High risk pregnancy

Vanishing twin

-If two fetuses are seen in the first trimester and one later dies. -The sac will disappear or metabolize.

twin to twin transfusion syndrome can be suspected when one twin is at least

25% larger than the other

Monozygotic Division

4 days are dichorionic and diamnionic. 4-8 days split is diamnionic monocorionic, 8-13 days is mono mono, after 13 days split is conjoined twins.

Perinatal mortality rate in twins is

6 times higher than in singletons

The perinatal mortality rate in twins is around

6 times higher than in singletons. This increased mortality, which is mainly due to prematurity-related complications, is higher in monochorionic than dichorionic twin pregnancies

Acardius amorphus

A formless blob is present, containing all tissue types, but no recognizable organs. This differs from a teratoma only by its attachment to an umbilical cord.

etus papyraceus (paper-thin fetus) or a macerated fetus

After demise of a twin later in gestation, the dead twin remains visible

Growth Restrictions in diabetes mellulitus

Although most fetuses of diabetic mothers exhibit growth acceleration, growth restriction occurs with significant frequency in pregnancies complicated by preexisting type I diabetes.

cardiovascular fetal structural abnormalities

Arrhythmias (tachyarrhythmias, bradyarrhythmias), cardiac tumors (rhabdomyoma, hemangioma, hamartoma), cardiomyopathy, Ebstein anomaly, endocardial fibroelastosis, high-output failure (fetal angiomas, sacrococcygeal teratomas, vein of Galen aneurysm, twin-twin transfusion syndrome, twin-reversed arterial perfusion [TRAP] syndrome), myocardial infarction, myocarditi

TWIN TO TWIN TRANSFUSION

Arteriovenous shunting of arterial blood from one twin (donor) to venous system of other twin (recipient) through the placenta

MONOCHORIONIC TWIN

Both embryos will then share the chorion, the placenta will not be able to infiltrate between the two gestational sacs and the membrane insertion will have the "T" appearance.

fetal Gastrointestinal-tract abnormalities

Bowel atresias and volvulus, cirrhosis, hemochromatosis, hepatic tumors (hemangioendotheliomas), hepatitis, hepatoblastoma, lymphangiomas, and meconium peritonitis

NONIMMUNE HYDROPS

Cardiovascular (CHF) Chromosomal (trisomy 21) Twin pregnancy (twin - twin transfusion) Pulmonary (diaphragmatic hernia)

cranial Fetal structural abnormalities

Cerebral tumor, intracranial hemorrhage, and vein of Galen aneurysm

Placental disorders

Chorioangioma, chorionic vein thrombosis, cord torsion (knot or tumor), umbilical artery aneurysm, and venous thrombosis

Acardiac twinning

Complications to the pump twin of an acardiac fetus include congestive heart failure, polyhydramnios, preterm labor and death in 50-70% of cases. no heart twin is a parasite to the normal twin.

Fetal RISKS ASSOCIATED WITH MULTIPLE PREGNANCIES

Congenital anomalies Premature delivery

fetal Neck or thoracic masses

Congenital cystic adenomatoid malformation, cystic hygromas, diaphragmatic hernia, hydrothorax/chylothorax, mediastinal teratoma, pulmonary sequestration, and thoracic tumors

fetal Urinary-tract abnormalities

Congenital nephritic syndrome, polycystic kidneys, prune belly syndrome, renal vein thrombosis, and urinary tract obstructions (lower or upper) Chromosomal anomalies - Trisomy 21, trisomy 18, trisomy 13 triploidy, and XO syndrome (Turner syndrome)

fetal infection

Coxsackie virus, cytomegalovirus (CMV), hepatitis A virus, leptospirosis, listerosis, B19V, rubella virus, syphilis, toxoplasmosis, and varicella virus

Zygosity can only be determined by

DNA fingerprinting

MONOZYGOTIC

Develop when a single fertilized ovum splits during the first 2 weeks after conception. Monozygotic twins also are called identical twins.

hypertension (HTN)

Eclampsia - seizures or coma Oligohydramnios

IMMUNE HYDROPS

Erythroblastosis fetalis Rh negative mother Rh positive fetus Alloimmune Thrombocytopenia Sonographically - fetal hydrops with organomegaly, thick immature placenta, polyhydramnios

Growth Accelerations in diabetes mellulitus

Excessive body fat stores, stimulated by excessive glucose delivery during diabetic pregnancy, often extend into childhood and adult life

stuck twin

Fetus is positioned in severely oligo sac, causing it to be immobile.

