Placental Characteristics of Monoamniotic Twin Pregnancies in Relation to Perinatal Outcome

Department of Obstetrics, Wilhelmina Children's Hospital, and Department of Pathology, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands.
Placenta (Impact Factor: 2.71). 11/2008; 30(1):62-5. DOI: 10.1016/j.placenta.2008.09.016
Source: PubMed


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

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Available from: Enrico Lopriore, Apr 08, 2015
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    • "The significant proximity of umbilical cord insertions may be a representative of the later splitting of inner cell mass in MA twin gestations (around 8e12 days after fertilization) compared to MC diamniotic twin gestations (around 4e8 days after fertilization). The short distance between cord insertions in MA placentas is reported to be one of the main causal factors leading to the ubiquitous entanglement of umbilical cords [7] [18]. This study also compared the angio-architecture in MC twin placentas with and without PCI. "
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    ABSTRACT: Not much is known on the definition, occurrence and characteristics of proximate umbilical cord insertions (PCI) in monochorionic (MC) placentas. The purpose of this study was to establish a reference range for the distance between cord insertions and to evaluate the prevalence and angio-architecture of MC placentas with PCI. All MC placentas not treated with laser surgery were included in this study. The reference range of distance between cord insertions was created using the standard methodology proposed by Royston and Wright. We defined PCI as a cord insertion distance below the 5th centile. A total of 369 MC placentas were analyzed during this study period. The 5th centile was calculated by the equation: 0.027 × gestational age (weeks) +2.91 (cm), and ranged from 3.3 to 4 cm throughout gestation. Accordingly, 18 of the 369 (5%) MC placentas fulfilled the definition criteria for PCI. PCI occurred frequently in MC monoamniotic placentas (53%, 9/17) but were rare in MC diamniotic placentas (3%, 9/352). The prevalence of arterio-arterial and veno-venous anastomoses in MC placentas with and without PCI was respectively 100% versus 80% (P = .12) and 56% versus 26% (P = .01). PCI may be representative of later splitting of inner cell mass. The threshold for PCI (5th centile) is approximately 4 cm throughout gestation. PCI are rare in MC diamniotic placentas, but are quite common in MC monoamniotic placentas. MC placentas with PCI are characterized by higher rates of superficial AA and/or VV anastomoses. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Placenta 12/2014; 36(2). DOI:10.1016/j.placenta.2014.11.016 · 2.71 Impact Factor
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    • "Several studies have found that an unequal distribution of the placenta is a major reason for differences in birth weight and selective IUGR in monochoriotic twin pregnancies 43,86,87. This inequality could possibly be an effect of intertwin artery-to-artery anastomoses 88 (Fig. 1C). "
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    ABSTRACT: Early genetic and environmental factors have been discussed as potential causes for the high prevalence of asthma and allergic disease in the western world, and knowledge on fetal growth and its consequence on future health and disease development is emerging. This review article is an attempt to summarize research on fetal growth and risk of asthma and allergic disease. Current knowledge and novel findings will be reviewed and open research questions identified, to give basic scientists, immunologists and clinicians an overview of an emerging research field. PubMed-search on pre-defined terms and cross-references. Several studies have shown a correlation between low birth weight and/or gestational age and asthma and high birth weight and/or gestational age and atopy. The exact mechanism is not yet clear but both environmental and genetic factors seem to contribute to fetal growth. Some of these factors are confounders that can be adjusted for, and twin studies have been very helpful in this context. Suggested mechanisms behind fetal growth are often linked to the feto-maternal circulation, including the development of placenta and umbilical cord. However, the causal link between fetal growth restriction and subsequent asthma and allergic disease remains unexplained. New research regarding the catch-up growth following growth restriction has posited an alternative theory that diseases later on in life result from rapid catch-up growth rather than intrauterine growth restriction per se. Several studies have found a correlation between a rapid weight gain after birth and development of asthma or wheezing in childhood. Asthma and allergic disease are multifactorial. Several mechanisms seem to influence their development. Additional studies are needed before we fully understand the causal links between fetal growth and development of asthma and allergic diseases.
    Clinical & Experimental Allergy 10/2012; 42(10):1430-47. DOI:10.1111/j.1365-2222.2012.03997.x · 4.77 Impact Factor
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    • "Median inter cord distance was 4 cm (range: 0e20 cm) [7]. Hack et al. (2009) determine that small distance between the insertions of both umbilical cords is a quite usual finding in MA twin gestations , thus severe complications in MA twin gestations, TTTS and cords entanglement and/or knotting are not related to the inter cord distance [7]. A review by Fraser et al. (1997) reported nine cases of single forked umbilical cord in MA twins in which the predominant causes for fetal death were severe fetal malformations [6]. "
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    ABSTRACT: A 29-year-old healthy woman at 10 weeks gestation was suspected for monoamniotic twin pregnancy, thus referred for evaluation and treatment. Ultrasound examination confirmed intrauterine monoamniotic twin gestation with central insertion of both umbilical cords by brief conjoined part (9 mm) - comprising a forked umbilical cord. Early diagnosis, planned prenatal care and close surveillance allowed preventing perinatal mortality.
    Placenta 09/2011; 32(12):1057-9. DOI:10.1016/j.placenta.2011.09.008 · 2.71 Impact Factor
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