Hirudo Medicinalis Research Articles

Evaluation of per- and polyfluoroalkyl substances (PFAS) toxic effects on the acute inflammatory response in the medicinal leech Hirudoverbana

Per- and polyfluoroalkyl (PFAS) substances are a large group of chemicals with elevated water and oil-resistance properties, widely implicated in various applicative fields. Due to the extensive use and high resistance to degradative factors, these compounds pose a significant risk of environmental spreading, bioaccumulating also in living organisms. In this context, despite many researches have been performed to demonstrate “legacy” PFAS harmfulness, only few data are still available about all the emerging fluorinated molecules, industrially introduced to replace the previous ones. For this reason, we proposed the medicinal leech Hirudo verbana as consolidated invertebrate model to assess the effects of four different PFAS (HFPO-DA, PFMoBa, PFOA and PFMOPrA) following freshwater dispersion. Morphological, immunohistochemical and molecular analyses demonstrate that, despite all the compounds basically induce an acute inflammatory and oxidative stress response, a different cellular and molecular response has been observed. Whereas for PFOA and PFMOPrA an increase in the tested concentration leads to a corresponding rise in the immune response, HFPO-DA and PFMoBa trigger an entirely opposite effect. Indeed, the significant recruitment of both granulocytes and macrophage like cells, typically involved in the removal of non-self, is inhibited with increasing concentrations of these compounds. The data collected revealed a different sensitivity of the leech immune system following PFAS exposure, requiring to deepen the current knowledge on the potential toxicity of these compounds.

A phylogeographic analysis of the North American medicinal leech, Macrobdella decora (Say, 1824)

AbstractIn spite of their important roles in many ecosystems, data regarding population structure and biogeographic patterns of leeches are scarce. To begin to address this knowledge gap, we herein perform a phylogeographic analysis of the North American medicinal leech, Macrobdella decora (Say, 1824). A total of 224 M. decora specimens were collected from 35 localities across large swaths of USA and Canada and covering most of the known range of the species. Using four loci (mitochondrial cytochrome c oxidase subunit I [COI] and NADH dehydrogenase I [ND1], as well as nuclear 18S rRNA [18S] and 28S rRNA [28S]), we construct phylogenetic trees using several optimality criteria and superimpose geographic patterns onto the trees in order to tease out any potential structure among the populations. Rather surprisingly, given the large geographic range of the species and abundance of potential geographic barriers to gene flow, the analyses showed a conspicuous lack of structure among the different populations of M. decora. However, an AMOVA did show statistically significant differences between the genetic variation within populations and between populations (COI: FST = 0.65412, p < .00001; ND1: FST = 0.69245, p < .00001), which was largely driven by only 6 out of the 35 populations, and indicated a potential barrier for dispersal across the Appalachian Mountains. Finally, a Mantel test showed a weak, but significant, correlation between geographic distance and genetic distance (COI: r = 0.209, p = .027; ND1: r = 0.1289, p = .030); however, this correlation was primarily driven by a single locality. The overall weak structure suggests that M. decora is panmictic throughout its range, and we discuss this in light of previous population level studies in both bloodfeeding and non‐bloodfeeding species, concluding that the lack of structure in M. decora might be due to its high capacity for dispersal via hosts.

Preventive and Therapeutic values of Leech Therapy: A Review

There are three therapeutic modalities in the Unani medical system: Ilaj bit Tadbeer (Regimenal Therapy), Ilaj bid Dawa (pharmacotherapy), and Ilaj bil Yad (surgery). Ilaj bit Tadbeer includes several regimenal therapies such as Hijāma (Cupping Therapy), Ta'līq or Irsal-e-'Alaq (Leech Therapy), Fasd (Venesection), Dalk (Massage), Nutūl (Therapeutic Irrigation), Qai (Emesis), Idrār-i-Bawl (Diuresis), Tariq (Diaphoresis), Mundij wa Mu'shil therapy (Concoction and purgation), Bukhoor (Medicated Steam), Kaiyy (Cauterization), Huqna (Enema) etc. Since ancient times, these therapies have been widely used for their preventive, therapeutic, and rehabilitative effects. One of the most significant regimenal therapies, Irsal-e-Alaq (Leech therapy), is still in use. Renowned Unani physicians Razi, Majoosi, Zahrawi, and Ibne Sina have discussed and recommended the use of non-poisonous (or medicinal) leeches in the prevention and treatment of a variety of illnesses, including joint disorders, chronic non-healing ulcers, and numerous skin disorders like eczema, psoriasis etc. This review paper aims to explore the preventive and therapeutic role of leech therapy. Keywords: Unani Medical System, Therapeutic Role, Leech Therapy

