UOG Journal Club: Impact of cord entanglement on perinatal outcome of monoamniotic twins

UOG Journal Club: February 2013Impact of cord entanglement on perinatal outcomes of

monoamniotic twins: a systematic review of the literature

AC Rossi and F PrefumoVolume 41, Issue 2, Date: February 2013, pages 131–135

Journal Club slides prepared by Dr Aly Youssef(UOG Editor for Trainees)

• Monoamniotic pregnancies represent about 1% of cases of monozygotic twins

• Monoamniotic twins are at high risk of fetal death and neonatal morbidity, secondary to congenital anomalies, premature birth and also presumably to umbilical cord entanglement

• Cord entanglement is an almost universal finding at delivery in monoamniotic twins (Dias et al. 2010). However, a relatively recent review including literature from as early as 1990s showed that this was only documented on scan in 22% of cases (Roque et al. 2003)

• Because of advances in obstetric ultrasound resolution, it is likely that prenatal diagnosis of cord entanglement has improved significantly over the last decade

Dias T et al. Ultrasound Obstet Gynecol. 2010;35:201-4. Roque F et al. J Matern Fetal Neonatal Med 2003;13:414-21.

Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a systematic review of the literature

Rossi and Prefumo, UOG 2013

The aim of this meta-analysis was to review the literaturepublished in the last decade on perinatal outcomesof monoamniotic pregnancies with documentation

of cord entanglement at birth

Search of the literature between January 2000 and December 2011 for relevant articles that described perinatal outcomes of

monoamniotic twin pregnancies complicated by cord entanglement



Inclusion criteria

• Studies which included monoamniotic twins with documented cord entanglement at the time of delivery and perinatal outcomes reported as proportional rates rather than graphs or percentages

Exclusion criteria

1) Higher-order multiple pregnancies, selective feticide, pregnancies complicated by twin reversed arterial perfusion sequence, conjoined twins and non-English language publications

2) Case reports and case series with <4 cases

Methods



Perinatal outcomes consisted of:1. Overall survival rates2. Number of surviving twins for each pregnancy,3. Intrauterine demise 4. Neonatal mortality and morbidity*

*Neonatal morbidity was defined as at least one of the following: an Apgar score <7 at 5 min, respiratory distress syndrome, admission to the NICU, congenital heart block, necrotizing enterocolitis and neurological impairment.

Results78 potentially relevant studies concerning cord

entanglement in monoamniotic pregnancies

62 articles retrieved for more detailed evaluation

16 studies excluded based on title or abstract

13 studies not meeting the inclusion criteria



22 articles potentially appropriate to be included in the systematic review

9 studies with relevant information included in the systematic review. Final analysis included 114 monoamniotic

twin sets with cord entanglement (228 fetuses)

40 studies excluded an inappropriate



Cord entanglement at birth*

(9 articles, 114 pregnancies)

Cord entanglement at ultrasound

(4 articles, 60 pregnancies)

Overall survival raten/fetuses (%)

202/228(88.6%)

105/120(88%)

No survivorsn/pregnancies (%)

8/114(7.0%)

4/60(7%)

Single survivaln/pregnancies (%)

10/114(8.8%)

7/60(12%)

Double survivaln/pregnancies (%)

96/114(84.2%)

49/60(81%)

Results: outcome of pregnancies with cord entanglement at birth and at prenatal ultrasound

*At least 1 survivor was present in 106/114 (93.0%) pregnancies cord entanglement at birth



Perinatal outcome of pregnancies complicated by cord entanglement vs controls

Overall survival rate

No significant difference in overall survival rate was observed between pregnancies with and without cord entanglement at birth



Perinatal outcome of pregnancies complicated by cord entanglement vs controls

Neonatal morbidity

Controls showed a higher rate of neonatal morbidity



• Cord entanglement appears to be a minor complication of monoamniotic twin pregnancies

• This review confirms that both neonatal morbidity and mortality of monoamniotic pregnancies do not depend on the presence of cord entanglement. Other factors, such as TTTS, prematurity and congenital anomalies are the main contributers to poor outcome

• Prenatal management of monoamniotic pregnancies should focus on

the detection of sonographic signs of TTTS, structural anomalies or risk of preterm birth, rather than the presence of cord entanglement

Findings



Limitations

• Most of the reviewed articles did not provide specific data on Doppler findings, therefore the authors could not comment on whether they were associated with neonatal morbidity and mortality

• Pooled data did not provide sufficient information on the benefit of

inpatient vs outpatient prenatal management of women with prenatal diagnosis of cord entanglement

• The present review did not have sufficient power to demonstrate the effect of any particular antenatal management protocol on pregnancy outcome

• Further studies are needed to investigate whether elective delivery at a specific gestational age is effective in improving perinatal outcome in pregnancies with prenatal diagnosis of cord entanglement

• Ideally, such studies should be randomized controlled trials of monoamniotic pregnancies free of other complications. However, the rarity of monoamniotic pregnancy may preclude their completion.



Future perspectives



Discussion points

• How frequently should monoamniotic (MA) pregnancies be monitored and from which gestational age?

• Should MA pregnancies have inpatient or outpatient monitoring?

• Should cord entanglement be routinely searched for in MA pregnancies?

• At what gestational age should women with MA pregnancies with and without prenatal diagnosis of cord entanglement be delivered?

• Are there any specific Doppler findings associated with umbilical vessels narrowing due to cord entanglement?

Health & Medicine

UOG Journal Club: Impact of cord entanglement on perinatal outcome of monoamniotic twins