Conjoined Twins Treatment & Management

Historically, conjoined twins in general have been placed into three groups:

• Group 1 - Those who do not survive delivery plus those who die shortly after birth
• Group 2 - Those who survive to undergo an elective procedure
• Group 3 - Those in whom an emergency procedure is required

Of all types of conjoined twins, omphalopagus twins are the most favorable candidates for elective surgery because of good survival rates. ^[32]  A conjoined heart is a contraindication for surgery because the heart complex is usually inseparable; postoperatively, the divided heart often goes into congestive cardiac failure. Cephalopagus twins with extensive brain union cannot be separated. Furthermore, in the United States, parental refusal is a contraindication for surgery.

Emergency conditions may arise at any time; examples include intestinal obstruction, rupture of an omphalocele, congestive cardiac failure, severe degree of respiratory compromise, and terminal illness in one of the twins.

Harper and Kenigsberg suggested that the abdominal cavities grow as the twins age, whereas the bridge connecting the omphalopagus twins does not grow in diameter. ^[33]  Hence, abdominal wall closure can be performed more easily at approximately age 1 year.

Ethical, ^[34] legal, ^[21]  and religious questions frequently arise with conjoined twins. For example, will the surgery be successful? Is sacrificing one twin to save the other justified? The moral and ethical aspects of separation must be considered, especially in the following circumstances:

• A choice must be made concerning single organ systems - The twin who receives the organ system will live and thrive, whereas the other twin will suffer or die; a similar problem arises when unequal limbs are present
• The twins have conjoined hearts - Surgical separation of the cardiac complex has been mostly unsuccessful; in some cases, one twin is allowed to live with the entire cardiac complex; the availability of two heart transplants at the same time may improve the options
• The twins are craniopagus and have complete brain junction - These twins are usually inseparable

Sometimes, the choice is made to sacrifice one twin in order to give the other one a chance of survival. In these instances, consulting with the hospital ethics committee before going to the courts has helped. In these cases, a legal ruling must be made before surgery can be performed.

Nutritional support is very important for the survival of the separated twins, in that delayed healing and infections may occur. Parenteral or enteral feedings must be carefully planned.

Once the diagnosis has been confirmed, the parents should be counseled on the possible outcomes. The team that will attempt the possible separation should provide this advice. The delivery should take place close to the surgical unit where the separation will be performed. With antenatal diagnosis, the delivery should always be by cesarean section. An elective cesarean delivery should be performed near term after confirmation of fetal lung maturity. Twin delivery may otherwise lead to overdistention and uterine atony.

The following are indications for emergency separation:

• One or both twins are in a life-threatening situation
• A correctable life-threatening associated congenital anomaly (eg, intestinal atresia, malrotation with midgut volvulus, ruptured exomphalos, or anorectal agenesis) is present

If the condition of the twins is stable and early separation is not indicated, surgery is usually delayed until age 6-12 months. At that age, the twins are larger and better able to tolerate the surgical procedure. Rapid expansion of the body wall can occur to close substantial defects. The anatomy of the junction and the shared organs and structures will dictate the technical details of the procedure.

Reconstructive surgery is important in ischiopagus twins, who require gastrointestinal (GI), genitourinary (GU), reproductive, or skeletal reconstruction. One twin keeps the shared anus and rectal canal, and the other receives reconstructed ones. Reconstruction is easier in twins with tetrapus than in twins with tripus.

