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EndoRepro 2 Exam 1 > Clin: Multifetal Gestation and Malpresentation - Moulton > Flashcards

Clin: Multifetal Gestation and Malpresentation - Moulton Flashcards

1
Q

two separate ova are fertilized by two separate sperm

  • are distinct pregnancies coexisting in the same uterus
  • each will have it’s own amnion, chorion and placenta
A

fraternal (dizygotic) twins

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2
Q

arise from the cleavage of a single fertilized ovum at various stages during embryogenesis
- arrangement of fetal membranes and placentas will depend on the time at which the embryo divides

A

identical (monozygotic) twins

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3
Q

how many chorions, how many amnions for dichorionic diamniotic monozygotic placentation?

A

2 placenta
2 amnions
- cleavage at days 0-3
- can be two separate placentas or one fused
- 30% on monozygotic twins have this presentation

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4
Q

how many chorion, how many amnions for monochorionic diamniotic monozygotic placentation?

A

1 placenta
2 amnions
- cleavage at days 4-8
69% of monozygotic twins have this presentation

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5
Q

how many chorion, how many amnion for monochorionic monoamniotic monozygotic placentation?

A

1 placenta
1 amnion
- cleavage days 9-12
- 1% on monozygotic twins have this placentation
- is the most dangerous since there are not separating amnions
- cord entanglement risk if high
- net mortality in these twins is 50-80%

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6
Q

what is a craniopagus?

A

twins joined at the cranium

- 2% incidence

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7
Q

what is a thoracopagus?

A

twins joined at the chest wall

- 30-40% incidence

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8
Q

what is an ischiopagus?

A

twins joined by the coccyx and sacrum

- 6% incidence

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9
Q

what is the frequency of monozygotic twins?

A

constant among all populations at 1 in 250 births

- 1/3 of spontaneous twins are monozygotic

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10
Q

what are the influences of dizygotic twins?

A
  • maternal age: 2x more common after 35 y/o
  • family hx and ethnicity: lower among asians, Western nigerian tribe has dizygotic twinning occurance of 1 in 22 gestations
  • 2/3 of spontaneous twins are dizygotic
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11
Q

when would you suspect multiple gestations?

A
  • hCG higher than normal
  • uterus palpates larger than dates
  • auscultation of more than 1 fetal HR
  • pregnancy has occurred after ovulation induction or IVF
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12
Q

prognosis and expected morbidity of twins is strongly dependent on what?

A

zygosity

- is the most important step after diagnosing twins!

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13
Q

monozygotic twins have increased incidence of what?

A
  • congenital anomalies
  • weight discordancy
  • twin-twin transfusion syndrome (TTTS)
  • neorologic squeale
  • premature delivery
  • fetal demise
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14
Q

US to determine zygosity:

  • different fetal gender
  • visualization of a thick amnoin-chorion septum
  • “peak” or “inverted V” sign at the base of the septum
A

dizygotic

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15
Q

US to determine zygosity

- dividing membrane is fairly thin

A

monozygotic

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16
Q

what if US is not definitive in determining zygosity?

A
  • inspect placenta after delivery

- DNA analysis

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17
Q
  • cleavage occurs 13-15 days
  • 1 in 70,000 deliveries
  • mortality rates 50%
  • c-section delivery
  • advancement of imaging allows mapping of shared organs and more successful surgical separation procedures
  • elective termination if cardiac or cerebral fusion is identified
A

conjoined twins

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18
Q
  • 90% occur in monochorionic twins
  • most common type is arterial-arterial followed by arterial-venous and then venous-venous
  • vascular communications between 2 fetuses through the placenta can cause problems (abortion, polyhydramnios, TTTS, fetal malformation)
A

interplacental vascular anastomoses

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19
Q

results secondary to uncompensated arterial-venous anastomoses in a monochorionic placenta
- leads to a net transfer of blood flow going from 1 twin to other

A

twin-twin transfusion syndrome (TTTS)

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20
Q

what are the fetal complications of TTTS?

  • donor twin
  • recipient twin
A
  • donor twin: hypovolemia, hypotension, anemia, oligohydramnios, growth restriction
  • recipient twin: hypervolemia, polyhydramnios, thrombosis, HTN, polycythemia, edema, cardiomegaly, CHF
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21
Q

what are both twins at risk for in TTTS?

A

heart failure -> demise

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22
Q

can you diagnose TTTS on US?

A

yes!

  • donor twin: smaller, “stuck” appearance, oligohydramnios
  • recipient twin: larger, polyhydramnios, ascites
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23
Q

what is the tx of TTTS?

