Ischiopagus tetrapus conjoined twins

zyxwvutsrqponm zyxwvuts zy zyxwvutsrq z zyxwvutsrqp 738-741 Br. J. Surg. 1986, Vol. 73, September, K. Somasundaram and K. S. Wong Department of Surgery, University Hospital, Kuala L umpur, Malaysia Correspondence to: Professor K. Somasundaram lschiopagus tetrapus conjoined twins T w o sets of ischiopagus conjoined twins were successfully operated on at the University Hospital, Kuala Lumpur in 1981 and 1982. The anatomy of the organ and system malformations are discussed which determined the technique of reconstruction after surgical separation to obtain ovtimum cosmetic and functional results. Permanent colostomy was not required in any of thefour twins and in only one twin was there a need for urinary diversion. Keywords: Ischiopagus conjoined twins, multiple organs and systems malformations, rectal continence Ischiopagus twins constitute about 6 per cent of all forms of conjoined twins and consequently there have been reports of only about nine previous attempts a t surgical separation' -4. The anatomical malformations involve more organ systems than any other form of conjoined twins and hence detailed preoperative evaluation and planning of operative separation is required in addition to precise plans for organ and system reconstruction to obtain optimum functional results in both twins. There are significant advantages if all reconstructive procedures are done at the initial operation since they are somewhat interdependent and enhance the overall final result. Th e extremely high operative mortality when separation is undertaken in the neonatal period is attributable t o the lifethreatening emergency that demands the operation, and to some extent the unpreparedness of the surgical team to deal with a rare complex malformation without having had the advantage of previous experience. There have been only two previous instances of a surgical team having a second opportunity t o deal with identical malformations in conjoined twins6,'. This paper describes our experience of operating on two sets of ischiopagus tetrapus twins with almost identical malformations within an interval of just over a year. The detailed study and operative strategies in the first set of twins was of immense help in the operation o n the second set of twins. All four children are alive and developing satisfactorily. babies subsequently seemed stable and it was decided to make detailed investigations before planning the operation. Barium enema through the single anal opening demonstrated a common large bowel and duplicated small intestines. X-rays after barium meal of each baby revealed individual stomachs, duodena and small intestines. Intravenous urography outlined the pelvi calyceal system of four kidneys, two in each twin. All four kidneys showed satisfactory function and appeared normal in shape and size. Two separate bladders were noted to lie adjacent to the fused pubic bones on either side of the corn mon bony pelvic cavity. Each bladder received two ureters, one from each baby. Further evaluation of the twins did not reveal any significant abnormality in the nervous system, lungs or heart. Skeletal radiographs showed a common large pelvic ring formed by the union of the two pelvic girdles. The pubic bones of each pelvis were widely separated and displaced laterally to unite with the pubic bones of the opposite twin and supported the fused pelvic floor musculature (Figure 2).?'he sacrum and coccyx of each twin were complete and separate. One of the twins had a moderate scoliosis of the thoracic spine due to hetriivertebrae in the 6th and 7th thoracic vertebral bodies. Patients and methods Case 1 A set of ischiopagus conjoined twins were born on 8 August 1980 at a private maternity clinic near Ipoh, Malaysia. The pregnancy and delivery were essentially uneventful. The twin pregnancy was an unexpected surprise for both mother and attending medical staff. There was one placenta and one umbilical cord. Both infants breathed and cried spontaneously. The conjoined twins together weighed 3500 g at birth and both babies appeared healthy. On the second day they were transferred 180 km to the University Hospital, Kuala Lumpur. The babies were fused at the pelves, their trunks being joined together in the same longitudinal axis with the head and thorax of each twin at opposite poles. Cephalad to their common umbilicus each twin appeared entirely normal. The four lower extremities were oriented at right angles to the long axis,with the two adjacent limbs on each side of the common trunk belonging to opposite trunks. Both twins were female (Figure 1). Posteriorly the area of fusion was represented by a common perineum and fused buttocks. The buttocks of each twin were separated and fused along a transverse ridge at the middle of which was the common perineum. A single anal opening was at the centre and on either side were the vulva of each twin with urethral and vaginal orifices. Each twin appeared to be a complete individual except for the apparent deficiency of the infra-umbilical abdominal wall. The babies were nursed in strict isolation. Meconium freely evacuated through the anus but on the second day of admission the umbilicus appeared inflamed and bowel sounds in both babies were impaired. This responded to intravenous fluids, nasogastric suction and antibiotics. From the fifth day onwards, oral feeds were commenced. The 738 zyxwv Figure 1 Anterior view of ischiopagus conjoined twins: case 1 0007-1323/86/0907384$3.00 