EXPERIMENTAL AND CLINICAL TRANSPLANTATION

En bloc kidney transplant remains a technically challenging procedure, especially in pediatric transplants. The intra-abdominal approach has been the preferred operation for very young children. However, the transverse incision could result in more abdominal muscle damage and intra-abdominal adhesions. If the extraperitoneal approach, which is the standard method for adult kidney transplant, could be performed in pediatric recipients, then adverse effects after a transverse incision could be avoided. A 30-month-old female recipient (13.1 kg) underwent an en bloc kidney transplant from a 36-month-old female donor (13.3 kg) who had cardiac arrest of unknown origin. The kidneys were retrieved with the en bloc technique using a bladder patch. A right Gibson incision was made along the lateral fascia of the rectus muscle of the recipient to prevent muscle fiber damage. The inferior vena cava and aorta of the donor were anastomosed to the inferior vena cava and right common iliac artery of the recipient, respectively. The bladder patch with 2 ureteral openings was directly anastomosed to the bladder of the recipient. Urination was excellent immediately after the operation. The recipient recovered quickly. The total extraperitoneal approach is feasible and has some advantages over the transverse incision, even in pediatric recipients.

Key words : Abdominal muscle damage, Pediatric kidney transplant

The results of pediatric kidney transplant have improved in the past few decades.¹ However, en bloc kidney transplant (EBKT) remains a technically challenging procedure, especially in pediatric donors and pediatric recipients.² Pediatric patients who are on the wait list for kidney transplant have a higher probability of transplant from pediatric deceased donors because of changes in the allocation system in Korea since October 2018. Therefore, the likelihood of EBKT from pediatric donors to pediatric recipients has increased. Traditionally, transverse incision was preferred over midline incision for infants and younger children, even though the transverse incision could result greater severity of abdominal muscle damage.³ Moreover, the transperitoneal approach is often selected for EBKT in pediatric patients, especially when the patient’s body weight is less than 20 kg.⁴ The transperitoneal approach has been considered advantageous, as it allows sufficient space for dual kidney grafts. Nevertheless, because all kidney transplant procedures are performed in the retroperitoneal space, the total extraperitoneal approach (as in adult kidney transplant) remains an important option by which to reduce the risk of muscle injury and other adverse effects such as intra-abdominal adhesion, bleeding, and delayed detection of urinary leakage.

This report was approved by the Institutional Review Board (approval No. 05-2020-116).

Deceased donor and bench procedure
A 36-month-old female patient with no medical history of disease was referred to the emergency room to treat sudden cardiac arrest. The pulse was recovered after resuscitation; however, ischemic brain damage was exaggerated, resulting in brain death. Her height was 110 cm, and her weight was 13.3 kg. Only the kidneys were allocated for transplant. En bloc kidney grafts were retrieved with a bladder patch that included the openings of the ureters. The grafts weighed 127 g each.

We performed the standard bench procedure for EBKT. All lumbar arteries were ligated, and the upper openings of the aorta and inferior vena cava (IVC) were closed with continuous sutures. Ureteral openings and remnant bladder tissue removal were confirmed.

Recipient profile
The recipient was a 30-month-old girl under peritoneal dialysis for end-stage renal disease of unknown origin. She had no other medical diseases, except for mild developmental delay. Her height was 88 cm, and her weight was 13.1 kg.

Surgical procedure
A right Gibson incision was attempted along the lateral border of the rectus fascia to prevent muscle fiber damage. The retroperitoneal space was secured by gentle dissection of the perineum at the medial side. The IVC and right common iliac artery were dissected for anastomosis. The graft IVC was anastomosed to the IVC of the recipient, and the graft aorta was anastomosed to the recipient’s right common iliac artery. The cold ischemic time was 131 minutes, and the anastomotic time was 35 minutes. Urinary output was observed immediately after anastomosis.

The anastomosis of the bladder patch of the graft to the bladder of the recipient was performed by inserting a single, double J catheter. The catheter could not pass through the other ureteral opening; however, the urination was excellent. Therefore, the catheter was not forcibly inserted to prevent ureteral injury.

