Evidence-Based Wound Irrigation: Separating Fact from Fiction.

SUMMARY: The relationship between wound irrigation and healing has been recognized for centuries. However, there is little evidence and no official recommendations from any health care organization regarding best wound irrigation practices. This is the first review of wound irrigation that systematically summarizes the literature using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and distills the evidence into a practical format. In this comprehensive review, the authors outline the irrigation fluids and delivery methods used in the identified studies, analyze reported treatment outcomes, summarize irrigation effectiveness, and propose evidence-based guidelines to improve wound healing outcomes and enhance the consistency of wound irrigation. Thirty-one high-quality studies with a combined total of 61,808 patients were included. Based on the current evidence provided by this review, the authors propose the following guidelines: (1) acute soft-tissue wounds should receive continuous gravity flow irrigation with polyhexanide; (2) complex wounds should receive continuous negative-pressure wound therapy with instillation with polyhexanide; (3) infected wounds should receive continuous negative-pressure wound therapy with instillation with silver nitrate, polyhexanide, acetic acid, or povidone-iodine; (4) breast implant wounds should receive gravity lavage with povidone-iodine or antibiotics; and (5) surgical-site infection rates can be reduced with intraoperative povidone-iodine irrigation.

Use of Negative-Pressure Wound Therapy With Instillation and Dwell Time: An Overview.

SUMMARY: The use of negative-pressure wound therapy (NPWT) has become an established therapy for wound management. There have been many advancements in the technology of NPWT including NPWT with instillation and dwell (NPWTi-d). NPWTi-d promotes wound healing by wound cleansing, irrigation, and nonexcisional debridement. NPWTi-d has been shown in comparative clinical studies to decrease the time to definitive wound healing and length of hospitalization. NPWTi-d-using a reticulated open-cell foam dressing with "through" holes (ROCF-CC)-has been postulated to facilitate solubilization, detachment, and elimination of infectious materials, such as slough and thick exudate, before or after operative debridement, and in cases where surgical debridement is not an option. The authors provide an overview on the use of NPWTi-d by reviewing the components of the system, proposed mechanism of action, clinical outcomes, and current consensus guidelines for its utilization.

Negative-Pressure Wound Therapy With Instillation: A Tool in the Multidisciplinary Approach to Limb Function Preservation.

SUMMARY: The multidisciplinary approach to lower extremity function preservation is well established and is globally considered the standard of care. Every member of the team contributes their unique skills and knowledge to patient care. The effective integration of negative-pressure wound therapy with instillation (NPWTi) has fundamentally changed the approach to the infected or contaminated wound. Initially, in conjunction with excisional debridement, NPWTi has demonstrated its utility of expediting wound bed preparation for closure or coverage. With the introduction of a novel foam design, the effectiveness has increased and provided an option in cases where surgical intervention is not available or recommended. The successful implementation and continued monitoring of NPWTi provides an efficient tool to expedite ultimate wound healing and involves all members of the team.

Use of Negative-Pressure Wound Therapy With Instillation and Dwell in Breast Reconstruction.

SUMMARY: The use of negative-pressure wound therapy (NPWT) has expanded over the last 3 decades, paralleled and documented by an increase in research. This article discusses the evolution and current applications of NPWT in modern breast reconstruction. Negative-pressure wound therapy with instillation and dwell (NPWTi-d) technology can be used to remove infectious material, facilitate salvaging compromised tissue, and stabilize the soft-tissue environment. Published consensus NPWTi-d guidelines can aid in treatment selection and implementation of this new technology. The therapeutic approach of simultaneously removing infectious material and actively improving mastectomy flap perfusion and thickness is a burgeoning concept, and illustrative cases are presented. NPWTi-d preliminary use has led to reconstruction salvage with reproducible early experience and outcomes, and it is hoped that it will raise interest and awareness of this promising application of the technology to improve breast reconstruction outcomes.

The Efficacy, Safety, and Convenience of a New Device for Flushing Intravenous Catheters (Baro Flush™): A Prospective Study.

