1st Trimester OB

Question 1

patient history questions

Answer 1

Parity?
Any problems with previous pregnancies?
Any Abnormal Bleeding? Remember implantation bleeding
Pain?
Where?
When?
Type?
Previous spontaneous or induced abortion?
Lab’s related to current condition
Confirm as much as possible in order to help make the correct diagnosis for the patient

Question 2

getting ready for the exam

Answer 2

Type all OB data into the US machine: LMP, Previous US date & measurement as applicable

Ask if patient has any questions
Position the patient
Use warm gel for transabdominal
Get TV probe ready once ready to do TV
Begin Imaging

Question 3

performing an OB exam remember…

Answer 3

Be methodical
Each & every exam done must be given importance and thoroughness
Answer the ordering MD’s suspicions
Include all measurements
Follow a standard routine – AIUM or other

Question 4

Why do a TA ?

Answer 4

Studies are used in a global fashion because of the restricted view of TV studies

If a relatively large mass is found on TA, TV may not be useful because of the increasing size of the gravid uterus

Is generally followed up with TV for better crown-rump-lengths (CRL’s) and M-mode (motion mode)

Question 5

TA limitations

Answer 5

Attenuation of the beam by the anterior wall

Inability to correlate areas of visible pathology with direct clinical palpation

Poor resolution of internal consistency of structures

Question 6

Why do a TV (indications)?

Answer 6

Better evaluation of relatively small masses (5-10 cm)

Determine the presence or absence of a mass or normal pelvic structures

Determine origin of a mass: Ovarian, Uterine, Tubal

Detail consistency of masses

Better evaluation of endometrium and myometrium and their relationship to pelvic masses

Help determine mobility of masses

Ultrasound guided aspirations

Question 7

TV limitations

Answer 7

Limited field of view (depth)

Patient’s history: Age limitations (Ask the physician if she is a pregnant adolescent – We should do the ‘gold standard’ which is TV). Virginal patients (no longer applies if she is pregnant). Abuse (rape)

Patient’s with inflammatory disease are very tender, may cause too much pain compared to TA

Male sonographer’s especially need a chaperone

Question 8

documentation

Answer 8

Clearly demonstrate a thorough series of images to document exam

Show anatomical relationships

Have labeled images with scan plane and area of body. Examples: Long ML Placenta (Longitudinal midline), Trans RT OV (Transverse right ovary), CRL

optimize each image by changing depth or mangification and positioning the focal zone

Demonstrate scanning through the entire pelvis region
Use highest frequency transducer – Linear or sector
Low output machine power – Especially with Doppler settings

check things out before showing the patient!

Question 9

imaging the uterus

Answer 9

In Longitudinal
Scan through entire uterus
Measure in longitudinal
Measure AP dimension

In transverse (TA) & coronal (TV)
Scan through entire uterus
Measure width of uterus

Question 10

imaging the ovaries

Answer 10

Do TA & TV (as appropriate) document each in

Longitudinal and Transverse/Coronal
Identify the corpus luteum
Measure ovaries & corpus luteum (as applicable)

Question 11

1st sonographic signs of IUP

Answer 11

On a transvaginal US exam

Decidual reaction
Gestational sac
At 3-5 weeks menstrual age

Question 12

imaging the gestational sac (length and ap)

Answer 12

In longitudinal with appropriate imaging parameters
Scan through
Measure length of gestational sac
Measure AP (anterior-posterior) of gestational sac

In transverse (TA) & coronal (TV) with appropriate imaging parameters
Scan through
Measure width*

Question 13

image the yolk sac

Answer 13

1st Structure seen inside the gestational sac

Identified as early as 5 weeks on TV and 7 weeks on TA US
Scan through
Measure

Question 14

what 1st tri measurements are required?

Answer 14

Gestational sac

Crown Rump Length

M-mode tracing with heart rate

Yolk sac

Question 15

crown rump length

Answer 15

Most accurate fetal measurement

On TV US it can be measured from 6-12 weeks gestation

Measured along the long axis of the embryo from the top of the head to the bottom of the rump

Question 16

when hCG is at ____ level, a gestational sac should be seen (TA and TV)

Answer 16

Transvaginally
500-1,000 mIU/ml (SIS method)
May be as low as 500 mIU/ml per HA
1,000-2,000 mIU/ml (IRP or 3IS)
HA says 1,800 mIU/ml or greater
Curry-Tempkin & other labs say 2,000 mIU/ml or greater

Transabdominal
1,800 mIU/ml or greater (SIS)
3,600 mIU/ml (IRP or 3IS)

Question 17

what is developing?

Answer 17

placenta

Question 18

what can you see in this image?

Answer 18

chorion and amniontic cavity and placenta

Question 19

what is the arrow pointing to?

Answer 19

normal nuchal or neck area

Question 20

what needs to be measured at ~ 12 weeks gestational age?

Answer 20

CRL & gestational sac measurements
 Biparietal diameter (BPD)  - Most accurate from 13-20 weeks
 Head circumference (HC)
 Abdominal circumference (AC)
 Femur length (FL) --Most accurate from 13-20 weeks

Question 21

1st structure in gestational sac followed by…

Answer 21

Yolk sac –5 wks. GA with TV or
6-7 wks. GA with TA

Embryo – 5-6 wks. GA with TV

Heartbeat – 5.5 wks. with TV

Question 22

1st sonographic sign of IUP

Answer 22

3-5 wks. TA

Gestational sac & decidual reaction