The pipeline embolization device has emerged as an important endovascular option. This is in part due to safety, efficacy, and possibly the ability to shorten the operative time considerably. With this new technology, some limitations are emerging as experience accumulates. We report three cases of posterior communicating (PCOM) artery aneurysms associated with fetal posterior cerebral artery where pipeline embolization was unsuccessful in obliterating the aneurysms. PCOM artery aneurysms associated with a fetal PCA should be managed either by microsurgical clipping or coiling when feasible.

BACKGROUND: There is a growing body of evidence that sonographic signs of placenta accreta spectrum can be observed in the first trimester of pregnancy. The most significant marker is placental location next to or in the scar niche in women with a prior cesarean delivery. OBJECTIVE: This study aimed to assess the performance of transvaginal ultrasound in the early prediction of placenta accreta spectrum in women with a prior cesarean delivery. STUDY DESIGN: This was a retrospective cohort of women with a history of cesarean delivery who had transvaginal ultrasound at 11 to 14 weeks' gestation between September 2016 and May 2018. Ultrasound reports were reviewed and graded for suspicion of placenta accreta spectrum as follows: Grade 0 (no suspicion) if the placenta is not next to the scar; Grade 1 (intermediate suspicion) if the placenta is next or on the scar; Grade 2 (high suspicion) if the placenta was inside the scar niche. In addition, all images were reviewed and graded by trained specialists blinded to the outcome. The primary outcome was a histologic diagnosis of placenta accreta spectrum. Sensitivity, specificity, positive predictive value, and negative predictive value of first-trimester transvaginal ultrasound to detect placenta accreta spectrum were assessed. RESULTS: In this study, 467 patients were included, and 8 (1.7%) had placenta accreta spectrum at delivery. Using the original report, 442 patients (94.6%) were Grade 0, 20 (4.3%) Grade 1, and 5 (1.1%) Grade 2. The revised grading had 456 patients (97.6%) with Grade 0, 5 (1.1%) with Grade 1, and 6 (1.3%) with Grade 2. Patients with Grade 2 yielded a sensitivity of 62.5% (95% confidence interval, 24.5e91.5), specificity of 100% (95% confidence interval, 99.2e100.0), positive predictive value of 100% (95% confidence interval, 97.0e100.0), and negative predictive value of 99.4% (95% confidence interval, 98.4e99.7). Any sonographic suspicion of placenta accreta spectrum (Grade 1 or Grade 2) had a sensitivity of 75% (95% confidence interval, 34.9e96.8), specificity of 95.9% (95% confidence interval, 93.6e97.5), positive predictive value of 24% (95% confidence interval, 14.8e36.4), and negative predictive value of 99.6% (95% confidence interval, 98.5e99.9). The blinded image review yielded a better specificity (99.1% vs 95.9%; P¼.001) and a positive predictive value (63.6% vs 24%; P¼.02) with similar sensitivity (87.5% vs 75%; P¼.52) and negative predictive value (99.8% vs 99.6%; P¼.55). CONCLUSION: Transvaginal ultrasound between 11 and 14 weeks' gestation in women a with prior cesarean delivery can identify at least 3 of 4 cases of placenta accreta spectrum. A finding of placental implantation within the scar niche has high positive predictive value for placenta accreta spectrum. Prospective studies are needed to assess routine screening for placenta accreta spectrum at 11 to 14 weeks' gestation in women with a prior cesarean delivery.

Transplanting stem cells before birth offers an unparalleled opportunity to initiate corrective treatment for numerous childhood diseases with minimal or no host conditioning. While long-term engraftment has been demonstrated following in utero hematopoietic cellular transplantation (IUHCT) during immune quiescence, it is unclear if prenatal tolerance becomes unstable with immune activation such as during a viral syndrome. Using a murine model of IUHCT, the impact of an infection with lymphocytic choriomenigitic virus (LCMV) on prenatal allospecific tolerance was examined. The findings in this report illustrate that established mechanisms of donor-specific tolerance are strained during potent immune activation. Specifically, a transient reversal in the anergy of alloreactive lymphocytes is seen in parallel with the global immune response toward the virus. However, these changes return to baseline following resolution of the infection. Importantly, prenatal engraftment remains stable during and after immune activation. Collectively, these findings illustrate the robust nature of allospecific tolerance in prenatal mixed chimerism compared to models of postnatal chimerism and provides additional support for the prenatal approach to the treatment of congenital benign cellular disease.

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