.IncidenceThe incidence of multiple pregnancy Increased in recent yrs . Incidence is highest in black race and as frequent as 1:19 in Nigerians India & UK 1:80-90 ; while it is 1:155 in Japan Increased incidence in present era owes to IVF(50%) & GIFT technique. CC7-10% ,FSH30-40%,GNRH induces 1% Multiple pregnancy. 75% pregnancies are dizygotic and 25% are monozygotic at constant rate of 4/1000 world over. Hellins Law it is 1:80. N2:(80) 2 ,N3: (80)3 and so on. N for Twin pregnancy, 1:N2 for Triplets and N3 for Quadruplet and so on
Aetiology True incidence is twice in early pregnancy then that in late pregnancy.USG Study show Twin Gestation, followed by disappearance of one Sac. Age & Parity : advancing age>35 , and parity>4 Dizygotic twin : pregnancy runs in family. Drugs used in induction of ovulation & Assisted Reproductive Techniques (ART) Local environmental disturbances in early embryonic stage result in Monozygotic twin pregnancy.
Pathology Fertilization of two separate ova in same menstrual cycle ---results in Binovular- Dizygotic(DZ)Dichorionic-Diamniotic twin pregnancy. They are not identical and behave as different siblings in the family. Their sex may be same or different . 98 % have separate placenta and 4 layers of amnion
Monozygotic Several varieties of MZ twinsare possible depending upon the number of days after fertilization when the zygote splits.Division upto Day- 3 results Dichorionic-Diamniotic If cleavage occurs after formation of inner cell mass (4-7days after fertilization)Monochorionic –Diamniotic .Division between Day 8-12 the amnion is alreadyformed by the time split occurs,MonochorionicMonoamniotic twin develops 1%. Split after 13-14 days—results in Conjoined twins. MZ twins are identical in sex, genetically and acquire the same diseases in later life.
Cont------- Entaglementof cord may end in IUFD. Locked twins can also occur. Conjoined twins are rare (1:60,000)- Thoracophagus,craniophagus,ischiophagus. The incidence of abnormities in twins is high 2.7%compared to 1.4% in singletons and 6.1% in triplets. Acute hydramnios occurs in MZ in 2nd trimester and leads to spontaneous abortion.
Positions of the fetuses VX—VX 38% VX—Breech 25% Breech—VX 10% Breech—Breech 5% VX –Transverse Breech-Transverse Transverse-Transverse
Unfavourability of MZ twins Sharing of blood supply between two fetuses in MZ---a varying degree of anastomosis will cause discordant blood flow=>one fetus will be growing bigger, Polycythaemic and develops polyhydramnios. The donor fetus is growth retarded and at times shrinks(fetus papyraceous or compresses) dies in utero. Twin to Twin Transfusion Syndrome (TTTS) occurs in 10% cases of MZ. It is Rx— amniocentesis/laser ablation of anastomosing blood vessels.
TWIN to TWIN TRANSFUSION SYNDROME QUINTERO STAGES STAGE I : Oligohydramnios 1st Twin, Polyhydramnios 2nd Twin STAGE II : Supra, Absence of Bladder in donor Twin STAGE III : Supra, Additionally Doppler studies Show critical abnormalities i.e. absent/reverse end diastolic velocity in Umbilical artery, reverse flow in ductus venosus, pulsatile flow in Umbilical vein
TWIN to TWIN TRANSFUSION SYNDROME QUINTERO STAGES STAGE IV: Supra, Recipieny Twin shows evidence of heart failure & fetal hydropsSTAGE V : In addition to above, one of the twins has died. Usually donor twin first to die, but death can occur in either twin.
TWIN REVERSED ARTERIAL PERFUSION SYNDROME (TRAP Syndrome) OR ACARDIAC TWIN Unusual form of TTTS. Incidence 1: 15,000 pregnancies As name suggests one twin develops normally, while the other develops without a heart as well as other body structures. Features : Cardiac structures are absent or non-functional & the head, upper body and extremities are poorly developed. The lower body and lower extremities are more or less normal. The Acardiac twin acts as a recipient & depends on the donor pump for obtaining its blood supply via TRANSPLACENTAL ANASTOMOSES and RETROGRADE PERFUSION of the UMBILICAL CORD. Deoxygenated Umbilical Artery blood flows from the Donor to the Recipient via it’s Umbilical Artery with direction reversed. The Umbilical Cord of the Acardiac Twin arises as a branch from the normal twin. Thus the Circulatory load on the donor twin becomes extremely large resulting in heart failure, Polyhydramnios. 50 % mortality of the pump twin. Radio-frequency ablation of a major blood vessel in acardiac twin.
Complications of twin Pregnancy Maternal ------- Hyperemessis, abortions,hydramnios befre 20 wks(1;;200) Anaemia-Iron deficiency and Nutritional. PIH 25% as compared to 5-7% in singleton APH (accidental & placenta praevia) more common. Coagulation failure ---Accidental hemorrhage and retained IUFD. Preterm labor----hydramnios, over distended uterus, incompetent os—50%. PPH –atonic ,traumatic---uterine inertia,large placenta, following APH. Puerperium---feeding problem, sub involution,several psychiatric problems.
