Placental Characteristics of Monoamniotic Twin Pregnancies in Relation to Perinatal Outcome

Hack, K.E.A.; van Gemert, M.J.C.; Lopriore, E.; Schaap, A.H.P.; Eggink, A.J.; Elias, S.G.; van den Wijngaard, J.P.H.M.; Vandenbussche, F.P.H.A.; Derks, J.B.; Visser, G.H.A.; Nikkels, P.G.J.

doi:10.1016/j.placenta.2008.09.016

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Volume 30, Issue 1 , Pages 62-65, January 2009

Placental Characteristics of Monoamniotic Twin Pregnancies in Relation to Perinatal Outcome

K.E.A. Hack
- Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Corresponding author. Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, K.E.04.123.1, P.O. Box 85090, 3508 AB Utrecht, The Netherlands. Tel.: +31 30 2506426; fax: +31 30 2505320.
M.J.C. van Gemert
- Laser Center, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
E. Lopriore
- Department of Neonatology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
A.H.P. Schaap
- Department of Obstetrics, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
A.J. Eggink
- Department of Obstetrics, Radboud University Nijmegen Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
S.G. Elias
- Julius Center for Health Sciences and Primary Care, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
J.P.H.M. van den Wijngaard
- Laser Center, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
F.P.H.A. Vandenbussche
- Department of Obstetrics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
J.B. Derks
- Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
G.H.A. Visser
- Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
P.G.J. Nikkels
- Department of Pathology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands

Accepted 29 September 2008. published online 17 November 2008.

Abstract

Objective

To study placental characteristics in relation to perinatal outcome in 55 pairs of monochorionic monoamniotic (MA) twins.

Methods

Between January 1998 and May 2008 55 pairs of MA twins were delivered in 4 tertiary care centers and analysed for mortality, birth weight discordancy and twin-to-twin transfusion syndrome (TTTS) in relation to type of anastomoses, type and distance between cord insertions and placental sharing. Five acardiac twins, 2 conjoined twins, 4 higher order multiples and one early termination of pregnancy were excluded, leaving 43 MA placentas for analysis. Of these 43, one placenta could not be analysed for placental vascular anastomoses due to severe maceration after single intra-uterine demise leaving 42 placentas for analysis of anastomoses.

Results

Arterio-arterial (AA), venovenous (VV) and arteriovenous (AV) anastomoses were detected in 98%, 43% and 91% of MA placentas, respectively. Velamentous cord insertion was found in 4% of cases. Small distance between both umbilical cord insertions (<5 cm) was present in 53% of MA placentas. Overall perinatal loss rate was 22% (19/86). We found no association between mortality and type of anastomoses, type and distance between cord insertions and placental sharing. The incidence of TTTS was low (2%) and occurred in the only pregnancy with absent AA-anastomoses.

Conclusion

Perinatal mortality in MA twins was not related to placental vascular anatomy. The almost ubiquitous presence of compensating AA-anastomoses in MA placentas appears to prevent occurrence of TTTS.

Keywords: Monoamniotic twins, Perinatal mortality, Outcome, Vascular anastomoses, Umbilical cord insertion, Placental sharing, TTTS