Characterization of a Fatty Acid Amide Hydrolase (FAAH) in Hirudo Verbana

The endocannabinoid system plays a critical role in modulating both peripheral and central nervous system function. Despite being present throughout the animal kingdom, there has been relatively little investigation of the endocannabinoid system beyond traditional animal models. In this study, we report on the identification and characterization of a putative fatty acid amide hydrolase (FAAH) in the medicinal leech, Hirudo verbana. FAAH is the primary enzyme responsible for metabolizing the endocannabinoid signaling molecule arachidonoyl ethanolamide (anandamide or AEA) and therefore plays a critical role in regulating AEA levels in the nervous system. mRNA encoding Hirudo FAAH (HirFAAH) is expressed in the leech central nervous system (CNS) and sequence analysis suggests that this is an orthologue of FAAH-2 observed in vertebrates. Functionally, HirFAAH has serine hydrolase activity based on activity-based protein profiling (ABPP) studies using the fluorophosphonate probe TAMRA-FP. HirFAAH also hydrolyzes arachidonyl 7-amino, 4-methyl coumarin amide (AAMCA), a substrate specific to FAAH. Hydrolase activity during both the ABPP and AAMCA assays was eliminated by a mutation at a conserved catalytic serine. Activity was also blocked by the known FAAH inhibitor, URB597. Treatment of Hirudo ganglia with URB597 potentiated synapses made by the pressure-sensitive mechanosensory neuron (P cell), mimicking the effects of exogenously applied AEA. The Hirudo CNS has been a useful system in which to study properties of endocannabinoid modulation of nociception relevant to vertebrates. Therefore, this characterization of HirFAAH is an important contribution to comparative studies of the endocannabinoid system.

The Medical Benefits of Medicinal Leeches

The Medical Benefits of Medicinal Leeches

Effects of light on reproduction of the Mediterranean medicinal leech, Hirudo verbana Carena, 1820: do circadian rhythm disruptions positively affect reproductive performance of leeches?

ABSTRACT This study aimed to assess the impact of light on the reproductive performance of leeches for the first time using the Mediterranean medicinal leech Hirudo verbana Carena, 1820, which is important in medicinal leech aquaculture. Gravid leeches were subjected to three different light conditions: 24-h Light, 24-h Dark, and Daylight (14-h light and 10-h dark) for 11 weeks. Gravidity ended at the 8th week for the Dark (5.33 ± 0.38 weeks) and Daylight (5.41 ± 0.29 weeks) groups, whereas it persisted for 11 weeks in the Light group (6.75 ± 0.51 weeks) (p = 0.031). In comparison to the Daylight group (cocoons: 40, offspring: 538), the Light (cocoons: 50, offspring: 723) and Dark (cocoons: 45, offspring: 576) groups achieved a greater yield of cocoons (p = 0.312) and offspring (p = 0.323). We invite discussion on the notion that the enhanced reproductive capacity of leeches in full light and full dark conditions, as opposed to daylight, may be attributed to the disturbance of their circadian rhythms.

Evaluation of Methylene Blue as An Effective Antiseptic for Medicinal Leeches (Hirudo verbana).

Medicinal leeches (Hirudo spp.) have been used for therapeutic purposes in humans since ancient times. Because of their growth conditions, leeches carry certain bacteria and endosymbionts (e.g., Aeromonas spp). In both leech farms and hirudotherapy clinics, there are no reliable antiseptics that can be used with leeches. This study aimed to determine whether methylene blue (MB) is a safe antiseptic for medicinal leeches and assess its safe usage. This study evaluated the efficacy of MB by determining lethal concentrations (LC), effective concentrations (EC), and lethal times (LT) for the medicinal leech Hirudo verbena Carena, 1820. A total of 570 H. verbana specimens obtained from a local farm were used in this study. Eighteen different concentrations of MB (between 1 ppm and 512 ppm) were tested. The LC50 and EC50 values for H. verbana were determined to be 60.381 (53.674-66.636) ppm and 2.013 (1.789-2.221) ppm, respectively. The LT50 durations for MB concentrations of 32 and 512 ppm were calculated as 212.92 h (138.43 h-1485.78 h) and 17.82 h (8.08 h-23.90 h), respectively. The results show that MB concentrations between 2 and 19 ppm can be safely used as antiseptics in hirudotherapy clinics and leech farms to address bacterial concerns caused by medicinal leeches.

