Monoamniotic twins: an update on antenatal diagnosis and treatment

Presence of an umbilical artery notch in monochorionic/monoamniotic twins

OBJECTIVE

To examine the association between an umbilical artery notch and fetal deterioration in monochorionic/monoamniotic (MC/MA) twins.

METHODS

Six MC/MA twin pregnancies were admitted at 24-28 weeks of gestation for close fetal surveillance until elective delivery at 32 weeks or earlier in the presence of signs of fetal deterioration. Ultrasound (US) examinations were performed twice weekly. The presence of cord entanglement, umbilical artery notch, abnormal Doppler parameters, a non-reassuring fetal heart rate pattern, or an abnormal fetal biophysical profile were evaluated.

RESULTS

Umbilical cord entanglement was observed on US in all pregnancies. The presence of an umbilical artery notch was noted in four out of six pregnancies and in two of them an umbilical artery notch was seen in both twins. The umbilical artery pulsatility index was normal in all fetuses. Doppler parameters of the middle cerebral artery and ductus venosus, fetal biophysical profile and fetal heart rate monitoring remained normal until delivery in all pregnancies. All neonates experienced morbidity related to prematurity; however, all were discharged home in good condition.

CONCLUSION

The presence of an umbilical artery notch and cord entanglement, without other signs of fetal deterioration, are not indicative of an adverse perinatal outcome.

Amniotic fluid as a vital sign for fetal wellbeing

Introduction: Amniotic fluid, once thought to merely provide protection and room for necessary movement and growth for the fetus, is now understood to be a highly complex and dynamic system that is studied as a data point to interpret fetal wellbeing. Methods: Assessment of amniotic fluid volume is now routine when performing a sonographic evaluation of fetal status and is an important consideration in the assessment and management of perinatal morbidity and mortality.1,2 In this review, we will cover the dynamics that affect amniotic fluid volume, review methods for measurement and quantification of volume, review definitions for normative data as related to neonatal outcomes, and provide evidence based guidance on the workup and management options for oligoydramnios and polyhydramnios in singleton and twin pregnancies. Conclusions: When abnormalities of fluid exist, appropriate workup to uncover the underlying etiology should be initiated as adverse fetal outcomes are sometimes associated with these variations from normalcy.

A rare case of antepartum spontaneous septostomy in a monochorionic diamniotic twin pregnancy

Spontaneous septostomy in a monochorionic diamniotic twin pregnancy is a rare phenomenon. We present a case of monochorionic diamniotic twin pregnancy with an intact dividing membrane seen in the 1st half of the pregnancy. At 26 weeks, when she was assessed for preterm contractions, the dividing membrane was not documented, which suggested spontaneous septostomy. There had been no invasive procedures during the pregnancy. She subsequently delivered at 29 weeks, secondary to preterm labor. No dividing membrane was noticed at the time of caesarian section. Spontaneous septostomy can complicate the management of monochorionic diamniotic twins by creating a pseudomonoamniotic environment resulting in cord entanglement, and difficulty in the diagnosis and management of twin-twin transfusion syndrome. We believe that such a case should be managed as monochorionic monoamniotic twin gestation.

Ultrasound to Identify Cord Knotting in Monoamniotic Monochorionic Twins

This case report demonstrates the use of ultrasound and doppler flow in the management of mono-amniotic monochorionic (M/M) twins. M/M twinning is a rare but significant event. It is associated with high rates of fetal mortality, most commonly cited at anywhere from between 30% and 70%. A common cause of death is cord entanglement. The case presented is that of a 19-year-old gravida 1 at 30 weeks with M/M twins in which multiple cord knots were found by ultrasound color doppler flow after variable fetal heart rate decelerations occurred. This prompted a decision for immediate cesarean delivery with normal fetal outcomes. Improvements in perinatal imaging systems are therefore beneficial in the management of M/M twins.