Gabbe Chapter 9 Flashcards
(20 cards)
The term for the lightness or darkness of ultrasound images
Gain
Setting that shows changes along a single ultrasound beam over time (used to document fetal heart rate)
M-mode (motion mode)
At ___ weeks gestation, the uterus has grown enough that advantages of transvaginal US are lost
10-12 weeks
Gestational sac can be seen around __ weeks gestation
4-5 weeks gestation
Until ___ weeks gestation the CRL should be measured for gestational age determination
12 weeks gestation
The stomach can be consistently seen by __ weeks gestation
11 weeks gestation
When cardiac activity has been demonstrated, the miscarriage rate is __ (A. 0-1%; B. 2-4%; C. 8-10%; D. 12-15%)
2-4% (although higher in high risk populations such as women >35 years undergoing infertility treatments)
The rate of spontaneous abortion in all clinically established pregnancies is 15% (reduced after cardiac activity is demonstrated)
First trimester ultrasound findings predictive of a chromosome abnormality:
thick nuchal translucency, absent nasal bone, abnormally fast or slow heart rate
In a twin gestation, an early pregnancy ultrasound showing a “lambda sign” indicates…?
the presence of two chorions
What is the definition of polyhydramnios (AFI)?
greater than 24cm
What is the definition of polyhydramnios (MVP)?
Greater than 8 cm
What is the definition of oligohydramnios (AFI)?
Less than 5 cm
What is the definition of oligohydramnios (MVP)?
Less than 2 cm. ACOG recommends using MVP as the definition of oligohydramnios to use to make clinical decisions as AFI is less reliable in predicting perinatal outcomes
Placental edge that ends ___ cm or more from the cervix is considered normal (at 16 weeks or greater gestation)
2 cm
How do you manage a patient with a placental edge less than 2cm from the internal os but not covering it?
low-lying placenta –> follow up US at 32 weeks gestation
Condition where fetal vessel runs through the membranes over or close to the cervix
vasa previa (can occur with velamentous cord insertion, when there is a succenturiate lobe, or when a previa resolves)
A “globular’ placenta with a narrow base compared to height is associated with what?
increased rate of IUGR and fetal death
What is the lower limit of normal for a cervical length in the mid-second trimester?
25mm
What method of measuring (BPD, CRL, AC, HC, FL) is most susceptible to variations in fetal soft tissue mass?
AC (abdominal circumference) - fairly good marker of fetal growth
Is FGR caused by nutritional deprivation symmetric or asymmetric?
Asymmetric (AC is less than HC)