A
  • serial amniocentesis with amniotic fluid reduction (can reduce preterm contractions secondary to uterine distention)
  • laser photocoagulation of the anastamotic vessels on the placenta (performed at specialized centers)
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24
Q
  • arterial blood flow from the donor twin enters the arterial circulation of the recipient twin
  • reversed blood flow may cause thrombosis within critical organs or atresias due to trophoblastic embolization
  • the recipient twin, being perfused in reverse direction with poorly oxygenated blood fails to develop normally -> known as ACARDIAC twin (fully formed lower extremities, no amatomic structures cephalad of the abdomen)
A

abnormalities in monozygotic twins with arterial to arterial anastomoses

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25
Q

this abnormality is primarily associated with monochorionic twins

  • absence of umbilical artery
  • occurs in 3-4% of twins (1% in singletons)
  • velamentous umbilical cord insertions occur more frequently (may cause growth abnormalities)
A

umbilical cord abnormalities in monozygotic twins

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26
Q

what is vanishing twin syndrome?

A

when <12 weeks, the dead fetus is reabsorbed

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27
Q

what is retained dead fetus syndrome

A

if gestation >20 weeks

  • disseminated intravascular coagulopathy in the mother
  • single fetal death in utero
  • check platelets and fibrinogen levels weekly
28
Q

what is fetus papyraceus?

A

if >12 weeks, the fetus shrinks, dehydrates and flattens

29
Q
  • polyhydramnios
  • anemia
  • gestational HTN
  • preeeclampsia
  • GDM
  • preterm labor
  • c-section
  • postpartum hemorrhage
  • uterine atony
A

maternal complications of multiple gestations

30
Q
  • prematurity
  • malpresentation
  • placenta previa
  • placental abruption
  • PROM
  • umbilical cord prolapse
  • IUGR
  • congenital anomalies
  • increased perinatal morbidity/mortality (RDS, intracranial hemorrhage, necrotizing entercolitis)
A

fetal complications of multiple gestations

31
Q

what is the antepartum management of multiples in first and second trimesters?

A
  • 2 week office visits

- US cervical length assessments

32
Q

what is the antepartum management of multiples in the third trimester?

A
  • serial US to check intrauterine growth q 4-6 weeks, begin at 24 weeks
  • antepartum test (NST weekly, or BPP)
  • pt often placed on bed rest
33
Q

what are you looking for in serial US during third trimester?

A

looking for discordant fetal growth

- defined by 20% reduction in fetal weight of the smallest fetus compared with the largest

34
Q

when should monoamniotic twins be delivered?

A

by 32 weeks

  • secondary to increased risk of lethal cord entaglement
  • hospitalization at 26 weeks, antenatal steroids, and fetal heart monitoring several times daily
35
Q

when do the majority of twin gestations deliver?

A

35-36 weeks

- recommend delivering at 38 weeks if pregnancy has no complications

36
Q

what are the prerequisites for intrapartum management of twins?

A
  • large bore IV
  • simultaneous fetal HR monitors
  • anesthesiologist
  • US to determine presentation
  • two pediatricians/NICU personnel, one for each baby
37
Q

after delivery of first twin, cord is clamped and cut

  • vaginal exam is performed to assess presentation and station of second twin
  • second twin at increased risk of cord prolapse, placental abruption and malpresentation
  • pay close attention to fetal monitoring!
  • after second twin delivers, obtain cord samples and deliver placenta
  • be prepared for postpartum hemorrhage secondary to uterine atony
A

vertex-vertex presentation

- can manage similar to singleton

38
Q

difficulty extracting a breech second twin can result in what?

A
  • umbilical cord prolapse
  • head entrapment
  • neck injury
  • asphyxia
39
Q

how are breech-breech and breech-vertex twins delivered?

A

c-section

NOTE: vertex-transverse and vertex-breech can be delivered vaginally

40
Q

why is there a 5x greater perinatal mortality in twins?

A
  • secondary to prematurity and congenital anomalies
  • RDS and intracranial hemorrhage
  • birth asphyxia: second twins have 2x more perinatal mortality than the first born twin, 4x more likely than first to die from birth trauma complications
41
Q

4 fold increase in what is noted in twins?

A

cerebral palsy

- stillbirths occur 2x more frequently than singletons

42
Q

what are the most likely causes of higher order multiples?

A

embryo splitting and polyovulation

  • most frequently result of ovulation induction agents
  • triplets 1 in 3,000 with ART, spontaneous = 1 in 8,000
  • spontaneous quads 1 in 700,000
43
Q

what are the average gestation ages at delivery of triplets and quads?

A

triplets: 33 weeks
quads: 29 weeks
- by c-section

44
Q

what are the factors associated with breech presentation?

A
  • prematurity (before 28wks, 24% of fetuses are breech)
  • fetal malformations: hydrocephaly, anencephaly
  • multiple pregnancies
  • uterine malformations: bicornate uterus
45
Q

how to you dx a breech presentation?

