Infections following facial composite tissue allotransplantation--single center experience and review of the literature

First Composite Woman-to-Woman Facial Transplantation in Turkey: Challenges and Lessons to Be Learned

ABSTRACT

After the first face transplantation from woman to woman we performed in our clinic, it was aimed to eliminate the lack of knowledge about the subject in the literature by transferring our experiences and long-term results to the problems we had with the patient. A 20-year-old patient underwent partial osteomyocutaneous facial transplant (22nd facial transplant), which included 2 functional units of the face. The patient had no major problems in the early period and had a good aesthetic appearance. In the postoperative period, the patient ended her social isolation and adopted the transplanted face.In the late period, secondary surgical interventions, management of the problems caused by immunosuppression, and the patient's living in a remote location to our clinic were the difficulties encountered. Six revision surgeries were performed after the transplantation. Due to immunosuppression, opportunistic infections and metabolic problems required intermittent hospitalization. The patient died at the end of 56 months because of complications secondary to immunosuppression.A successful transplant involves the management of long-term problems rather than a successful tissue transfer in the early period. In today's conditions, long-term success can be achieved with a good patient compliance, as well as each team member should take an active role in the team at the transplantation centers. More case series are needed to adapt the standard treatment and follow-up protocols for solid organ transplantations for composite tissue allotransplantations. This will be possible by sharing the results and experiences transparently in the centers where face transplantation is performed worldwide.

A Systematic Review of the Reported Complications Related to Facial and Upper Extremity Vascularized Composite Allotransplantation

INTRODUCTION

Twenty three years after the first successful upper extremity transplantation, the role of vascularized composite allotransplantation (VCA) in the world of transplantation remains controversial. Face and upper extremity reconstruction via transplantation have become successful options for highly selected patients with severe tissue and functional deficit when conventional reconstructive options are no longer available. Despite clear benefit in these situations, VCA has a significant potential for complications that are more frequent when compared to visceral organ transplantation. This study intended to perform an updated systematic review on such complications.

MATERIALS AND METHODS

MEDLINE database via PubMed, Embase and Cochrane Library were searched. Face and upper extremity VCA performed between 1998 and 2021 were included in the study. Relevant media and press conferences reports were also included. Complications related to face and upper extremity VCA were recorded and reviewed including their clinical characteristics and complications.

RESULTS

One hundred fifteen patients underwent facial (43%) or upper extremity (57%) transplantation. Overall, the surgical complication rate was 23%. Acute and chronic rejection was identified in 89% and 11% of patients, respectively. Fifty eight percent of patients experienced opportunistic infection. Impaired glucose metabolism was the most common immunosuppression-related complication other than infection. Nineteen percent of patients ultimately experienced partial or complete allograft loss.

CONCLUSIONS

Complications related to VCA are a significant source of morbidity and potential mortality. Incidence of such complications is higher than previously reported and should be strongly emphasized in patient consent process. Strict patient selection criteria, complex preoperative evaluation, consideration of alternatives, and thorough disclosure to patients should be routinely performed prior to VCA indication.

Cytomegalovirus-related Complications and Management in Facial Vascularized Composite Allotransplantation: An International Multicenter Retrospective Cohort Study

BACKGROUND

There is a paucity of data on the impact of cytomegalovirus (CMV) serostatus and CMV infection on outcomes in facial vascularized composite allotransplantation.

METHODS

This international, multicenter, retrospective cohort study presents data on CMV and basic transplant-related demographics, including pretransplant viral D/R serostatus, and duration of antiviral prophylaxis. CMV-related complications (viremia, disease), allograft-related complications (rejection episodes, loss), and mortality were analyzed.

RESULTS

We included 19 patients, 4 of whom received CMV high-risk transplants (D+/R-). CMV viremia was noted in 6 patients (all 4 D+/R- patients and 2 D-/R+), mostly within the first-year posttransplant, shortly after discontinuation of antiviral prophylaxis (median 2 mo). CMV disease occurred in 2 D+/R- patients. The high-risk group experienced relatively more rejection episodes per month follow-up. None of D+/R- patients suffered allograft loss due to rejection (longest follow-up: 121 mo).

