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Endo/Repro > Multifetal Gestations and Malpresentation > Flashcards

Multifetal Gestations and Malpresentation Flashcards

1
Q

What is multiple gestations defined as?

A
  • Any pregnancy in which two or more embryos or fetus occupy the uterus simultaneously
  • Have increased over the years secondary to ovulation induction agents and assisted reproductive technology
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2
Q

What are dizygotic twins?

A
  • Arise when two separate ova are fertilized by two separate sperm
  • Are distinct pregnancies coexisting in the same uterus
  • Each will have its own amnion, chorion, and placenta
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3
Q

What are monozygotic twins?

A
  • Arise from cleavage of a single fertilized ovum at various stages during embryogenesis
  • Thus the arrangement of fetal membranes and placentas will depend on the time at which the embryo divides
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4
Q

What is the nature of the membrane if monozygotic twins separate at 0-3 days?

A
  • Dichorionic

- Diamniotic

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5
Q

What is the nature of the membrane if monozygotic twins separate at 4-8 days?

A
  • Monochorionic

- Diamniotic

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6
Q

What is the nature of the membrane if monozygotic twins separate at 9-12 days?

A
  • Monochorionic

- Monoamniotic

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7
Q

What is the nature of the membrane if monozygotic twins separate at >13 days?

A
  • Conjoined twins
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8
Q

What is the placenta like when monozygotic twins split at 0-3 days?

A
  • Could be separate but could be fused
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9
Q

What is the most common presentation of monozygotic twins?

A
  • 1 chorion and 2 amnions

- Splitting in 4-8 days

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10
Q

What is the most dangerous cleavage of monozygotic twins?

A
  • Cleavage in 9-12 days
  • 1 chorion and 1 amnion
  • Most dangerous because they are not separating amnions which leaves high risk for cord entanglement
  • High net mortality in these twins
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11
Q

What is craniopagus?

A
  • Conjoined twins at the head
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12
Q

What is thoracopagus?

A
  • Conjoined twins at the chest wall

- Highest incidence of conjoined twins

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13
Q

What is ischiopagus?

A
  • Conjoined at the coccyx and sacrum
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14
Q

What is the epidemiology of monozygotic twins?

A
  • Frequency is constant in all populations at 1 in 250
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15
Q

What can influence dizygotic twins?

A
  • Maternal age: 2x more common after 35 years old

- Family history and ethnicity: twinning is low in asians, intermediate in whites and high in blacks

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16
Q

What may a history and physical look like for multiple gestations?

A
  • hCG is higher than normal
  • Uterus palpates larger than dates
  • Auscultation of more than one fetal heart rate
  • Pregnancy has occured after ovulation induction or in vitro fertilization
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17
Q

What confirms the presence of multiple fetus?

A
  • Ultrasound

- Determine the number of fetuses, gestational sacs and chorionicity

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18
Q

What are monozygotic twins more at risk for?

A
  • Congenital anomalies
  • Weight discordancy
  • Twin-twin transfusion syndrome
  • Neurologic sequelae
  • Premature delivery
  • Fetal demise
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19
Q

What it the most important step after finding out about multiple gestations?

A
  • Determination of zygosity
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20
Q

What will be seen under ultrasound that points towards dizygotic twins?

A
  • Different fetal genders
  • Visualization of a thick amnion-chorion septum
  • “Peak” or “inverted V” sign at the base of the septum
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21
Q

What will be seen under ultrasound that points towards monozygotic twins?

A
  • Dividing membrane is fairly thin
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22
Q

What is done if ultrasound is not definitive in determining zygosity?

A
  • Inspect placenta after delivery

- DNA analysis

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23
Q

What is the mortality rates of conjoined twins?

How are they delivered?

A
  • 50%

- Delivered via C section

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24
Q

What will imaging show for conjoined twins?

A
  • Mapping of shared organs allows for more successful surgical separation procedures
  • Elective termination is done if cardiac or cerebral fusion is identified
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25
Q

What are interplacental vascular anomalies?

A
  • Most common type is arterial-arterial followed by arterial-venous and then venous-venous
  • Vascular communications between the 2 fetuses through the placenta can cause several problems (abortion, polyhydramnios, TTTS, and fetal malformations)
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26
Q

What does twin twin transfusion syndrome result from?

A
  • Secondary to uncompensated arteriovenous anastomoses in monochorionic placenta which leads to a net transfer of blood flow going from one twin to the other
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27
Q

What fetal complications are seen in the donor twin in twin twin transfusion syndrome?

A
  • Hypovolemia
  • Hypotension
  • Anemia
  • Oligohydramnios
  • Growth restriction
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28
Q

What fetal complications are seen in the recipient twin in twin twin transfusion syndrome?

A
  • Hypervolemia
  • Polyhydramnios
  • Thrombosis
  • HTN
  • Polycythemia
  • Edema
  • Cardiomegly/CHF
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29
Q

What are both twins at risk for in TTTS?

