Ch. 18 Fetal Biometry and Lie

Question 1

What is the most accurate measurement for determining gestational age?

Answer 1

Crown-rump length in the first trimester

Question 2

Measurements taken in the second and third trimesters have a rang of aprox

Answer 2

+ or - 2 weeks

Question 3

Term for how estimated due dates are determined from LMPs

Answer 3

Naegele’s Rule

Question 4

What is Naegele’s rule

Answer 4

EDD=LMP - 3 months + 7 days

Question 5

Term for a normal oval head shape

Answer 5

Mesocephaly

Question 6

BPD measurements are not accurate at how many weeks

Answer 6

Accurate until 33 weeks

Question 7

Which measurement is more accurate, HC or BPD?

Answer 7

HC, especially when dolichocephaly or brachycephaly is present

Question 8

What measurement is the least reliable in determining gestational age

Answer 8

AC

Question 9

Cephalic index (CI) defines head shape and is determined by

Answer 9

Dividing BPD by OFD (occipital-frontal diameter)

Question 10

What is the normal range of CI

Answer 10

0.70 - 0.86 (70-86%)

Question 11

Dolico CI would be

Answer 11

CI <70%

Question 12

Brachycephaly CI would be

Answer 12

CI >86%

Question 13

Term for an abnormally elongated head shape

Answer 13

dolichocephaly

Question 14

Term for an abnormally rounded head shape

Answer 14

Brachycephaly

Question 15

In cases of brachy or dolicocephaly, what should be disregarded

Answer 15

the BPD is eliminated from estimation of GA

Question 16

The femur length is best obtained with what kind of transducer

Answer 16

Linear array

Question 17

What portion of the femur should be measured and what should be excluded

Answer 17

Include only the ossified diaphysis, exclude the epiphyseal cartilage

Question 18

When should skeletal dysplasia by considered in terms of the FL

Answer 18

When the FL falls more than 2 SD ratios below the mean

Question 19

List other parameters that may be used to determine GA in cases of skeletal dysplasia when the bone measurements are inaccurate

Answer 19

Clavicular length, foot length (foot=femur length), binocular distance, transcerebellar distance

Question 20

The system that is designed to detect fetal asphyxia

Answer 20

Biophysical profile (BPP)

Question 21

What is the first ultrasound parameter in a BPP that will disappear with fetal hypoxia

Answer 21

Fetal breathing movements will be the first parameter to disappear in a BPP

Question 22

What is the BPP criteria

Answer 22

30 seconds of breathing, 3 discrete gross body movements, 1 tone movement all within a 30-minute period and at least one pocket of amniotic fluid measuring 2 cm in the vertical axis (MVP) or an AFI of >5cm

Question 23

What does NST stand for

Answer 23

Non-stress test. The demonstration of reactive FHR, consisting of 2 episodes of acceleration >15 BPM for 15 seconds over a 30 minute time frame (first NON US parameter to disappear with hypoxia)

Question 24

In which type of cephalic presentation can vaginal delivery not occur

Answer 24

Brow cephalic presentation

Question 25

Another term for cephalic is

Answer 25

Vertex

Question 26

Describe all types of breech presentations

Answer 26

Footling - hips are extended, feet are presenting
Frank - hips are flexed and knees are extended. Legs in front of face
Complete - hips flexed, knees flexed