CONCLUSIONS

D+/R- patients were at increased risk of CMV-related complications. Although a higher number of rejections was noted in this group, none of the D+/R- patients lost their allograft or died because of CMV or rejection. Thus, CMV D+/R- face transplantation can likely be safely performed with prophylaxis, active surveillance, and prompt treatment.

The Second Helsinki Face Transplantation and the World Experience of Revision Surgery During the First Posttransplantation Year

INTRODUCTION

We conducted a review of all surgical interventions performed during the first postoperative year in published face transplantation (FT) cases. In addition, we herein present our second FT patient, a full-face composite FT with an emphasis on surgical revisions after transplantation.

MATERIALS AND METHODS

A literature review was conducted and resulted in 376 publications of which 33 included reference to surgical interventions during the first post-FT year. For our second FT patient, a thorough review of all medical records was performed.

RESULTS

Among the first 41 FTs, 32 FT patients had reports with reference to corrective surgery during the first year (22 composite and 10 soft-tissue FTs). Soft-tissue FTs had a median of 2 procedures (range, 1-8 procedures), and composite FTs, 3 procedures per patient (range, 1-9 procedures). Nearly all early interventions (<1 month) were performed in composite FT patients (anastomotic occlusion, hematoma, sialocele, palatinal dehiscence). The most common late interventions were scar corrections, tissue suspensions, periorbital corrections, osseal and dental procedures, and interventions for palatinal dehiscence and sialocele. Our second FT patient has recovered well and has undergone 3 surgical interventions during the first year.

CONCLUSIONS

Surgical interventions are very common during the first postoperative year after FT, and composite FTs are more prone to complications necessitating surgical intervention than soft-tissue FTs. There is a wide variety of complications reflecting the heterogeneity of FT allografts. Corrective surgery in FT patients appears safe with only a few reported complications.

Donor and Recipient Matching in Facial Vascularized Composite Allotransplantation: A Closer Look at the Donor Pool

BACKGROUND

Identifying a donor for facial vascularized composite allotransplant recipients can be a lengthy, emotionally challenging process. Little is known about the relative distribution of key donor characteristics among potential donors. Data on actual wait times of patients are limited, making it difficult to estimate wait times for future recipients.

METHODS

The authors retrospectively reviewed charts of nine facial vascularized composite allotransplant patients and provide data on transplant wait times and patient characteristics. In addition, they analyzed the United Network for Organ Sharing database of dead organ donors. After excluding donors with high-risk characteristics (e.g., active cancer or risk factors for blood-borne disease transmission), the authors calculated the distribution of relevant donor-recipient matching criteria (i.e., ethnicity, body mass index, age, ABO blood group, cytomegalovirus, Epstein-Barr virus, hepatitis C virus) among 65,201 potential donors.

RESULTS

The median wait time for a transplant was 4 months (range, 1 day to 17 months). The large majority of United Network for Organ Sharing-recorded deaths from disease were white (63 percent) and male (58 percent). Female donors of black, Hispanic, or Asian descent are underrepresented, with 7, 5, and 1 percent of all recorded deaths from disease, respectively. Potential donors show cytomegalovirus and Epstein-Barr virus seropositivity of 65 and 95 percent, respectively. The number of annual hepatitis C-positive donors increased over time.

CONCLUSIONS

Actual facial vascularized composite allotransplant wait times vary considerably. Although most patients experience acceptable wait times, some with underrepresented characteristics exceed acceptable levels. Cytomegalovirus-seropositive donors present a large portion of the donor pool, and exclusion for seronegative patients may increase wait time. Hepatitis C-seropositive donors may constitute a donor pool for underrepresented patient groups in the future.

Facial Transplantation

Facial transplantation represents a unique surgical solution for challenging facial injury patterns in which conservative reconstructive techniques fail to provide a satisfactory functional and aesthetic result. With advances in the field of vascularized composite allotransplantation over the past 15 years, more than 40 of these procedures have been performed worldwide with two recent reports of facial re-transplantation. In this article we discuss the multidisciplinary approach that is required for successful transplantation as well as the surgical techniques used and postoperative management. With ongoing research, recent technological innovation, and increased efforts to promote greater generalizability and transparency in this field, patients with these complex injuries will continue to see improvements in their treatment options, and thus quality of life.

Infectious complications of vascularized composite allograft transplantation

PURPOSE OF REVIEW

Vascularized composite allograft (VCA) transplants constitute multiple tissues transplanted together as one functional unit. These procedures are increasing in frequency and complexity, yet data about graft survival, quality of life, and infection risk remain limited.

