Gemelos unidos (siameses): descripción de hallazgos anatomopatológicos / Conjoined twins (siamese): description of anatomopathological findings

Resumen OBJETIVO: Describir los hallazgos anatomopatológicos y placentarios en una serie de autopsias de 5 siameses. CASOS CLÍNICOS: Serie de casos de autopsias efectuadas entre 2013 y 2018 de pacientes entre 14 y 30 semanas de embarazo, con diagnóstico de gemelos unidos. RESULTADOS: Se encontraron 5 casos de gemelos unidos, hijos de madres multíparas, 3 tuvieron muerte intrauterina y 2 fallecimiento a los pocos minutos de vida. Tres casos correspondieron a uniones ventrales (2 toracoonfalópagos y 1 cefalópago) y dos a uniones laterales de tipo parápagos, dicéfalos. Hubo corazón único en los gemelos toracoonfalópagos y sistemas cardiacos separados en los tres restantes, donde hubo fusión aórtica distal. En 4 casos el hígado se encontró fusionado, con dos vías biliares independientes. Los cordones umbilicales de los casos de unión ventral tenían 5 vasos sanguíneos. Los de unión lateral tenían cordón umbilical trivascular. Los discos placentarios mostraron grados variables de hipoxia preplacentaria y cambios de malperfusión vascular materna. CONCLUSIONES: Las fusiones ventrales tienen grados variables de estructuras compartidas; entre mayor sea la fusión de los órganos internos, menor es el número de vasos umbilicales. De las teorías etiológicas propuestas, la esférica es la que mejor soporta los grados variables de fusión.

Abstract OBJECTIVE: Description of the anatomopathological and placental findings in a series of autopsies of 5 conjoined twins. MATERIALS AND METHODS: Series of cases of autopsies performed between 2013-2018 of patients between 14-30 weeks of gestation, with diagnosis of conjoined twins. RESULTS: Five cases of conjoined twins, product of multiparous mothers, 3 of these presented intrauterine death and 2 deaths within a few minutes of life. Three cases corresponded to ventral junctions (2 thoracoomphalopagus and 1 cephalopagus) and two to lateral junctions of parapagus type. A single heart was observed in the thoracoomphalopagus twins and separated cardiac systems in the remaining three where there was distal aortic fusion. In 4 cases the liver was found fused with two independent bile ducts. The umbilical cords of the cases of ventral union presented 5 blood vessels; those with lateral junction presented a trivascular umbilical cord. The placentas showed varying degrees of preuterine hypoxic pattern and changes of Maternal Vascular malperfusion of the Placental Bed. CONCLUSIONS: Ventral fusions have varying degrees of shared structures; the greater the fusion of the internal organs, the smaller the number of umbilical vessels will be. Of the proposed etiological theories, it is the so-called spherical theory, which best supports the variable degrees of fusion and how it can be saltatory on the vertical axis.

Presentación de un caso de siameses cefalópagos / A case report of cephalopagus siamese

Se denominan siameses a aquellos gemelos que comparten estructuras anatómicas en grado variable. La incidencia varía entre 1:50 000 a 1:100 000 embarazos, 1:4 de los casos fallecen in utero y 40-60 por ciento mueren poco después del parto.Los hallazgos en autopsias médico-científicas de gemelos unidos cefalópagos, que son aquellos que presentan fusión cefálica con dos hemicaras, son el cuarto tipo de siameses en ocurrencia y su incidencia está estimada en 1 por cada 3'000.000 de embarazos o 1/58 siameses. El objetivo es presentar los hallazgos de una autopsia médico-científica de gemelos unidos cefalópagos. Se trata de gemelos cefalópagos, con terminación de embarazo por incompatibilidad con la vida extrauterina. Presentan cordón umbilical único de cinco vasos, tenían cráneos fusionados a nivel frontofacial con dos caras en lados opuestos de la cabeza (Janiceps), con fusión ventro-ventral de los ejes somáticos hasta debajo del ombligo sobre la pelvis, con sistemas respiratorios, cardiaco y genitourinario independientes, el sistema digestivo superior esta fusionado hasta el intestino medio, con duplicación a partir de la tercera porción del duodeno. Los gemelos siameses cefalópagos no son los más infrecuentes, pero es difícil encontrar series de casos y revisiones sistemáticas de sus características y patogénesis en Latinoamérica. Son escasas las estadísticas sobre siameses y no se ha descrito previamente ningún caso como éste. Se hace necesaria la realización de estudios de autopsias para mejorar la descripción y caracterización de estos casos y poder determinar si existen otras condiciones asociadas además de las teorías de unión embriológica(AU)

