Clinical laboratories are healthcare facilities providing a wide range of laboratory procedures which aid the physicians in carrying out the diagnosis, treatment, and management of patients. These laboratories are manned by medical technologists (clinical laboratory scientists) who are trained to perform various tests to samples of biological specimens collected from its patients. Most of the clinical laboratories are situated within or near hospital facilities to provide access to both physicians and their patients.Classifications of clinical laboratories indicated below reveal that these facilities can provide quality laboratory tests that are significant for addressing medical and public health needs. The list below should not be used as a fixed guide for classifying clinical laboratories because of new areas continually arising in the field of laboratory medicine.

• According to ownership - can be government-owned (public) which is usually part of hospitals and medical centers under the department of pathology or laboratory medicine; or can be a private facility as part of a privately-owned medical/healthcare institution
• According to function - can be general clinical laboratories which provide common diagnostic laboratory tests; or can be specialty laboratories that provide disease-specific diagnostic and confirmatory tests
• According to test specialization - facilities can provide tests on a particular field of interest listed below:
  • Clinical Chemistry
  • Clinical Microbiology
  • Hematology
  • Blood banking and Serology (aka Immunohematology, Transfusion Medicine)
  • Clinical Microscopy
  • Histopathology and Cytopathology
  • Molecular Biology
  • Public Health - providing tests such as water analysis, testing for environmental substances, among other tests concerning public and environmental health
• As part of the laboratory network - these facilities operate in a coordinated manner which is usually managed and supervised by authorities at different levels of the network
  • Peripheral laboratories - provide routine screening, diagnostic (e.g. conventional and rapid diagnostic tests) and follow up tests for patients; usually situated in the community where people can access its services
  • Intermediate-level laboratories - can be at the district, provincial and regional-level facilities; may conduct additional tests than those provided in peripheral laboratories and can serve as referral laboratories for special cases (district-level); aside from performing tests, they carry out management and supervisory tasks under specific areas of jurisdiction (particularly provincial and regional laboratories)
  • National reference laboratories - also known as the central level, which performs oversight and overall management of the laboratory network in terms of policy and program implementation, training and development, monitoring and evaluation and research; these facilities also provide a range of routine and highly-specialized laboratory testing, including the introduction and phasing in of new diagnostic tests

In the past, the value of clinical laboratories as an integral part of the healthcare system was not well realized.[1] Throughout time, more physicians have recognized the need for laboratory tests to confirm their diagnoses and to support the monitoring of their patients as to its response to therapy.[2] Aside from its known value to individual patients, the function of clinical laboratories was also used for screening and surveillance of diseases significant to public health. On a larger scale, program managers used some relevant tests as surrogate indicators to assess the progress of public, international and global health programs.

Laboratory networks were developed across countries and states to foster proper coordination and collaboration among clinical laboratories within the specified geographic areas.[3] Quality management systems within these laboratories have also become significant issues recently, including the standardization of laboratory services, strengthening of laboratory systems[4] and the development of new and rapid diagnostic tools. These issues are continually addressed by local and international health authorities and technical experts using the framework of a patient-centered approach.

Clinical laboratories perform testing in a logical and strict manner. Generally. there are three phases of the laboratory testing process that each facility should follow. Standard operating procedure manuals and job aids are written for guidance for carrying out each step of the phase: pre-analytical, analytical and post-analytical.[5][6] While clinical laboratories, especially in the modern day era, are usually known for its state-of-the-art laboratory machines and instruments that do the majority of actual sample testing, these facilities still heavily rely on the laboratory professionals that ensure that results are accurate and reliable.

Providing high-quality, diagnostic testing is the goal of all clinical laboratories. To attain this goal, several issues and problems are needed to be addressed which ultimately underline the need for improving laboratory capacity. Addressing human and financial resources, training and supervision, planning and budgeting, quality assurance, logistics and supply, biosafety and equipment management and other relevant laboratory aspects were found to be necessary to optimize laboratory services provided to patients.

In 2018, the World Health Organization developed and released the Essential Diagnostics List (EDL). This list was expected to be used to align the health community in bridging the gap to the accessibility and availability of high-quality testing of clinical laboratories, especially in resource-limited settings.[7] Using the EDL with essential medicines list (EML), authorities can now focus their efforts so that people can receive laboratory services they need the most.[8]

Accreditation for clinical laboratories became common recently with the emergence of international laboratory standards. Several guidelines for laboratories have been developed to regulate laboratory test procedures and maintain its quality.[9] An example of laboratory accreditation is the ISO 15189 provided by the International Organization for Standardization (ISO) which focuses on meeting the requirements for quality and competence of medical laboratories.[10] Another example is biosafety guidelines around microbiological agents such as bacteria, viruses, parasites, and other agents and microbiological products.[11]

The need for risk management in clinical laboratories was highlighted to maintain the accuracy and reliability of laboratory tests. The Clinical Laboratory Standards Institute (CLSI) developed a guideline to introduce the principles of risk management specifically in the clinical laboratory.[12] From risk assessment to risk analysis, evaluation and control down to the process of continuous quality improvement, the clinical laboratory should and must be able to minimize errors along its path of the workflow (i.e., pre-analytic, analytic and post-analytic phases). Such significant risks identified, for instance, in specimen collection and handling and the disposal of laboratory wastes must be taken into consideration by all clinical laboratories.

A laboratory information system is valuable in the management of results and other pertinent information regarding patients and their samples. The development of a laboratory information system started in the 1960s concentrating on data reduction-analogue-digital conversion and radioimmunoassay analysis. Recently, the focus has evolved into the aspects of digital histopathology and genomics, and issues about patients’ access to data, and a lot more.[13] In a rapidly changing environment for the modalities of patient record systems, there is a need for collaboration between clinical systems developers and laboratory-based informaticians to change and improve the existing technology to meet patient needs.

As the challenges faced by the clinical laboratories constantly arise, the most important value for each healthcare professional is the recognition its significance for the patient welfare. While patients and people in the community are not well aware of its role, the function and mandate of clinical laboratories remain the same: the provision of high-quality laboratory diagnostic tests. The development of newer diagnostic tests from its pipeline should not overestimate the need for improving existing laboratory services. Health authorities at the global level and stakeholders including clinicians, experts and other healthcare professionals at the local level must meet at both ends recognizing that the existence of clinical laboratories taking its hold within the most important clients of healthcare, its patients.[14][15]