1. UOG Journal Club: February 2013
Impact of cord entanglement on perinatal outcomes of
monoamniotic twins: a systematic review of the literature
AC Rossi and F Prefumo
Volume 41, Issue 2, Date: February 2013, pages 131–135
Journal Club slides prepared by Dr Aly Youssef
(UOG Editor for Trainees)

2. • 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.

3. 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 literature
published in the last decade on perinatal outcomes
of monoamniotic pregnancies with documentation
of cord entanglement at birth

4. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Methods
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
Exclusion criteria
Inclusion criteria
• Studies which included monoamniotic 1) Higher-order multiple
twins with documented cord pregnancies, selective
entanglement at the time of delivery feticide, pregnancies complicated by twin
and perinatal outcomes reported as reversed arterial perfusion
proportional rates rather than graphs or sequence, conjoined twins and non-
percentages English language publications
2) Case reports and case series with <4
cases

5. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Perinatal outcomes consisted of:
1. Overall survival rates
2. 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.

6. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Results
78 potentially relevant studies concerning cord
entanglement in monoamniotic pregnancies
16 studies excluded based on title or abstract
62 articles retrieved for more detailed evaluation
40 studies excluded an inappropriate
22 articles potentially appropriate to be included in
the systematic review
13 studies not meeting the inclusion criteria
9 studies with relevant information included in the systematic
review. Final analysis included 114 monoamniotic
twin sets with cord entanglement (228 fetuses)

7. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Results: outcome of pregnancies with cord entanglement at birth and at
prenatal ultrasound
Cord entanglement Cord entanglement
at birth* at ultrasound
(9 articles, 114 pregnancies) (4 articles, 60 pregnancies)
Overall survival rate 202/228 105/120
n/fetuses (%) (88.6%) (88%)
No survivors 8/114 4/60
n/pregnancies (%) (7.0%) (7%)
Single survival 10/114 7/60
n/pregnancies (%) (8.8%) (12%)
Double survival 96/114 49/60
n/pregnancies (%) (84.2%) (81%)
*At least 1 survivor was present in 106/114 (93.0%) pregnancies cord entanglement at birth

8. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
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

9. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Perinatal outcome of pregnancies complicated by cord
entanglement vs controls
Neonatal morbidity
Controls showed a higher rate of neonatal morbidity

10. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Findings
• 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

11. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
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

12. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
Future perspectives
• 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.

13. Impact of cord entanglement on perinatal outcomes of monoamniotic twins: a
systematic review of the literature
Rossi and Prefumo, UOG 2013
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?