Viscoelastic Testing and Factor Concentrate Therapy to Reduce Bleeding and Transfusions in the Surgical Separation of Ischiophagus Twins

The surgical procedure to separate conjoined twins represents a rare and major multidisciplinary challenge. The evidence supporting the management of these patients is restricted mainly to case reports.¹ Broadly, the approach is individualized considering fused structures, since morbidity and mortality appear to be greater when there is extended visceral sharing.²

One of the most feared perioperative scenarios is the presence of coagulopathy secondary to bleeding.³ This complication is usually seen during the separation phase and the individual reconstructions needed thereafter. The increased usage of perioperative blood components is a predictor of poor clinical outcomes and postoperative complications in pediatric surgical patients.^4,5 Therefore, it is imperative to consider during this particular surgery: 1) the use of diagnostic strategies that allow early recognition of acquired coagulation disorders, and 2) a patient blood management strategy that reduces unnecessary exposure to blood components.

We present a case of the surgical separation of ischiopagus tetrapus twins (ie, conjoined by the pelvis and featuring 2 individual sets of lower limbs²) using intraoperative viscoelastic testing and factor concentrate therapy to reduce bleeding and transfusions. Written informed consent for publication was obtained from the parents with approval of the local research ethics committee, in compliance with the applicable Enhancing the Quality and Transparency of Health Research (EQUATOR) guidelines.

CASE DESCRIPTION

The female ischiopagus twins were diagnosed during the second trimester of pregnancy. They were delivered by cesarean and underwent an uneventful postnatal period. The extensiveness of the conjoined structures consisted of a priori of perineal soft-tissue featuring separate cloacae. Solid abdominal organs and the urinary systems appeared not to be involved, but the same could not be confirmed for enteral structures, which are frequently shared in ischiopagus twins.² They were treated for tubular kidney acidosis with conserved preoperative renal function.

The separation surgery was scheduled for 1 year of life, and at that time, the twins weighed 15 kilograms together, evenly distributed. Two teams were created—one for each twin, coded “RED” and “BLUE”—featuring anesthesiologists, urologists, and colorectal, orthopedic, and plastic pediatric surgeons.

The planned procedure consisted of a diagnostic laparoscopy and cystoscopy, including subsequent separation of the partially conjoined abdominal walls, a Smith-Petersen pelvic osteotomy to allow appropriate abdominal closure, and perineal dissection with individualization of cloacae.

The diagnostic phase of the surgery confirmed individual urinary tract systems. The distal ileus and colon were shared, but their irrigation was mainly supplied by the RED twin. Thus, a terminal ileostomy was performed on the BLUE twin, while a temporary colostomy was performed on the RED twin. Complete separation was achieved 10 hours after induction of anesthesia.

During the pelvic osteotomy, a high volume of blood loss (up to 30% of estimated total blood volume [TBV]) was anticipated. To avoid progressive unrecognized coagulopathy, frequent intraoperative hemostatic evaluations were performed using viscoelastic testing, specifically rotational thromboelastometry (ROTEM; Delta, Werfen)⁶ assays FIBTEM (a whole blood test reflecting mainly fibrinogen contribution and fibrin polymerization) and EXTEM (an extrinsically activated whole blood test comprehensively analyzing clot strength and kinetics).

These 2 assays (considered the most valuable for high-risk pediatric surgery)^7,8 per twin were selected to allow simultaneous assessment during bleeding suspicious for consumption of hemostatic components using the 4-channel ROTEM Delta device. There were 7 pairs of simultaneous ROTEM tests during this 16-hour surgery. The intraoperative hemostatic algorithm (Figure) focused mainly on the early detection and treatment of hypofibrinogenemia, as this has been shown to be the most frequently acquired coagulopathy in complex pediatric surgery.⁹ Both twins received a bolus of tranexamic acid (TXA; 15 mg/kg) followed by a continuous intraoperative infusion of 5 mg kg⁻¹ h⁻¹. Notably, regarding hemostatic replacement, only boluses of fibrinogen concentrate (FC) were needed, and no platelet or plasma transfusions were administered (Figure; Table 1).

Fluid therapy consisted of a basal infusion of crystalloids at a rate of 5 mL kg⁻¹ h⁻¹ plus boluses of 4 mL/kg of isotonic 5% albumin in case of fluid-responsive hypotension. Intraoperative urine output was conserved at a rate of 1.2 mL kg⁻¹ h⁻¹ despite frequent periods of moderate hypotension resolved by fluid boluses and norepinephrine infusion guided by macrohemodynamic parameters and blood gas analyses (Table 2). RED received a total of 121 mL/kg of crystalloids and 12 boluses of colloids intraoperatively, while BLUE received 124 mL/kg and 3 boluses, respectively.

