Transcript Gestational Age

Dr. Januchowski
2012
Based on an original presentation by
Hing Har Lo, MD
Chair, Radiology/Nuclear Medicine
[email protected]
Name the different Imaging modalities available
for the OB/GYN patient
 Compare and contrast the modalities available
 Know the different indications for imaging of the
OB/GYN patient
 Choose the most appropriate modality based on
the clinical presentation and desired results
 Recognize common OB/GYN Clinical
presentations on imaging

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X-Ray
Ultrasound (US)
 Most important imaging
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Computerized Tomography (CT)
Magnetic Resonance Imaging (MRI)
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a low-dose, low voltage x-ray exam of the
The results are recorded on x-ray film or directly into a
computer (digital)
Lump or mass
Calcifications:
• Macrocalcifications are large calcium deposits often caused by
aging. These usually are not a sign of cancer.
• Microcalcifications are tiny specks of calcium that may be found
in an area of rapidly dividing cells.
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Distortion
Still the diagnostic tool for detecting breast cancer
Recommend screening after 40 yo
Dense breast
CC (cranial
caudate)
Analog
MLO of a fatty breast
Digital
Small carcinoma
Performed with observing with fluoroscopy
Injecting iodinated contrast via the catheter in the cervix/uterus/fallopian tubes
Infertility evaluation
Repeated miscarriages
Monitor tubal patency after surgery
A: right tube,
B: uterine cavity,
C: left tube,
D: catheter with
balloon tip
Spillage into
pelvis
Sagittal scan through the long axis of uterus
Need a full bladder for an acoustic window.
A transducer in vaginal probe inserted .
Need a empty bladder.
Adapted from: Danforth's Obstetrics and Gynecology 9th Edition
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Sending high frequency sound waves in the transducer,
Produce “echoes” of varying intensities received by the transducer
Isoechoic
•
Anechoic
Hypoechoic
Hyperechoic (echogenic)
Echoes
Calcification
Acoustic
shadowing
 Acoustic
enhancement
www.ultrasound-images.com/uterus.htm
Uses x-ray beams & detector arrays
Barium in
small bowel
Attenuation, density
uterus
air in colon
• Strong magnetic field
• Radio frequency (RF)
Signal
 Which
of the following modalities would
expose the patient to the largest amount of
radiation?
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Ultrasound of the pelvis
MRI of the abdomen
Hysterosalpingogram
Abdominal flat plate
Mammography
 SEE NOTES FOR ANSWER