A
  • Heart failure causing death
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30
Q

What is seen in ultrasound in TTTS?

A
  • Donor twin: smaller in size, “stuck appearance, oligohydramnios
  • Recipient twin: larger in size, polyhydramnios, ascites
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31
Q

How is TTTS treated?

A
  • Serial amniocentesis with amniotic fluid reduction
  • Can reduce preterm contractions secondary to uterine distention (polyhydramnios) and maternal symptoms
  • Laser photocoagulation of the anastomosis vessels on the placenta is performed at specialized centers
32
Q

What is an aretial to arterial anastomomes?

A
  • Arterial blood flow from the donor twin enters the arterial circulation of the recipient twin
  • The reversed blood flow may cause thrombosis within critical organs or atresias due to trophoblastic embolization
  • Recipient twin, being perfused in a reverse direction with poorly oxygenated blood fails to develop normally (Known as arcardic twin)
33
Q

What is an arcadic twin?

A
  • Recipient twin that is poorly perfused due to reverse blood flow direction
  • Fully formed lower extremities
  • No anatomic structures cephalad of the abdomen
34
Q

What umbilical cord abnormalities could be seen in multiple gestations?

A
  • Primarily associated with monochromatic twins
  • Absence of umbilical artery (30% of cases is associated with other congenital anomalies like renal agenesis)
  • Velamentous umbilical cord insertions occur more frequently and may cause growth abnormalities
35
Q

What is retained dead fetus syndrome?

A
  • Incidence of a single fetal death in utero is 5%
  • If gestation is 20 weeks or greater retained dead fetus syndrome can develop due to disseminated intravascular coagulopathy in mother (check platelets and fibrinogen weekly)
36
Q

What happens in retained dead fetus syndrome if gestation is <12 weeks?

A
  • Fetus is reabsorbed called “vanishing twin syndrome”
37
Q

What happens in retained dead fetus syndrome if gestation is >12 weeks?

A
  • Fetus shrinks, dehydrates, and flattens called fetus papyraceus
38
Q

What are some maternal complications with multiple gestations?

A
  • Polyhydramnios
  • Anemia
  • Gestational HTN
  • Preeclampsia
  • Preterm labor
  • Gestational diabetes
  • C section
  • Postpartum hemorrhage
  • Uterine atony
39
Q

What are some fetal complications with multiple gestations?

A
  • Prematurity
  • Malpresentation
  • Placenta previa
  • Placental abruption
  • PROM
  • Umbilical cord prolapse
  • IUGR
  • Congenital anomalies
  • Increased perinatal morbidity and mortality
40
Q

What is the antepartum management in multiple gestations during the first and second trimesters?

A
  • 2 week office visits

- Ultrasound cervical length assessments

41
Q

What is the antepartum management in multiple gestations during the third trimester?

A
  • Cervical length of less than 25mm at 24-28 weeks doubled the risk of for premature births in twins
  • Serial ultrasounds to check for intrauterine growth every 4-6 weeks begin at 24 weeks looking for discordant fetal growth
  • Antepartum testing
  • Often placed on bed rest
42
Q

When should monoamniotic twins be delivered? Why?

A
  • At 32 weeks

- Secondary to increase risk for lethal cord entanglement

43
Q

When do a majority of twin gestations deliver?

A
  • 35-36 weeks

- 38 weeks if no complications

44
Q

What are prerequisites for intrapartum management?

A
  • Delivery room equipped for immediate cesarean section
  • Large IV bore needle, blood products
  • Capability to monitor fetal heart rates simultaneously
  • Anesthesiologist immediately available
  • Ultrasound to determine precise presentations of twins
  • Two pediatricians/NICU personnel, one for each baby
  • Appropriate number of nurses to assist in delivery and care
45
Q

What is the process of delivery in a vertex-vertex presentation?

A
  • After delivery of the first twin, cord is clamped and cut
  • Vaginal examination is performed to assess presentation and station of second twin
  • Careful attention to fetal monitoring is necessary
  • After second twin delivers obtain cord samples and deliver placenta
  • Be prepared for postpartum hemorrhage secondary to uterine atony
46
Q

What is the second twin at risk for in a vertex-vertex presentation?

A
  • Cord prolapse
  • Placental abruption
  • Malpresentation
47
Q

How are vertex-transverse and vertex-breech presentations delivered?

A
  • Able to be done vaginally but often by C sections

- No evidence that C section is superior but there is a difficulty in extracting breech second twin

48
Q

What could result during delivery of a breech second twin?

A
  • Umbilical cord prolapse
  • Head entrapment
  • Neck injury
  • Asphyxia
49
Q

How are breech-breech or breech-vertex twins delivered?

A
  • C section
50
Q

What are some perinatal outcomes in twins?