RECENT FINDINGS

Informative guidance for this patient population is often inferred from the solid organ transplantation literature. Yet, it is important to understand that VCA transplantation additionally carries its own significant and distinctive risk factors for infection.

SUMMARY

In this review, we give an overview of previously described infectious complications of VCA transplantation in the literature, discuss risk factors for future infection in these patients, and discuss how to manage such obstacles.

Pathologies of oral and sinonasal mucosa following facial vascularized composite allotransplantation

BACKGROUND

Cutaneous changes of facial vascularized composite allotransplants (fVCAs) are extensively described in the literature. Parts of the nose, nasal, and oral cavities are included in most fVCAs. Distinctively, the nose and mouth are lined by mucosa. Little is known about the histopathology and complications of the mucosa involved in fVCA patients.

METHODS

The study constitutes a retrospective cohort study of nine fVCA patients. Medical records were reviewed for information about changes of oral and nasal mucous membranes. Types of mucosal lesions were recorded and analyzed. Uni- and multivariate generalized estimating equation (GEE) models were used to assess the odds of developing mucosal inflammation in the presence of clinico-pathologic variables.

RESULTS

A total of 186 clinical encounters with examination of oral and nasal mucous membranes were included. Membranes were devoid of clinical pathology in 101 instances (53% of all clinical assessments). Ulcerations/erosions (27%), edema (18%), and erythema (14%) were the most common lesions. Oral lesions affected the lips (58%), buccal mucosa (38%), and palate (5%). Sinonasal processes predominantly affected nasal vestibules and septae. In univariate analysis, sirolimus, skin rejection, and skin Banff grade were associated with the presence of an acute inflammatory mucosal lesion (p<0.05). In multivariate analysis, skin Banff grade and sirolimus were independent predictors of mucosal inflammation.

CONCLUSION

Pathologies of fVCA mucous membranes are more common than previously reported. Mucosal assessment plays an important role in the pleomorphic allograft rejection process evaluation rather than diagnosis and treatment based on cutaneous pathology.  A closer look at the pathophysiology of fVCA mucosal rejection and inflammation is warranted.

Anesthetic Considerations in Facial Transplantation: Experience at NYU Langone Health and Systematic Review

Anesthetic considerations are integral to the success of facial transplantation (FT), yet limited evidence exists to guide quality improvement. This study presents an institutional anesthesia protocol, defines reported anesthetic considerations, and provides a comprehensive update to inform future directions of the field.

Changing Concepts and Current Definition of Majocchi's Granuloma

Dermatophytic granuloma characterized by perifollicular granulomatous inflammation was first described by Domenico Majocchi and was later named after him, Majocchi's granuloma (MG). Although the initial description was related to a dermatophyte Trichophyton tonsurans, later reports linked MG to non-dermatophytes (Phoma, Aspergillus, Malbranchea), which led to a confusion of disease patterns caused by cutaneous pathogens and general opportunistic microorganisms. Furthermore, several causative agents of MG described in the literature were not confirmed as such. Our review addressed the following aspects: (1) significance of histopathological finding for MG diagnosis, (2) dermatophytes as exclusive agents of MG, (3) spectrum of etiological agents causing different types of invasive dermatophytic infections, and (4) treatment options.

Composite tissue allotransplantation: opportunities and challenges

Vascularized composite allotransplants (VCAs) have unique properties because of diverse tissue components transplanted en mass as a single unit. In addition to surgery, this type of transplant also faces enormous immunological challenges that demand a detailed analysis of all aspects of alloimmune responses, organ preservation, and injury, as well as the immunogenicity of various tissues within the VCA grafts to further improve graft and patient outcomes. Moreover, the side effects of long-term immunosuppression for VCA patients need to be carefully balanced with the potential benefit of a non-life-saving procedure. In this review article, we provide a comprehensive update on limb and face transplantation, with a specific emphasis on the alloimmune responses to VCA, established and novel immunosuppressive treatments, and patient outcomes.

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.