RED had an estimated blood loss of 25 mL/kg (roughly one-third of the estimated TBV), while BLUE lost 10 mL/kg of blood. This was assessed by field drainage debit in canisters and visual estimation of bleeding absorbed by the surgical compresses. Concordantly, RED’s hemodynamic profile was also worse, especially during pelvic osteotomy.

Due to low hemoglobin concentrations (nadir of 7.3 g/dL), RED received an intraoperative transfusion of 10 mL/kg of red blood cells (RBCs) on just 1 occasion. No other blood components were utilized.

The twins underwent postoperative pediatric intensive care unit (PICU) surveillance with invasive mechanical ventilation for 48 hours. Their kidney function remained stable. During their PICU stay, BLUE received a 10-mL/kg bolus of RBCs during her first postoperative day, while RED did not receive any postoperative transfusions. The remainder of their hospitalization was uneventful, and no thromboembolic events were noted. Both twins are scheduled to undergo perineal reconstruction of the cloacae next year.

DISCUSSION

In this case report, we described the complex surgical separation of ischiophagus twins requiring only a single bolus of RBC transfusion for each twin during the entire hospitalization. No other allogeneic blood components were transfused. This was achieved using TXA, point-of-care diagnostic testing throughout the surgery, and targeted replacement of fibrinogen.

The intraoperative hemostatic algorithm prioritized the use of lyophilized coagulation factor concentrate (CFC) instead of blood components to avoid fluid overload and unnecessary exposure to transfusions, both recognized as detrimental perioperative factors in complex noncardiac pediatric surgery⁴ and in critically ill pediatric populations.^5,10 Moreover, it has been shown that these patients infrequently require blood components while bleeding, provided there is availability of viscoelastic tests and CFC.⁹ Accordingly, there is an increasing trend toward the use of CFC guided by viscoelastic testing for this particular population,¹¹ although prioritizing CFC in lieu of blood components is not yet supported by randomized control trials, even for adult populations. Nevertheless, the potential benefits of a fixed-ratio transfusion protocol in pediatric patients have not been prospectively evaluated either.¹² Thus, there is currently equipoise as to which approach is superior; further prospective evidence to validate either approach is needed, especially in pediatrics.

Regarding specific hemostatic diagnostic approaches in pediatric surgery, Nakayama et al¹³ described in a randomized controlled study that use of the A10 amplitude parameter in FIBTEM and EXTEM to guide intraoperative hemostatic management was associated with reduced blood loss, fewer RBC transfusions, and reduced length of stay in the PICU. In another study, Haas et al⁹ used the maximum clot firmness on the FIBTEM to guide fibrinogen replacement in complex noncardiac pediatric surgery. They concluded that its early substitution led to improved hemostasis with a subsequent decrease in RBC transfusions and blood loss. Accordingly, we used a modified version of a recent bleeding management algorithm.¹⁴ Some of the thresholds used in our algorithm have not been validated for the pediatric population, reinforcing the fact that more pediatric experience in thromboelastometry is urgently needed.¹⁴ Moreover, since low doses of prothrombin complex concentrates (PCCs) appear to be safe and useful in pediatric patients,¹⁵ we integrated this therapeutic option in the hemostatic management algorithm, although PCCs were not needed during this case.

The RED twin experienced more episodes of hypofibrinogenemia (ie, low amplitudes of the FIBTEM assay) due to bleeding, especially during pelvic osteotomy, and thus received more boluses of human FC. Point-of-care blood gas analysis revealed that the physiological objectives for maintaining optimal hemostasis were achieved consistently during surgery for both twins.

The most interesting observation was that despite major bleeding, especially affecting the RED twin, hypofibrinogenemia was the only detected acquired coagulopathy intraoperatively assessed by thromboelastometry. Consequently, fibrinogen substitution using FC was the sole coagulation treatment needed during this 17-hour procedure, despite the profound volume exchange described throughout the operation. The carefully executed hemostasis strategy, in addition to the meticulous surgical preparation, most likely explains the minimal transfusion requirements.

The use of viscoelastic assays performed simultaneously for each twin during an ischiophagus separation surgery was not only feasible, but extremely helpful to proactively monitor and treat intraoperative hemostatic abnormalities. This strategy allowed individually tailored coagulation supplementation for each patient, both while still conjoined and after separation.

In conclusion, in this very rare surgical procedure, focusing on detecting and treating early hypofibrinogenemia using viscoelastic testing and CFC therapy resulted in minimal exposure to blood components, despite the high risk of severe blood loss for this type of surgery. This case presents one option for the hemostatic perioperative management of conjoined twins and acknowledges the importance of avoiding fibrinogen deficiency in complex noncardiac pediatric surgery.

REFERENCES