Hepatic arterial buffer response: activation in donor fetuses and the effect of laser ablation of intertwin anastomosis.

OBJECTIVES: Hepatic arterial buffer response (HABR) is an important defence mechanism for maintaining liver blood flow. It is suspected that HABR is active in monochorionic diamniotic twins (MCDA) with twin-to-twin transfusion syndrome (TTTS) where donor compensates a setting of volume depletion and the recipient an overload. The present study investigates whether in TTTS, HABR is active in donor and/or recipient individually and try to determine if the activation of HABR is a direct response to TTTS. METHODS: Hepatic artery (HA) peak systolic velocity (PSV) was measured in normal MCDA fetuses and TTTS. Correlation with relevant fetal Dopplers and characteristics were determined. Z-scores for HA-PSV (HAV-Z) were calculated and its association with TTTS in donors and recipients were determined as well as changes in HAV-Z after laser treatment. RESULTS: In this study 118 MCDA were included, 61.9 % normal and 38.1 % TTTS. Of the TTTS 22 required laser treatment. A total of 382 scans were performed in normal group and 155 in TTTS. Our data demonstrates that in donors HAV-Z was 2.4 Z-scores higher compared to normal fetuses (ß=2.429 95 % CI 1.887, 2.971; p<0.001) and after laser treatment HAV-Z reduced (ß=-1.829 95 % CI -2.593, -1.064; p<0.001). There was no significant difference between recipients and normal (ß=-0.092 95 % CI -0.633, 0.449; p=0.738). CONCLUSIONS: HABR is active in TTTS, promoting an increased hepatic blood flow in donors. The activation is direct response to TTTS as shown by the reduction in HAV-Z after laser. This finding provides important insights into the pathophysiology of TTTS.

Initial Experience of Superb Microvascular Imaging for Key Cardiac Views in Foetal Assessment before 15 Weeks Gestation.

BACKGROUND: In the first trimester, ultrasound confirmation of normal or abnormal cardiac anatomy is difficult. B-mode and colour flow Doppler (CFD) are used to assess the foetal heart. Superb microvascular imaging (SMI) can visualise blood flow within the heart and vessels in early gestation. OBJECTIVE: We report an initial experience of SMI for visualisation of normal and abnormal cardiac anatomy in the first trimester. METHODS: Transabdominal foetal echocardiography was performed between 11 + 6 and 14 + 3 weeks (Aplio 500 US system, Toshiba Medical Systems, Tokyo, Japan) from January 2017 to December 2017. All scans were performed at a tertiary foetal cardiology unit. To assess the potential utility of the technique for early gestation screening, normal scans were reviewed by foetal medicine trainees with respect to the B-mode, CFD and SMI. Three key views were selected to compare modalities: the 4-chamber view, outflow tracts and the 3-vessel and trachea view (VTV). Visualisation rates of key echocardiographic features of significant cardiac abnormalities by SMI were reviewed. RESULTS: Fifty-five normal echocardiograms and 34 cardiac abnormalities were included. In the normal heart, when B-mode, CFD and SMI were assessed separately, SMI had the highest rate of visualisation of 4-chamber, outflow tracts and 3-VTV (93, 85 and 83%, respectively). Intra-observer reliability was moderate for SMI of the 3 standard views (kappa 1, 0.64 and 0.64); inter-observer for 4-chamber and outflow tract views was moderate (kappa 0.64 and 0.77). In 29/34 abnormal cases, SMI showed key features, enhancing greyscale visualisation. CONCLUSION: SMI has potential to become a useful, complementary modality for early foetal echocardiography. Further prospective studies are warranted to establish the place of the technique in assessment of the first trimester foetal heart.

Maternal serum screening marker levels in women with a previous aneuploidy pregnancy.

OBJECTIVE: To re-evaluate in a larger cohort of patients if the maternal serum biochemical markers used in first trimester aneuploidy screening have the same marker distributions in pregnancies with a previous history of aneuploidy compared with those that have no previous history. METHODS: Information related to previous pregnancy history is routinely recorded as part of first trimester screening in three centres King George, Kings College and Fetal Medicine Centre, London. From the database, records were extracted for women who had a previous pregnancy diagnosed with trisomies 13, 18 or 21. For each woman with a previous aneuploidy, five unaffected pregnancies in women of the same maternal age and with no previous aneuploidy pregnancy were selected as controls. A comparison was made between the marker distributions for pregnancy associated plasma protein-A (PAPP-A) and free beta-human chronic gonadotrophin (beta-hCG) amongst the cases and controls using nonparametric statistical tests. RESULTS: A series of 8240 controls were compared against group of 1032 cases with a previous trisomy 21, 293 with a previous trisomy 18 and 158 with a previous trisomy 13. Cases with multiple previous trisomies were excluded. There were no significant differences in the level of free beta-hCG; however, in cases of trisomy 21 and trisomy 13 the levels of PAPP-A were increased by 5 and 16%, respectively. CONCLUSION: Risk calculation algorithms may need to take account of the increased PAPP-A levels in women with a previous trisomy 21 or trisomy 13.