Infections after upper extremity allotransplantation: a worldwide population cohort study, 1998-2017

Risk-to-benefit analysis of upper extremity allotransplantation (UEA) warrants a careful assessment of immunosuppression-related complications. This first systematic report of infectious complications after UEA aimed to compare incidence and pattern of infections to that observed after kidney transplantation (KT). We conducted a matched cohort study among UEA and KT recipients from the International Registry on Hand and Composite Tissue Transplantation and the French transplant database DIVAT. All UEA recipients between 1998 and 2016 were matched with KT recipients (1:5) regarding age, sex, cytomegalovirus (CMV) serostatus and induction treatment. Infections were analyzed at three posttransplant periods (early: 0-6 months, intermediate: 7-12 months, late: >12 months). Sixty-one UEA recipients and 305 KT recipients were included. Incidence of infection was higher after UEA than after KT during the early period (3.27 vs. 1.95 per 1000 transplant-days, P = 0.01), but not statistically different during the intermediate (0.61 vs. 0.45/1000, P = 0.5) nor the late period (0.15 vs. 0.21/1000, P = 0.11). The distribution of infectious syndromes was significantly different, with mucocutaneous infections predominating after UEA, urinary tract infections and pneumonia predominating after KT. Incidence of infection is high during the first 6 months after UEA. After 1 year, the burden of infections is low, with favorable patterns.

Application of a New Paradigm for Cytomegalovirus Disease Prevention in Mayo Clinic's First Face Transplant

The optimal approach to preventing cytomegalovirus (CMV) disease after face transplant is unknown. We report an individualized hybrid approach, initially using valganciclovir prophylaxis followed by surveillance and preemptive therapy guided by viral and immunologic markers. A 31-year-old man received a near-total face allotransplant for gunshot injury-related severe facial deformities. He was CMV seronegative, and the donor was CMV seropositive (D+/R- mismatch), and he received intravenous ganciclovir followed by oral valganciclovir prophylaxis. Monthly CD8⁺ T-cell immune competence assay revealed no CMV-specific CD8⁺ T-cell immunity development during valganciclovir prophylaxis. Because of severe leukopenia, valganciclovir was discontinued at 7 months after transplant when the patient had recovered and sustained normal global CD8⁺ T-cell function. Weekly CMV polymerase chain reaction testing detected asymptomatic CMV replication (plasma CMV, 549 IU/mL) 3 months later. Short-course preemptive valganciclovir treatment resulted in sustained virologic clearance. The patient had development of CMV-specific CD8⁺ T cells (12 cells/μL) together with CMV IgM and IgG. No rejection or infection relapse was detected 20 months after transplant. In conclusion, viral and immunologic monitoring allowed for an individualized approach to effective CMV disease prevention after face transplant. This case highlights the importance of understanding the interplay between the host immunity and the pathogen in determining the clinical course and outcome of CMV and other infectious disease syndromes.

Innovations in reconstructive microsurgery: Reconstructive transplantation

In the past 20 years, reconstructive transplantation (RT) has emerged as a viable reconstructive option for carefully selected patients. More than 100 upper extremity and 40 face transplants have been performed worldwide to date. Concomitantly, the portfolio of reconstructive transplantation has been extended by additional procedures such as lower extremities, abdominal wall, neck, uterus, genitourinary, and pediatric transplants. In the present review article, we aim to summarize the current state of knowledge about this exciting field.

Majocchi's granuloma: current perspectives

Majocchi’s granuloma (MG) is a rare fungal infection of the dermis that is mainly caused by dermatophytes (in ≥95% of cases); the most frequently identified cause is anthropophilic Trichophyton rubrum. In the rest of the cases, the causes are non-dermatophytic fungi such as Aspergillus species. This review aimed to provide information about the current perspectives on MG regarding its clinical characteristics, predisposing factors, laboratory diagnosis, and treatment strategies. Although the lower extremities were reported to be the most common site of infection, facial involvement has been predominant in the past 5 years. Our literature research showed that the most common predisposing factor (55%) is the use of topical steroid creams without potassium hydroxide examination during treatment of erythematous squamous dermatoses. A reliable diagnosis of MG is based on histopathological examination, including fungal culture and molecular analyses. MG should be treated not only with topical agents but also with systemic antifungal agents that are continued until the lesions are completely resolved. In systemic treatment, the most preferred drug is terbinafine, because of its efficacy, side effects, and safety.

