Second and Third Trimester Fetal Biometry, Anatomy, and Structural Anomalies — WACS Viva & Clinical Scenarios (Obstetric and Gynaecological Imaging)

Exam-style second and third trimester fetal biometry, anatomy, and structural anomalies viva scenarios with examiner probes and model answers for Radiology…

Scenarios covered

• SCENARIO 1: Standardized Fetal Biometry and Quality Criteria: Outline the required anatomical landmarks, acoustic plane criteria, and caliper placement standards for measuring biparietal diameter, head circumference, abdominal circumference, and femoral diaphysis length during second- and third-trimester obstetric ultrasound.
• SCENARIO 2: Fetal Central Nervous System and Neural Tube Defects: A 20-week anomaly scan demonstrates scalloping of the frontal bones, downward displacement and curvature of the cerebellum, and lateral ventricular atrium measuring 12.5 mm. Describe the imaging findings, identify the underlying diagnosis, and detail the systematic sonographic evaluation of the fetal spine and cranium.
• SCENARIO 3: Anterior Abdominal Wall Closure Defects: Differentiate between omphalocele and gastroschisis on prenatal ultrasound with respect to cord insertion site, covering membranes, herniated contents, associated chromosomal or structural anomalies, and delivery considerations.
• SCENARIO 4: Obstructive Uropathy and Amniotic Fluid Derangements: A third-trimester scan of a male fetus demonstrates severe oligohydramnios, bilateral pelvicalyceal dilatation, a distended thick-walled bladder, and dilatation of the posterior urethra. Discuss the diagnosis, sonographic staging of renal parenchymal integrity, and secondary pulmonary implications.
• SCENARIO 5: Congenital Thoracic and Diaphragmatic Anomalies: Detail the sonographic differentiation between congenital diaphragmatic hernia, congenital pulmonary airway malformation, and bronchopulmonary sequestration, highlighting mediastinal shift, vascular supply on colour Doppler, and stomach positioning.