Twin-twin transfusion syndrome and the definition of recipient polyhydramnios

BACKGROUND: Controversy exists regarding the threshold of recipient twin polyhydramnios required to diagnose twin-twin transfusion syndrome at a gestational age of >= 20 weeks. One criterion set (Quintero staging) requires the amniotic fluid maximum vertical pocket for the recipient twin to measure >= 8 cm, whereas another (European) system uses a maximum vertical pocket for the recipient twin of >= 10 cm. OBJECTIVE: This study aimed to characterize the patients with twintwin transfusion syndrome who were treated with laser surgery and would be excluded from laser surgery according to the European criteria. STUDY DESIGN: A total of 366 monochorionic diamniotic twins diagnosed with twin-twin transfusion syndrome from 20 to 26 weeks' gestation who underwent laser surgery at our center were studied. A maximum vertical pocket for the recipient twin of >= 8 cm was used to diagnose twin-twin transfusion syndrome. Patients were retrospectively divided into the following 2 groups: group A with a maximum vertical pocket for the recipient twin of >= 8 cm and <10 cm and group B with a maximum vertical pocket for the recipient twin of >= 10 cm. The association of each of the groups with the survivorship outcomes was tested. Bivariate associations between the patient characteristics and the 30-day donor twin and dual survivorship outcomes were evaluated. Tests used in the analysis were chi-square or Fisher exact tests as appropriate for categorical variables and Kruskal-Wallis tests for continuous variables. Multiple logistic regression models for each of the survivorship outcomes were then assessed. The results are reported as mean +/- standard deviation. RESULTS: Of the 366 studied patients, 53 (14.5%) had a maximum vertical pocket for the recipient twin of >= 8 and <10 cm (group A) and 313 (85.5%) had a maximum vertical pocket for the recipient twin of >= 10 cm (group B). Groups A and B did not differ in the Quintero stage. Notably, 60.4% (32 of 53) of group A patients were stage III or IV. When compared with group B, group A was diagnosed with twin-twin transfusion syndrome at an earlier gestational age (21.7 +/-.6 vs 22.3 +/- 1.6 weeks; P=.0037) and had a higher prevalence of donor growth restriction (81.1% [43 of 53] vs 65.5% [205 of 313]; P=.0260). Rates of at least 1 twin and dual twin survival between group A and B were similar (98.1% [52 of 53] vs 95.8% [300 of 313]; P=.7023, and 79.2% [42 of 53] vs 83.4% [261 of 313]; P=.4369, respectively). Logistic regression models adjusted for perioperative characteristics showed no difference in the outcomes between the groups (group B as reference) (donor twin survival odds ratio, 0.64; 95% confidence interval, 0.29-1.42; P=.2753; and dual survivor odds ratio, 0.90; 95% confidence interval, 0.42-1.91; P=.7757). CONCLUSION: Restriction of the definition of twin-twin transfusion syndrome to a maximum vertical pocket for the recipient of >= 10 cm beyond 20 weeks gestational age would potentially exclude 14.5% of patients from laser surgery, the majority of whom had advanced stage twin-twin transfusion syndrome. A unifying criterion of a maximum vertical pocket for the recipient of >= 8 cm regardless of gestational age would allow inclusion of these patients and access to surgical management.

Automated summary

This study aimed to characterize patients with twin-twin transfusion syndrome who would be excluded from laser surgery according to European criteria. The results showed that restricting the definition of twin-twin transfusion syndrome to a maximum vertical pocket for the recipient of >= 10 cm may potentially exclude 14.5% of patients from laser surgery, majority of whom had advanced stage of twin-twin transfusion syndrome.