Ultrasound is an integral part of early pregnancy assessment. This chapter covers the normal findings in early pregnancy, the ultrasound diagnosis of early pregnancy failure, and the spectrum of appearances of perigestational hemorrhage. It discusses the first-trimester evaluation of chorionicity and amnionicity in multiple gestations. Chorionicity is the most important prognostic indicator in multiple gestations therefore it is vital to make an accurate determination of this any time a multiple pregnancy is seen. Monochorionic diamniotic twins are at risk for specific complications such as twin-twin transfusion syndrome; this makes the prognosis worse than for dichorionic twins. Knowledge of the normal imaging findings and expected developmental milestones is vital for accurate interpretation. Recognition of monochorionic pregnancies and significant anomalies allows for appropriate early referral for specialist evaluation. Ultrasound is the most accurate way to triage patients with pain and/or bleeding in the first trimester.

Pregnancy, labor, and delivery are associated with major physiologic changes that can decrease maternal reserves. Consequently, various techniques of analgesia and anesthesia can have profound effects on maternal physiology. Furthermore, obstetric pain management and operative obstetric anesthesia are recognized as secondary causes of neonatal respiratory depression. Improper management of labor is the common claim in obstetrical malpractice cases. Malpresentation and/or dystocia are some of the most fertile areas for medical negligence lawsuits. The clinician must be fully aware of the general predisposing factors to complications in the third stage of labor. Common postpartum complications include urinary tract problems, such as infections, urine retention, or incontinence. Obstetricians have long recognized the excessive perinatal morbidity and mortality associated with the breech-presenting fetus. Multiple gestations often pose intrapartum management problems. Emphasizing the shoulder dystocia was a true obstetric emergency, and greater emphasis was placed on team approach, including neonatal resuscitation.

This chapter explores the maternal and fetal complications, advances in prenatal diagnosis, and management of complications unique to multiple gestations. Tidal volume and oxygen consumption in multiple gestations are increased, as is the normal alkalosis seen in singleton pregnancy. Hypertensive disorders increase by at least twofold in twin gestations. Hemorrhagic complications occur more frequently with twins. Growth of singletons and twins is comparable until 27 weeks gestation. The uterus accommodates the larger volume imposed by twins by overdistension, and beyond a certain limit, premature labor can result. Preterm deliveries (less than 37 weeks' gestation) occurred in 10.6% of singleton pregnancies against a phenomenal rate of 61.2% of live births in multiple gestations. Diagnosis of multiple gestations, establishing chorionicity, identifying anomalies, foreseeing possible maternal and fetal complications, prevention and treatment of preterm labor, and management of growth restriction are some of the areas of medicolegal concerns in multiple gestations.