Maternal disorders

Graves disease, severe anemia, severe diabetes mellitus, and severe hypoproteinemia

Acardius anceps

Head and face are partially developed.

recipient twin

Hypervolemic, hydropic, cardiac insufficiency, polyhydramnios

donor twin

IUGR, oligohydramnios

TWIN TO TWIN TRANSFUSION

In about 25% of monochorionic twin pregnancies, imbalance in the net flow of blood across the placental vascular arterio-venous communications from one fetus, the donor, to the other, the recipient, results in twin-to-twin transfusion syndrome; in about half of these cases, there is severe twin-to twin transfusion syndrome presenting as acute polyhydramnios in the second trimester.

Conjoined twins

Incomplete late division (13 days post fertilization) of monozygotic twins produces conjoined twins. Conjoined twins are connected at identical points and are classified according to site of union.

MONOAMNIOTIC / MONOCHORIONIC

Intertwined umbilical cord Greater than 3 vessels in the cord Conjoined twins (know the different terms and where they are connected) Parasitic twin Twin to twin transfusion

Xiphopagus/omphalopagus

Joined at abdomen (34%)

Pygopagus

Joined at buttocks (18%)

Thoracopagus

Joined at chest (40%)

Craniopagus

Joined at head (2%)

Ischiopagus

Joined at ischium (6%)

Fetal obesity in diabetes

Macrosomia is typically defined as a birth weight above the 90th percentile for gestational age or greater than 4000 g. In pregnant diabetic women, macrosomia occurs in 15-45% of cases, a 3-fold increase from normoglycemic controls.

fetal Genetic disorders

Metabolic disorders - Gaucher disease, Hurler disease, hypothyroidism, hyperthyroidism, mucolipidosis, and mucopolysaccharidosis Skeletal dysplasias - Achondrogenesis, achondroplasia, asphyxiating thoracic dystrophy, lethal osteoporosis, Noonan syndrome, short rib-polydactyly syndrome, and thanatophoric dysplasia Fetal hypokinesis - Arthrogryposis, congenital myotonic dystrophy, Neu-Laxova syndrome, and Pena Shokeir syndrome

twin to twin transfusion

Monochorionic / Diamniotic Monochorionic / Monoamniotic

TYPES OF TWINS

Monozygotic (identical twins) and dizygotic (fraternal twins)

Birth defects with diabetes mellitus

Most lesions involve the central nervous and cardiovascular systems. Birth defects occur during the critical time 3-6 weeks after conception

Acardius acephalus

No cephalic structures; this is the most common type, seen in 60-75% of the reported cases. the deoxygenated blood reaches the acardiac twin and barely oxygenates part of tissues (results in lack of development)

the most common form of hydrops

Nonimmune hydrops

Superfetation

Not the same cycle (fertilization of a second ovum after a pregnancy has begun; results in two fetuses of different ages in the uterus at the same time). Historically these were misinterpretations of growth discordance, but recent DNA studies have demonstrated that the condition is occasionally possible, in particular with assisted reproductive techniques

Superfecondation

Not the same father (fertilization of two or more ova released during the same menstrual cycle by sperm from separate acts of coitus)

COMPONENTS OF HYDROPS

Pleural effusion Pericardial effusion Ascites Skin thickening Placentomegaly Polyhydramnios If any one feature of hydrops is seen, search immediately for the other signs.

RISKS ASSOCIATED WITH MULTIPLE PREGNANCIES Maternal

Preeclampsia Bleeding in 3rd trimester Prolapsed cord

Kell (K) system, Duffy (Fy) system

Rare blood group antibodies can cause hydrops

fetal idiopathic disorders

Recurrent isolated hydrops

Reduction amniocentesis

Selective laser ablation of the placental anastomotic vessels

Diamniotic / Dichorionic

Separate amnions, chorions, and placentas are formed in dizygotic twins. The placentas in dizygotic twins may fuse if the implantation sites are proximate. The fused placentas can be separated easily after birth.

virtually specific for acardiac twin

Severe skin thickening

Sonographic findings (Monoamniotic / Monochorionic):

Single placenta and same sex twins · Close approximation of the cord insertions; · Entanglement of the cords; · Normal and identical amniotic fluid volume around both fetuses; · Unrestricted fetal movement; and · Absence of a dividing membrane demonstrated on two studies at least 12-15 hours apart. · A single yolk sac may be a normal finding.

