Imaging of conjoined twins

The incidence of conjoined twins is estimated to be around 1 in 250,000 live births. There is a distinct female predominance. In this paper the imaging of conjoined twins both antenatally and postnatally is reviewed, in particular taking into consideration recent advances with multidetector CT. Accurate counselling of parents regarding the likely outcome of the pregnancy and the likelihood of successful separation is dependent on good prenatal imaging with ultrasound and MRI. Planning of postnatal surgical separation is aided by accurate preoperative imaging which, depending on the conjoined area, will encompass many imaging modalities, but often relies heavily on CT scanning.Not all the examinations presented as figures in this article were performed at our institution, but all these patients were referred to us for review. No patient therefore is identifiable from these anonymized images.     

Angiographic evaluation of conjoined twins

Two sets of conjoined twins were studied by angiocardiography and cerebral angiography. Conjoined heart was demonstrated in the thoracopagus twins and surgical separation was impossible. Cerebral angiography disclosed the separate circulations in craniopagus twins and surgical separation was performed.Presented at 14th Meeting of the European Society of Pediatric Radiology, Luzern, May 11–14, 1977     

先天性联体畸形的外科处理

目的 总结4例联体儿分离术的经验,对联体儿诊治提供参考。方法 回顾性分析自1982～2001年,我院小儿外科共收治的4例先天性联体儿外科分离手术的临床资料,着重在手术时机、产前诊断、合并畸形、分离技术、术后监护、随访等方面。结果 4例联体儿畸形,其中胸部-脐联合畸形3例,坐骨联体1例,男性1例,余均为女性。均不同程度合并先天性心脏缺损,坐骨联体儿合并严重大血管畸形,泄殖腔畸形及Pieer-Robin综合征。2例产前超声检查获得诊断。2例紧急分离术时间为出生后7d内,存活1名。另2例延迟分离手术时间>1个月,均存活。随访存活的5名患儿,1982年分离的剑突-脐联体儿其中1名于术后4年“肺炎”死亡。另1名已20岁,健在。另一对胸部-脐联体儿术后1年发育良好。1例坐骨联体儿1名死亡,1名失随访。结论 手术时机与分离方式必需依据每一对联体儿局部环境及器官结构而定。紧急分离术存活率低,能延迟行分离术则存活率高。     

Pulmonary function studies of conjoined thoracopagus twins.

Lung functions were measured on 13-day-old conjoined thoracopagus twins. Mean values for tidal volume and minute ventilation were 14.8 ml and 1102 ml/min for twin A and 12.8 ml and 963 ml/min for twin B. Functional residual capacities (FRC) were 35 ml/kg and 39 ml/kg for twins A and B, respectively. Pulmonary compliance and flow resistance for twin A were 2.8 ml/cm H2O and 75 cm H2O/liter.sec-1 with 45% of the total work used to overcome elastic resistance. Although values for resistance and work of breathing are within the normal range for studies reported elsewhere, these results tend to be elevated and probably reflect an abnormal state.     

Unusual cardiac malformations in conjoined twins: thoracopagus twins with conjoined pentalogy of Cantrell and an omphalopagus twin with atretic ventricles

Two unrelated cases of conjoined twins were found to have cardiac malformations that apparently have not been reported previously. In one case, thoracopagus twins had an extensive thoracoabdominal wall defect that resulted in ectopia cordis of a conjoined heart along with evisceration of the shared liver and intestine along with one spleen. These malformations, accompanied by defects in the sternum, diaphragm, and supraumbilical abdominal wall, constitute a conjoined pentalogy of Cantrell. In the second case, the heart of one of omphalopagus twins consisted of a solid ventricular mass with only a minute aortic cavity but no atrioventricular communication-an ineffective heart that could develop only in a conjoined or chorioangiopagus twin. In both cases, a common atrium lay in the primitive (embryologic) position caudal to the ventricles.     

Parasitic conjoined twins with omphalocele and tetralogy of Fallot

Human parasitic twins are very rare. Here we report a unique case of a partial twin attached to the host in the midline at the forehead, chin, chest, and epigastrium. The parasite lacked thoracic organs and major neural tube derivatives. However, it had small peripheral nerves and ganglia within perirenal and pericolonic connective tissue. Also present were a well-developed small intestine, colon, and appendix with normal submucosal and myenteric plexuses. These findings may represent either the initial presence of a neural tube that later regressed or migration of autosite neural crest cells. The parasite had a mature, functioning kidney with its ureter opening to skin and complete absence of urinary bladder or genital organs. This raises questions about the embryological development of the ureteric bud, which is an outgrowth of the mesonephric duct. The host had tetralogy of Fallot and omphalocele containing the parasitic kidney and bowel. Parasitic twinning occurs at 3 weeks of gestation, tetralogy of Fallot at 3-7 weeks, and omphalocele at 6-10 weeks. A single noxa acting at 3 weeks could have caused sequential malformations that initially seem unrelated.     