0 1986 Butterworth & Co (Publishers) Ltd zy zyxwvut lschiopagus conjoined twins: K. Somasundaram and K. S. Wong Twin 11 Twin 1 Figure 2 Diagrammatic representation of pelvis and pelvic floor: case 1 Operation. After detailed studies of the anatomy, operative strategies for separation and reconstruction were planned and rehearsed with operating theatre staff and anaesthesiologists. On 5 March 1981, surgical separation was undertaken when the twins were 7 months old and weighed 8 kg. Both babies were simultaneously anaesthetized, with intravenous and intra-arterial lines inserted for continuous monitoring. A lazy S-shaped incision was made transversely across the anterior abdominal wall from a point between the adjacent legs on one side to the corresponding point on the opposite side. Each infant had a normal stomach, duodenum, gallbladder, liver, pancreas and spleen. There were two small intestines of normal length on each side which united to form a single terminal ileum measuring 20cm. The latter continued into an unduplicated large bowel which entered the solitary anal opening posteriorly. There were two urinary bladders in the pelvis, one on each side of the common pelvic cavity. The uteri and two normal pairs of uterine tubes and ovaries were present medial to the bladders on each side. The rectum was between the two uteri. There were two superior rnesenteric arteries, one from each twin. Blood supply to the terminal ileum and the proximal large bowel was from the middle colic vessels of Twin I while a single inferior mesenteric artery from Twin I1 supplied the distal colon and rectum. The separation of the intestinal tract was the first step in the procedure. The distal ileum of Twin I1 was divided at its point of entry into the distal ileum of Twin I and the defect in the ileum closed. The colon was then transected at its middle preserving the blood supply for the proximal segment from Twin I and the distal from Twin I1 (Figure 3). The right ureter of each infant was divided at the lower end. The union of the pubic bones between the twins were divided and the dissection extended between the legs. The fused pelvic musculature was then divided and each twin was assigned bladder, vagina, uterus and adnexa that were to the left of each twin. The left ureter of each twin therefore remained intact with the appropriate bladder. The skin incision on the back followed this tine of division, each twin retaining the external genitalia corresponding to the internal genitalia. The single anus was assigned to Twin 11. Twin I1 had ileo-colic anastomosis, right ureteric reimplantation and approximation of pubic bones with repair of the pelvic floor. Twin I had right ureteric reimplantation, approximation of pubic bones and reconstruction of the pelvic floor with the divided proximal colon brought through into the perineum. Bilateral posterior iliac osteotomies were performed to enable the pubic bones to be approximated anteriorly. The lower recti thus came to lie parallel to each other to create the infra-umbilical abdominal musculature. Final abdominal wall repair was achieved by folding anterior and posterior transverse skin incisions at their midpoints to effect closure vertically from umbilicus to coccygeal region. The total operating time was 8: hand the blood loss was less than one litre. Both babies made an uneventful recovery and had bowel actions through the anus. The suprapubic urinary catheters were removed after 6 weeks with return of spontaneous bladder function. Br. J. Surg., Vol. 73, No. 9, September 1986 zyxwv zyxwvu Case 2 The twins were born on 22 December 1981 at homein the town of Bagan Serai, about 200 km from Kuala Lumpur. The twins were girls. Birth was by normal vaginal delivery with a midwife in attendance. The combined birth weight was 5 kg. The twins were initially taken to Taiping district hospital and transferred to the University Hospital the following day when their condition was stable. The twin pregnancy was not detected antenatally. There was a history of dizygotic twins on the paternal side. The babies were in external appearance similar to the previous set of twins with the exception that there was a single urogenital sinus lying very close to the single anus into which opened two vaginae and a single urethra. Apart from umbilical sepsis during the neonatal period which responded well to antibiotics, the babies made satisfactory progress until their separation 4 months later. Barium studies of the gastrointestinal tract, intravenous pyelogram and skeletograms showed similar findings as in the previous set of ischiopagus tetrapus twins. On 19 April 1982, when the combined weight was 8.2 kg, separation was performed. The operative technique was as described for the earlier twins but with a difference in the genito-urethral reconstruction. Since there was a single urethra, one twin was assigned the urethra in continuity with its bladder. The other twin had a urethra reconstructed from a flap of anterior bladder wall. The babies made uneventful recovery except for an operation to reinsert the suprapubic catheter that dislodged on the fourth postoperative day in one twin. Both babies had normal bowel action through the anus from the fourth postoperative day. The reconstructed urethra in Twin B later stenosed, necessitating a permanent cystostomy; Twin A has normal micturition. Discussion The main purpose of this communication is to highlight the operative strategies and anatomical details