INSULIN DEPENDENT DIABETES MELLITUS

Skeletal/CNS Caudal regression syndrome Cardiac Renal GI Macrosomia- >4000 grams Fetal morbidity with diabetes during pregnancy

CONJOINED TWINS

Splitting of the embryonic mass after day 12 of fertilization results in conjoined twins, which are found in about 1% of monochorionic pregnancies

MONOAMNIOTIC TWIN

Splitting of the embryonic mass after day 9 of fertilization results in monoamniotic twins In these cases, there is a single amniotic cavity with a single placenta and the two umbilical cords insert close to each other. Monoamniotic twins are found in about 1% of all twins or about 5% of monochorionic twins.

When scanning multiple gestations, the sonographer should attempt to find

The location of the placenta should be determined. The twins should each then be scanned for corroboration of dates and size, measuring parameters that include biparietal diameter (BPD) and head circumference (HC), abdominal circumference (AC), and femur length (FL).

a strong marker of conjoint twins

The presence of more than 3 vessels in a cord

SONOGRAPHIC MANAGEMENT OF MULTIPLE PREGNANCIES

The sonographer needs to identify the number of gestational sacs, yolk sacs, and embryos.

Fetus in fetu

The twin survives as a parasite inside brother or sister. It has an umbilical cord like structure and leaches on to the host blood supply. 92 cases total. Mostly 1 twin inside but have seen 2 and even 5.

Acardius acormus

There is a head, but no body; this is the rarest type

TRAP SYNDROME (ACARDIAC TWINNING)

Twin reversed arterial perfusion pathology Most extreme manifestation of twin transfusion Usually has large venous-to-venous and arterial-to-arterial anastomosis Pump donor twin supplies blood to itself and to the acardiac / recipient / perfused twin

DIZYGOTIC

Twins produced by two separate ova, separately fertilized; also called fraternal twins.

monochorionic twins

Twins that share the same placenta.

Effect on Survivor Following Demise of One Twin

When one twin dies in utero, the sonographic findings and risk to the surviving co-twin depend on the chorionicity and the gestational age at the time of the demise

fetal anemias

a Thalassemia, congenital leukemia, fetomaternal hemorrhage, glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, human parvovirus B19 (B19V) infection, twin-twin transfusion syndrome (donor), and fetal closed-space hemorrhage

In dichorionic twins, the intertwin membrane is composed of

a central layer of chorionic tissue sandwiched between two layers of amnion, whereas in monochorionic twins there is no chorionic layer.

Lambda sign

a triangular extension of the placenta at the base of the membrane is indicative of a dichorionic diamniotic pregnancy

Evolution of Lambda Sign

absence of the lambda sign at 16 or 20 weeks, and presumably thereafter, does not constitute evidence of monochorionicity and consequently does not exclude the possibility of dichorionicity or dizygosity. the identification of this feature at any stage of pregnancy should be considered as evidence of dichorionicity.

Eclampsia develops

after the 20th week of gestation and is considered a complication of severe preeclampsia. The progression from severe preeclampsia to seizures and coma is thought to be due to hypertensive encephalopathy with associated cortical hemorrhage. Eclampsia is most common during the antepartum period, yet 20-25% of cases occur during the postpartum period. Although seizures may occur as long as 3 weeks postpartum, the majority of cases (98%) occur on the first postpartum day. Eclampsia is not the cause of seizures that occur during the first trimester or well into the postpartum period. These seizures are suggestive of central nervous system (CNS) pathology.

The best way to determine chorionicity is by

an ultrasound examination at 6-9 weeks of gestation, when in dichorionic twins there is a thick septum between the chorionic sacs.

Determination of chorionicity

can be performed by ultrasonography and relies on the assessment of fetal gender, number of placentas and characteristics of the membrane between the two amniotic sacs.

