First‐trimester diagnosis of conjoined twins

Abstract

Conjoined twins are a rare and complex complication of monozygotic twinning, which is associated with high perinatal mortality. Early prenatal diagnosis of conjoined twins allows better counselling of the parents regarding the management options, including continuation of pregnancy with post-natal surgery, termination of pregnancy or selective fetocide in case of a triplet pregnancy. With the introduction of high-resolution and transvaginal ultrasound imaging, accurate prenatal diagnosis of conjoined twins is possible early in pregnancy. We have reviewed the medical literature on the early prenatal diagnosis of suspected conjoined twins using a MEDLINE search. Although first-trimester diagnosis of conjoined twins is feasible, false-positive cases are common before 10 weeks because, earlier in gestation, fetal movements are limited and monoamniotic twins may appear conjoined. As most parents opt for immediate termination of pregnancy at confirmation of the diagnosis, there are limited data on the prenatal follow-up of conjoined twins. When the parents opt for conservative management, half of the fetuses die in utero and another 44% will die during the neonatal period. A detailed analysis of case reports where 3D imaging was used indicates that this modality does not improve on the diagnosis made by 2D ultrasound. Overall, very early prenatal diagnosis and first-trimester 3D imaging provide very little additional practical medical information compared to the 11-14 weeks' ultrasound examination.

Prenatal Diagnosis and Management of Conjoined Fetuses

“…Parents need detailed counseling in order to decide among various management options, which include the following: (a) pregnancy continuation and scheduled neonatal surgery, (b) termination of pregnancy, and (c) multifetal pregnancy reduction or selective fetocide in cases of high-order multifetal pregnancies with a component of conjoined fetuses. 31 Diagnosis of conjoined fetuses should be suspected whenever a monochorionic-monoamniotic pregnancy is detected. Sonographic identification of distinct placentae or intervening amniotic membrane(s) rules out fetal conjunction.…”

Conjoined Twins: A Case Report of Thoraco-Omphalopagus

“…The false positive ratio is very high before the 10 th week of pregnancy. In the earlier weeks of pregnancy fetal movements are limited and monochorionic twins may be mistaken for conjoined twins (4). Hence the ultrasonography screening should be repeated in the 11 th and 12 th weeks of pregnancy.…”

Thoraco-omphalopagus conjoined twins diagnosed at 14 weeks of gestation

“…This patient followed up one week later, and we found that the conjoined twins' one heart had no cardiac activity under the ul- earlier in gestation and monoamniotic twins may be mistaken for conjoined twins. 7 Although the diagnosis of conjoined twins can be made at mid-pregnancy using 2D sonography, diagnosis using 3D sonography has become more prevalent. 8 Pajkrt and Jauniaux 7 concluded that 3D ultrasonography does not provide more accurate information than 2D sonography, and an early diagnosis of conjoined twins is also possible with 2D sonography, as Taner et al 9 recently reported a case of conjoined twins at about seven weeks of gestation.…”