Conjoined twinning is a severe and rare complication of multigestational pregnancies. The first scientific report was published in the 19
th century
5. CTs are classified by side of union. The side of union is not only used for classification but can also be a prognostic factor. Although the etiology of conjoined pregnancy is not clear, some theories attempt to explain the pathogenesis. The most accepted etiology is incomplete division of embryos after conception
3,6,7. Some studies also suggest that secondary union of the embryonic disk may play a role. However, diamniotic CTs have been reported
8. The secondary fusion theory could explain diamniotic twinning
9,10.
CTs are classified according to side of union and can be a major prognostic factor. Ventral unions (87%), which can occur rostrally (48%), laterally (28%) and caudally (11%), are the most frequent form. Dorsal unions (13%) are rare3,11. Depending on the severity of visceral malformation, survival of CTs is extremely low4,12. With the wide spread use of prenatal screening these anomalies can be detected before viability.
First trimester ultrasound screening is useful for early diagnosis of CTs. In our case, the patient did not have prenatal follow up. If two fetuses cannot be visualized clearly, conjoined twinning must be suspected. Umbilical cord anomalies, fetal motion abnormalities and increased nuchal translucency are ultrasound findings which could be helpful in the diagnosis of CTs13-15. Polyhydramnios is seen in 50 to 76 % of cases. Pregnant women are recommended to have at least one ultrasound examination during pregnancy.
Depending on the severity of visceral anomalies, most CT pregnancies do not reachterm. Although vaginal deliveries have been reported at term, cesarean section is the preferred for prevent fetal and maternal complications16-18.
After birth of live CTs, the most challenging period for the physicians starts. Most CTs live for minutes or hours. The fetal outcomes depend on visceral organs status. Fetal visceral anomalies can occur in many types. Immediate separation is a plausible option if appropriate resources are available. In our case, the twins were doing extremely well during the early postpartum period so the decision was made not to immediately separate them. In most parapagus twins, visceral organs can be shared with twins after thorough preoperative evaluation.
Cardiovascular anomalies are the most severe and life-threatening anomalies that CTs encounter. The type and severity of heart anomalies depends on the side of union. The reason for death is cardio-pulmonary insufficiency in most cases. Complex congenital heart disease, transposition of the great vessels, atrioventricular septal defects are the most common anomalies in dicephalus parapagus twins19. Gastrointestinal system anomalies are another prognostic factor. Since there was no information regarding the gastrointestinal tract, the patient had an orogastric catheter placed for feeding. After insertion of catheters, x-ray images were used to confirm correct placement. X-ray images revealed that the catheters were located in two individual stomachs (Figure 4). One patent anus was identified. The digestive systems therefore united after the stomach but the precise segment of union was not clear. These types of visceral organ sharing are the limiting factor of surgical repair.
In most parapagus twins, there is a single but shared genitourinary tract3. Conjoined twinning is more common in the female gender, and nearly 70% of all CTs are female20,21. In our case, we could not clearly identify the gender.
Most CTs pregnancies do not result in live births, however viable CTs are possible if they are followed closely during the prenatal period. Management of living CTs is a complex issue for health professionals and the patient's families. Perinatal and ethical outcomes must be discussed in a multidisciplinary setting. Early diagnosis of this anomaly is the main stay for prevention. Prenatal screening tests and routine ultrasound are recommended for all pregnant women.
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