Doppler for artery-artery anastomosis and stage-independent survival in twin-twin transfusion.

OBJECTIVE: Treatment selection in twin-twin transfusion syndrome is increasingly determined by disease severity. We investigated whether detection of arterio-arterial anastomoses predicts perinatal survival. METHODS: An artery-artery anastomosis was sought by Doppler and disease stage was determined in 105 cases of twin-twin transfusion syndrome at presentation, first treatment, and worst stage. Outcome measures were perinatal, double, and any (1 or more babies) survival rates. RESULTS: After exclusion of 10 noninformative pregnancies, perinatal, double, and any survival rates were 61%, 44%, and 77%, respectively. When an anastomosis was detected at each of the 3 time points, perinatal and double survival rates were higher than when one was not (at first treatment, perinatal survival 83% versus 53%, respectively, P =.003; double survival 78% versus 33%, P <.001). Perinatal and double survival (P < or =.01) were poorer with more advanced stage, but any survival rates were not influenced by stage or anastomosis detection. Multiple logistic regression demonstrated that anastomosis detection at treatment increased the chance of perinatal (odds ratio [OR] 5.1, 95% confidence interval [CI] 1.6, 15.9) and double survival (OR 19.3, 95% CI 2.7, 138), independently of stage. For stages I-III at treatment, anastomosis detection predicted better perinatal (100% versus 63%, 100% versus 59%, and 83% versus 44%, respectively) and double survival rates (100% versus 52%, 100% versus 46%, and 78% versus 26%). Stage III, with anastomoses detected, had better perinatal (83% versus 63%) and double survival (78% versus 52%) than did stage I without detection. CONCLUSION: Antenatal detection of artery-to-artery anastomosis predicts higher perinatal and double survival in twin-twin transfusion syndrome, independently of disease stage. LEVEL OF EVIDENCE: II-3

Reversal of twin-twin transfusion syndrome: frequency, vascular anatomy, associated anomalies and outcome.

OBJECTIVE: To determine the frequency of reversal of transfusional gradient and phenotype in a large cohort of prospectively studied cases of twin-twin transfusion syndrome (TTTS) and seek evidence of clinical or placental anastomotic associations. METHODS: Consecutive cases of TTTS seen over an eight-year period with serial documentation of ultrasonic growth, liquor volume and fetal and placental Doppler studies were reviewed. Postnatal injection studies were inspected. RESULTS: Reversal of TTTS occurred in 5 of 96 affected pregnancies (5%). Two of the five cases had underlying aneuploidy or genetic syndrome, higher than the 2% frequency found in cases without reversal of TTTS (p < 0.05). Placental anastomotic configurations provided no consistent explanation for reversal of phenotype. CONCLUSION: This study documents the frequency of reversal of the direction of TTTS, and suggests that it is a heterogeneous condition. Reversal of donor-recipient phenotype may be explained by haemodynamic changes secondary to underlying aneuploidy/genetic syndromes, to the presence of multiple anastomoses in either direction or following laser ablation. This series together with previous case reports argues for a high level of suspicion for underlying aneuploidy, genetic syndrome or structural defects where there is reversal of the donor-recipient phenotype.

Non-invasive fetal electrocardiography in singleton and multiple pregnancies.

OBJECTIVES: To document the duration of fetal cardiac time intervals in uncomplicated singleton pregnancies using a novel non-invasive fetal electrocardiography (fECG) system and to demonstrate this technique's ability to acquire recordings in twin and triplet pregnancies. DESIGN: Prospective cross sectional observational study. SETTING: Antenatal wards and clinics, day assessment unit and centre for fetal care at a tertiary referral hospital, London, UK. POPULATION OR SAMPLE: Three hundred and four singleton and multiple pregnancies, 15-41 weeks of gestation. METHODS: Using electrodes sited on the maternal abdomen, a fetal electrocardiography (fECG) system was developed and tested on 304 pregnant women from 15 to 41 weeks of gestation, of whom 241 were uncomplicated singletons, 58 had twin and 5 had triplet pregnancies. The composite abdominal signals were stored on a laptop computer and the fECG derived off-line using a digital signal processing technique. For singletons, linear regression was used to analyse PR, QRS, QT and QTc intervals, and construct time-specific reference ranges. MAIN OUTCOME MEASURE: Duration of fECG time intervals as a function of gestational age. Success of signal separation in singleton, twin and triplet pregnancies. RESULTS: For singletons, a total of 250 recordings was obtained from 241 individuals with a signal separation success rate of 85% (213/250). Success rates were significantly poorer between 27 and 36 weeks of gestation (2 x k chi(2), P < 0.0001), with 84% (31/37) of separation failures occurring during this period. P, Q, R and S waves were seen in all cases where fetal signals were separated and were used to generate fECG time interval reference ranges. In 22% (43/199) of analysed cases, no T waves were identified, 63% (27/43) of whom were < or =24 weeks of gestation. In twins and triplets, separate fetal signals were obtained in 78% (91/116) and 93% (14/15), respectively; P, Q, R and S waves were evident in all averaged fECGs, while T waves were identified in 59% (54/91) and 57% (8/14). CONCLUSIONS: This study provides reference ranges with gestation for fECG intervals derived non-invasively from normal singleton pregnancies and demonstrates the feasibility of obtaining complete fECG recordings non-invasively across a wide gestational range in pregnancies of all pluralities. The fECG time intervals described will enable the identification of pathological fECG recordings from high risk pregnancies where fECG abnormalities are suspected.

The twin-twin transfusion syndrome.

The aetiology of twin-twin transfusion syndrome (TTTS), which affects 10-15% of monochorionic (MC) twin pregnancies, remains poorly understood. Although all MC twins have placental vascular anastomoses, unbalanced intertwin transfusion has been shown by ex vivo injection and in vivo Doppler studies of chorionic plate vasculature to be mediated by > or =1 arterio-venous anastomoses (AVA) in association with absent bi-directional arterio-arterial anastomoses (AAA). TTTS presents in the mid trimester with the oligo-polyhydramnios sequence, the donor may have a small or non-visible bladder and abnormal umbilical artery Doppler, while the recipient has a large bladder and may develop cardiac hypertrophy, triscupid regurgitation, and eventually hydrops. Recently, discordant renal renin angiotensin expression, endothelin and atrial natriuretic peptide have been implicated in the pathogenesis. Survival has increased from <20% to <60-70% with modern treatments, although survivors remain at increased risk of antenatally acquired cerebral white matter injury, and neurodevelopmental sequelae are documented in c.10% (range 5-23%). The recent introduction of a staging system for TTTS facilitates selection of therapy with less invasive amnioreduction and septostomy preferred for early stage disease, and more aggressive modalities such as laser ablation and cord occlusion with their attendant risk of procedure related fetal loss, reserved for advanced stage disease.