Scimitar syndrome fetal ultrasound

Scimitar syndrome, a rare congenital heart defect, can be suspected and sometimes diagnosed via fetal ultrasound. Key features on ultrasound include right lung hypoplasia and a mediastinal shift, with abnormal drainage of pulmonary veins into the inferior vena cava (IVC). While the diagnosis can be confirmed postnatally, fetal ultrasound can be the initial modality, especially when combined with spatiotemporal image correlation (STIC-HD) flow, which allows visualization of the abnormal pulmonary venous connection. 

Fetal Ultrasound Findings:

• Right lung hypoplasia and mediastinal shift:The heart may be shifted towards the right due to the underdeveloped right lung. 
• Abnormal pulmonary venous drainage:The right pulmonary veins may be seen draining into the IVC, rather than the left atrium. 
• Cardiac dextroposition:The heart may be positioned more towards the right side of the chest. 
• Hypoplastic right pulmonary artery:The branch of the pulmonary artery to the right lung may appear smaller than normal. 
• Aortic arch abnormalities:In some cases, there may be an aortic arch anomaly such as a right aortic arch. 

Diagnostic Tools and Techniques:

• 2D and STIC-HD flow:Spatiotemporal image correlation with high-definition flow can help visualize the abnormal pulmonary venous connection. 
• Color Doppler:Color Doppler imaging can confirm the direction of blood flow within the abnormal vein. 
• Fetal echocardiogram:A detailed heart ultrasound (echocardiogram) is crucial to assess for associated heart defects. 
• Fetal MRI:Fetal MRI may be useful in confirming the diagnosis and assessing the extent of the abnormalities. 
• Postnatal confirmation:Radiography, angiography, transthoracic or transesophageal echocardiography, CTA, or MRA may be used to confirm the diagnosis after birth. 

Clinical Significance:

• Early diagnosis:Prenatal diagnosis allows for early management and potential interventions to improve outcomes. 
• Associated anomalies:Scimitar syndrome can be associated with other heart defects, including atrial and ventricular septal defects, and genetic syndromes. 
• Prognosis:The prognosis can vary depending on the severity of the pulmonary hypertension and associated anomalies.