Ultrasound

Question 1

1st trimester scan is for what between 11 weeks and 13 weeks and four days

Answer 1

1. To confirm intrauterine gestation and cardiac activity [pulse] also estimate gestational age
2. Anomalies in high risk including ancephaly
3. Vaginal bleeds, pelvic pain - masses and fibroids,ectopic pregnancy and molar pregnancy
4. To measure nuchal translucency-chromosomal aneuploidy
5. also used as and adjunct to chorionic villus sampling or localization andremoual of an intrauterine device
6. to confirm number of fetuses - multiple chroniocity and amniotic

Question 2

Uses of transvaginal sonar

Answer 2

• Gestational sac: at 4 weeks filled with fluid with echogenic border growing atleast 0.6mm daily
• Yolk sac: 33 days - 4,7 weeks
• embryonic echoes: 38 days - 5.4 weeks
• In normal pregnancy when sac is 25mm - embryo
• infrautenne Mac should be visualised by TVS with B-hCG values between 1000-2000 IU and abdominal exam 5500-6500 IU

Question 3

How sonar confirms age

Answer 3

Use crown rump length -CRL
→ longest length excluding limbs and yolk sac
→ made between 7-13 weeks
→ feral CRL in cente meters plus 6.5 = gestational age

Question 4

What screening tools can defect down syndrome

Answer 4

• normal ultrasound at 11-13 weeks using CRL (42-79mm)
• fatal nuchal translucency
• maternal blood
• b-hcg
• pregnancy- associated plasma protein A (PAPP-A)
• defect 60-80%

Question 5

Explain what is measured in nuchal translucency

Answer 5

→ translucent space between the back of the neck and the overlying skin
→ important to distinguish beaten underlying amniotic membrane and skin
→ > 6mm considered abnormal

Question 6

What do you screen in second trimester

Answer 6

• To screen for Fetal anomalies or determine well being
• to evaluate fatal growth and age
• to determine presentation
• to evaluate pre-rupture of membranes or preterm labour
• to evaluate abnormal biochemical markers
• placental abruption
• adjunct - amniocentesis, cervical cerclarge placement, external cephalic version
• to look for findings that increase risk of aneuploidy eg nuchal thickening, two vessel cord
• to examine pt with history of congenital abnormality
• to confirm metal demise
• follow up evaluation for placental anomaly

Question 7

What is the TVS used for in second trimester

Answer 7

To determine cervical length
Procedure: need full bladder
→ measure from internal os - external os
→ funneling

Question 8

What is screen in 3rd trimester

Answer 8

Fetal growth
How? → by measuring Fetal biometry -12-28 weeks best accuracy using Bi parietal diameter (bpd) = for head measurement
So this basically measures the head circumference = longest ap length
Can measure abdomen and also femur with humerus

Question 9

Explain fetal biometry of abdominal

Answer 9

• Determined on transverse view at the level of the junction of the umbilical vein, portal sinus and fetal stomach
• Measured from the outer diameter to outer diameter
• assessing fetal weight - macrosomia or IUGR

Question 10

How is poly or oligohydromnios measured

Answer 10

Amniotic fluid is measured - (deepest pool) normal 2-80m

Question 11

What is important when monitoring the placenta

Answer 11

Position - excluding placenta previa (Dx 24-28 weeks)
Placenta grading - maturity
Placentomegaly = diabetes, fatal hydros, Rh iso- immunization
Small placenta - severe IUGR - symmetrical or asymmetrical