Objective: To report additional diagnoses in presumed twin transfusion syndrome (TTS) presenting with polyhydramnios / oligohydramnios(poly/oli) sequence treated with amnioreduction.

Study Method: Maternal and infant charts were reviewed by a combination of retrospective and prospective analysis. Amniotic fluid from each pregnancy was obtained for infection screen and chromosome analysis. Neonatal investigation was completed as clinically indicated.

Results: Between Jan. 1993 and Dec. 1996, 1 triplet and 26 twin pregnancies presented fitting standard ultrasound criteria of poly/oli sequence. Of 26 completed pregnancies, 6 pregnancies representing 9 fetuses were identified with additional diagnoses. Table

Table 1
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Conclusions: Additional diagnoses were identified in 23% of pregnancies with poly/oli sequence presumed due to TTS. These pregnancies fit accepted definitions of prenatal diagnosis of TTS. In view of the potential contribution to amniotic fluid dynamics seen in association with the additional diagnoses identified, it is possible that poli/oli sequence as a definition for TTS may overestimate it's true incidence. Careful evaluation pre and post natally for exclusion of these and other diagnoses is warranted for proper counseling of pregnancy and neonatal outcome.