in ischiopagus conjoined twins that enabled surgical separation and complete reconstruction. Although visceral abnormalities have been described in detail', the anatomy of the abdominal wall, the pelvic girdle and its musculature have received little attention. In the two sets of ischiopagus twins, the operation was planned on the basis of these anatomical details that have eventually influenced the satisfactory functional and cosmetic results of reconstruction. None of the babies required colostomies and only one of the four twins required permanent urinary diversion. Pre-operative evaluation The indications for emergency operative separation ofconjoined twins in the neonatal period have been clearly outlined in previous reports5. In all other situations a planned elective operation with adequate investigations is madatory. In ischiopagus twins there are few indications for emergency operations. Colonic obstruction due to stenosis of the single anus and bladder outlet obstruction due to deformity of the urethrae may occur soon after birth5. This is more likely in the presence of a cloaca with distortion of urethrae and anus rather than in those with complete duplication of external genitalia. Anal and urethral dilatation should be attempted as an initial Twln II Twin I zyxwvut Ileum Figure 3 Separation of the intestinal tract with preservation of blood supply 739 zyxwvuts zyxwvut lschiopagus conjoined twins: K . Somasundaram and K. S. Wong manoeuvre, failing which a colostomy and cystostomy are recommended. Aside from this, intensive nursing care is necessary in the months proceeding operation to prevent pneumonia and urinary tract infection. Pre-operative evaluation with barium studies of the intestinal tract, intravenous urogram, cystograms and skeletal X-rays are absolutely essential. Although the alimentary tract abnormality in ischiopagus twins is consistently similar in most instances, rarer anomalies of the rectum have been described'. The high incidence of renal and lower urinary abnormality justifies urogram. Major vascular abnormalities, particularly in limb vessels, are rare except in ischiopagus tripus twins" and thus angiography is not routinely required. All operative strategies with alternative options should be careful studied by the team of surgeons, anaesthesiologists and operating theatre staff. Suprapubic drainage was required for 6 weeks because of the extensive pelvic dissection and injury to autonomic nerves on oneside of the pelvis. The bladder control in the three twins with intact urethrae is adequate. The urethral reconstruction in the fourth twin has stenosed and she is left with a permanent cyatostomy. Abdominal wall The anterior abdominal walls of ischiopagus twins have a broad uninterrupted area of union with a single central umbilicus, and each twin appears to be deficient in the infra-umbilical abdominal wall and musculature. In effect however, the two recti abdominis muscles of each twin below the umbilicus diverge from each other to gain separate attachments to the coxresponding pubic bones at the side. The space between the diverging recti is occupied by a dense wide linea alba that stretches over to the opposite twin and forms the basis of union between the anterior abdominal musculature. In our reconstruction of the abdominal wall, the widely separated pubic bones were initially approximated. This enables the two recti to come together without tension thus creating an infi-a-umbilical abdominal wall. The transverse skin incision is folded in the middle at the site of the umbilicus to lie vertically (Fbgure 4). Pre-operative pneumoperitoneum to enlarge the abdominal cavity was not required. Furthermore, skin flaps or composite flaps obtained by sacrifice of a limb in tripus twins would not be required in this method of reconstruction".". zyxwvutsrqpon Alimentary tract The alimentary tract abnormalities were essentially similar to those in previously reported operations. The proximal half of the colon received its blood supply from a predominant ileocolic vessel of one twin while the distal colon and rectum received its blood supply from the opposite twin (Figure 3).In our operative strategy it is essential that this be carefully determined for appropriate assignment of rectum and distal colon. One baby is left with continuity of small bowel with the proximal colon, the end of which is brought out into the perineum between the approximated pelvic muscles, while the other twin retains the anus and distal colon which is anastomosed t o the divided terminal ileum. The pattern of intestinal vasculature determines the assignment of rectum and anus to the appropriate twin and enables separation of the intestinal tract without the need for abdominal colostomy. These features have not been discussed in previous reports. Anal reconstruction has been reported only once among ischiopagus twins'. The anal function in our two twins with the anatomic anus is satisfactory with n o faecal soiling while in the two twins with pullthrough anus there is minimal soiling between acts of defaecation. Pei'uicfloor and skeletal abnormalities The pelvic girdles of ischiopagus twins are widely separated anteriorly and fused into the corresponding bones of the opposite twin. In both sets of twins reported, the girdle was symmetrical with a normal size sacrum for each twin. Asymmetry of pelvic girdle union is however not infrequently observed in ischiopagus tripus twins with limb abnormalities Urinary tract and