10,12,13 antenatal testing, isoimmunization, prenatal infections

Question 1

Syphilis

• how transmitted to baby
• how dx (screening, confirm)
• tx

Answer 1

1. transplacental
2. Dx:

Primary chancre: dark field microscopy (no Ab yet)

Secondary dz: screen: RPR, confirm: FTA-Ab

Tertiary: LP (neuro)

3. Tx: PCN always. If allergic, use doxy if non-pregnant. If pregnant, must desensitize to PCN.

Question 2

Pregnant woman comes to clinic and is worried about decreased fetal movement. Do what, in what order? (4)

Answer 2

NST-VAS-BPP-CST

1. NST to see 15,15,2 in 20. If non-reactive, go to next step
2. Vibroacoustic stimluation (may wake up sleeping baby)
3. Calculate BPP. If low, deliver (fetal demise imminent). If good, monitor qweek. If moderate score:
4. do CST, admit pt and monitor. Baby may need to be deliered soon.

Question 3

Prenatal infections

-list 8

Answer 3

1. GBS
2. Hep B
3. HIV
4. Herpes
5. Varicella
6. Syphilis
7. Toxo
8. Rubella

Question 4

Herpes

• how transmitted to baby
• how to prevent
• how to dx

Answer 4

• 1. primary viremia: through blood transplacentally
     
     2. seconday reactivation: baby touches lesions
• PPx mom with acyclovir to prevent outbreaks. C/S to avoid touching lesions.
• Dx with Tzanck prep (multinucleated cells) from vesicle.

Question 5

Toxoplasmosis

• how transmitted
• Baby sx (triad)
• how to ppx
• how does 1st exposure present?

Answer 5

• transplacental
• Triad of congenital toxo:
• Intracranial calcification = milk on cat head
• Hydrocephalus = water bowl stuck on head
• Chorioretinitis = camera flash bulb
• If mom is Ab-, avoid cats/litter.
• 1st exposure has mono-like syndrome.

Question 6

GBS

1. how to dx
2. how to ppx

Answer 6

1. vaginal cx @35-38 weeks
2. PCN (or erythromycin) if cx positive at week 35+

Question 7

Varicella

• how transmitted to baby
• how to dx
• how to prevent

Answer 7

Just like herpes: 1) primary viremia (chickenpox), transplacental

2) secondary reactivation (shingles), physical touch
- Clinical dx
- PPx: If mom never got varicella, give her vaccine before pregnancy (not during). If already pregnant, she must be isolated from children who could spread to her. (including her own). If she is exposed, give IVIG varicella Ab to her (bind virus beore it gets to baby).

Question 8

Contraction stress testing

-what are we looking for

Answer 8

For adequate test, we need 3 CTX in 10 min.

We are looking for decels:

VEAL CHOP

variable–cord

early–head

accels–OK

late–placental insuff.

Question 9

Non stress test

-what are we looking for

Answer 9

“15,15,2 in 20”: we are looking for increased HR of 15bpm for 15 seconds, twice in 20 min.

Question 10

Hep B

• how transmitted to baby
• Tx (3)

Answer 10

-transmitted by blood-blood exposure (eg vaginal delivery). baby has no immune system so will become carrier.

Tx: 1. C/S (reduce exposure)

2. IVIG Hep B to baby
3. Hep B vaccine to Baby

Question 11

How does Rhogam work?

-when to give?

Answer 11

It’s an Ig that binds to the Rh antigen and hides it from mom’s immune system.

-give at 28 weeks, and within 72 hrs of delivery, and at any fetal-maternal mixing of blood

Question 12

HIV

• how transmitted to baby
• How to prevent
• why is diagnosis for baby difficult?

Answer 12

• blood exposure during birth. HIV cannot cross placenta.
• C/S, get mom on HAART or at least AZT with delivery.
• diagnosis for baby is tough b/c HIV Ab cross the placenta (HIV doesn’t). So, non-HIV baby will have false positive HIV test after birth. Wait 6 months for Ab to disappear, then do HIV test. If positive, start tx immediately.

Question 13

Fetal anemia:

• how to screen
• how to confirm
• tx

Answer 13

• TCD (increased flow = anemia)
• PUBS (get the fetal blood Hb level).
• transfuse through PUBS

Question 14

Rubella

• how transmitted to baby
• congenital sx
• ppx

Answer 14

• transmitted only during primary viremia
  1. deafness
  2. cataracts
  3. heart defects

PPx: vaccine before/after pregnancy.