••• Chapter 17^ Obstetrical Ultrasound and Fetal Abnormalities^181
❍ Other imaging modalities that can be used to evaluate placenta accreta are?
Color Doppler and MRI.
❍ Macrosomia due to maternal diabetes is associated with?
Increased abdominal circumference to head circumference ratio.
❍ What ultrasound-estimated fetal weight is the cut-off for suspected macrosomia?
4500 in association with maternal diabetes or 5000 g without diabetes.
❍ How can amniotic fluid volume be evaluated?
Single vertical pocket with normal being between 2 and 8 cm and the amniotic fluid index with is the sum of the
largest vertical pockets in four quadrants.
❍ What abnormalities cannot be ruled out on four-chamber view of the heart?
Small atrial septal defects (ASDs) and ventricular septal defects (VSDs) and abnormalities of the great vessels.
Hence, the right and left ventricular outflow tracts should also be visualized. The chamber closest to the spine is
the left atrium. The mitral valve appears to be at a higher level than the tricuspid valve. Important information
regarding the size, position, and the axis of the heart can be obtained from this single view.
❍ What follow-up study should be performed on a fetus with increased nuchal translucency?
Fetal echocardiogram as there is an increased risk of cardiac defects even in fetuses with normal karyotype.
❍ Multicystic mass posterolateral to the fetal neck?
Cystic hygroma. Risk of aneuploidy is 60% to 75%, the most common being Turner syndrome.
❍ What is Potter sequence?
Severe oligohydramnios or anhydramnios leading to multiple anomalies including hypoplastic lungs, limb deformities,
and abnormal facies. Most commonly associated with bilateral renal agenesis or second trimester ruptured membranes.
❍ Single umbilical artery is associated with?
15% to 20% incidence of cardiovascular abnormalities. It is seen in over 50% of fetuses with trisomy 18. Found in
1 /200 newborns. Color flow Doppler of the umbilical arteries at the level of the fetal bladder is used to confirm a
three-vessel cord.
❍ Cervical length of > ___ mm has good negative predictive value of preterm labor.
25.
❍ Should all women be routinely offered cervical length screening?
While there is evidence that shortened cervix on ultrasound is a predictor of preterm birth in women at high risk,
current data does not support routine cervical length screening in low-risk populations.
❍ Ultrasound at 7 weeks demonstrates a midgut herniation. This finding is most likely?
Normal.