On the occurrence of the Dragon leech Hirudo troctina Johnson, 1816 (Annelida, Hirudinea) in Sardinia (Italy)

In recent decades, medicinal leeches of the genus Hirudo have experienced a sharp decline throughout their distribution range due to their overexploitation for medical use and habitat alteration. Such a phenomenon is not fully understood because of the complex taxonomy of the genus, which remained unsettled until the beginning of the XXI century, when the implementation of DNA taxonomy allowed for a better understanding of the diversity of the genus and the distribution ranges of Hirudo species. Only the Mediterranean medicinal leech Hirudo verbana Carena, 1820 is currently reported to occur in Italy and its major islands, although records of other Hirudo species have been reported in the literature. In this study, we report the occurrence of the Dragon leech Hirudo troctina Johnson, 1816 in Sardinia and provide its molecular characterization. In addition, based on a review of the existing literature and museum collections, we provide an ample synopsis of the available evidence regarding the occurrence of the species on the island. Hirudo troctina proved to be widespread and abundant in Sardinia during the XIX century but became rarer and rarer in the XX and XXI centuries possibly due to its overexploitation for medicinal use and export in mainland Europe, the abandonment of traditional grazing practices, and the decline of wetland habitats and amphibian populations. Currently, the only recently validated occurrence sites of the species are the water bodies of the “Giara di Gesturi”, a basaltic plateau in central-southern Sardinia. No corroborated evidence of the possible occurrence of other Hirudo species on the island was found. A better understanding of Hirudo troctina distribution in Sardinia will allow the amelioration of its protection and management practices, also under the provisions of the European “Habitats Directive”, where the H. medicinalis species complex is listed in Annex V.

Evidence-based approach to Jaloukavacharana with special reference to Aeromonas species: a case series

Abstract Jalukavacharana (medicinal leech therapy) is a time-tested bloodletting therapy employed to treat inflammatory, ischemic, and infectious diseases. Aeromonas spp., commonly found in the leech’s gut, is known to cause two major diseases: gastroenteritis and wound infections (with or without bacteremia). In cases such as diabetes mellitus where the patient can be immuno-compromised, the possibility of complications through leech therapy and Aeromonas spp. is high. The current study was carried out on five subjects, indicated for Jalukavacharana. The blood culture was studied, and the vomitus of a Jalouka (leech) post Jaloukavacharna (medicinal leech therapy) was obtained to rule out the presence of any pathogenic bacteria, especially Aeromonas spp. Five subjects who fulfilled the inclusion criteria were treated with Jaloukavacharna under all the therapeutic precautions, and then blood samples were collected and sent for blood culture and sensitivity analyses to confirm the presence of Aeromonas species in these samples, and one leech vomitus blood sample has been studied for the presence of the same. All the five blood samples tested negative for any pathogenic organism, including the Aeromoans spp., and the leech vomitus blood sample tested positive for Aeromonas spp. From the aforementioned case series, it is evident that though the leech vomitus contained the pathogenic gut bacteria Aeromonas spp., all the blood samples of the study subjects tested negative for the same, indicating that the proper practice of Jaloukavacharna (medicinal leech therapy) according to the classics can help us prevent the complications of leech therapy from affecting the individual.

Therapeutic Potentials of Medicinal Leech in Chinese Medicine.

The use of medicinal leeches in clinical therapy has been employed for a long time, as it was originally recognized for exerting antithrombin effects. These effects were due to the ability of the leech to continuously suck blood while attached to human skin. According to Chinese Pharmacopoei, leeches used in traditional Chinese medicine mainly consist of Whitmania pigra Whitman, Hirudo nipponia Whitman, and Whitmania acranulata, but the latter two species are relatively scarce. The main constituents of leeches are protein and peptide macromolecules. They can be categorized into two categories based on their pharmacological effects. One group consists of active ingredients that directly target the coagulation system, such as hirudin, heparin, and histamine, which are widely known. The other group comprises protease inhibitor components like Decorsin and Hementin. Among these, hirudin secreted by the salivary glands of the leech is the most potent thrombin inhibitor and served as the sole remedy for preventing blood clotting until the discovery of heparin. Additionally, leeches play a significant role in various traditional Chinese medicine formulations. In recent decades, medicinal leeches have been applied in fields including anti-inflammatory treatment, cardiovascular disease management, antitumor treatment, and many other medical conditions. In this review, we present a comprehensive overview of the historical journey and medicinal applications of leeches in various medical conditions, emphasizing their pharmaceutical significance within traditional Chinese medicine. This review offers valuable insights for exploring additional therapeutic opportunities involving the use of leeches in various diseases and elucidating their underlying mechanisms for future research.

