Davies, Norman

Importance Monochorionic (MC) twins are hemodynamically connected by vascular anastomoses within the single shared placenta. The transfer of fluid or blood from one fetus to the other may result in development of pathologic complications, such as twin-twin transfusion syndrome, twin anemia polycythemia sequence, selective intrauterine growth restriction, and twin reversed arterial perfusion sequence. Monoamniotic gestations, which comprise a small fraction of MC pregnancies, can also present with unique challenges, particularly antepartum umbilical cord entanglement. All these complications carry a high risk of fetal morbidity and mortality if not recognized and managed in a timely fashion. Objective The purpose of this article is to review evidence-based management of complicated MC twin gestations and propose a standardized approach to surveillance. Evidence Acquisition Monochorionic gestations account for the majority of complications that occur in twin pregnancies; however, there is unclear evidence on the appropriate surveillance for and management of specific complications associated with these pregnancies. Results This article summarizes management for each specific type of MC complication in a structured and clear manner. Conclusions Early pregnancy ultrasound, ideally between 10 and 13 weeks' gestation, is critical for the diagnosis and characterization of twin pregnancies. To improve outcomes for MC twins, appropriate fetal surveillance should be initiated at 16 weeks' gestation and continued until delivery. Relevance Improve perinatal outcomes in MC twin pregnancies. Target Audience Obstetricians and gynecologists, family physicians Learning Objectives After completing this activity, the learner should be better able to describe the sonographic findings used to establish the diagnosis of MC twin pregnancies; identify complications unique to MC twins pregnancies, including twin-twin transfusion syndrome, twin reversed arterial perfusion sequence, twin anemia polycythemia syndrome, co-twin demise, cord entanglement, and conjoined twins; and explain the management of complications associated with MC twin pregnancies.

Glomerular damage is common in preeclampsia (PE), but the extent and etiology of tubular injury are not well understood. The aim of this study was to evaluate tubular injury in patients with PE and to assess whether it predates clinical disease. We performed a prospective cohort study of 315 pregnant women who provided urine samples at the end of the second trimester and at delivery. This analysis included women who developed PE ( n = 15), gestational hypertension (GH; n = 14), and normotensive controls (NC; n = 44). Urinary markers of tubular injury, α1-microglobulin (A1M), retinol-binding protein (RBP), kidney-injury molecule-1 (KIM1), complement C5b-9, tissue inhibitor metalloproteinase-2 (TIMP-2), and insulin-like growth factor binding protein-7 (IGFBP-7) were measured by enzyme-linked immunosorbent assay (ELISA) and reported in relation to urine creatinine concentration. Second-trimester concentrations of all markers were similar among groups. At delivery, A1M concentrations were higher in the PE group than in the GH and NC groups as an A1M/creatinine ratio >13 (66.7, 8.3, and 35%, respectively, P = 0.01). Concentrations of C5b-9 were higher in the PE group than in the GH and NC groups (medians 9.85, 0.05, and 0.28 ng/mg, respectively, P = 0.003). KIM1, RBP, TIMP-2, and IGFBP-7 concentrations did not differ among groups at delivery. In conclusion, proximal tubular dysfunction, as assessed by A1M and C5b-9, developed during the interval between the end of the second trimester and delivery in patients with PE. However, this was not matched by abnormalities in markers previously associated with tubular cell injury (KIM-1, IGFBP-7, and TIMP-2).