Intracranial magnetic resonance imaging findings in the surviving fetus after spontaneous monochorionic cotwin demise.

OBJECTIVE: This study was undertaken to evaluate intracranial magnetic resonance imaging abnormalities in the surviving fetus after a cotwin demise. STUDY DESIGN: This is a retrospective observational study evaluating the intracranial findings of surviving twins after demise of a monochorionic cotwin. A total of 47 cases of cotwin demise were identified from an magnetic resonance imaging database consisting of all fetal magnetic resonance imagings performed at the University of California San Francisco. Twenty-one of these cases were monochorionic twins who had not undergone an intervention (fetal radiofrequency ablation and placental laser ablation) and these comprised the study group. The magnetic resonance imagings were reviewed by a pediatric neuroradiologist who was blinded to the ultrasound and clinical findings. RESULTS: The mean gestational age at the time of cotwin demise was 19(6/7) weeks (range 12(4/7) weeks-26(5/7) weeks) with an average interval of 4(3/7) weeks between the time of cotwin demise and fetal magnetic resonance imaging (range 0-12(1/7) weeks). Nine cases (41%) were associated with diagnosed twin-twin transfusion syndrome. Abnormal findings, including polymicrogyria, germinolytic cysts, intracranial hemorrhage, ventriculomegaly, and delayed sulcation were identified by fetal magnetic resonance imaging in 7 (33%) cases, the majority of which had a normal ultrasound. CONCLUSION: Prenatal magnetic resonance imaging is a valuable tool in evaluating the fetal brain after a cotwin demise.

Transabdominal cerclage: can we predict who fails?

OBJECTIVE: To examine the outcome of pregnancies in women with transabdominal cerclage (TAC) and to determine whether aspects of the obstetric history predict failure. METHODS: This was a cohort study of pregnant women referred for a transabdominal cerclage between 1978 and 2004. Records were reviewed for obstetric history and maternal demographics. Predictor variables were prior pregnancy loss, prior vaginal cerclage, associated factors for TAC, and maternal age. The outcome variable was delivery of an infant beyond 24 weeks who survived the neonatal period. Outcomes were compared using Student's t-test, standard z-test, and Chi-square test. RESULTS: Eighty-eight women delivered 96 pregnancies after TAC placement. The fetal salvage rate prior to TAC was 18%, 93% after the procedure (p<0.001). Delivery beyond 37 weeks occurred in 70% of pregnancies. Maternal age, prior cerclage history, associated factors for TAC, or previous delivery of a viable infant did not predict the eight failures out of the 96 pregnancies. CONCLUSION: Women with TAC had a higher rate of successful pregnancies than prior to TAC. Neither maternal age nor prior pregnancy loss predicted failure. However with such a high success rate, we would have needed 948 women to do so. TAC is an option for women with a poor obstetric history including failed vaginal cerclage.

Unequal placental sharing and birth weight discordance in monochorionic diamniotic twins.

OBJECTIVE: The purpose of this study was to define the association between unequal placental sharing and birth weight discordance in monochorionic/diamniotic twin pregnancies. STUDY DESIGN: The study comprised a prospective cohort of monochorionic/diamniotic twin pregnancies who were delivered in Kaiser Permanente-Northern California, 1997-2003. Dye injection studies of fresh postpartum placentas were performed. Placental sharing, cord insertion combinations, vascular anastomoses, gestational age, and birth weights were recorded. Statistical comparisons of birth weight and gestational age were made with the Student t test. Rates of birth weight discordance were compared with the chi-square test. Multivariate logistic regression models analyzed the relationship between variables of interest. RESULTS: Mean birth weights for larger and smaller twins were 2400 g and 2109 g, respectively. Twenty-two percent of the monochorionic/diamniotic twin pairs had birth weight discordance > or = 20%, and 8% of these pairs had twin-twin transfusion syndrome. Monochorionic/diamniotic twin pairs with unequal placental sharing had a 9.8 times greater likelihood of birth weight discordance (95% CI, 5.4-17.9) as compared with those pairs with equal placental sharing. CONCLUSION: Unequal placental sharing is a significant risk factor for birth weight discordance in monochorionic/diamniotic twins. Antenatal diagnosis of unequal placental sharing would enable improved counseling in the setting of monochorionic/diamniotic twins.