[en] &lt;p&gt;Imperfect twins are rare but of great interest to obstetricians. Early diagnosis through ultrasound can facilitate gestational prognosis, delivery route, and postnatal planning. With that said, this article aims to report a case of imperfect twinning, of conjoined twins, at 24 weeks and 5 days, with striking structural anomalies demonstrated by imaging exams. The methodology used for this research was a literature review (utilizing databases such as PubMed, SciELO, and Lilacs), with the descriptors "siamese twins, imperfect twinning, conjoined twins, twin gestation"; reporting on a case of conjoined twins, with various structural anomalies, and discussing their external characteristics and findings according to imaging exams. The result presented a pregnant woman with obstetric history GI, P0, A0; routine prenatal physical and laboratory exams were normal; gestation with premature rupture of membranes (at 36 weeks and 5 days); emergency cesarean section performed; characteristics of the twins: weighing 3.590kg, both females; twin 1: height 42cm, HC 33.5cm, ATD 36.5cm, AC 33.6cm; twin 2: height 41cm, HC 31.5cm, ATD 36.5cm, AC 33.6cm; Apgar score of 3/7 (at the first minute) for both; subjected to ventilation with 100% O2 positive pressure. It was possible to conclude that imperfect twins are rare and of great interest to obstetricians in general. Early diagnosis can facilitate gestational prognosis, correct determination of delivery route, and postnatal planning. Fused twins are mostly stillborn or die shortly after birth. When born alive, they may undergo separation surgery depending on the type of fusion they exhibit.&lt;/p&gt;

[pt] &lt;p&gt;Gemelares imperfeitos s&atilde;o raros, mas de grande interesse para obstetras. O diagn&oacute;stico precoce por ultrassonografia pode facilitar progn&oacute;stico gestacional, a via de parto e o planejamento p&oacute;s-natal. Dito isso, o presente artigo tem por objetivo relatar um caso de gemelaridade imperfeita, de gemelares unidos, com 24 semanas e 5 dias, com anomalias estruturais exuberantes demonstradas pelos exames de imagem. Utilizando como metodologia &agrave; pesquisa bibliogr&aacute;fica (portais como PubMed, SciELo e Lilacs), com descritores "g&ecirc;meos siameses, gemelaridade imperfeita, g&ecirc;meos unidos, gesta&ccedil;&atilde;o gemelar"; relato de caso de gemelares unidos, com v&aacute;rias anomalias estruturais e discuss&atilde;o de suas caracter&iacute;sticas externas e achados de acordo com exames de imagem realizados. Apresentando como resultado uma gestante com antecedentes obst&eacute;tricos GI, P0, A0; exame f&iacute;sico e laboratoriais da rotina pr&eacute;-natal normais; gesta&ccedil;&atilde;o com amniorrexe prematura (36 semanas e 5 dia); submiss&atilde;o &agrave; cesariana de emerg&ecirc;ncia; caracter&iacute;sticas dos g&ecirc;meos: com peso 3,590kg, ambas do sexo feminino; gemelar 1: altura 42, PC 33,5, PT 36,5, PA 33,6; gemelar 2: altura de 41cm, PC 31,5, PT 36,5, PA 33,6; Apgar de 03/07 (primeiro minuto) para ambas; submetidos &agrave; ventila&ccedil;&atilde;o com press&atilde;o positiva de O2 a 100%. Na qual foi poss&iacute;vel concluir que gemelares imperfeitos s&atilde;o raros e de grande interesse para obstetras em geral. O diagn&oacute;stico precoce pode facilitar o progn&oacute;stico da gesta&ccedil;&atilde;o, correta determina&ccedil;&atilde;o da via de parto e planejamento p&oacute;s-natal. G&ecirc;meos fusionados, em sua maioria, s&atilde;o natimortos, ou morrem pouco tempo ap&oacute;s o nascimento. Quando nascidos vivos, podem submeter-se &agrave; cirurgia de separa&ccedil;&atilde;o, dependendo do tipo de fus&atilde;o que apresentam.&lt;/p&gt;