Facial restoration by transplantation

Hundred years ago, Sir Harold Gillies laid a foundation to the modern plastic surgery trying to reconstruct facial defects of severely disfigured soldiers of World War I. Some years later, Joseph Murray experimented with rejection of skin grafts aimed for treatment of burned patients who sustained their injuries on battlefields of World War II. In 1954, the acquired expertise and intensive research allowed him to perform the first successful kidney transplantation in the world at Peter Bent Brigham Hospital in Boston. For his achievements in organ transplantation he was awarded Nobel Prize in 1990. The face transplantation appears to be a natural evolution of the work of these two extraordinary plastic surgeons. The first case of partial face transplant from 2005 in France revealed the world that facial restoration by transplantation is superior to conventional reconstruction methods. Since 2009, our team has performed 7 cases of face transplantation at Brigham and Women's Hospital, which is to our best knowledge the largest living single center face transplant cohort in the world. In this article, we want to reflect on the experience with face transplantation at our institution from the past years. We aim to briefly review the key points of the know-how which was given to us from the care of these unique patients.

Vascularized Composite Allotransplantation: Medical Complications

The objective of this review is to summarize the collective knowledge regarding the risks and complications in vascularized composite tissue allotransplantation (VCA), focusing on upper extremity and facial transplantation. The field of VCA has entered its second decade with an increasing experience in both the impressive good outcomes, as well as defining challenges, risks, and experienced poor results. The limited and selective publishing of negative outcomes in this relatively new field makes it difficult to conclusively evaluate outcomes of graft and patient survival and morbidities. Therefore, published data, conference proceedings, and communications were summarized in an attempt to provide a current outline of complications. These data on the medical complications of VCA should allow for precautions to avoid poor outcomes, data to better provide informed consent to potential recipients, and result in improvements in graft and patient outcomes as VCA finds a place as a therapeutic option for selected patients.

Facial transplantation: worth the risks? A look at evolution of indications over the last decade

PURPOSE OF REVIEW

The first face transplant was performed 10 years ago by Dubernard and his team in France. Since then, surgeons have continued to push the frontiers of vascularized composite allotransplantation and broaden the indications for face transplantation. In this review, we summarize some of the recent successes and failures in facial transplantation from the point of view of indications.

RECENT FINDINGS

Recent literature includes case reports on face transplants in sensitized patient, with simultaneous bilateral upper extremity transplants, positive HIV status, and postmalignancy. Additionally, we summarize some of the outcomes of face transplants, including chronic rejection and latent viral infections.

SUMMARY

Facial injuries vary widely, thus candidacy for face transplant should be assessed based on current guidelines, and a case-by-case basis. Although sensitization to donor-specific antigens should not be an absolute contraindication for facial allotransplantation, along with other comorbidities such as positive HIV status, history of malignancy should be evaluated cautiously. Additionally, multiple case studies advice against simultaneous transplantation of multiple vascularized composite allotransplantations. Other considerations include psychological health, social support, and availability for long-term follow-up. Ultimately, face transplant is not simply a surgery; it is a lifelong commitment between a patient and his/her medical team.

What is the future of 'organ transplantation' in the head and neck?

PURPOSE OF REVIEW

To update readers on the current state and future of head and neck tissue transplantation.

RECENT FINDINGS

Many exciting advances have recently occurred in the field of head and neck transplantation and regenerative medicine. Larynx, face, and trachea transplants have all been successfully performed. Significant advancements in tissue engineering have occurred, including the ability to generate three-dimensional tissue structures. Transplantation of regenerated tissues has been successfully incorporated into airway reconstruction.

SUMMARY

These exciting advancements set the foundation to expand reconstructive options for dysfunctional tissues and to improve a patient's quality of life.

Initial experience of dual maintenance immunosuppression with steroid withdrawal in vascular composite tissue allotransplantation

Current immunosuppression in VCA is largely based on the experience in solid organ transplantation. It remains unclear if steroids can be reduced safely in VCA recipients. We report on five VCA recipients who were weaned off maintenance steroids after a median of 2 months (mean: 4.8 months, range 2-12 months). Patients were kept subsequently on a low dose, dual maintenance consisting of tacrolimus and mycophenolate mofetil/mycophenloic acid with a mean follow-up of 43.6 months (median = 40 months, range 34-64 months). Early and late acute rejections responded well to temporarily augmented maintenance, topical immunosuppression, and/or steroid bolus treatment. One late steroid-resistant acute rejection required treatment with thymoglobulin. All patients have been gradually weaned off steroids subsequent to the treatment of acute rejections. Low levels of tacrolimus (<5 ng/mL) appeared as a risk for acute rejections. Although further experience and a cautious approach are warranted, dual-steroid free maintenance immunosuppression appears feasible in a series of five VCA recipients.

