Successful separation of a conjoined biliary tract in a set of omphalopagus twins

Phenotypically Discordant Anomalies in Conjoined Twins: Quirks of Nature Governed by Molecular Pathways?

A multitude of additional anomalies can be observed in virtually all types of symmetrical conjoined twins. These concomitant defects can be divided into different dysmorphological patterns. Some of these patterns reveal their etiological origin through their topographical location. The so-called shared anomalies are traceable to embryological adjustments and directly linked to the conjoined-twinning mechanism itself, inherently located within the boundaries of the coalescence area. In contrast, discordant patterns are anomalies present in only one of the twin members, intrinsically distant from the area of union. These dysmorphological entities are much more difficult to place in a developmental perspective, as it is presumed that conjoined twins share identical intra-uterine environments and intra-embryonic molecular and genetic footprints. However, their existence testifies that certain developmental fields and their respective developmental pathways take different routes in members of conjoined twins. This observation remains a poorly understood phenomenon. This article describes 69 cases of external discordant patterns within different types of otherwise symmetrical mono-umbilical conjoined twins and places them in a developmental perspective and a molecular framework. Gaining insights into the phenotypes and underlying (biochemical) mechanisms could potentially pave the way and generate novel etiological visions in the formation of conjoined twins itself.

Hepatobiliary anomalies in conjoined twins

INTRODUCTION

Conjoined twinning is an extremely rare anomaly. Very few diagrammatic descriptions are provided for the various hepatobiliary anomalies seen in these twins. We aimed to review our experience with the various subtypes of hepatobiliary anomalies and their association with the inability to separate as well as provide diagrammatic descriptions of these anomalies.

METHODS

We retrospectively reviewed our experiences within separating twins. We reviewed patterns of hepatobiliary anomalies and the required investigations and intraoperative workups.

RESULTS

Of the 60 cases we evaluated, 28 were successfully separated. The reasons for nonseparation were possession of: a single heart, major communicating hearts, or major chromosomal anomalies. The liver was involved in 17 cases (60.7%) in the operative group and 23 cases (71.8%) in the nonoperative group. All cases had a computed tomographic scan and ultrasound as preoperative workup. Only 2 cases required a magnetic resonance cholangiopancreatography for preoperative evaluation. Intraoperative ultrasound was not used, and only 3 cases required an intraoperative cholangiogram. Diagrammatic depictions of the various categories of anomalies are presented.

CONCLUSION

In our experience, we did not find hepatobiliary anomalies to be the sole reason for inseparability in any of the conjoined sets. Hepatobiliary anomalies seem to be more frequent in the nonseparable group.

Conjoined twins--past, present, and future

BACKGROUND/PURPOSE

Conjoined twins are rare and complex anomalies of the newborn. They require a highly experienced team and a center equipped to deal with such challenging anatomy.

METHOD

A review of 31 sets of conjoined twins was managed by one team over a 15-year period. The spectrum of the anomalies, management strategies, and outcomes will be analyzed with future recommendations.

RESULTS

Ten sets of complete conjoined twins and two sets of parasitic conjoined twins were successfully separated. Tissue expanders and prosthetic meshes were not required. A separation of one set of craniopagus parasiticus conjoined twins was attempted, but abandoned owing to major vascular and brain sharing. The remaining 18 sets were not separable owing to major cardiac anomalies and/or sharing, and all died within several weeks of birth.

CONCLUSION

Careful planning, a multidisciplinary approach, rehearsal, and experience are important factors in dealing with conjoined twins. Tissue expanders and prosthetic meshes are not required in most cases. Selective abortion or fetal intervention may play a role in the future.

