Monochorionic Twins: A Delicate Balance

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 (β=2.429 95 % CI 1.887, 2.971; p<0.001) and after laser treatment HAV-Z reduced (β=-1.829 95 % CI -2.593, -1.064; p<0.001). There was no significant difference between recipients and normal (β=-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.

Chorionicity and neurodevelopmental outcomes in twin pregnancy: a systematic review and meta-analysis

OBJECTIVE

Through a systematic review and meta-analyses, we aimed to analyze the impact of chorionicity on neurodevelopment outcomes.

STUDY DESIGN

We conducted a comprehensive search strategy through Medline, Embase, Web of Science, and reference lists of the retrieved studies until August 2022. Studies that examined the association between chorionicity and children's neurodevelopment outcomes were included.

RESULTS

Twelve studies were included. Monochorionic (MC) twins increased the odds of neurodevelopment impairment, cerebral palsy compared to dichorionic (DC) twins. The differences in neurodevelopmental impairment and cerebral palsy between the two groups disappeared after excluding infants with twin-twin transfusion (TTTS). After fetoscopic laser surgery (FLS) for MC twins, there were no differences too.

CONCLUSIONS

Compared to DC twins, MC twins were associated with an increased risk of neurodevelopment impairment. MC twins complicated by TTTS were at high risk of neurologic disability, and FLS was an acceptable treatment modality for them.

Hepatic arterial buffer response in monochorionic diamniotic pregnancies with twin-to-twin transfusion syndrome

OBJECTIVES

Hepatic arterial buffer response (HABR) is an important regulatory process for hepatic blood flow. Its activity has been described in some fetal adverse conditions but in twin-to-twin transfusion syndrome (TTTS) it is unknown if such response is present. The aim of this study is to test the hypothesis that HABR operates in monochorionic diamniotic twins (MCDA) with TTTS.

METHODS

Hepatic artery pulsatility index (PI) and peak systolic velocity (PSV) were measured prospectively in 64 MCDA pregnancies. 43 without TTTS (group 1) and in 21 pregnancies with TTTS (group 2). We calculated ratios for PI (HAPI-ratio) and PSV (HAV-ratio) between recipient and donor in group 2 or bigger and smaller fetus in group 1 and compared groups. The association of HAV-ratio and HAPI ratio with TTTS, relation with other fetal Dopplers and reliability of measurement by a single operator were investigated.

RESULTS

HAV-ratio and HAPI-ratio appears to be independent from fetal Dopplers, estimated weight and gestational age. In group 2, HAV-ratio is lower than group 1 (p<0.001, 95% CI 0.443-0.643). In group 1 the mean HAV-ratio is 1.014 (±0.021) while in group 2 is 0.47 (±0.035). HAPI-ratio is lower in group 2 than in group 1 although this difference was not significant (p=0.066, 95% CI -0.007-0.231). A good reliability of measurements of hepatic artery PSV and PI was demonstrated by intraclass correlation coefficient analysis (ICC 0.971 95% CI 0.963-0.977, p<0.001 and ICC 0.694 95% CI 0.596-0.772, p<0.001, respectively).

CONCLUSIONS

Monochorionic pregnancies with TTTS are associated with lower HAV-ratios. This could be explained by an active HABR.

Video-feedback promotes sensitive limit-setting in parents of twin preschoolers: a randomized controlled trial

BACKGROUND

Primary aim of the current randomized controlled trial was to test the effectiveness of the parenting intervention 'Video-feedback to promote Positive Parenting and Sensitive Discipline' (VIPP-SD) in a sample of parents of preschool-aged twins, as well as differential susceptibility to intervention efforts, that is, whether more temperamentally reactive parents would profit more from the VIPP-SD than parents with lower reactivity.

METHODS

The sample consisted of 202 families with same-sex twins [N = 404 children, mean age 45 months (SD = 6.81)]. Randomization was done at the family level in a 2:3 ratio, with 83 families (41%) randomized to the VIPP-SD group, and 119 families (59%) to the control group. After two pre-tests in year 1 and year 2 of the study, the VIPP-SD was implemented in the third year, with a post-test assessment 1 month after the five intervention sessions. Parental sensitivity was observed during structured play in which parent and child copied a drawing together in a computerized Etch-A-Sketch paradigm. Parental limit-setting was observed in a 'don't touch' task in which the parent required from the child to abstain from playing with attractive toys. Parents interacted with each of their twins in separate sessions.

RESULTS

The VIPP-SD intervention had a positive impact on the level of parents' positive limit-setting in interaction with their preschool twins, and this positive effect was most pronounced when the parents completed at least five intervention sessions. However, the intervention did not enhance parental sensitivity during structured play. Parents with higher reactivity were not more open to the impact of the intervention, thus for this temperamental marker differential susceptibility in adults was not supported.

CONCLUSIONS

The current study is unique in targeting families with twin preschoolers, providing proof of principle that coaching parents with video-feedback promotes parental sensitive limit-setting to both children. It remains to be seen whether this finding can be replicated in families with non-twin siblings, or other parental susceptibility markers. Trial registration Trial NL5172 (NTR5312), 2015-07-20.

Review of International Clinical Guidelines Related to Prenatal Screening during Monochorionic Pregnancies

We conducted a search for international clinical guidelines related to prenatal screening during monochorionic pregnancies. We found 25 resources from 13 countries/regions and extracted information related to general screening as well as screening related to specific monochorionic complications, including twin-twin transfusion syndrome (TTTS), selective fetal growth restriction (SFGR), and twin anemia-polycythemia sequence (TAPS). Findings reveal universal recommendation for the early establishment of chorionicity. Near-universal recommendation was found for bi-weekly ultrasounds beginning around gestational week 16; routine TTTS and SFGR surveillance comprised of regularly assessing fetal growth, amniotic fluids, and bladder visibility; and fetal anatomical scanning between gestational weeks 18-22. Conflicting recommendation was found for nuchal translucency screening; second-trimester scanning for cervical length; routine TAPS screening; and routine umbilical artery, umbilical vein, and ductus venosus assessment. We conclude that across international agencies and organizations, clinical guidelines related to monochorionic prenatal screening vary considerably. This discord raises concerns related to equitable access to evidence-based monochorionic prenatal care; the ability to create reliable international datasets to help improve the quality of monochorionic research; and the promotion of patient safety and best monochorionic outcomes. Patients globally may benefit from the coming together of international bodies to develop inclusive universal monochorionic prenatal screening standards.