In living-donor liver transplantation (LDLT), a partial liver, usually the left lateral section or the left liver, is harvested for use as the graft liver. A relatively small-sized partial liver graft may fall into the relatively large right subphrenic fossa, which can induce twisting around the hepatic vein anastomosis. Such a size mismatch can result in graft hepatic vein outflow obstruction as well as excessive stretching of the reconstructed portal vein. A tissue expander (TE) has been used to prevent such detrimental dextro-rotation of the partial liver graft through obliteration of the dead space at the right subphrenic fossa [1-3]. Liver transplantation (LT) using dual left-liver graft is an indication for TE application, because the right-sided left liver graft is vulnerable to anastomotic rotation of the hepatic vein and portal vein due to the size mismatch [4-6]. In the present study, we present our experience with TE application in a high-volume LT center.

TEs of various sizes and shapes are commercially available. The most frequently used TE is a dome shape with an external connecting tube and an injection port (Fig. 1) that is used in various reconstructive surgeries because its flat-bed can prevent unwanted migration and the injection port facilitates subcutaneous installation [7]. The selection of a suitable TE depends on the size and shape of the dead space.

Figure 1. A pediatric case of tissue expander application. (A) The patient was an 8-year-old boy weighing 28 kg suffering from large multiple hepatoblastomas invading the retrohepatic inferior vena cava. A 250 g-weighing left liver graft with a graft-to-recipient weight ratio of 0.89% was implanted with vein homograft interposition of the inferior vena cava. (B) The liver graft was relatively small compared with the native 2,064 g-weighing tumor-bearing liver and its corresponding right subphrenic fossa. (C) A tissue expander was placed to prevent collapse toward the right subphrenic fossa. (D) The water within the tissue expander was gradually aspirated after 7 days, and the tissue expander was removed in 2 weeks.

The indications for TE application can be classified into four categories, including pediatric LT cases using a living-donor or split deceased-donor left-sided liver graft, adult LT cases using a living-donor left liver graft, LT with dual-graft implantation, and unusual conditions such as a recipient with situs inversus. The underlying cause of TE application is basically identical in all four categories, but the technical details of TE application differ from each other.

Tissue Expander Application for Pediatric Patients Receiving a Living-Donor or Split Deceased-Donor Left-Sided Liver Graft

A large-for-size liver graft is a common challenge in pediatric LT, but a partial liver graft can be too small relative to the size of the recipient’s abdominal cavity. When a left-sided liver graft carries a risk of detrimental dextro-rotation, the first option is firm fixation of the round ligament to the abdominal wall, which enables three-point anchoring of the liver graft via hepatic vein anastomosis, portal vein anastomosis and fixation suture at the round ligament. An excessively large space at the right subphrenic fossa is an indication for TE application.

Sample case: The patient was an 8-year-old 28 kg-weighing boy suffering from large multiple hepatoblastomas with invasion of the retrohepatic inferior vena cava. A 250 g-weighing left liver graft, that is a graft-to-recipient weight ratio (GRWR) of 0.89%, was harvested from his mother and a 4 cm-long vein homograft was anastomosed at the back table. This graft was implanted along standard procedure similar to deceased-donor LT. Because the liver graft was very small compared with the native 2,064 g-weighing tumor-bearing liver, a TE was placed to prevent collapse toward the right subphrenic fossa [3]. The water within the TE was gradually aspirated after 7 days and the TE was surgically removed at 2 weeks after LT (Fig. 2).

Figure 2. Gross photograph of a dome-shaped tissue expander with an external connecting tube and an injection port.

Tissue Expander Application for Adult Patients Receiving a Living-Donor Left Liver Graft

A small-for-size liver graft is a common challenge in adult LDLT, especially when a left liver graft is implanted. If the GRWR of a left liver graft is smaller than 0.8%, it is important to place the liver graft in the right position to prevent twisting of the hepatic and portal vein anastomoses under TE application (Fig. 3). Decompression of the TE water should be adjusted carefully according to the graft regeneration observed in the serial follow-up computed tomography scans, in which TE removal occurs in 1 to 3 weeks (Fig. 4).

Figure 3. An adult sample case of tissue expander application. (A) A small-for-size left liver graft is implanted. (B, C) A tissue expander is inserted to place the liver graft in the right position to prevent twisting of the hepatic and portal vein anastomoses. (D) The desirable configuration of the outflow graft hepatic veins is illustrated.

Figure 4. An adult case showing progressive regeneration of the left liver with caudate lobe graft. (A) A dotted line in the donor liver computed tomography indicates the hepatic transection line. (B–D) The water within the tissue expander was gradually evacuated along the graft regeneration. The tissue expander was removed on day 22 after transplantation.

