The sequence of the examinations performed during the evaluation procedure is typically based on a progression from least to most invasive, but the key factor is also to determine which examinations identify a higher proportion of unsuitable candidates. Consequently, a person with no real chance of donation could be excluded as soon as possible during the selection process, saving considerable time and expenses for the LDLT program.
At this regard, different multistep and -disciplinary evaluation protocols have been proposed. Table 3 shows our standardized evaluation protocol at the University of Essen [4,24].
Blood tests results that confirm donor infection with HIV, HCV or HBV (HBsAg+) are a contraindication for living liver donation. The HBc-Ab positivity does not represent a contraindication to donation for a recipient affected by HBV-cirrhosis. Notwithstanding, testing for serum HBV DNA is recommended in donors with detectable anti-HBc with or without anti-HBs. [7,24].
Laboratory testing for a pre-existing hypercoaguable condition should be performed especially if the potential donor has a history of venous thrombosis [7,24].
The role of liver biopsy (LB) in donor selection remains controversial, as the procedure is associated with additional potential risks for the donor.
The Vancouver Forum participants  suggested that a donor LB should be performed if blood specimen liver tests are abnormal and if steatosis or other abnormalities are noted on imaging studies. The LB may be considered if the BMI is >30 or in potential donors genetically related to an intended recipient with autoimmune hepatitis, primary sclerosing cholangitis or primary biliary cirrhosis . Additionally, the histological findings that should preclude living liver donation were also clearly defined during the Forum. They include (i) portal or sinusoidal fibrosis (ii) nonalcoholic steatohepatitis, (iii) Steatosis >20% (only for right liver) and (iv) portal inflammation or necrotic-inflammatory changes .
In our center, 31 (21%) out of 144 candidates who underwent LB had a positive finding at histological examination that induced their exclusion from donation. Of the 31 excluded candidates, 21 (67%) had liver steatosis of varying kind and grade (10–80%) and 10 (33%) had a nonsteatotic hepatopathy (non-A-D hepatitis in six cases, diffuse granulomatosis in 2, schistosomiasis in 1, fibrosis in 1) .
Based on these findings, we believe that not invasive screening modalities can be unreliable, and therefore (on the contrary of Vancouver Forum participants) we are convinced that preoperative LB in the donor selection for adult LDLT should be always performed, once the initial donor screening and noninvasive evaluation is complete in order to detect not only the presence and extent of hepatic steatosis, but also any underlying and often unexpected histological liver damage, which would adversely affect the recipient allograft and donor remnant.
In fact, an accurate quantification of hepatic fat as a contraindication to donation cannot be afforded by BMI and imaging studies alone. The use of the BMI as a predictor of hepatic steatosis, and thus the need for a donor LB is not absolute. Rinella et al.  reported that hepatic steatosis increases linearly with the BMI. They suggested that individuals with a BMI >28 should undergo LB, whereas those with a BMI <25 and the absence of risk factors do not need one. Remarkably, Ryan et al.  observed that 73% of potential donors with a BMI >25 had <10% hepatic steatosis. Therefore, the indication for LB was extended to all patients with high BMI, permitting additional candidates to be considered as potential donors.
Recently, Park et al.  demonstrated that unenhanced CT can accurately depict moderate-to-severe (i.e. ≥30%) macro-vesicular steatosis, thereby avoiding a biopsy in potential living liver donors demonstrating an unacceptable degree of steatosis for transplantation by imaging. Biopsy will still be needed in donors with macro-vesicular steatosis of <30% by unenhanced CT to rule out occult chronic liver disease and more severe steatosis not detected at CT . Iwasaki et al.  proposed the liver-to-spleen CT attenuation values ratio (L/S ratio) on noncontrast-CT as an reliable index of hepatic steatosis in comparison with other parameters including BMI.
In our experience, we excluded patients with BMI >30 a priori not only because of the higher risk of liver steatosis, but also mainly because of BMI >30 also correlates with a high rate of perioperative complications (i.e. lung embolism and wound healing problems). Surprisingly, we also found that some potential donors with normal BMI had a high percentage of liver steatosis.
Because of the reversibility of liver steatosis, dieting is recommended in patients with initially prohibitive hepatic steatosis. A repeat LB should be obtained after weight reduction [7,13,50,51].
During the psychological evaluation, donors are assessed for altruism and possible coercion .
Forsberg et al.  investigated the expressed deeper emotions and the experiences of parents who donated a part of their liver to their own child. Based upon the results, the authors were able to generate precise recommendations for the formation of guidelines for living parental liver donation.
Similarly, our group has provided important guidelines for psychosomatic evaluation of potential donors for adult LDLT . Our psychosomatic evaluation consists of following relevant aspects: (i) psychological stability of the potential donor and (ii) verification of informed consent (iii) competence to consent and (iv) absence of coercion. The evaluation has been performed in two steps: firstly, verification of informed consent and assessment of mental stability (i.e. previous psychiatric disorders, social functioning and healthy behavior, psychological coping, analysis of mood); secondly, evaluation of psychodynamics of the relationship between donor and recipient (sufficient autonomy of both, realistic outcome expectations) and the ability of each to anticipate the transplantation procedure (psychological preparation for LDLT e.g. shift in attention from donor to recipient, coping with pain, emotional care for both) . In our preliminary experience, 12% of potential donors who underwent a psychosomatic evaluation were excluded as a result.
