15. Multifetal Gestation and Malpresentation Flashcards
Dizygotic twins (fraternal) two separate ova fertilized by two separate sperm, each has own amnion, chorion, placenta (dichorionic/Diamniotic), Monozygotic twins (identical) from cleavage of single fertilized ovum at various stages- thus placentas depends on when they divided... 0-3 days : dichorionic/diamniotic 4-8 days: monochorionic/diamniotic 9-12 days: monochorionic/amniotic >13 days:?
CONJOINED TWINZ
What is the MC presentations (69%) of twins- monozygotic?
4-8 day cleavage, 1 chorion-2 amnions
Monochorionic monoamniotic monozygotic placenation occurs at 13-15 days or grater and causes conjoined twins, craniopagus, ischiopagus and what is the MC and conjoined at the chest wall?
Thoacopagus (30-40%)
Monozygotic twins make up 1/3 of all twins, dizygotic twins are influenced by maternal age (older) and family history and ethnicity (low in asians, high in blacks), 2/3 of spontaneous twins are dizygotic… Suspect mutiple gestations if uterus palpates larger than dates, ausculation of more than one heart, preg occured via induction or in vitro fert, confirmation of multiples by US and most importantly?
hCG is higher than normal
porgnosis and expected morbidity of twins is STRONGLY dependent on zygosity… Monozygotic have increased congen anomalies, weight discordancy, TTTS, neurologic sequale, premature delivery and fetal demise- determining zygosity is THE MOST IMPORTANT step after?
diagnosing twins
on US: dizygotic will see different fetal gender, visualization of THICK amnion-chorion septum and peak or inverted V sign at base of septum*, monozygotic the dividing membrane is THIN, US not definitive in determing zygosity, then inspect placenta after delivery or do a DNA?
analysis
Interplacental vascular anastomoses occurs in 90% of monochoirionic twins, MC is arterial arterial, vascular communications between 2 fetuses through placenta can couse abortion, polyhydramnios, TTTS, and fetal malformations. What results secondary to uncompensated arterial-venous anastomoses in a monochorionic placent which leads to a net transfer of blood flow going from one twin to the other twin?
Twin Twin Transfusion Syndrome TTTS
*both twins at risk of heart failure - poor prog if untreated
- dx on US, donor is smaller/stuck/oligohydramnios
- recipient is larger, polyhydramnios,ascites
- tx with amniocentesis (historically) or laser photocoagulation of the anastamosis vessels
Monozygotic can also lead to fetal malformations due to arterial arterial anastomoses, arterial blood flow from donor twin enters arterial circulation of reicpient twin, causing thrombosis within ciritical organs and atresias due to trophoblastic embolization, recipient twin being perfused in reverse direction with poorly oxygenated blood is known as?
acardiac twin (fully formed LE/ no structures above abd)
Monozygotic can also cause umbilical cord abnormalities primarily assoc with monochorionic twins*, absence of umbilical artery can occur with other congenital anomalies (renal agenesis) and velamentous umbilical cord insertion occur more freq and may cause growth?
abnormalities
Retained dead fetus syndrome: single fetal death gestation greater than 20 weeks- see DIC in mom/ check platelets and fibrinogen levels weekly, if gestation is less than 12 weeks dead fetus is reabsorbed = vanishing twin syndrome, if >12 weeks the fetus shrinks, dehydrates and flattens, called fetus?
papyraceus
Complications of multiple gestations includes polyhydramnios, anemia, HTN, preeclampsia, GDM, preterm labor, Csection, hemorrhage, uterine atony, fetal: premature, malpresentation, placentra previa, palcental abruptions, PROM, umbilical cord prolapse, IUGR,congential anomalies, increase perinatal morbidity and mortality including RDS, intracranial hemorrhage and necrotizing?
entercolitis
anterpartum management of multiple gestations during 1/2nd trimester: 2 week office visits w US cervical length assesments, 3rd trimester: US q 4-6 weeks checking IU growth, beinging at 24 weeks, *** antepartum testing (NST/weekly BPP) and often patients will be put on?
bed rest
Monoamniotic twins should be delivered at 32 weeks, secondary to increase risk for lethal cord entaglement, hospitalization at 26 weeks, steroids and FHR monitoring several times per day, most twin gestation deliver at 35-36, recommond delivering at what if there are no complications?
38 weeks
Intrapartum management of multiple gestations requires delivery room w immediate access to cesaread, large bore IV, FHR monitoring, anethesiologist availble, US to determine presentaions, two pediatricians… What is the best presentation- twin A and twin B, occurs 40-50% of time, managed same as normal pregnancy?
Vertex-Vertex presentation
all other presentations deliverd c section usually
High perinatal mortality: 5x greater than single deliveries, 2nd twin 2xinc mortality and 4x more likely to die from birth trauma, 4fold inc in cerebral palsy in twins. Prematurity increases as the number of fetuses increases, triplets at 33 weeks, quadruplets at 29 weeks, delivery is done via?
C section (triplets/quadruplets mortality twice that of twins)