Overall Perinatal mortality is 10-15% (4-6 times higher) Abortion ,IUFD occurs in 2% cases . 25% of surviving babies develop necrotizing enterocolitis, neurological ,renal lesions. 50% mortality is due to cord entanglement in monozygotic twins IUGR and Preterm births –spontaneous or iatrogenic are on account of APH PIH ,Placenta praevia occurs in 40% cases of twins as compared to5-7% in singleton . Fetal anomalies are noted in 2-3%.>1%in general Cord presentation & prolapse are more common. Asphyxia ---intra natal death of fetus2nd of twins suffer more asphyxia due to direct pressure of uterine contraction and pre mature separation of placenta. Neonatal asphyxia,RDS, Feeding problems may increase morbidity Mental ,physical and intellectual maybe more in infancy—5-10% MZ twins are less favorable than DZ. Perinatal loss is 3 times more in MZ.
Diagnosis a previous delivery of multiple Family history, pregnancy and treatment by assisted reproduction. 1st trimester---Hyperemesis,Threatened Abortion occur more. uterine size larger than period of amenorrhea.(d/d—wrong dates, H. mole, Acute Hydramnios and presence of fibroids.) 2nd trimester---unduly enlarged uterus ,multiple fetal parts palpable . Audible fetal hearts at different and 10cm apart areas with at least 10-20beats/min difference in FHR. USG---confirms all above ,incompetent /dilated os its length--indicating premature labor.
USGin 10-14 wks helps in identifying number of USG fetuses ,sex(discordant indicating Zygocity) ,their growth pattern and maturity. Placental localization,presence of hydramnios Any congenital anomalies other than conjoined twins their nature can be identified The study of chorionicity and identification of monozygous twins at 10-14 wks pregnancy is important. Doppler will help in diagnosing vascular anastomosis.
Management during Pregnancy Feto-reduction----If >2 fetus ,one of the fetus is malformed and is unable to be corrected by surgery —intra cardiac injection of KCl. Risk Factor are failure of technique, abortion, IUFD of healthy fetus, trauma to another fetus, placenta, amnionitis, structural or neurological damage to co-twin . Diet—Woman with multiple pregnancy should be advised to take extra 300 calories along with extra Iron, Folic acid, vitamins minerals and proteins in diet. Hydramnios– paracentesis in acute and Sulidac 400 mg / day to chronic cases. It is NSAID . It reduces fetal urine out put,reduces hydramnios,prevents preterm delivery Strict surveillance of mother and fetus is more frequent.Ante natal clinics by USG, EFCTD..colour doppler,biophysical profile at 30-32 wks. Preterm delivery--adequate rest ,controlling hydramnios,PIH,Anaemia,Tocolytic drugs. Dexamethasone 12mg at 12 hrs interval injection at 30 -34 wks for lung maturity.
Indications for L.S.C.S. Transverse lie or Breech presentation of 1st baby. Big babies. Placenta praevia. Conjoined twins. Pr. LSCS. Mono-amniotc twins if alive. Emergency LSCS Cord prolapse of 1st baby. Fetal distress. Abruptio placenta Persistent transverse lie of the 2nd twin and failed version. Locked twins---1:30,000 to 1:70,000.
Delivery Institutional delivery. Post dates very rare—if so –LSCS. Vaginal delivery-induction and acceleration of labor --- in woman with no previous CS, 1st fetus in vertical lie, average weight of fetus and normal gyneacoid pelvis. Pt should be kept lying in left lateral position to avoid PROM. PV examination as soon as membranes rupture---to note cord prolapse, cervical dilatation, position and level of presenting part. Partogram should be maintained. To cut short 2nd stage of labor outlet Forceps may also be used, assisted vaginal delivery for breech under Pudendal block and wide episitomy is a must.
Delivery====== Maintain good hydration of mother. Prophylactic IV line may be kept at slow rate.
Injection Methergin should be withheld till the delivery of 2nd child. Umbilical cord is clamped at 2 places and divided in between 2 clamps PLACENTA OF 1ST BABY USUALY FOLLOWS THE DELVERY OF 2ND CHILD.it rarely gets separated and expelled before. If Profuse bleeding and fetal asphyxia occurs . Then 2nd fetus is delivered expeditously. After delivery of 1st fetus palpate the abdomen to identify lie, presentation and position of fetus in utero. If it is transverse external version should be done before rupture of membranes.If one fails do ECV, then do internal podalic version on rupture of membranes.Conduct the assisted breech delivery.
In case of vertical lie , as soon as presenting part gets engaged , ARM is done and delivery is conducted. if needed uterine action may be augmented. An inteval of >20 minutes between delivery of 1st and 2nd fetuses----increases asphyxia and mortality of 2nd fetus. Injection methergin 0.2mg iv is given with delivery of 2nd fetus. Syntocinon 20 units shall be continued for 2- 3 hrs after delivery. 3rd stage is managed actively to avoid PPH. Placenta and membranes are examined carefully.