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Abstracts Ursodeoxycholic acid improves feto-placental and offspring metabolic outcomes in intrahepatic cholestasis of pregnancy and in a mouse model of hypercholanaemic pregnancy Abstracts 740The correlation between epigenetic change and neonatal plasma glucose level in maternal gestational diabetes offspring

The accuracy of in-vivo detection of arterio-arterial anastomoses (AAA) in monochorionic (MC) twins and its predictive value for twin-twin transfusion syndrome (TTTS) was assessed in 105 consecutive MC twins scanned at fortnightly intervals. AAA were sought using spectral and colour energy Doppler and ultrasound findings were compared with placental injection studies. AAA were identified in vivo in 59 (56%) pregnancies and at injection study in 68 (65%). The overall sensitivity and specificity was 85 and 97.3% respectively for the detection of AAA. Detection rates were higher at later gestations, with anterior placentae and with larger diameter AAA. The median insonation time to detect an AAA was 10 min (range 1-30). Where an AAA was identified, 15% of pregnancies (nine of 59) developed TTTS compared to 61% (28 of 46) when no AAA was seen (odds ratio 8.6). We conclude that AAA can be detected in vivo with high sensitivity and specificity without undue prolongation of scanning times and have a role in risk stratification in the antenatal assessment of MC twins.

Objective To determine in vivo whether monochorionic pregnancies complicated by twin-to-twin transfusion syndrome are associated with absence of haemodynamically-compensatory arterioarterial anastomoses.Design Forty monochorionic pregnancies were prospectively recruited for an ultrasonographic survey of the chorionic plate using colour Doppler energy. Arterio-arterial anastomoses were identified by their characteristic bidirectional interference pattern on spectral Doppler. Angioarchitecture was confirmed by postnatal injection study.Setting Fetal medicine tertiary referral centre in London. Main Outcome MeasuresPresence of arterio-arterial anastomoses, development of twin-to-twin transfusion syndrome, survival.Results Arterio-arterial anastomoses were detected by colour Doppler energy in 2 1 pregnancies (53%), and there were no false positives. An arterio-arterial anastomosis was more commonly found in unaffected (n = 28) compared to pregnancies affected by twin-to-twin transfusion syndrome (n = 12), both by colour Doppler energy [20/28 (71%) vs 1/12 (8%); A = 63%, 95% CI 400/1A6%;,] and by postnatal injection study [25/28 (89?4) vs 3/12 (25%); A = 64%, 95% CI 37%-91%]. In pregnancies in which no arterio-arterial anastomoses were detected, a diagnosis of twin-to-twin transfusion syndrome was made in 58%, and the perinatal loss rate was 40%, compared with one case of twin-to-twin transfusion syndrome (5%) (P C 0.001) and a loss rate of 12% (P = 0.005) in pregnancies in which an arterio-arterial anastomosis was detected.Conclusion Twin-to-twin transfusion syndrome is associated with an absence of functional arterioarterial anastomoses in vivo in monochorionic twin pregnancies. This contributes to our understanding of the pathophysiology of twin-to-twin transfusion syndrome and confirms ex vivo studies demonstrating that twin-to-twin transfusion syndrome is associated with a paucity of superficial anastomoses. Prospective studies are indicated to determine the utility of colour Doppler energy for arterio-arterial anastomoses in predicting risk in monochorionic pregnancies.

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Polysaccharide-based microgels are effective vectors for biopharmaceutics delivery and functional components in tissue engineering due to their bioactivity and biocompatibility. Currently, the synthesis of chemically crosslinked microgels typically requires long reaction times, high energy input and are low yielding due to low volumes of water phase used. Herein, we report the synthesis of norbornene-derivatized chitosan (CS-nbn-COOH), which can undergo rapid gelation in the presence of a thiolated crosslinker through the highly efficient thiol-ene photoclick reaction. This water-soluble photocrosslinkable derivative, synthesized on scale via a single step