A
  • High perinatal mortality rate 5x greater than in singletons secondary to prematurity and congenital anomalies
  • Stillbirths occur 2x more frequently
  • 4x increase in cerebral palsy
  • Postnatally twins are on average shorter and lighter than singletons of same birth weight
51
Q

What is the perinatal mortality due to in twins?

A
  • RDS and intracranial hemorrhage

- Birth asphyxia

52
Q

What can higher order multiples result from?

A
  • Embryo splitting and polyovulation

- Most frequently a result of iatrogenic causes

53
Q

How does prematurity increase in higher order multiples?

A
  • Triplets are delivered at 33 weeks via C section

- Quads are delivered at 29 weeks via C section

54
Q

What are some fetal malpresentations?

A
  • Any fetal presentation other than vertex
  • Breech
  • Face
  • Brow
  • Shoulder
  • Compound
55
Q

What is the breech presentation?

A
  • Fetal buttocks or lower extremities present into the maternal pelvis
56
Q

What are some factors associated with fetal breech?

A
  • Prematurity is most common factor
  • Fetal malformation –> hydrocephaly and anencephaly
  • Multiple pregnancies
  • Uterine malformations –> bicornuate uterus
57
Q

How is a breech presentation diagnosed?

A
  • Leopolds maneuver

- Ultrasound and pelvic exams

58
Q

What is the frank breech presentation?

A
  • Most common presentation
  • Thighs flexed
  • Lower extremities are extended at the knee
59
Q

What is the complete breech presentation?

A
  • Thighs are flexed

- Lower extremities are flexed

60
Q

What is the incomplete breech presentation?

A
  • 1 or both thighs are extended

- 1 or both feet are below the buttocks

61
Q

What is external cephalic version?

A
  • Involves applying pressure to the mother’s abdomen to turn the fetus in either a forward or backward somersault to achieve vertex presentation
62
Q

Who are candidates for the ECV?-

A
  • 36 week gestation not in labor
63
Q

What are some contraindications of ECV?

A
  • Placental previa
  • Nonreassuring fetal monitoring
  • Oligohydramnios
  • Previous uterine surgery that is a contraindication for vaginal delivery
64
Q

How is the ECV performed?

A
  • In a hospital that is equipped for an immediate C section
  • Patient should be NPO x 7hrs
  • Review risks, benefits, alternatives and obtain consent
  • IV access
  • Place on continuous electric monitoring
  • Confirm breech presentation with ultrasound
  • Consider tocolytics or anesthesia
  • Perform procedure
65
Q

What is the criteria for vaginal delivery of breech presentation?

A
  • Fetus must be in frank or complete presentation
  • Gestational age >37 weeks
  • Fetal head must be flexed
  • Adequate maternal pelvis
  • No maternal or fetal contraindications for vaginal delivery
  • Availability of anesthesia and neonatal support
  • Assistant must be scrubbed and prepared to assist
66
Q

What is important when doing a breech vaginal delivery?

A
  • Allow fetus to deliver to scapulae
  • Premature aggressive traction can cause deflexion of the fetal vertex and increase risk of head entrapment or nuchal arm entrapment
67
Q

What is done to the fetus after it has expulsed to the scapulae?

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
  • Wrap a towel around the fetus for better traction
  • When the scapulae appear under the symphysis
  • The operator reaches over the left shoulder, sweeps the arm across the chest and delivers the arm
68
Q

How is delivery of the head achieved in a breech presentation?

A
  • Often delivery of head is easily accomplished with continued uterine contractions, suprapubic pressure, and gentle traction
  • Maintain cephalic flexion by applying pressure on fetal maxilla NOT fetal mandible
69
Q

What is the prefered delivery method for breech presetnations?

A
  • C section due to the risk of fetal head becoming entrapped and leading to fetal asphyxia with increased morbidity and mortality
70
Q

What is the brow presentation?

A
  • Presenting part of fetus is between the facial orbits and anterior fontanelle
  • Presenting diameter is supraoccipitomental diameter
  • Frontal bones are the point of designation
71
Q

Can a brow presentation be delivered vaginally?

A
  • No, very difficult

- Deliver by C section

72
Q

How can a brow presentation be altered to allow a vaginal delivery?

A
  • Go into extension for a face presentation

- Go into flexion for a vertex presentation

73
Q

What is the supraoccipitomental diameter?

A
  • 13.5 cm
74
Q

What is the face presentation?

A
  • Full extension of the fetal head and neck with occiput against upper back
  • Can be seen in fetal malformations like anecephly
75
Q

What is the point of designation in the face presentation?

A
  • Chin

- 60% of mentum anterior allows for a vaginal delivery

76
Q

What is the trachelobragmatic diameter?

A
  • 12.6 cm
77
Q

What are some compound presentations?

A
  • When a fetal extremity is found prolapsed alongside the presenting fetal part (head)
  • More frequently in premature gestation
  • May resolve on its own as it comes down the pelvis
  • C section done if failure to progress, cord prolapse, or nonreassuring fetal status is noted

Endo/Repro (31 decks)

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