Despite in utero separation of the fetal circulations remote from delivery, hematologic chimerism persisted after birth. We speculate that the greater degree of blood chimerism in the recipient compared with the donor was related to the pathophysiology of twin-twin transfusion syndrome before laser surgery.

BACKGROUND:The current standard for confi rmation of correct supra-diaphragmatic central venous catheter (CVC) placement is with plain fi lm chest radiography (CXR). We hypothesized that a simple point-of-care ultrasound (POCUS) protocol could effectively confi rm placement and reduce time to confi rmation. METHODS:We prospectively enrolled a convenience sample of patients in the emergency department and intensive care unit who required CVC placement. Correct positioning was considered if turbulent flow was visualized in the right atrium on sub-xiphoid, parasternal or apical cardiac ultrasound after injecting 5 cc of sterile, non-agitated, normal saline through the CVC. RESULTS:Seventy-eight patients were enrolled. POCUS had a sensitivity of 86.8% (95%CI 77.1%-93.5%) and specifi city of 100% (95%CI 15.8%-100.0%) for identifying correct central venous catheter placement. Median POCUS and CXR completion were 16 minutes (IQR 10-29) and 32 minutes (IQR 19-45), respectively. CONCLUSION:Ultrasound may be an effective tool to confirm central venous catheter placement in instances where there is a delay in obtaining a confi rmatory CXR.

Twin anemia-polycythemia sequence (TAPS) is an atypical form of twin-twin transfusion syndrome (TTTS) that presents as a large intertwin hemoglobin difference with one twin developing anemia and the other developing polycythemia, without oligohydramnios-polyhydramnios sequence (Lopriore et al., Placenta 2007;28:47-51). The prenatal diagnostic criteria for TAPS require that the middle cerebral artery-peak systolic velocity (MCA-PSV) measure greater than 1.5 multiples of median (MoM) in the donor twin and less than 0.8 MoM in the recipient twin (Robyr et al., Am J Obstet Gynecol 2006;194:796-803; Klaritsch et al., Ultrasound Obstet Gynecol 2009;34:149-154; Mari et al., N Engl Med 2000;342:9-14). The presumed etiology of TAPS involves the presence of small caliber arteriovenous anastomoses, which generate a slow transfusional process allowing for hemodynamic compensation (Lopriore et al., Placenta 2007;28:47-51; Lopriore et al., Placenta 2009;30:223-225; Lewi et al., Am J Obstet Gynecol 2006;194:790-795; Lopriore et al., Am J Obstet Gynecol 2008;112:753-758; Van den Wijngaard et al., Placenta 2007;28:611-615). The resulting polycythemia in the recipient twin is a risk factor for fetal and placental thrombosis (Van den Wijngaard et al., Am J Physiol 2005;288:R799-R814). We present a case of spontaneous TAPS complicated by a large placental vessel thrombosis and hydrops fetalis. Treatment via selective laser photocoagulation of communicating vessels (SLPCV) resulted in normalization of the MCA-PSV discordance.