It is denominated siamese to those twins that share anatomical structures to a variable degree. The incidence varies between 1/50.000 and 1/100.000 pregnancies, 1:4 of the cases die in the uterus and 40-60 percent die shortly after birth. Findings in a medical-scientific autopsies of conjoined cephalopagus twins, those that presenting cephalic fusion with two hemi faces, are the fourth type of Siamese in occurrence and their incidence is estimated in 1 every 3´000.000 pregnancies or 1/58 siamese. It is about cephalopagus twins, with termination of pregnancy due to incompatibility with extrauterine life. They presented a five vessels common umbilical cord, fused craniums at frontofacial level with two faces in opposed sides of the head (Janiceps), ventro-ventral fusion of the somatic axis until below the umbilicus and above the pelvis, independent respiratory, cardiac and genitourinary systems. The superior digestive system was fused until the medium intestine, with duplication parting from the third portion of the duodenum. Conjoined cephalopagus twins are not the most frequent but it is hard to find a series of cases and systemic revisions of their characteristics and pathogenesis in Latin America. Statistics on Siamese twins are scarce and it has not been previously described any case like this one. Autopsy studies becomes necessary to improve the description and characterization of these cases and to determine the existence of any other associated conditions different to those of the embryologic union theory(AU)

A Case of Cephalopagus / 대한산부인과학회잡지

Conjoined twins are rare congenital malformation that occurs one in 50,000-100,000 births. The site and fusion are variable. In recent years, prenatal diagnosis of conjoined twins with ultrasonogram (US), computed tomography (CT), and magnetic resonance imaging (MRI) has been reported. Early prenatal diagnosis and assessment of the degree of conjoining provided couples with the option for pregnancy termination via vaginal delivery. We report a case of cephalopagus diagnosed prenatally by ultrasonogram in the second trimester and subsequently which was terminated, with a brief review of literature.

A Case of Prenatally Diagnosed Cephalopagus / 대한산부인과학회잡지

Conjoined twin rarely occurs in human, with a reported incidence of 1:50,000 to 1:100,000 pregnancies. The site and extent of fusion are infinitely variable. Classification systems for conjoined twins are usually based on the fused anatomic region. The early prenatal diagnosis and assessment for shared vital organs are desirable for optimal obstetrical counseling and management. When severe forms are diagnosed prior to 24 weeks, pregnancy termination via vaginal delivery can be considered. With the advent of ultrasound, prenatal diagnosis is possible during the late first trimester or early second trimester. We report a case of cephalopagus diagnosed prenatally by ultrasonogram in the second trimester and subsequently was terminated, with a brief review of literature.

Prenatal Sonographic Diagnosis of Cephalopagus Twins Associated with Multiple Anomalies / 대한산부인과학회잡지

Conjoined twins are uncommon complications of monoamniotic twinning. Among them, cephalopagus twins are very rare. The accurate prenatal diagnosis of conjoining is essential for the optimal obstetric counseling and management. We describe a case where prenatal sonographic diagnosis of cephalopagus associated with multiple anomalies including meningomyelocele, diaphragmatic hernia, omphalocele, and club feet was made at 18 weeks of gestation.