Background and Objectives: An effective flushing technique is essential to reduce intravenous (IV)-related complications and improve patient care. New technology should contribute to such improvements, while reducing costs and increasing care efficiency. This study evaluated the efficacy, safety, and convenience of a new flushing technique using a Baro Flush™ controller. Materials and Methods: We evaluated the efficacy and safety of Baro Flush™ by measuring the infusion flushing volume and pressure in vitro. Afterwards, we prospectively enrolled 3000 patients with flushing and assigned 1500 patients with a new technique for flushing and 1500 with a conventional flushing method, which was performed by 48 registered nurses (RNs) at the Gil Medical Center in June 2018. The efficacy, safety, and convenience of the new flushing method were evaluated though a questionnaire survey. Results: The average flushing pressure was 12.5 ± 0.6 psi (86.18 ± 4.14 kPa) with 1.2 ± 0.2 mL per flush, as recommended by the Centers for Disease Control and Prevention based on 85 experiments. No IV-catheter-related complications were reported by the RNs during the study. More than 80% of the RNs reported that the new flushing method was easier to learn, improved care efficacy, and was more convenient than conventional flushing. Conclusions: The new flushing method using a Baro Flush™ controller showed improved efficacy, safety, and convenience compared with the conventional flushing method, and no IV-catheter-related complications occurred, including occlusion and inflammation. The new flushing method promises to reduce IV-catheter-related complications and shows improved efficacy, safety, and convenience.

Outcomes in patients with late debridement of open long bone fractures of the lower extremities in penetrating trauma: a retrospective review of the National Trauma Data Bank.

BACKGROUND: The morbidity and mortality associated with open long bone fractures have been greatly reduced due to antibiotics and early surgical washout and debridement. Guidelines recommend early washout and debridement within 6-8 h; however, newer studies have shown that delaying surgical washout and debridement up to 24 h can be done safely without an increase in surgical site infection, wound nonunion or sepsis. All studies thus far have looked at combined blunt and penetrating open long bone fractures, without distinguishing between mechanism or type of injury. Our study looked specifically at open long bone fractures of the lower extremity caused by a penetrating mechanism of injury. METHODS: We utilized the US National Trauma Data Bank and included patients who had diagnosis of lower extremity open long bone fracture from a penetrating mechanism and underwent irrigation and debridement (I&D) within 24 h of arriving to the hospital. RESULTS: A total of 1014 patients qualified for the study. Of those, 736 (72.6%) patients underwent an I&D within 8 h and 278 (27.4%) underwent an I&D between 8 and 24 h after hospital arrival. When examining the patient outcomes, there were few cases and no significant differences in the occurrence of surgical site infections, sepsis or wound disruptions between the two groups. CONCLUSION: The majority of the open long bone fractures were due to firearm injury. I&D of penetrating open long bone fracture can be performed within 24 h without any added infective morbidity.

Intraoperative Irrigation: Fluid Administration and Management Amidst Conflicting Evidence.

Surgeons use irrigation during open cavity procedures to improve their view of the patient's anatomy and to reduce the patient's risk of infection. However, there are no standard guidelines that recommend a specific type of fluid, additive, or volume of irrigation to use during open procedures. Intraoperative hypothermia can occur if irrigation fluids have not been warmed or have cooled before use, causing adverse patient outcomes. In addition, failing to manage (eg, measure and document) fluid volume accurately may affect clinical decision making and cause other complications. Perioperative personnel should evaluate new technologies that may improve the efficiency and accuracy of irrigation temperature and volume measurements. More research is needed to develop standardized practice guidelines for intraoperative irrigation and fluid management.

Just add water? Chlorhexidine's antimicrobial properties are minimally affected by dilution in saline compared to water.

BACKGROUND: Dilute chlorhexidine gluconate (CHG) in sterile water is an antiseptic solution approved for intraoperative wound irrigation by the United States Food and Drug Administration. In practice, however, CHG is commonly diluted with normal saline, which can result in its precipitation potentially reducing the antimicrobial effect. The purpose of this study was to determine if the antimicrobial properties of CHG are reduced after dilution with normal saline compared to sterile water. MATERIALS AND METHODS: Sterile paper disks were placed into undiluted 4% CHG (positive control), 0.05% CHG in sterile water, 0.05% CHG in normal saline, or normal saline alone (negative control) and then placed in triplicate onto the agar plates inoculated with Staphylococcus aureus. After incubating at 37 °C for 24 h, the diameter of the zone of inhibition around each disk was measured. RESULTS: The mean zone of inhibition for 4% CHG, 0.05% CHG in sterile water, 0.05% CHG in normal saline, and normal saline alone was 24 ± 0.6 mm, 16 ± 0.9 mm, 14 ± 0.5 mm, and 0 ± 0 mm, respectively (p < 0.01). The zone of inhibition for dilute CHG in normal saline was on average 2.5 mm less (95% CI 1.7-3.2 mm) than that of CHG in sterile water. CONCLUSIONS: Dilute CHG in normal saline, versus sterile water, retained its antimicrobial activity with a small reduction in the zone of inhibition. Surgeons and scientists should be aware of the interaction between normal saline and CHG. Future scientific studies need to control for what solution is used for dilution.

