Multiple Pregnancy
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Multiple pregnancy Dr. Nderitu MULTIFETAL PREGNANCY Epidemiology ⋅ 1:70 Black ⋅ 1:90 White ⋅ 1:150 Asian ⋅ 1:89 Twins ⋅ 1:892 Triplets Etiology 1.Identical/Uniovular/monozygoti c twins - arise from a single fertilized ovum that subsequently divides into two similar structures, each with the potential for developing into a separate individuals • If division occurs before the inner cell mass (morula) is formed and the outer layer of blastocyst is not yet committed to become Chorion - that is, within the first 72 hours after fertilization - two embryos, two amnions, and two chorions will develop. • There will evolve a diamnionic, dichorionic, monozygotic twin pregnancy. • If division occurs between the fourth and eighth day, after the inner cell mass is formed and cells destined to become chorion have already differentiated but those of the amnion have not, two embryos will develop, each in separate amnionic sacs. • The two amnionic sacs will eventually be covered by a common chorion, thus giving rise to diamnionic, monochorionic, monozygotic twin pregnancy. •If, however, the amnion has already become established, which occurs about 8 days after fertilization, division will result in two embryos within a common amnionic sac, or a monoamnionic , monochorionic , monozygotic twin pregnancy. •- If division is initiated even later - that is, after the embryonic disk is formed - cleavage is incomplete and conjoined/siamese twins are formed. • Have an identical genotype and phenotype. 2.Fraternal/Biovular/dizyg otic twins .Result from fertilization of two separate ova .Have different genotype and phenotype. Predisposing factors to twinning • Black race • Familial - only for fraternal cases and inherited on the maternal side only (double ovulation) • Double ovulation is also increased with advancing age and increasing parityRaptured uterus,risks and management Complications of twin pregnancy Maternal a)Polyhydramnios due to a large placenta with more amniotic fluid production. b)Adominal tightness leads to maternal respiratory embarrassment c)Hyperemesis gravidarum due to increased hCG (peaks at 11-12wks) d)The large uterus exerts more pressure on the Inferior Vena Cava with a reduction in venous return leading to varicose veins and hemorrhoids. e)Pre-eclampsia due to high blood volumes and increases pressor amines. f)Prolonged rupture of membranes. g) Placenta previa/Vasa previa(fatal vessles running or closing in close proximity to the internal os) due to the large size of the placenta ⋅ h) Abnormal presentations (breech) ⋅ i) Premature labor due to over distension ⋅ J) Increased nutritional demand ⋅ k)Malpresentation (55%) Cephalic/cephalic (45%) Cephalic/Breech (35%) If the breech comes out first, then the 2 heads get stuck - Locked twins - and the first twin definitely dies and is decapitated and the next twin is born by C/S Others (20%) - Breech/Transverse • - Breech/Breech • - Transverse/Transverse others ⋅ Increases C/S rates ⋅ Post partum uterine atony - PPH; poorly responsive to ergometrin ⋅ maternal renal function may become impaired as the consequence of obstructive uropathy ⋅ Inadequate uterine contraction during labor due to the large size of the uterus Fetal ⋅ a) IUGR ⋅ b) Prematurity as at 7mo/3wks the term fundal height is achieved ⋅ c ) Twin-twin transfusion - An artery from one twin delivers blood that is drained into the vein of the other. The latter becomes plethoric and large while the former is anemic and small . ⋅ d) Monoamniotic twins have an increased likelihood of entangling their cords, which may lead to asphyxia. ⋅ e) Also, cord compression, cord prolapse ⋅ f) Congenital anomalies that occur predominantly in monozygotic twins ⋅ g)Abortion especially in triplets h) Undiagnosed retained second twin - On use of ergometrin after delivery of the 1st twin, the 2nd dies due to tetanic contractions that cut-off blood supply to the placenta Dx Demonstration of 2 or more fetuses by • ultrasonography, • fetal heartbeats, • multiplicity of fetal parts) • Disproportionately large (> 4 cm) uterus for dates DDx • Elevation of the uterus by a distended bladder • Inaccurate menstrual history • Hydramnios • Hydatidiform mole • Uterine myomas • A closely attached adnexal mass • Fetal macrosomia late in pregnancy ⋅ Increased and persistent fetal activity ⋅ Greater-than-expected maternal weight gain that is not explained by edema or obesity ⋅ Earlier and more severe pressure in the pelvis resulting in - • - Hyperemesis gravidarum • - Backache • - Varicosities • - Edema • - Constipation • - Hemorrhoids • - Abdominal distention • - Difficulty in breathing. examination ⋅ Outline or ballottement of more than one fetus ⋅ Multiplicity of small parts ⋅ Uterus containing 3 or more large parts ⋅ Simultaneous recording of different fetal heart rates, 10 cm apart, each asynchronous with the mother's pulse and with each other and varying by at least 8 beats per minute. ⋅ Palpation of one or more fetuses in the fundus after delivery of one infant ⋅ A familial history of twins ⋅ Recent administration of either clomiphene or pituitary gonadotropin Ix Obstetric ultra sound Mx • Principles ⋅ Delivery of markedly preterm infants is prevented. ⋅ Several techniques have been applied in attempts to prolong multifetal gestations. ⋅ These include bed rest , especially through hospitalization, prophylactic administration of anti-mimetic drugs/tocolytics e.g. Ventolin, and prophylactic cervical cerclage. ⋅ Failure of one or both fetuses to thrive be identified and fetuses so afflicted be delivered before they become moribund ⋅ Fetal trauma during labor and delivery be eliminated ⋅ Expert neonatal care be provided ⋅ Administration of hematinics to prevent anemia Delivery of Twin Fetuses 1st stage ⋅ oxytocin augmentation of labor due to uterine hypotonia being common ⋅ labor is allowed only if the 1st twin is in cephalic presentation; otherwise C/S Indications for C/S; • - 1st twin not in cephalic presentation • - Twins with any other obstetric complications • - All multifetal pregnancies > twins ⋅ IV 10% dextrose to inhibit anaerobic respiration ⋅ Twin pregnancies should not be allowed to go post date (within 2 weeks) due to increased risk of placental insufficiency (placenta degenerates after term) 2nd Stage ⋅ Episiotomy is always advised - 2nd twin’s head hardly moulds therefore risk of intracranial hemorrhage ⋅ 1st fetus is delivered in the usual way (cephalic with good contractions) ⋅ Clamp the cord at 2 points and cut it in-between ⋅ Don’t apply traction to the remaining cut cord - risk abruptio placenta which leads to death if they’re sharing one placenta ⋅ Don’t give ergometrin . Palpate via vaginal examination for the umbilical cord of the 2nd twin to r/o cord presentation/prolapse (feel a pulsation under the membranes on vaginal examination) . Palpate the abdomen for lie of 2nd twin (if there was no cord presentation/prolapse) – If not longitudinal, align it. ⋅ Palpate for presenting part; •- If cephalic, then artificial rupture of membranes is done as the fundus is being pressed downwards to cause head engagement (cord can’t come out) • -If breech/transverse, then do; • - External cephalic version •- Internal podalic version (done with the hand in the vagina creating a breech) - Important if there’s cord prolapse in 2nd twin • Breech extraction follows the IPV. ⋅ If cord prolapse with cephalic presentation, the IPV cant be done, therefore go for vacuum extraction to prevent cord compression ⋅ After the delivery of the 1st twin, an interval of 5mins is normal before contractions resume •After 5mins without contractions with a cephalic 2nd twin, then give an IV oxytocin drip to restart the contractions ⋅ Delay in 2nd twin delivery > 30mins increases neonatal mortality 3rd stage ⋅ Increased risk of post partum hemorrhage due to uterine atony. ⋅ This is prevented by active management of 3rd stage; • - IV ergometrin 0.5mg stat (tetanic contractions lasting 1hr) • - IV oxytocin 40IU in 500ml 5% dextrose drip to run 40-60 drops/min Labor Complications ⋅ preterm labor ⋅ Uterine dysfunction ⋅ Abnormal presentations ⋅ prolapse of the umbilical cord ⋅ Premature separation of the placenta ⋅ Immediate postpartum hemorrhage.