Tissue Expander Application for Adult Patients Receiving Dual Grafts

A right-sided graft that is a left lateral section or left liver graft is vulnerable to detrimental anastomotic rotation of the hepatic and portal veins due to the size mismatch similar to that of left-liver graft implantation [4-6]. Decompression of the TE water depends on the graft regeneration, and the TE was removed within 2 weeks (Fig. 5).

Figure 5. An adult case of dual-graft implantation with tissue expander application. (A, B) A tissue expander is placed under the right-sided left liver graft. (C) The tissue expander was decompressed along the graft regeneration. (D) Uneventful full generation of both left-liver grafts is visible.

Tissue Expander Application in a Recipient with Situs Inversus

Sample case: A 42-year-old man weighing 95 kg with situs inversus totalis who was diagnosed with acute-on-chronic hepatic failure underwent deceased-donor whole-liver transplantation. A modified piggy-back technique with side-to-side cavo-cavostomy was used for the outflow vein reconstruction. The deceased donor weighed 58 kg, thus donor-recipient body weight ratio was 0.61, and the GRWR was 1.43%. To maintain the orientation of the outflow and inflow vessels of the liver graft in the initially designed position, a large TE was inserted into the left subphrenic space for mechanical support of the liver graft (Fig. 6) [8]. The TE water was gradually removed, and the TE was removed on day 46 after transplantation.

Figure 6. An adult case of situs inversus with tissue expander application. (A) A 42-year-old man weighing 95 kg with situs inversus totalis underwent deceased-donor whole-liver transplantation. The deceased donor weighed 58 kg, thus donor-recipient body weight ratio was 0.61 and the graft-to-recipient weight ratio was 1.43%. (B) A large tissue expander was inserted into the left subphrenic space for mechanical support of the liver graft. (C, D) The tissue expander was decompressed along the graft regeneration.

The timing of TE removal depends on the degree of graft regeneration and the amount of water within the TE, which is usually 1 to 3 weeks after LT. The abdominal wound is partially reopened after complete aspiration of the water. The infusion port with the connecting tube acts as a guide toward the deeply implanted TE in the right subphrenic fossa, so its gentle extrication leads to gradual mobilization of the TE (Fig. 7). Some resistance may be felt during its traction when it is left for 2 weeks or longer, but the TE can be smoothly removed because the TE material does not induce tissue reaction-associated heavy adhesions. Because of such TE removal, the transverse wound of the recipient should be repaired with interrupted sutures during the initial LT operation.

Figure 7. Intraoperative photographs showing removal of a tissue expander. (A) Water within the tissue expander is completely aspirated. (B–D) The abdominal wound is reopened and the connecting tube is gently extracted to deliver the tissue expander.

Since the introduction of TE application in pediatric LDLT in mid-1990’s [1], it has been regarded as a safe and effective technique for mechanical support of small-sized liver grafts. Traditionally, the TEs are used for progressive expansion of the overlying skin in various reconstructive plastic surgeries including breast reconstruction. Conversely, the TEs in the field of LT are used for progressive shrinkage of the dead space according to graft regeneration.

A few studies involving TE application have been sporadically reported worldwide, in which the majority of patients were pediatric recipients. A report using ping-pong balls instead of a TE has been reported [9]. To the best of our knowledge, this is the first case series on TE application covering both pediatric and adult recipients. Since TE application used in the world-first case of dual-graft LT, it has been an important component of LDLT using two left liver grafts. TE application is a simple and safe technique, thus there is no reason to hesitate performing it if indicated.

In our early experience, we used ovoid TEs without flat-bed plate for easy removal through a small incision. During the learning curve, we recognized that such round TEs were vulnerable to unwanted migration. Further, the incision for its removal was not smaller than that of other TEs. Furthermore, the dome-shaped TEs with a flat-bed plate are always available in our institution. After the learning curve, we have used only dome-shaped TEs with a flat-bed plate during the last 20 years.

Any TE is a kind of foreign body, and thus increases the risk of abdominal infection theoretically. In real-world practice, mild tissue reaction or fluid collection around the TE occurred in LT recipients, but we experienced no serious adverse TE-associated complications in more than 100 cases of TE application. In fact, TEs were originally designed as long-term implants within the human body. Therefore, we emphasize that TE application is a safe procedure in LT recipients.

In conclusion, we suggest that TE application is simple, safe, and effective to provide mechanical support for the liver graft, and therefore performed readily if indicated.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: SH. Data curation: WHK, SH, CSA, TYH, GWS, DHJ, GCP, JMN, YIY. Formal analysis: WHK, SH, CSA, DBM, TYH, GWS, DHJ, GCP, JMN, YIY. Investigation: WHK, SH, CSA, TYH, GWS, DHJ, GCP, JMN, YIY. Methodology: WHK, SH, CSA, TYH, GWS, DHJ, GCP, JMN, YIY. Project administration: SH, SGL. Supervision: SGL. Validation: SH. Visualization: SH. Writing - original draft: SH. Writing - review & editing: All.