multifetal gestation pregnancies

Question 1

what is incidence of multifetal gestaitons without art? with art?

Answer 1

twins - 1:80

triplets: 1:6400
quadruplets: 1:512K

with ART; population incidence is 3%

Question 2

is family history involved in dizygotic or monozygotic pregnacies?

Answer 2

dizgyotic. these involve two egg and two sperm. 67% of twins are dizygotic.

as opposed to monozygotic. 1 egg and 1 sperm. then separateion/twinning process happens -> two pregnancies

Question 3

what are possibilities for fertilization/splitting that end up with mono/di chorionicity and mono/di amnionicity?

Answer 3

dizygotic - always diamniotic/dichorionic
monozygotic - depends on when splitting happens
if 0-3 days: diamnion/dichorion
if 4-8 days: diamnion/monochorion
9-12 days: monoamnion/monochorion
13 days and after: conjoined twins

Question 4

determination of chorionicity?

Answer 4

1st or early 2nd tri US (11-14 weeks): lambda/twin peak sign = dichorionic

Question 5

general twin pregnancy management strategies?

Answer 5

• determination of chorionicity early
• increase nutrition: 3000 kcal/day
• if triplets or higher – offer multifetal reduction
• growth US at 18 weeks (then schedule depending on chorionicity etc)
• genetic counseling - increased risk of aneuploidy in twins (monochorionic > dichorionic).

Question 6

what are additional risks of monochorionic pregnancy?

Answer 6

• sIUGR
• aneuploidy
• structural anomalies
• TTTS
• single twin IUFD

Question 7

what is US surveillance for monochorionic pregnancies?

Answer 7

q2weeks to check AFI, bladder filling
fetal echo by 22 weeks
q2-4 weeks to assess growth (same as dichornionic)

Question 8

delivery timing

Answer 8

di/di: 38-39 weeks
mo/di: 34w0d - 37w6dd
mo/mo: 32w0d -34w0d

give ANC if anticipated del before 34 weeks

Question 9

delivery mode

Answer 9

• all mo/mo pregnancies = CD
• if vtx/vtx = vaginal
• if nonvtx presenting = CD
• if vtx/non-vtx: VD possible (i.e. no discordance, experience provider with breech delivery/internal podalic version)

Question 10

what are risks of single twin death to other twin?

Answer 10

• death (15% in MC, 3% in DC)

- neuro damage (18% MC, 1% DC)

Question 11

dx crtieria of TTTS?

Answer 11

1) MCDA pregnancy

2) polyhydramnios in one twin (> 8 cm MVP) and oligo in other (< 2 cm MVP)

Question 12

how is TTTS staged?

Answer 12

Quintero staging

1: oligo/poly
2: decompressed bladder
3: dopplers: umbilical, ductus venosus
4: hydrops
5: absent cardiac activity

Question 13

TTTS prognosis:

Answer 13

stage 1: 3/4 will regress or stay stable -> usually expectant management

stage 3: if persists to > 26 weeks, near 100% death of fetus

stage II/III -> fetoscopic coagulation of placental anastamoses, serial amnioreduction, amniotic septoplasty

Question 14

how do you calculate growth discordance?

Answer 14

(efw larger twin - efw smaller twin) / (larger twin efw)

Question 15

ddx for growth discordance

Answer 15

• aneuploidy/structural anomalies
• single fetal infection
• incorrect dating/measurements
• abnormal placentation/vascular flow