The total operation took 3.5 hours with an estimated blood loss of 150 mL (Figure 1).

Postoperative course
Urination was normal, and the serum creatinine level was quickly normalized after transplant (Figure 2). Hematuria was observed within 3 postoperative days, and hematoma (2.4 cm × 2.2 cm × 4.3 cm) was observed in the bladder by ultrasonography. Therefore, urokinase (100,000 U mix to 100 mL of normal saline) was administered at 30 mL every 4 hours (without Foley catheter clamping) directly to the bladder to resolve the hematoma, which disappeared after 5 days.

However, ascites of unknown origin with mild elevation of liver enzyme occurred; therefore, ultrasonography-guided ascites aspiration was performed. The creatinine level of ascites was very low (< 0.1 mg/dL); therefore, urinary leakage to the abdominal cavity was ruled out. Liver enzymes also decreased thereafter.

Doppler ultrasonography and mercaptoacetyltriglycine kidney scans were performed to evaluate the graft (Figure 3). The perfusion and spectral wave were within the normal range on Doppler ultrasonography, and the uptake and excretion were also within the normal range in the mercaptoacetyltriglycine kidney scan.

Immunosuppressants
We used the standard steroid-based immunosuppressant protocol, including basiliximab induction (10 mg on the day of operation and on postoperative day 4), tacrolimus, and mycophenolate mofetil. Tacrolimus (0.1 mg/kg every 12 h) and corticosteroid (2 mg/kg) were started 1 day before transplant, and mycophenolate mofetil was started after fasting and then discontinued postoperatively. Diltiazem (2 mg/kg), a calcium channel blocker, was also administered to prevent vascular spasm intraoperatively and to increase the tacrolimus level.

A pediatric en bloc kidney graft compared with an adult living donor kidney for adult recipients has been shown to result in similar positive outcomes.⁵ However, EBKT from pediatric donor to pediatric recipient is still considered a “marginal” transplant procedure because of the technical complexity, and special considerations for pediatric recipients must be considered; such potential complications are absent in these procedures for adult recipients.²

Surgeons prefer the transverse incision for younger patients because the shape of the abdomen of younger children is circular compared with the oval shape of adults. Therefore, the transperitoneal approach is the preferred method for surgical visibility.³ In contrast, the extraperitoneal approach is the standard incision technique for kidney transplant in adult recipients.⁶ Because the vessels and bladder for transplant are all located in the extraperitoneal space, the extraperitoneal approach enables surgeons to avoid the risks of adhesion or intra-abdominal organ injuries. These observations tell us that, if we have access to sufficient space to locate the graft in the extraperitoneal cavity in pediatric recipients, then the peritoneal cavity need not be opened. According to our experience, the space was sufficiently larger than the space made through an intra-abdominal approach. Moreover, we expect this approach to provide a better view for graft biopsy.

We had always thought that the transperitoneal approach was better than the extraperitoneal approach in pediatric patients. Therefore, we performed all EBKT procedures on pediatric recipients using the transperitoneal approach. The transperitoneal approach has a benefit in native nephrectomy, which is frequently requested by pediatric nephrologists. However, in this case, there was no need for nephrectomy because the patient did not have a typical pediatric body shape, and the longitudinal distance was sufficient. Therefore, we chose the extraperitoneal approach.

Another advantage of the total extraperitoneal approach was observed in this case. Large volume ascites of unknown origin occurred after drain removal; however, the ascites was not caused by kidney grafts because the grafts were totally separated by the peritoneal membrane, as confirmed in the ascitic fluid analysis. If transverse incision had been made as usual, then the drain could not have been removed until the complete disappearance of ascites.

However, surgeons should remain aware that pediatric kidney recipients have a higher risk of other concurrent abdominal diseases, which could increase the likelihood of other types of abdominal surgeries during their lifetimes.⁴ Therefore, the intra-abdominal cavity must be preserved, intact without adhesion, if possible.

In conclusion, the total extraperitoneal approach for pediatric EBKT to a pediatric recipient is a feasible surgical procedure without increasing the surgical difficulty. Furthermore, the method is more advantageous than the intra-abdominal approach.

Volume: 18 Issue: 7 December 2020

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