The Presence and Population Status of Medicinal Leeches in the Some Wetlands in the Susurluk Basin

In this study, the population status of the wetlands in the Susurluk Basin (except Uluabat and Manyas Lakes) in terms of medicinal leeches and the stock status of the existing areas were investigated. Between March and October 2022 and 2023, studies were carried out in a total of 108 areas, including 26 wetlands in Kütahya, 49 wetlands in Bursa and 33 wetlands in Balıkesir. Medicinal leech population and stock studies were carried out in the wetlands located in Keles Epçeler in Bursa, Balıkesir İvrindi Çelimler and Balıkesir Dursunbey Aşağımusalar regions. A total of 378 medicinal leeches (0.02-5.19 g weight and 10.48-153.92 mm) were sampled from the study areas. The catchable amount of medicinal leeches was determined as 4.956 g for Epçeler, 218 g for Çelimler and 44 g for Aşağımusalar. When the population status and stock amounts of medicinal leeches obtained from wetlands and their habitats were analysed, it was determined that there was a decrease in medicinal leeches as a result of hunting pressure and habitat change and loss. This situation has shown that breeding systems should be increased and the pressure on nature should be reduced against the increasing demand for medicinal leeches in recent years.

Intraspecies Molecular DNA Polymorphism and Threat of Hirudo orientalis

Medical leeches play the role of a natural factory for the production of a complex of unique biologically active substances such as hirudin, eglins, bdellins, hementin, bradykinins, which are urgently needed by modern medicine and veterinary medicine. Medical leeches produce a wide range of enzymes such as hyalinodase, destabilase, collagenase, apyrase, elastase and triglyceride. All these substances are biologically active substances of natural origin. It is used to treat a wide range of diseases, such as amenorrhea, osteoarthritis, trauma, and blood stasis syndrome. In modern times, leeches also serve as an important model system for understanding the structure, function, development, regeneration, and repair of the nervous system. The currently seven known species of the HirudoLinnaeus, 1758 genus of the Hirudinidae family are widespread in different regions of the Eurasian contingent. The results of the phylogenetic analysis based on the nucleotide sequences of the oxidase enzyme subunit I (12S r-RNA, COI) allow us to assume that the Hirudo genus is monophyletic. In 2005, P. Trontelj and S. Utevsky, while studying the molecular systematics of medical leeches, analyzed 2 samples of medical leeches from Azerbaijan together with others. According to the results of the cluster analysis, two medicinal leech samples of Azerbaijan (Hirudo sp. AZ1 and Hirudo sp.AZ2) form a separate cluster and are located between H. medicinalis and H. verbanaspecies. As a result of recent phylogenetic studies, it was determined that those two samples are H. orientalisspecies. The main goal of the conducted research is to study the intraspecies polymorphism of medical leeches collected from different regions of Azerbaijan at the genome level. Isolation of leech chromosomal DNA was performed with the Gene Elute Mammalian Genomic DNA miniprep reagent kit.

Comparative genomics of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis: With emphasis on antithrombotic genes and their corresponding proteins

Leeches secrete various biologically active substances which have important medical and pharmaceutical values in antithrombotic treatments. Here, we provide a high quality genome of two Asian medicinal leeches Hirudo nipponia and Hirudo tianjinensis, based on which, we identified 22 antithrombotic gene families, including fourteen coagulation inhibitors, four platelet aggregation inhibitors, three fibrinolysis enhancers, and one tissue penetration enhancer. The total numbers of antithrombotic genes were similar between H. nipponia (N = 86) and H. tianjinensis (N = 83). Molecular evolution analysis showed that no significant differences were detected between the two species in any of the three selection indices (dN, dS, and dN/dS), nor in the number of sites under positive/purifying selection. RNA-Seq based gene expression analysis showed that the overall expression patterns of the antithrombotic gene families were not significantly deviated between the two species. Our results indicated that there were rather close similarities between the two leeches on genomic characteristics, especially for the molecular evolution and expression of antithrombotic genes. Our study provides the most comprehensive collection of antithrombotic biomacromolecules from the two Asian medicinal leeches to date. These results will greatly facilitate the research and application of leech derivatives for medical and pharmaceutical purposes of thrombosis.