Zygosity

can only be determined by DNA fingerprinting. Prenatally, such testing would require an invasive procedure to sample amniotic fluid (amniocentesis), placental tissue (chorionic villus sampling) or fetal blood (cordocentesis).

Documentation of a membrane separating the fetuses confirms the presence of a

diamniotic pregnancy

Thick membrane, Sonogram demonstrates thick membrane (arrow) of a

dichorionic-diamniotic gestation. The two placentas are clearly separate.

Different-sex twins are

dizygotic and therefore dichorionic but in about two-thirds of twin pregnancies the fetuses are of the same sex and these may be either monozygotic or dizygotic.

Miscarriages with diabetes mellitus

double the miscarriage rate.

Hydrops can be defined as

fluid accumulation in at least two fetal sites or a single serous effusion and anasarca.*** basic problem is an imbalance in fluid homoeostasis

Deuel's sign

has been associated with intrauterine death of the fetus. also known as the halo sign, is a halo effect that subcutaneous scalp edema produces on radiography of the fetal head. It was first described by Deuel on x-ray in 1946.

HYDROPS FETALIS

is Latin for edema of the fetus. The hallmark of the disease is the abnormal accumulation of fluid in body cavities (pleural, pericardial, peritoneal) and soft tissues with a wall thickness of greater than 5 mm. In addition, hydrops fetalis is associated with polyhydramnios and a thickened placenta (>6 cm) in as many as 30-75% of patients. Many affected fetuses also have hepatosplenomegaly.

Preeclampsia

is a hypertensive disorder of pregnancy associated with proteinuria and pathologic edema. If proteinuria and pathologic edema are complicated by seizures or coma, the condition is known as eclampsia.

Cord entanglement

is generally thought to be the underlying mechanism for the majority of fetal losses, and attempts have been made to prevent this complication by the administration to the mother of sulindac during the second trimester to stabilize the fetal lie by reducing the amniotic fluid volume. However, cord entaglement is found in most cases of monoamniotic twins and this is usually present from the first trimester of pregnancy.

The majority of acardiac fetuses have

large cystic hygromas

Macrosomia

large-bodied baby commonly seen in diabetic pregnancies. Birth injury, including shoulder dystocia and brachial plexus trauma, is more common among IDMs, and macrosomic fetuses are at the highest risk. Another risk is prolonged labor. greater than 4000 grams

Determination of chorionicity can be performed by

ltrasonography and relies on the assessment of fetal gender, number of placentas and characteristics of the membrane between the two amniotic sacs.

Perinatal mortality rate is 3-4 times higher in

monochorionic compared to dichorionic twins, regardless of zygosity

COMPLICATIONS OF TWIN PREGNANCIES

monozygotic twins have an increased incidence of fetal anomalies, including anencephaly, hydrocephalus, holoprosencephaly, sirenomelia, and sacrococcygeal teratoma.

acute twin-to-twin transfusion syndrome

more likely cause of fetal death in monoamniotic twins

The precise underlying mechanism by which select populations of those mono chorionic pregnancies with vascular communications go on to develop twin-to-twin transfusion syndrome is

not fully understood

Immune-related hydrops fetalis (IHF)

results from alloimmune hemolytic disease or Rh isoimmunization. The mother is sensitized and has antibodies against fetal blood cells, causing hemolysis in the fetus when circulated maternal antibodies (immunoglobulin G [IgG]) cross the placenta to reach fetal circulation.

Spaulding's Sign

sonographic sign of overlapping sutures, fetal demise

Failure to image the membrane separating the twin fetuses does not reliably predict

the presence of a monoamniotic pregnancy

Thin membrane

thin, wispy membrane (arrow) of a monochorionic-diamniotic twin gestation.

dichorionic twins

type of twin pregnancy where each twin has its own chorionic and amnionic sacs.

Maternal mirror syndrome

with extreme fetal hydrops, the mother may be at risk for maternal mirror syndrome, which is a condition where the mother's condition mimics that of the sick fetus. Because of a hyperdynamic cardiovascular state, the mother develops symptoms that are similar to pre - eclampsia and may include vomiting, hypertension, peripheral edema, proteinuria and pulmonary edema. Despite resection of the anomaly, maternal mirror syndrome may still occur.