Assessment of the cardiovascular system in conjoined thoracopagus twins

The thoracoomphalopagus conjoined twins comprise 75% of all conjoined twins. In the assessment of the organ systems of the twins, the cardiovascular system is important since union of this system in the twins has occurred in 75% of the cases. Of the five cases reported here, two had separate hearts and vessels with a common pericardium only. Two twins were joined at the right atrial level. The fifth pair were connected at both atrial and ventricular levels. It has been suggested that the presence of two separate QRS complexes in the ECG indicates complete separation of the two hearts. Case 4 shows that even in the presence of atrial union, the existence of an atrioventricular block in one twin may produce a very slow heart rate, while the other twin may have a normal rate that will not influence the ventricular rate of the other. In our experience, angiocardiography has been the most useful diagnostic procedure.     

Long-term urological outcomes in six sets of conjoined twins

Aim

To review the long-term urological outcomes of six sets of ischiopagus and pygopagus conjoined twins. Emphasis is placed on the particular genitourinary challenges of separation, reconstruction and monitoring of these patients.

Patients and methods

We performed a longitudinal, retrospective analysis of six sets of conjoined twins who presented to a single center and describe their long-term urological outcomes.

Results

Six sets of ischiopagus (4) and pygopagus (2) conjoined twins presented from 1993 to 2003 and have been followed up for a mean of 12 years (range 7–17 years). Separation was achieved in 5/6 cases; the remaining one died of intestinal perforation and resultant sepsis. One further child died of malaria after separation. Patterns of genitourinary anatomy found in these conjoined twins are described. Urinary continence was achieved in 2/6 ischiopagus and 3/4 pygopagus twins. Renal failure has developed in one child. Urinary tract infections have been common. Secondary urological surgery has been required in 3/6 ischiopagus twins, usually to perform an incontinent urinary diversion.

Conclusion

Complex urological problems occur in ischiopagus and pygopagus conjoined twins. Beyond the challenge of surgical separation, they continue to provide management challenges requiring secondary reconstructive surgery and close urological monitoring.     

Separation of ischiopagus tetrapus conjoined twins in the sultanate of oman

Premature male ischiopagus tetrapus twins weighing 2.2 kg were born unexpectedly. They required initial ventilation for respiratory distress syndrome and an emergency laparotomy for intestinal obstruction at 10 days of age. At 8 months of age, formal separation was carried out. Primary skin closure was possible without the use of any tissue expander. Anaesthesia was supplemented with continuous intra- and post-operative epidural analgesia, with great benefit. Both twins are alive and well 18 months after surgery. Details of the anatomical findings and preparation for surgery are discussed.     

联体畸形的诊断与治疗方法探讨

目的 探讨联体畸形的诊断和治疗方法，增进对该少见疾病的认识，提高疗效，以及生存率。方法 采用B超、CT 消化道钡餐等检查，判定内脏连接情况，手术分离2对联体畸形婴儿。2对病例分别为剑脐联体畸形及胸腹联体畸形，均有肝脏连接，但胆囊及胆管各自独立，于生后第28d、第96d时分别实施分离手术，对于肝脏连接的处理，采用“局部血流阻断法”，行共用肝离断术。结果 2对联体畸形经充分术前准备，均手术分离成功，术后患儿生长及发育正常。经采用局部血流阻断共用肝离断术方法，术中出血少，术后肝功能恢复顺利。结论 联体畸形较为罕见，充分的术前准备及合理的分离术式可提高患儿的双双存活率。局部血流阻断共用肝离断术，仅阻断了离断线局部的肝脏血流，对非操作区的肝脏血液供应毫无影响。有利于对创伤及失血耐受性很差的婴幼儿术后康复。     

Echo-Doppler assessment of cardiac status in conjoined (thoraco-omphalopagus) twins

Summary Cardiac status was assessed noninvasively in a case of thoraco-omphalopagus conjoined twins by two-dimensional and Doppler echocardiography which showed completely separate hearts and major arteries and veins. The twins were successfully separated surgically, without preoperative invasive cardiac investigation. Echocardiography can provide an accurate assessment of cardiac status in conjoined twins and may obviate the need for cardiac catheterization.     

