total (8.3% vs. 27.7%) and non-anomalous (7.0% vs. 21.6%) perinatal mortality in pregnancies with an antenatal diagnosis of cord entanglement compared to those without the antenatal diagnosis of cord entanglement. The presence of fetal anomalies was associated with a 42.9% perinatal mortality rate.

CONCLUSIONS

Contrary to previous reports, there is a significant increase in the incidence of perinatal loss beyond 32 weeks among monoamniotic twins, suggesting that delivery after corticosteroid therapy should be strongly considered at this gestational age.

Monoamniotic twins: diagnosis and management

Monoamniotic twins, although uncommon, are associated with high antenatal and perinatal morbidity and mortality. The associated complications include cord entanglement, congenital anomalies, twin-twin transfusion syndrome, intrauterine growth retardation and preterm delivery. A thorough literature search using Medline and OVID was performed to look at the current diagnostic criteria for monoamniotic twins and the subsequent management. Specific criteria are employed during ultrasonography for making the diagnosis. Different opinions in the literature exist regarding the proper antepartum monitoring of monoamniotic twins, the optimal timing and the mode of delivery. Generally, it is agreed that there should be regular antepartum fetal heart trace monitoring and serial sonograms with umbilical artery Doppler flow study. Most studies advocate delivery at 32 weeks to reduce the risk of intrauterine deaths related to cord entanglement. Cesarean section is the preferred mode of delivery even though cases of successful vaginal delivery have been reported.

Management of monoamniotic twin pregnancies: a case series and systematic review of the literature

OBJECTIVES

To review the experience of the University of Toronto Perinatal Complex, Ontario, Canada concerning antenatally diagnosed monoamniotic twin pregnancies; and to compare our results with cases reported in the literature with respect to antenatal surveillance and perinatal outcome.

METHODS

A retrospective chart review of all twin gestations from 1993 to April 2000 was performed. A systematic review of the literature, 1966 to April 2000, of perinatal outcome in monoamniotic twin pregnancies was undertaken.

SETTING

All monoamniotic twin gestations at the University of Toronto.

RESULTS

Case-series: 25 prenatally diagnosed monoamniotic twin pregnancies were identified. Seven pregnancies were affected by fetal anomalies. One fetus died at 29 weeks. Neonatal complications occurred below 33 weeks of gestational age and were related to immaturity. Systematic review of the literature: 49 studies met our selection criteria and reported 88 cases diagnosed antenatally. Fourteen pregnancies were affected by major congenital anomalies. Twenty fetuses died after 24 weeks of gestation. Neonatal complications varied widely in severity and depended on gestational age at birth. The risk of intrauterine fetal death was 10% at the University of Toronto and 12% in the review of the literature.

DISCUSSION

Our experience, the largest so far, suggests that regular fetal surveillance and appropriate steroid administration leads to a good perinatal outcome. The risk of fetal death (10%-12%) is lower than the previously quoted risk of 30%-70%. A careful review of obstetric interventions and further work examining outpatient surveillance of monoamniotic twin pregnancies are needed. The best treatment of monoamniotic twin pregnancies can only be determined by randomised trials.