pelvic organs The urinary tract malformations in both sets of twins were very similar, each bladder receiving two ureters from the mirror image kidneys of both babies. Renal abnormalities such as hypoplasia and ureteric dilations have been previously reported. Invariably this is unilateral and prior knowledge is necessary to avoid a reimplantation of the ureter of a hypoplastic non-functional kidney. Reimplantation of the divided right ureter of each twin t o the appropriate bladder is possible without tension after approximation of the pubic bones which in effect transposes the bladder from a lateral position in the pelvis to its normal position. Communication between the two bladders across the pelvic cavity has been reported'. This is evident in cystograms and should be divided during the pelvic dissection. External genitalia and perineum The two halves of the perineum are laterally displaced and fused with that of the opposite twin along a transverse furrow at the centre of which is the anal opening. In the first set of twins the external genitalia were duplicated and lying on either side of the single anus. There were two urethrae, one from each bladder, draining separately into the two vulvae. In the second set of twins the external genitalia were fused and lying very close to the anal opening. There was in fact a single urogenital sinus with two vaginal openings and a single urethral opening. The two halves of the perineum are approximated in the midline with the anatomic anus or the pullthrough colon as the case may be lying at the posterior end of the suture line. The external genitalia will thus come to lie anterior to the anus from its lateral position. This would not be possible without posterior iliac osteotomies and reconstruction of the pelvic girdle. 740 zyxw zyxw Figure 4 Postoperative photographof one of the babies showing midline scar and perineum Br. J . Surg., Vol. 73, N o . 9, September 1986 lschiopagus conjoined twins: K. Somasundaram and K. S. Wong bladder to be reimplanted to the bladder on the left side of each twin. Bilateral iliac osteotomies are necessary preliminary procedures for reconstruction. This helps in easy approximation of the abdominal wall and pelvic floor and realignment of pelvic organs from a lateral to an anterior position when the open pelvic girdle is approximated anteriorly. It also rotates the hips into normal alignment. The first set of twins are now 4 years and 8 months old. Their physical and mental development is normal with satisfactory bladder and rectal control. The second set of twins are 3 years and 5 months old and are also physically normal like the first set of twins (Figure 5). Twin A has normal bladder and bowel control while Twin B has a permanent cystostomy. zy zyxw zyxwvu zyxwvu Acknowledgements We express our thanks to the staff of the Departments of Surgery, Paediatrics, Anaesthesiology, Orthopaedics and the Operating Theatre for their invaluable assistance which contributed to the successful outcome in the management of these two sets of conjoined twins. Our thanks go to Mrs Rohana Dingkel for skilled secretarial assistance. References 1. Bankole MA, Oduntan SA, Oluwasanmi JO, Itayemi SO, Khawaya S. The conjoined twins of Warri, Nigeria. Arch Surg 2. Rosenberg HK, Spackman TJ, Chait A. The Dominican Republic conjoined twins: ischiopagus tetrapus omphalopagus. Am J 3. Akiyama H. Ischiopagus tetrapus conjoined twins. Japanese J 4. Akahiko U. Ischiopagus tetrapus. Clinical Gynaecol Obstet 1968; 1972; 104: 294-301. Roentgenol 1978; 130: 921-6. Figure 5 Twins A and B at 3 years and 3 months and is invariably associated with asymmetry and distortion of pelvic organs". Abnormality of the iliac vessels is another associated feature in asymmetrical pelvic union and angiography would be indicated in such situations. Symmetry of the pelvic girdle, and normal sacral development is also an indication of adequate development of the pelvic floor muscles which should influence satisfactory outcome of the colonic pullthrough procedure. The two halves of the levator ani of each twin when brought together in the midline along a saggital axis provide support for the pelvic organs and a muscular anorectal sling for the twin with a colonic pullthrough. Pelvic organs are completely duplicated but displaced laterally to the central rectum. In the dissection of these organs left-sided structures within the pelvis relating to each twin remain with that infant. The blood supply and autonomic innervation to these organs also remain undisturbed on this side. The right ureter of each twin is divided at its lower end from its Br. J. Surg., Vol. 73, No. 9, September 1986 Ped Surg 1977; 9 966-75. 22: 2014. 5. 812-21. 6. 7. 8. 9. zy Cywes S, Block EC. Conjoined twins. S Afr Med J 1964; 38: Cywes S, Louw JH. The Siyepuconjoined twins. S Afr Med J 1967; 41: 105C7. OConnel JE. Surgical separation ofcraniopagus. Br Med J 1964; 1: 1333-5. Eades JW, Thomas CG. Successful separation of ischiopagus tetrapus conjoined twins. Ann Surg 1966; 164: 1059-72. Poradowska W, Jaworska M, Reszke S, Lodzinski K. Conjoined twins and twin parasite. Clinical analysesof three examples. J Ped Surg 1969; 4: 688-93. 10. 11. Mestrel AL, Golenko RJ, Wax SH, Steiger B, Kenin A, Filler R, Landau S. Ischiopagus tripus conjoined twins: case report of a successful separation. Surgery 1971; 6 9 75-83. Spencer R. Surgical separation of Siamese twins: case report. Surgery 1956; 39: 827-33. Paper accepted 3 January 1986 741