Ventrally Fused Conjoined Twins (Omphaloischiopagus): A Roadmap to Successful Separation

Abstract

Conjoined twining is one of the most fascinating and challenging situations which a pediatric surgeon may face in his career. Only few surgeons may have the opportunity to share in separation of such cases. In this report, we aim to share our experience with the successful separation of ventrally fused male conjoined twins (omphaloischiopagus). The case was thoroughly studied via preoperative cross-sectional imaging modalities (magnetic resonance imaging [MRI] and computed tomography [CT] angiography), complemented by data obtained from reviewing similar cases in the literature. A clear delineation of the complex anatomy was achieved preoperatively which proved to be well consistent with the operative findings. A detailed description of the operative procedure to divide/redistribute the shared abdominal/pelvic organs between both twins is provided. To the best of our knowledge, this is the first report to describe the detailed and unique internal anatomy of a common central phallus associating ischiopagus conjoined twins. The penis was centrally located in the perineum in between both twins with an open urethral plate. This common phallus had a peculiar configuration with four crura anchoring ischial bones of both twins together.

Postnatal imaging of conjoined twins: a customized multimodality approach

“…The portovenous phase (hepatic phase) is optimum for the demonstration of the multiple irregular lobules of the liver at the site of fusion, which correspond to the surgical plane of separation (Fig. 7 ) [ 23 ]. It is crucial to show hepatic venous drainage into a discrete inferior vena cava.…”

“…However, the presence of a single shared duodenum raises the suspicion of fusion of common bile ducts and even of the pancreatic ducts. Magnetic resonance cholangiography accurately demonstrates the biliary system of both twins and reliably excludes biliary sharing [ 23 ]. If there is still any doubt concerning biliary system sharing, a hepatobiliary iminodiacetic acid scintigraphy can be performed by injecting the tracer into each twin on two separate days.…”

“…Separate hepatocyte uptake and excretion of the tracer imply separate biliary systems [ 26 ]. A shared biliary system is found in about a quarter of thoraco-omphalopagus twins [ 23 ].…”

“…Ventrally fused twins have variable degrees of gastrointestinal sharing. Thoraco-omphalopagus twins may have duodenal sharing with a single jejunum and ilium down to the level of Meckel’s diverticulum (at the site of the vitello-intestinal duct) [ 23 ]. In contrast, omphalo-ischiopagus twins commonly have bowel sharing distal to Meckel's diverticulum, with a single colon and rectum in 70%.…”

“…The advent of MR technology with the development of high-resolution thin section sequences that can be acquired in multiple planes has enabled accurate demonstration of pelvic anatomy, especially of the urethra and genital system (Figs. 8 and 10 ) [ 23 ].

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