Preparation for surgery

A systematic approach to the workup is necessary. The type of conjoined twinning present determines the specific studies needed; the possible areas of fusion are predictable in each type. Three-dimensional (3D) models ^{[35, 36]}  should be built to depict the shared anatomy. ^[37]  The shared structures must be divided, if possible, in such a way as to maintain functional integrity for each twin. Some shared organs (eg, a single rectum) may not be divisible. Particular considerations for different organ systems are as follows:

• Cardiovascular system - Antenatal and postnatal echocardiography must be performed to accurately define the extracardiac and intracardiac anomalies, and catheterization should be performed in complex cardiac anomalies; electrocardiography (ECG) and radionucleotide angiography may be helpful in deciding whether a separation operation can be carried out; a single QRS complex is an ominous sign
• Hepatobiliary tree - The number of gallbladders, livers, and pancreata should be known; the conjoined liver may be oriented in an oblique plane to the axis of the twins; hepatic venous drainage for each twin must be ascertained; a portoenterostomy or even a cutaneous biliary fistula in one of the separated twins may be required if only a single extrahepatic biliary tree exists
• GI tract - This should be evaluated from top to bottom because fusion may occur at any point; an anorectal malformation (imperforate anus) may be present; laparoscopy may be used to determine bowel distribution between the twins ^[38]
• Urinary tract - Imaging studies are performed to assess the status (eg, number, reflux, anatomy) of the kidneys, ureters, urinary bladders, and urethras
• Genital system - In pygopagus and ischiopagus twins, the number and duplicity of vaginas and the presence of a cervix and urogenital sinus must be noted; in males, penile and scrotal status must be established
• Central nervous system - The nature and extent of nervous system junction must be established in pygopagus twins, who may also have associated hemivertebrae
• Skin - Vascular territories of the skin must be mapped with intravenous (IV) fluorescein dye; the amount of skin needed to close the wound after separation must be evaluated; skin and tissue expanders may be required to allow subsequent wound closure
• Musculoskeletal system - All postoperative defects of the muscle and bone must be covered

Preoperative team conferences should be held, reviewing all the details and models. Moral, ethical, and legal issues must be fully addressed before surgery.

Operative details

Two complete anesthesia teams are required. Two surgical teams are necessary after the twins are apart. Full monitoring is necessary. All administered drugs and IV fluids are calculated on a total-weight basis, with half being delivered to each twin. The IV drugs may have an unpredictable effect because of the cross-circulation. Thus, particular care is needed when these drugs are administered.

During the procedure, abnormal vascular communications and previously unidentified anomalies (eg, GI and GU malformations) may be encountered. Unexpected findings are common even after an extensive preoperative evaluation. The surgical team should be aware of this and should be prepared to vary the operative procedure accordingly.

Where primary skin closure of the defect would otherwise be impossible, Silastic skin expanders have been used to achieve tension-free closure. A tight thoracic wall closure can lead to cardiac tamponade. Absorbable synthetic mesh has been used with success to close thoracic and abdominal gaps. A porous polyethylene implant and a monofilament polypropylene patch have been suggested for reconstruction of the sternum and abdominal wall, respectively. ^[39]

A skin graft from a nonviable twin may be used in certain cases. Because skin grafts need intact body wall for a bed, they are not a very useful primary form of skin coverage. ^[6]

Monitoring must be continued postoperatively in the intensive care unit (ICU). Because surgery is prolonged, infants are mechanically ventilated for a variable period. Fluid and electrolyte balance should be closely monitored. Sepsis is a major cause of morbidity and mortality, and precautions must be exercised, particularly when large skin defects are present.

Complications are common and may include the following:

• Congestive cardiac failure - This is observed when a conjoined heart is divided
• Inadequate or incomplete organ systems - This complication occurs when the twins have unequal distribution of their organs (eg, one shared biliary tract); adequate preplanning in these cases is essential
• Enormous skin defect - This may result from separation of a large bridge and can often be avoided by delaying the surgery until age 1 year; preseparation tissue expanders (essentially pouches that are gradually filled with saline solution) may be useful for avoiding this problem because by stretching the skin, they allow the surgeons to close the wounds after separation surgery
• Infection - Strict infectious precautions are required for 2 days after the surgical procedure, and patients are kept in the ICU; if they do well, routine precautions are adequate for follow-up care
• Hemorrhage - Life-threatening exsanguination can result, especially in craniopagus twins who have a large communicating venous sinus