Obstetrics
 Growth & development
 Fetal well-being
 Abnormal

Gynecology
 Anomalies
 Inflammatory
 Neoplastic
 Other
• Preembryonic period (conception to 5 menstrual wks);
• Embryonic period, during which time organogenesis is
the major activity (4 to 9 menstrual weeks);
• Early developmental or fetal period, during which time
the fetus continues to grow.
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Gestational sac visible ~ 4 weeks
Yolk sac visible ~ 4 -5 weeks
Embryo visible ~ 5 - 6 weeks
Heartbeat ~ 5 - 6 weeks
Yolk sac
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A gestational sac appears as a double ring that is comprised of the
decidua capsularis and the decidua parietalis.
The sac should be seen when the β human chorionic gonadotropin
(hCG) is between 1,000 and 2,000 mIU/mL.
Once identified, the sac diameter should grow by an average of 1 mm
per day
Crown-rump length
Biparietal
diameter (BPD)
Head
circumference
(HC)
Abdominal
circumference (AC)
Femur length
(FL)
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Gestational age
Fetal weight
Fetal growth
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CRL: +/- 3-4 days
BPD, HC, AC, FL
• 14-22 wks GA: +/- 1 wk
• 23-30 wks GA: +/- 2 wks
• > 30 wks GA: +/- 3 wks
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Use US age < 22 weeks
Use menstrual age > 22 weeks
Do not alter GA by US after 22 weeks
 Unless late 1st prenatal evaluation
 Unsure of LMP
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There are more than 40 formulas in the literature for
estimated fetal weight (EFW).
The Hadlock formula, which is incorporated into
most North American ultrasound machine software
packages, utilizes four variables: the BPD, HC, AC,
and FL.
Not highly accurate, but..
Benefits
 Growth rate evaluation
 Preterm labor
454gm=1lb
Amniotic Fluid Index
•Evaluate for fetal distress (hypoxia)
•Use Fetal Biophysical Profile
Attempt to identify fetal distress (hypoxia)
Analogous to neonatal Apgar score
Points for each: 2 or 0
1.
2.
3.
4.
5.
Heart rate reactivity (non-stress test) 2 or more episodes of
acceleration of ≥ 15 bmp and of >15 s associated with fetal movement
within 20 min
Sufficient amniotic fluid: 1 or more pockets of fluid measuring ≥ 2
cm in vertical axis
Fetal tone:1 or more episodes of active extension with return to
flexion of fetal limb(s) or trunk (opening and closing of hand
considered normal tone)
Normal: 8 – 10
Fetal movement
Fetal breathing
http://www.emedicine.com/radio/topic758.htm
points
Suspicious: 6 points
Abnormal: < 6 points
Tone 2 pts
Breathing 2 pts
Movement 2 pts
Amniotic fluid 2 pts
•Identify intrauterine pregnancy:
•Gestational sac
•Yolk sac
•Embryo
•By 6 weeks:
•Should see heart beat by
transvaginal US.
•If no embryo, or embryo without
heartbeat – likelihood of miscarriage.
•By 7+ weeks:
•Normal heart beat implies high
likelihood of progression to term.
Embryonic heart rate:
•Should not be less than 90-100 bpm.
•Normally 120-180 bpm after 8 weeks
•Bradycardia often associated with
miscarriage
•Less than 90 bpm at 5-6 weeks
•Less than 120 bpm after 8
weeks
Middleton: Ultrasound - The Requisites, 2nd ed. 2004 Mosby
 Under
ideal situations, at what gestational
age would the gestational sac be visible on
transvaginal pelvic ultrasound?
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4 weeks
5 weeks
6 weeks
7 weeks
 ANSWER
 At
what range would crown-rump length be
the best measurement for the estimation of
fetal gestational age?
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0-5 weeks
6-14 weeks
15-22 weeks
22-30 weeks
 ANSWER
 Which
of the following factors would be a
part of the biophysical profile ultrasound to
assess fetal well being?
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Umbilical artery flow rate
Femur length
Abdominal circumference
Fetal heart rate
Fetal lie
 ANSWER
• Relative risk of preterm delivery increases as
cervical length decreases. Normal > 25mm.
• 25 mm optimal cutoff for predicting preterm
delivery at all gestational ages.
40mm
• Usually due to placental insufficiency
• Increased risk for fetal distress
• Usually due to placental insufficiency
• Placenta requires adequate blood flow
Normal Uterine Artery Waveform
Abnormal Uterine Artery Waveform
Doppler Ultrasound
From Danforth's Obstetrics and Gynecology 9th Edition
Doppler US
ROI is at cardiac position of the fetus
Hydrocephalus
Anencephaly
Encephalocele
Adapted from Gabbe: Obstetrics: Normal and Problem Pregnancies, 5th ed. 2007
Danforth's Obstetrics and Gynecology 9th Edition
Adapted from: Danforth's Obstetrics and Gynecology 9th Edition
Gestational trophoblastic
disease
Placental neopastic
process
Usually benign
Adapted from: http://www.uhrad.com/mamarc/mam030.htm
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Find IUP by transvaginal US
 Note: Heterotopic pregnancy 1 in 4000 – 30000
Discriminatory βhCG level
 Point at which all IUPs should be visible on
TVUS
 Third International Standard: ~1500-2000
mIU/mL
 Exception: multiple gestations
US visualization of extrauterine gestational sac
Uterus
Free
Free
fluid
Fluid
Ectopic
GS
Adapted from Gabbe: Obstetrics: Normal and Problem Pregnancies, 5th ed. 2007
 Which
of the following ultrasound findings
would indicate that a patient may be at
higher risk for preterm labor?
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Fetal weight at <5th percentile
Uterine wall hypertrophy
Cervical length < 25 mm
Marginal placental previa
 SEE NOTES FOR ANSWER
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Clinical presentations
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Obstetrics
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Growth & development
Fetal well-being
Abnormal
Ectopic
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Uterine Anomalies
Inflammatory
Neoplastic
Miscellaneous
Gynecology
Infertility
Miscarriage
Ectopic pregnancy
radiology.rsnajnls.org
Transverse US: Bicornuate or septated
uterus
th
Danforth's Obstetrics and Gynecology 9 Edition
Coronal MRI: Bicornuate Uterus
imaging.consult.com
Left adnexa: Tubo-ovarian abscess
Berek & Novak's Gynecology
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Benign
• Leiomyomata (fibroids)
• Ovarian teratoma (dermoid)
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Malignant
• Uterine
• Ovarian
Ultrasound
http://fibroidshouston.com/uterine-fibrosis-diagnosed.htm
MRI
Berek & Novak's Gynecology
NOTE: Most fibroids will be seen with
smooth edges on ultrasound
http://www.fibroidspecialist.co.uk/fibroids.htm
Ultrasound
Tooth
CT
http://www.mghradrounds.org/index.php?src=gendocs&link=2005_april
Normal endometrial
thickness
< 5mm post-menopausal
Functional (physiologic)
• Follicular
• Corpus luteum cyst
Often acute abdominal pain due to:
•Large size
•Torsion
•Rupture
•Hemorrhage
Follicular Cyst
Corpus Luteum Cyst
Hemorrhagic Cyst
Normal right
ovary
Torsion left
ovary
Post-op left ovary
Normal ovary
PCOS
“String-of-pearls” sign
Pelvic congestion is
becoming
increasingly
recognised as a cause
of chronic pelvic pain.
It is associated with
pelvic varicosities,
increased blood flow
http://www.learningradiology.com/

An ultrasound is done on a postmenopausal
female for evaluation of vaginal bleeding. Which
of the following findings would be most
indicative of endometrial cancer in this patient?
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String of pearls sign
Endometrial thickness of 7 mm
Mass with smooth edges noted on ultrasound
Increased blood flow to the pelvis
 ANSWER
The End !