影像学检查在臀部联体儿术前诊断中的价值

目的 探讨影像学检查在臀部联体儿术前评估中的价值,及其对分离手术方案和分离后患儿预后的意义.方法 对我院最近成功分离的1例臀部联体患儿,结临床查体选择进行B超、X线、CT、MRI检查,分析其影像学特点,以明确联体儿连接部位、范围、内容,以及是否伴有身体内部其他器官的畸形.结果 连接部前后径7.9 cm,上下径6.0 cm,位于腰骶部.双侧患儿腰3以下椎板裂,无骨性结构连接,但存在脊柱及骨盆的软骨连接.患儿下消化道及肛门独立,泌尿道独立.硬膜囊相连,但脊髓及马尾神经无相连及交叉支配.联体双患儿均存在动脉导管未闭,其中一侧患儿存在隐睾,未见其他畸形.术中所见证实影像学的结果.选择交叉V型皮瓣覆盖创面,直接缝合硬膜,联体儿成功分离,无术后感染及脑脊液漏,皮瓣愈合良好,无神经损伤,随访6个月,2例患儿发育及神经功能均正常.结论 根据联体儿分型,结合查体选择和利用各种影像学检查,能较全面地反映连接部位的范围、内容,对手术的难度预测、手术方案制定、术后预后评估有重要意义.     

联体双胎分离手术4例

目的总结4例联体儿分离手术的经验,为联体儿的诊治提供参考。方法回顾性分析2007年10月至2011年12月作者收治的4例联体儿治疗经过,其中3例为对称性联体,1例为不对性联体。共有3例手术成功,1例对称性联体儿未手术死亡。重点分析术前准备、手术时机、分离技术及术后监护。结果4例患儿中,胸腹联合畸形3例,骶尾部不对性联体1例;男性1例,女性3例。未手术的1例因复杂心脏畸形合并循环衰竭,丧失手术时机。1例不对称性联体儿分离手术在入院后3d进行,对称性联体儿分离手术时间分别为出生后16d、43d,均存活。一对现术后2年,1对现术后9个月,均发育良好。结论手术时机与分离方式必须依据每一对联体儿的具体情况而定,充分的术前准备可提高手术成功率。     

Prenatal diagnosis of parasitic conjoined twins with three‐dimensional ultrasound

Asymmetric and parasitic conjoined twins are extremely rare anomalies of monochorionic monoamniotic twins, consisting of an incomplete twin attached to the fully developed body of the co‐twin. Sonographic examination is essential for prenatal diagnosis as early detection of fetal anomalies with poor prognosis provides a chance to deliver the infant vaginally for the mother. We herein describe a case with a prenatal diagnosis of a parasitic twin using three‐dimensional (3‐D) ultrasound. The clear images obtained with 3‐D ultrasound helped in counseling the parents. Making an early prenatal diagnosis of severe fetal anomalies with careful and sophisticated sonographic examinations should be warranted.     

Fetal MRI of cloacal exstrophy

Background

Prenatal ultrasonographic (US) diagnosis of cloacal exstrophy (CE) is challenging.

Objective

To define the fetal MRI findings in CE.

Materials and methods

We performed a retrospective review of eight patients with CE. Imaging was performed between 22 weeks and 36 weeks of gestation with US in four and MRI in eight fetuses. Abdominal wall, gastrointestinal/genitourinary, and spine and limb abnormalities detected were compared with postnatal evaluation.

Results

US failed to display CE in one of the four fetuses. Fetal MRI confirmed CE in all eight fetuses by demonstrating absence of a normal bladder and lack of meconium-filled rectum/colon, associated with protuberant pelvic contour and omphalocele. These findings correlated postnatally with CE, atretic hindgut and omphalocele. One fetus had imaging before rupture of the cloacal membrane, showing a protruding pelvic cyst. Absent bladder was noted in the remaining seven fetuses. Confirmed skin-covered spinal defects were noted in seven fetuses, low conus/tethered cord in one and clubfoot in three. Six fetuses had renal anomalies, two had hydrocolpos and one had ambiguous genitalia.

Conclusion

Fetal MRI provides a confident diagnosis of CE when a normal bladder is not identified, there is a protuberant abdominopelvic contour and there is absence of meconium-filled rectum and colon. Genitourinary and spinal malformations are common associations.