Prenatal Diagnosis and Screening in Early Pregnancy

Dr. Ruken Dayanan1
Assoc. Prof. Dr. Kadriye Yakut Yücel2

1Department of Perinatology, Ankara Etlik City Hospital, Ankara, Türkiye
2Department of Perinatology, Ankara Etlik City Hospital, Ankara, Türkiye

ABSTRACT

Placenta accreta spectrum (PAS) disorders comprise a range of severe placental abnormalities characterized by abnormal adherence to, or invasion of, the uterine wall by the placenta, often associated with prior cesare- an deliveries. The rising incidence of PAS parallels the increase in cesarean sections. Early prenatal diagnosis of PAS is critical for meticulous delivery planning, aiming to reduce maternal and neonatal morbidity and mor- tality. Traditionally diagnosed in the third trimester via ultrasound, early detection during the first trimester offers significant benefits for management and preparation.

This chapter explores the methodologies and importance of early prenatal screening and the diagnosis of PAS. Recent studies suggest that first-trimester sonographic indicators, such as cesarean scar pregnancy (CSP), can predict PAS. The chapter delves into first-trimester sonographic assessment techniques, partic- ularly transvaginal sonography (TVS), and the anatomical evaluation of the cervico-isthmic complex (CIC) for early diagnosis of CSP and low placentation. Key sonographic markers and classifications are discussed, including the identification of the “high-risk-for-PAS triangle” based on low implantation within the cesarean scar niche.

Despite the lack of a standardized early screening protocol for PAS, the chapter emphasizes the potential of early sonographic markers to enhance detection accuracy and improve outcomes. It advocates for routine TVS screening at 5-7 weeks of gestation for patients with previous cesarean deliveries and underscores the necessity of specialist referral upon early detection of CSP. The chapter concludes with a call for extensive prospective studies to evaluate the efficacy of first-trimester screening methods, aiming to establish stan- dardized protocols for early PAS disorder detection and management.

Keywords: Placenta accreta spectrum; Early prenatal diagnosis; Cervico-isthmic complex; Low placentation; Cesarean scar pregnancy; Abnormal placentation

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