Room Temperature Versus Warm Irrigation Fluid Used for Patients Undergoing Arthroscopic Shoulder Surgery: A Systematic Review and Meta Analysis.

PURPOSE: The aim of this study was to analyze whether warm irrigation fluid could reduce postoperative adverse effects in patients undergoing arthroscopic shoulder surgery compared with room temperature irrigation fluid. DESIGN: A systematic review and meta-analysis of clinical trials was performed. METHODS: A computerized search of electronic databases was performed. The inclusion criteria were studies comparing the clinical effects of room temperature and warm irrigation fluid on patients undergoing arthroscopic shoulder surgery. FINDINGS: Warm irrigation fluid reduced the degree of core body temperature drop and the incidence of hypothermia. A statistically lower incidence of shivering also occurred in the warm irrigation fluid group. CONCLUSIONS: The use of warm irrigation fluid better maintains core body temperature and reduces incidence of shivering than room temperature irrigation fluid. Therefore, warm irrigation fluid is a better choice for arthroscopic shoulder surgery.

Negative pressure wound therapy with instillation: International consensus guidelines update.

The use of negative pressure wound therapy with instillation and dwell time (NPWTi-d) has gained wider adoption and interest due in part to the increasing complexity of wounds and patient conditions. Best practices for the use of NPWTi-d have shifted in recent years based on a growing body of evidence and expanded worldwide experience with the technology. To better guide the use of NPWTi-d with all dressing and setting configurations, as well as solutions, there is a need to publish updated international consensus guidelines, which were last produced over 6 years ago. An international, multidisciplinary expert panel of clinicians was convened on 22 to 23 February 2019, to assist in developing current recommendations for best practices of the use of NPWTi-d. Principal aims of the meeting were to update recommendations based on panel members' experience and published results regarding topics such as appropriate application settings, topical wound solution selection, and wound and patient characteristics for the use of NPWTi-d with various dressing types. The final consensus recommendations were derived based on greater than 80% agreement among the panellists. The guidelines in this publication represent further refinement of the recommended parameters originally established for the use of NPWTi-d. The authors thank Karen Beach and Ricardo Martinez for their assistance with manuscript preparation.

Is Operative Debridement Greater Than 24 Hours Post-admission Associated With Increased Likelihood of Post-operative Infection?

BACKGROUND: The historical "six-hour rule" as a golden hour for timing to debridement has been refuted in modern literature. Current standards prompt a timely debridement; however, in the setting of polytrauma, patients are often resuscitated for periods >24 h, with delayed orthopedic intervention. Therefore, we sought to determine the association between prolonged time to operative debridement (>24 h) and infection. METHODS: We conducted a retrospective review of patients with open fractures that underwent irrigation and debridement at a single institution from 2008 to 2016. Demographic, injury, and operative variables were collected. Infection was defined as the need for intravenous antibiotics and/or repeat irrigation and debridement. Chi-squared test and univariate logistic regression were performed. P < 0.05 was the cutoff for significance. RESULTS: Of 642 patients examined, 56 (8.7%) developed an infection. Prolonged time to debridement was not associated with increased infection rates (P = 1.00). Gustilo-Anderson classification was associated with increased risk of infection (type I: 2.1%, type II: 7.6%, and type III: 14.6%; P < 0.001). In univariate analysis, infection was associated with after-hours surgery (between 7 PM and 7 AM (odds ratio [OR] = 2.02; P < 0.02), definitive fixation more than 24 h post-admission (OR = 3.08; P < 0.001), wound closure more than 24 h post-admission (OR = 4.36; P < 0.001), and more than two operations performed post-admission (OR = 8.73; P < 0.001). Multivariate analysis of these factors found number of operations (OR = 7.13; P < 0.001) and time to definitive wound closure (OR = 4.04; P < 0.001) to be independent predictors of developing an infection. CONCLUSIONS: Our data suggests that there is no association between infection and prolonged time to debridement.