Biliary tract anomalies in thoraco-omphalopagus conjoined twins

Thoraco-omphalopagus conjoined twins were separated urgently on the ninth day of life because of bowel obstruction and impending intestinal perforation. Preoperative studies clarified the cardiac, intestinal, and hepatic parenchymal anomalies, but the precise biliary anatomy remained obscure. Operative cholangiogram through the single gallbladder visualized only the extrahepatic biliary anatomy in twin A. At reoperation for abdominal patch removal, exploration in twin A found biliary atresia. Because of the unusual duodenal anatomy and extreme short bowel, the authors elected to treat the biliary atresia in twin A with an appendix portoenterostomy. Twin B had no gallbladder and a profoundly hypoplastic biliary tree. Both twins have normal bilirubin and liver function at 18 months of age. The anatomic details of 8 additional cases of complex biliary tract anomalies in thoraco-omphalopagus conjoined twins are reviewed. In all cases, the complex biliary anatomy has been associated with conjoined duodenum. In most cases the preoperative technetium 99m HIDA scan has been inconclusive or misleading.

Necrotizing enterocolitis in omphalopagus conjoined twins

Female omphalopagus twins underwent laparotomy on the second day of life after an antenatally diagnosed high jejunal bowel obstruction. Bowel resection and choldocho-enterostomies were performed. Despite recovery from laparotomy, the development of severe necrotizing enterocolitis (NEC) in one twin led to rapid deterioration and the death of both infants on day 34. The elucidation of the combined biliary tree, the dilemma of NEC in conjoined twins, and the possibilities of emergency separation are discussed. Consideration should be given to emergency separation of conjoined twins in the event of potentially lethal complications.

Conjoined twins--the Cape Town experience

This paper records our experience in the management of 25 sets of conjoined twins seen over a 32 year period (1964 - 1996). The twins were classified into 14 complete and symmetrical sets and 11 incomplete or heteropagus. The 14 symmetrical sets included 9 thoracopagus, 2 ischiopagus, 1 craniopagus and 1 omphalopagus twins. In the incomplete heteropagus group there was 1 ischiopagus, one twin being anencepahlic, 2 dipygus, 5 parasitic, 2 fetus-in-fetu and I cranial and caudal. The management is detailed case by case. Overall 10 of 14 symmetrical sets underwent attempts at separation with 16 surviving the procedure, but there were 3 late deaths. In the incomplete group 10 of 11 were operated on with 9 survivors. The importance of a multi-disciplinary approach, the extensive investigations required pre-operatively to define areas of organ and bony conjunction, congenital anomalies of each twin and surgical teamwork is emphasized. Specific problems encountered were identified. In thoracopagus twins the hearts were of paramount importance as conjuction was usually fatal, being associated with major congenital defects. The greater the extent of thoracic cage fusion the greater the chance of associated severe anomaly. Skin expansion to assist coverage of the defects after separation was of great assistance, as was the use of collagen coated vicryl. Evaluation of the liver and pancreatico-biliary systems with isotope excretion scanning was crucial to pre-operative planning. Where there was fusion of the duodenum a single pancreatico-biliary system could be expected and prior strategies for separation and Roux-en-Y enteric drainage of both pancreatic and biliary secretion should be planned. Gastro-oesophageal reflux led to considerable morbidity in both twins of a thoraco-omphalopagus set. In ischiopagus and dipygus conjoined twins bilateral posterior iliac osteotomies were an essential component to anatomic reconstruction of the pelvic ring and wound closure. Also in this group, due to the frequency and extent of shared genital, urinary and ano-rectal structures, long-term morbidity was expected and a component of this might be due to spinal cord tethering, or as in one of our cases, a progressive hydrosyringomyelia. Timing of separation was ideally set at between 5 and 9 months with 6 to 8 weeks of prior tissue expansion but earlier operation was frequently required because of cardio-respiratory problems or organ failure in one twin. In most cases the goal of obtaining separate, independent and intact individuals was achieved.

Emergency separation of conjoined twins

Female omphalopagus conjoined twins were successfully delivered vaginally and required emergency surgical separation shortly after birth for gastroschisis. Shared tissue included conjoined bowel; one twin also had a complex cloacal abnormality and patent urachus. A 2-year follow-up is presented. A review of the relevant literature confirms that this is the first example of gastroschisis conjoining omphalopagus twins.