Vascularized Composite Allografts: Procurement, Allocation, and Implementation

Vascularized composite allotransplantation is a continuously evolving area of modern transplant medicine. Recently, vascularized composite allografts (VCAs) have been formally classified as 'organs'. In this review, key aspects of VCA procurement are discussed, with a special focus on interaction with the procurement of classical solid organs. In addition, options for a matching and allocation system that ensures VCA donor organs are allocated to the best-suited recipients are looked at. Finally, the different steps needed to promote VCA transplantation in society in general and in the medical community in particular are highlighted.

Vascularized composite allotransplant in the realm of regenerative plastic surgery

Vascularized composite allotransplant (VCA) has led to new treatment options for patients with severe upper extremity and facial injuries. Although VCA can restore form and function, it exposes the patient to the risks associated with lifelong immunosuppression. Hopefully, ongoing advances in regenerative medicine will someday obviate the need for VCA, but until that time, VCA remains an immediate means of reconstructing otherwise unreconstructable defects. We review the outcomes of hand and face transplants, as well as the recent developments in immunosuppression as it relates to the field of VCA.

Update on infections in composite tissue allotransplantation

PURPOSE OF REVIEW

Several excellent recent reviews have summarized the infectious complications of all composite tissue allograft recipients previously reported. The current review will highlight key management principles derived from these reports.

RECENT FINDINGS

Severe Gram-negative infections may occur in the early posttransplant period, particularly Pseudomonas spp. Cytomegalovirus continues to be a major pathogen and is closely linked to allograft rejection; however, some patients have had uncomplicated cytomegalovirus (CMV) episodes. Candida has emerged as a cause of early infections, but the incidence of invasive mold infections has been low. More descriptions of infection risk in the late posttransplant period will be helpful, as more composite tissue allotransplantation recipients survive longer. Newer immunosuppressive regimens may reduce infection risks, but more information will be helpful.

SUMMARY

Recent reports have provided expanded information on infections in composite tissue allograft recipients. Centers may choose to broaden the Gram-negative prophylaxis, and to include antifungal prophylaxis directed at Candida spp. CMV prevention protocols should take into account recent reports of CMV outcomes. Future reports should contain infection outcomes in sufficient detail to allow for constructive modifications of antimicrobial management in an era of novel immunosuppression and increasing antimicrobial resistance.

Clinical utility of viral load in management of cytomegalovirus infection after solid organ transplantation

The negative impact of cytomegalovirus (CMV) infection on transplant outcomes warrants efforts toward improving its prevention, diagnosis, and treatment. During the last 2 decades, significant breakthroughs in diagnostic virology have facilitated remarkable improvements in CMV disease management. During this period, CMV nucleic acid amplification testing (NAT) evolved to become one of the most commonly performed tests in clinical virology laboratories. NAT provides a means for rapid and sensitive diagnosis of CMV infection in transplant recipients. Viral quantification also introduced several principles of CMV disease management. Specifically, viral load has been utilized (i) for prognostication of CMV disease, (ii) to guide preemptive therapy, (iii) to assess the efficacy of antiviral treatment, (iv) to guide the duration of treatment, and (v) to indicate the risk of clinical relapse or antiviral drug resistance. However, there remain important limitations that require further optimization, including the interassay variability in viral load reporting, which has limited the generation of standardized viral load thresholds for various clinical indications. The recent introduction of an international reference standard should advance the major goal of uniform viral load reporting and interpretation. However, it has also become apparent that other aspects of NAT should be standardized, including sample selection, nucleic acid extraction, amplification, detection, and calibration, among others. This review article synthesizes the vast amount of information on CMV NAT and provides a timely review of the clinical utility of viral load testing in the management of CMV in solid organ transplant recipients. Current limitations are highlighted, and avenues for further research are suggested to optimize the clinical application of NAT in the management of CMV after transplantation.