Cytotoxic effect of silver nanoparticles biosynthesized from Hirudo medicinalis saliva on HepG2 cells

Primary hepatocellular carcinoma is a devastating type of liver cancer. Silver nanoparticles (AgNPs) have been assessed for a variety of purposes, including being tested as an anticancer agent. The aim of this study was to assess the cytotoxicity of AgNPs that were biosynthesized from leech saliva on HepG2 cells, through the undertaking of a simple MTT assay. HepG2 cells were obtained from the cell bank of the Pasteur Institute of Iran. In this study, AgNP-treated HepG2 cells were cultured at a density of 104 cells per well, and 100 μL of MTT at a concentration of 0.5 mg/mL were added to each well; the treated cells were then let to incubate for 4 h. Subsequently, a plate reader device operating at a wavelength of 570 nm was used in order to determine the concentration of the chemical dissolved in isopropanol. Representative images of the cells show remarkable changes in their morphology at AgNP concentrations of 25 and 50 μg/mL. At 48 h, the nanoparticle’s IC50 value was 50 μg/mL. Our study shows that leech salivary extract-derived AgNPs are cytotoxic to HepG2 cells.

The Therapeutic Action of the Leech Hirudo medicinalis

The article under discussion examines the mechanism of the therapeutic effect of the medicinal leech Hirudo medicinalis. Today, studying the composition of the saliva of medicinal leeches is of the greatest relevance. The secretion of leech saliva contains a whole complex of biologically active substances — it contains more than a hundred medicinal components, enzymes, hormones, vitamins and amino acids, as well as a special substance hirudin, which makes the blood more fluid, which prevents the formation of unnecessary platelets. This is an indispensable way to prevent heart attacks, strokes and thrombosis. The author of the article believes that proof of the medicinal properties of specific components of saliva can lead to the development of new drugs or therapeutic methods.

Biomechanics of transduction by mechanosensory cilia for prey detection in aquatic organisms

Surface-feeding aquatic animals navigate towards the source of water disturbances and must differentiate prey from other environmental stimuli. Medicinal leeches locate prey, in part, using a distribution of mechanosensory hairs along their body that deflect under fluid flow. Leech’s behavioral responses to surface wave temporal frequency are well documented. However, a surface wave’s temporal frequency depends on many underlying environmental and fluid properties that vary substantially in natural habitats (e.g., water depth, temperature). The impact of these variables on neural response and behavior is unknown. Here, we developed a physics-based leech mechanosensor model to examine the impact of environmental and fluid properties on neural response. Our model used the physical properties of a leech cilium and was verified against existing behavioral and electrophysiological data. The model’s peak response occurred with waves where the effects of gravity and surface tension were nearly equal (i.e., the phase velocity minimum). This suggests that preferred stimuli are related to the interaction between fundamental properties of the surrounding medium and the mechanical properties of the sensor. This interaction likely tunes the sensor to detect the nondispersive components of the signal, filtering out irrelevant ambient stimuli, and may be a general property of cilia across the animal kingdom.

Dynamic relationship among extracellular matrix and body wall cells in Hirudo verbana morphogenesis

A great bulk of recent experimental evidence suggests the key role of the complex crosstalk between the extracellular matrix (ECM) and the cellular component of tissues during morphogenesis and embryogenesis. In particular, remodeling of the ECM and of its physical interactions pattern with surrounding cells represent two crucial processes that might be involved in muscle development. However, little information is available on this topic, especially on invertebrate species. To obtain new insights on how tuning the ECM microenvironment might drive cellular fate during embryonic development, we used the invertebrate medicinal leech Hirudo verbana as a valuable experimental model, due to its simple anatomy and the recapitulation of many aspects of the basic biological processes of vertebrates. Our previous studies on leech post-embryonic development have already shown the pivotal role of ECM changes during the growth of the body wall and the role of Yes-associated protein 1 (YAP1) in mechanotransduction. Here, we suggest that the interactions between stromal cell telocytes and ECM might be crucial in driving the organization of muscle layers during embryogenesis. Furthermore, we propose a possible role of the pleiotropic enzyme HvRNASET2 as a possible modulator of collagen deposition and ECM remodeling not only during regenerative processes (as previously demonstrated) but also in embryogenesis.