It is imperative for healthcare professionals to understand the decision-making process from the donors’ perspective in order to develop a more reliable process of informed consent and to provide a more efficient psychosocial support system once the donor makes a decision. Having a precise and formal psychosocial assessment, protocol aids the transplant team in supporting the donor's decision before and after donation .
The decision-making process of adult-to-adult LDLT involves several psychosocial factors. Compared with adult-to-child LDLT, in which a patient's parents often make an immediate decision to save their child, decision-making in adult-to-adult LDLT often evokes familial conflict and struggle as potential donors must be often chosen among themselves who will give to a sibling or parent.
Conceptual models can serve as a tool for healthcare professionals to understand a donor's preoperational experience as seen with living donor kidney transplantation . However, these models cannot be applied directly to LDLT as the two procedures differ in the risk to the donor and the alternatives for the recipient. Living donor kidney transplantation is an attempt to improve the patient QoL while LDLT serves as a ‘desperate remedy’ . On the opposite, the liver patient will die if a donor is not found within a short period of time .
Fujita et al.  defined a 5-step decision-making model of the psychological process that a potential donor experiences [(i) recognition, (ii) digestion, (iii) decision-making, (iv) reinforcement, and (v) resolution] leading up to donation in adult LDLT. The authors found that potential donors often moved from one phase to the next based on a feeling of ‘having no choice’. This perception of ‘having no choice’ was usually predicated on one of four justifications: priority of the recipient's life above all else, an understanding that LDLT was the only option, a willingness to do anything for family, or a sense that the donor was the only eligible candidate. This study has several implications for clinical practice in LDLT. In our opinion, this study's framework serves as an essential tool for healthcare professionals to understand a donor's experience and, based on that understanding, to provide sufficient support to the donor.
Donors must be able to comprehend the risks of liver resection and should understand the possible benefits and outcomes for their intended recipient. This includes understanding of the etiology of their recipient's liver disease and the expected outcome with transplantation for that specific indication. There can be considerable disparity in expected outcome for patients with different disease processes. Many liver diseases that lead to transplantation are often recurrent (e.g. hepatitis B, hepatitis C, and hepatocellular carcinoma), and donors must be informed of these risks for their intended recipients so that they can be truly informed with regard to their own decision whether to donate .
There are different opinions about what should potential donors also be told . The Ethics Group of the Vancouver Forum  deliberated that the potential donor should be informed about following aspects:
The risk of death, reported worldwide and at the center where the procedure is proposed.
Changes in health and organ function.
Impact upon insurability/employability.
Potential effects on family and social life.
Psychological impact of donation and nondonation.
The responsibility of the individual and of the health and social systems in the management of discovered conditions (such as the discovery during the evaluation process of HIV, tuberculosis or other transmissible diseases).
Any specific recipient conditions which may impact upon the decision to donate; however, no information can be given to the potential donor until permission is obtained from the recipient.
Expected transplant outcomes (favorable and un-favorable) for the recipient.
Information on alternative types of treatments for the recipient, including deceased organ transplantation.
The limited information available on extra-renal live donation results in uncertainty about donor and recipient outcomes.
The request that the potential donor participate in long-term information gathering (registries) to increase the knowledge base.
The death of a right lobe liver donor in 2002 at New York's Mount Sinai Hospital  led the New York State Department of Health to formalize rules that supported state-of-the-art care of the donor. One requirement is that live-donor liver transplant programs must have a ‘donor advocate team’ consisting of an independent medical specialist, a social worker who works with donors but not with their intended recipients, and a transplantation psychiatrist. The donor advocate team shares in an assessment of donor suitability and advises the donor surgeon. If the donor surgeon overrides recommendations of the donor advocate team, the reason for doing so must be documented and is subject to future review [25,59].
There should be a formal and deliberate ‘time out’ period between the completion of the donor's evaluation and the actual surgery, so the donor can reflect upon his or her decision and not get caught up in the urgency to transplant the recipient . This time for reflection provides the donors maximal freedom of withdrawing themselves from the process of donation at any time .
Potential donors should be informed from the outset that they can back out at any time, right up to the moment they undergo anesthesia. They should be formally offered a ‘medical out’– that is, a medical excuse so that the recipient may back out with dignity and without repercussions and without family members realizing the donor has decided to back out. It is important, however, not to fabricate any medical condition that might become a part of the donor's medical records .
If a potential donor is unsuitable for any reason, the transplant team offers to help the potential donor to convey this to significant others. Rather than giving reasons that are untrue, the team tells the recipient and/or any third parties that ‘it was not appropriate to proceed’ .