A

leopolds maneuver, US and pelvic exam

46
Q

most common breech presentation

  • thighs are flexed
  • lower extremities are extended at knees
A

Frank presentation (65%)

47
Q

thighs are flexed

- lower extremities are flexed (sitting cris-cross)

A

complete (25%)

48
Q

1 or both thighs are extended

- 1 or both feet are below the buttocks

A

incomplete (10%)

49
Q

applying pressure to the mother’s abdomen to turn the fetus in either a forward or backward somersault to achieve a vertex position

A

external cephalic version (ECV)

- candidates: 36 weeks, NOT in labor

50
Q

what are the contraindications for ECV?

A
  • placenta previa
  • non-reassuring fetal monitoring
  • oligohydramnios
  • previous uterine surgery that is a contraindication for vaginal delivery
51
Q
  • pt should be NPO x 7 hrs
  • IV access
  • performed in hospital that is equipped for immediate c-section if necessary
  • place on continuous monitoring (NST or BPP)
  • consider tocolytics (nulliparous) or anesthesia
A

ECV

- successful 58% of the time

52
Q

what are the criteria for vaginal delivery of breech presentation?

A
  • fetus must be in frank or complete presentation
  • > 37 weeks
  • fetal weight 2500-4000g
  • fetal head must be flexed
  • adequate maternal pelvis
  • no maternal or fetal contraindications for vaginal delivery
  • assistant and anesthesia prepared to assist
53
Q

what is the standard of care now regarding breech deliveries?

A

most practices, is to deliver all breeches by c-section

54
Q

assisted breech vaginal delivery

- premature aggressive traction can cause what?

A

deflexion of the fetal vertex and increase risk of head entrapment or nuchal arm entrapment
- allow fetus to deliver scapulae

55
Q

what do you do after spontaneous expulsion of the scapulae in an assisted breech vaginal delivery?

A

external rotation of each thigh combined with opposite rotation of the fetal pelvis results in flexion of the knee and delivery of the leg

56
Q

when the scapulae appears under the symphysis, what do you do in an assisted breech vaginal delivery?

A

wrap a towel around the fetus for better traction

  • reach over the left shoulder, sweep the arm across the chest and deliver the arm
  • delivery of the head is easily accomplished with continued uterine contractions, suprapubic pressure and gentle traction
57
Q

to deliver the head in an assisted breech vaginal delivery, maintain cephalic flexion by applying pressure where?

A

the fetal maxilla NOT mandible

58
Q

what kind of forceps can be used in breech deliveries?

A

piper forceps

59
Q

in a breech presentation, the head can become entrapped, leading to what?

A

fetal asphyxia with increased morbidity/mortality

NOTE: perinatal mortality for breeches is higher than for vertex fetuses

60
Q

what are the most common factors for perinatal mortality of breech presentations?

A

lethal congenital anomalies, prematurity (most common) birth trauma, asphyxia

61
Q

this presentation occurs when the presenting part of the fetus is between the facial orbits and anterior fontanelle

  • head is extended backwards (not flexed)
  • presenting diameter is the supraoccipitomental diameter (13.5cm compared to 9.5 for suboccipitobregmatic)
  • frontal bones are the point of designation
  • incidence: 1 in 1,400
A

BROW presentation
- 50-75% will convert to a face presentation (through extension) or a vertex presentation (through flexion) and then deliver

NOTE: persistent brow presentation makes vaginal delivery impossible -> deliver by c-section

62
Q

this presentation is characterized by full extension of the fetal head and neck with occiput against upper back

  • incidence in 1 in 500 deliveries
  • anencephaly seen in 1/3 of these presentations
  • fetal chin is chosen as point of designation
A

FACE presentation

63
Q

which face presentation can be delivered vaginally?

which MUST be done via c-section?

A
  • mentum anterior: 60% can deliver vaginally

- mentum posterior can NOT deliver vaginally

64
Q

trachelobregmatic diameter

A

head is completely extended backwards

- 12.6cm diameter

65
Q

this presentation is when a fetal extremity (usually the hand) is found prolapsed alongside the presenting fetal part (head)

  • occurs more frequently with premature gestation
  • incidence of fetal arm or hand prolapsing along side the presenting head occurs 1 out of every 700 deliveries
A

COMPOUND presentation

  • may resolve on its own as it comes down the pelvis
  • some recommend gently pushing the small part upward while simultaneously applying fundal pressure
  • c-section if failure progresses, cord prolapse, or non-reassuring fetal status noted
66
Q

what does cervical length <25mm at 24-48 weeks double the risk of?

A

preterm birth

EndoRepro 2 Exam 1 (25 decks)

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