Neurodevelopmental Outcomes After Laser Therapy for Twin–Twin Transfusion Syndrome: A Systematic Review and Meta-Analysis

Perioperative characteristics associated with preterm birth in twin-twin transfusion syndrome treated by laser surgery

OBJECTIVE

To identify perioperative risk factors for preterm delivery (PTD) in laser-treated patients with twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

Twin-twin transfusion syndrome patients who underwent laser surgery were followed prospectively. Univariate and multivariate analyses were performed to identify gestational and surgical characteristics associated with preterm delivery.

RESULTS

Of 318 eligible patients, the mean (SD) gestational age of delivery was 32.8 (4.2) weeks. The number of days from laser surgery to delivery had a bimodal distribution; group I delivered within 21 days and group II delivered after 21 days of surgery. Eighteen patients (5.7%) were in group I and demonstrated the following risk factors for delivery within 21 days: incomplete laser surgery suspected (odds ratio [OR], 11.14; P = .0106), preoperative subchorionic hematoma (OR, 7.92, P = .0361), preoperative cervical length <2.0 cm (OR, 4.71; P = .0117), and recipient's maximum vertical pocket ≥14 cm (OR, 3.23; P = .0335). In group II, 92 of 300 patients (30.7%) delivered <32 weeks, and 25 (8.3%) delivered <28 weeks; multivariate logistic regression analyses identified 5 risk factors for delivery <32 weeks: incomplete laser surgery suspected (OR, 10.0; P = .0506); incidental septostomy (OR, 4.4; P = .0009); triplet gestation (OR, 2.6; P = .0689); postoperative membrane detachment (OR, 2.4; P = .0393); and nonposterior placental location (OR, 1.8; P = .0282).

CONCLUSION

Timing of delivery after laser for twin-twin transfusion syndrome has a bimodal distribution with distinct gestational and surgical risk factors. This information may be useful in counseling patients and in directing future avenues of research.

Global gene expression analysis of amniotic fluid cell-free RNA from recipient twins with twin-twin transfusion syndrome

OBJECTIVE

The objective of this study was to understand the biological pathways involved in twin-twin transfusion syndrome (TTTS) by performing global gene expression analysis of amniotic fluid (AF) cell-free RNA.

METHODS

A prospective whole transcriptome microarray study analyzing cell-free RNA in AF from TTTS recipient twins and singleton controls was carried out. Significantly differentially regulated genes in TTTS cases (N = 8) versus matched controls (N = 8) were identified and pathways analyses performed. Significant gene expression differences between stage II TTTS recipients (N = 5) and stage III TTTS recipients with abnormal Doppler measurements (N = 5) were also analyzed.

RESULTS

Analysis of paired data from TTTS cases and controls revealed differential expression of 801 genes, which were significantly enriched for neurological disease and cardiovascular system pathways. We also identified cardiovascular genes and pathways associated with the presence of critically abnormal Doppler measurements in stage III TTTS recipients.

CONCLUSIONS

This study provides the first transcriptome-wide data on the impact of TTTS on fetal development. Our results show that gene expression involving neurological and cardiovascular pathways are altered in recipient fetuses prior to surgical treatment. This has relevance for the origins of long-term complications seen in survivors and for the development of future fetal biomarkers.

The vascular anastomoses in monochorionic twin pregnancies and their clinical consequences

Monochorionic twin pregnancies are at increased risk of adverse outcome because of the vascular anastomoses that connect the 2 fetal circulation systems. The shared circulation is responsible for some unique complications in monochorionic twins, such as the twin-to-twin transfusion syndrome, the twin anemia polycythemia sequence, the twin reversed arterial perfusion sequence, and monoamniotic twinning. Another consequence of the shared circulation is that the well-being of one twin critically depends on that of the other. In this review, we will describe the technique of placental injection. Further, we will discuss the role of the vascular anastomoses in each of the complications described above and provide an update on their management.

Prevalence and risk factors of cerebral lesions in neonates after laser surgery for twin-twin transfusion syndrome

OBJECTIVE

To identify risk factors for cerebral lesions among survivors of twin-twin transfusion syndrome treated with laser surgery.

STUDY DESIGN

A multilevel regression analysis examined risk factors for neonatal cerebral lesions identified by imaging. Imaging was routine in "high-risk survivors," defined as those delivered at <32 weeks' gestation, and by clinical indications if born later. Severe lesions were defined as: intraventricular hemorrhage grade III-IV, cystic periventricular leukomalacia, ventriculomegaly and/or hydrocephalus, microcephaly, infarctions, porencephalic/Dandy-Walker cysts, or bilateral other cysts.

RESULTS

For 262 consecutive laser-treated twin-twin transfusion syndrome patients, 18 neonates had severe lesions identified among 427 individual survivors (4.2%) and 242 "high-risk survivors" (7.4%). Forty-six newborns had any cerebral lesion, resulting in lesion rates of 10.8%-19.0%. Delivery <32 weeks' (odds ratio, 4.95; P < .001) and <28 weeks' (odds ratio, 6.25; P < .001) gestation were associated with increased likelihood of any cerebral lesion.

CONCLUSION

This cohort showed low rates (4-7%) of severe neonatal cerebral lesions, with prematurity being the primary risk factor.

Timing of delivery following selective laser photocoagulation for twin-to-twin transfusion syndrome

OBJECTIVE

We sought to compare intrauterine risks with postnatal outcome in monochorionic pregnancies operated by fetoscopic laser surgery for twin-to-twin transfusion syndrome.

STUDY DESIGN

A cohort of 602 consecutive cases was analyzed. Unexpected prenatal adverse events were identified when a fatal or potentially fatal event occurred that could have been avoided by timely delivery.

RESULTS

The prospective risk of an unexpected adverse event dropped from 16.8% (95% confidence interval [CI], 13.6-20.5%) to 0% (95% CI, 0-11%) between 26-36 weeks. At 32 weeks, the residual risk was 1 in 17 (95% CI, 1/28-1/11). The perinatal rate of death or severe brain lesions dropped from 35% (25-47%) in infants delivered at 26-28 weeks down to 3% (1-6%) at 34-36 weeks.

CONCLUSION

Our results did not identify an optimal cut-off for elective preterm delivery in laser-operated twin-to-twin transfusion syndrome. Perinatal morbidity appears low from ≥32 weeks and the decision for elective delivery should be based upon medical history, parental demand, and expert assessment.