IMPLICATION OF LEECH THERAPY AND ASBAB-E-SITTA ZAROORIYAH IN THE PREVENTION AND TREATMENT OF VARICOSE VEINS: A COMPREHENSIVE REVIEW

Varicose veins are characterized by abnormally twisted, dilated superficial vessels that are caused by the inefficient or defective valves within the vein. It is currently a prevalent disease with the incidence varying globally between 10% and 60%. The Unani Medicine (also called Greco-Arab medicine) is the ancient system of medicine practiced all around the world. According to the Unani classical text, Leech therapy (Irsal-e-Alaq) is one of the most important regimenal therapy for the successful treatment and management of varicose vein and a unique combination of Asbab-e-Sitta Zarooriyah (Six essential factors) is involved in the prevention of this disease. The research studies have proved that medicinal leech therapy displays anticoagulant, antimicrobial, anti-inflammatory and analgesic effects. Leech saliva contains medicinally useful bioactive molecules like hirudin, histamine, etc. that shows anti-coagulant effect and hence improve microcirculation in diseases like varicose vein. Leech therapy is reliable, well tolerated, cost effective treatment that has the potential of preventing varicose vein complications. This review seeks to describe medicinal leech therapy, present therapeutic leech species, and highlight the processes by which leech saliva affects wound healing. Additionally, the review paper highlights the role of Asbab-e-Sitta Zarooriyah in prevention and control of varicose veins. Irregularity in diet and lifestyle may cause disturbance in normal body functioning, which may lead to lifestyle disorder that is a major risk factor thought to influence the susceptibility of varicose vein. The Unani System exerts a major influence on preventing the development of varicose vein by making modification in Asbab-e-Sitta Zarooriyah.

Hirudin in the Treatment of Chronic Kidney Disease.

Chronic kidney disease (CKD) is a common public health concern. The global burden of CKD is increasing due to the high morbidity and mortality associated with it, indicating the shortcomings of therapeutic drugs at present. Renal fibrosis is the common pathology of CKD, which is characterized by glomerulosclerosis, renal tubular atrophy, and renal interstitial fibrosis. Natural hirudin is an active ingredient extracted from Hirudo medicinalis, which has been found to be the strongest natural specific inhibitor of thrombin. Evidence based on pharmacological data has shown that hirudin has important protective effects in CKD against diabetic nephrology, nephrotic syndrome, and renal interstitial fibrosis. The mechanisms of hirudin in treating CKD are mainly related to inhibiting the inflammatory response, preventing apoptosis of intrinsic renal cells, and inhibiting the interactions between thrombin and protease-activated receptors. In this review, we summarize the function and beneficial properties of hirudin for the treatment of CKD, and its underlying mechanisms.

The Use of Medicinal Leeching in Breast Surgery: A Systematic Review.

Background: The medicinal leech has been used in plastic surgery to resolve venous congestion that can threaten the viability of tissue transfer. Within the context of breast surgery, venous congestion is a pertinent consideration for reconstructive and non-reconstructive breast surgery such as mammoplasty and mastopexy. However, leeching is closely associated with complications such as infection, pain, and anaemia. This is the first systematic review that examines the methodology, efficacy, and post therapeutic outcome data across all existing studies on medicinal leeching in breast surgery. Methods: A systematic search of PubMed and Embase databases from their inception to November 2023 was conducted. Inclusion criteria included studies reporting on the use of leeches to resolve venous congestion in any breast surgery. The JBI Critical Appraisal Checklist for Case Series tool was used for bias analysis. Descriptive statistics were undertaken in Microsoft Excel. Results: A total of 18 studies with a combined sample size of 28 were examined, including 4 case series and 14 case reports. Patients mostly underwent reconstructive breast surgery (75%). The median number of leeches used was two, with a median number of three leeching sessions per day and 3 days of leeching. Medicinal leeching successfully prevented the loss of 75% of all tissue transfers. The complication rate was high at 81.14% and mainly included infection and anaemia. Conclusions: Medicinal leeching is an effective method to relieve venous congestion in breast surgery but must be judiciously used within the clinical context of the patient to maximise efficacy and mitigate harm from complications.