Volume of Irrigation Does Not Affect Rate of Abscess in Perforated Appendicitis.

Background: Although previous studies have evaluated whether use of irrigation decreases postoperative intraabdominal abscess (PO-IAA) formation, these studies treated irrigation as a dichotomous variable and concluded that no irrigation resulted in a decreased incidence of PO-IAA formation. However, a recent study found decreased incidence with small aliquots to a total volume of 6 L. We hypothesized that higher volumes of irrigation would result in a lower incidence of PO-IAA. Materials and Methods: A postoperative template was developed as a quality improvement initiative and included descriptors for complex appendicitis and volume of irrigation. Data were prospectively collected from February 2016 to December 2018. Patients with complex appendicitis (fibropurulent exudate, extraluminal fecalith, well-formed abscess, visible hole in the appendix) were identified and analyzed by using standard statistical analysis. Volume of irrigation was categorized for analysis. Results: Two thousand three hundred six appendicitis patients were identified; 408 had complex appendicitis (17.7%). Three hundred eighty-four patients with complex appendicitis had documented irrigation volumes. The overall incidence of PO-IAA was 13.8%. Irrigation was commonly used (92.7%). The median amount of irrigation was 1000 mL (500 mL, 2500 mL), but it ranged from none to 9000 mL. There was no overall difference in the volume of irrigation used between those who developed a PO-IAA and those who did not (P = .34). No specific intraoperative finding was associated with the development of PO-IAA. Increasing volume of irrigation did not lower PO-IAA incidence (P = .24). Conclusions: The volume of irrigation did not appear to affect the rate of PO-IAA formation. The use of irrigation should be left to the discretion of the operating surgeon.

Cerumen Impaction: Diagnosis and Management.

Cerumen production is a normal and protective process for the ear canal. However, cerumen should be removed when it causes symptoms (e.g., hearing loss, itching, pain, tinnitus) or prevents assessment of the external auditory canal, the tympanic membrane, or audiovestibular system. Cerumen should also be removed when it limits examination in patients who cannot communicate their symptoms, such as those with dementia or developmental delay, nonverbal patients with behavioral changes, and young children with fever, speech delay, or parental concerns. Patients with coagulopathies, hepatic failure, thrombocytopenia, or hemophilia, and those taking antiplatelet or anticoagulant medications, should be counseled about the increased risk of bleeding in the external auditory canal when cerumen is removed. Effective treatment options include cerumenolytic agents, irrigation with or without cerumenolytic pretreatment, and manual removal. Home irrigation with a bulb syringe may be appropriate for selected adults. Cotton-tipped swabs, ear candling, and olive oil drops or sprays should be avoided. If multiple attempts to remove the impacted cerumen-including a combination of treatments-are ineffective, clinicians should refer the patient to an otolaryngologist. Persistent symptoms despite resolution of the impaction should also prompt further evaluation for an alternative diagnosis.

Effect of Polyhexamethylene Biguanide Solution on Bacterial Load and Biofilm in Venous Leg Ulcers: A Randomized Controlled Trial.

PURPOSE: The purpose of this study was to investigate the effect of polyhexamethylene biguanide (PHMB) solution as a wound cleanser on bacterial load and bacterial biofilm in venous leg ulcers. DESIGN: Randomized controlled trial. SUBJECTS AND SETTING: The target population was adults attending the dermatology outpatient clinic of the Clinical Hospital of the Federal University of Minas Gerais, Brazil. The sample comprised 44 patients with venous leg ulcers recruited over a 6-month period. METHODS: Participants were divided into 2 groups: the intervention group had their wounds cleansed with PHMB, and the control group had their wound cleansed with a 0.9% saline solution. Tissue fragments of the wounds were collected for bacteriological analysis; transmission electron microscopy was used to identify the presence of biofilm. RESULTS: The bacterial load was reduced in both groups compared to baseline values; no significant difference was found when groups were compared. Correlation analysis between wound duration (months), wound area (cm²), necrosis (%), variables, and bacterial count (colony forming units [CFUs]/g) after cleansing showed a significant relationship between area of the wound and CFUs/g (P = .0070, r = 0.51). Transmission electron microscopy revealed the presence of bacterial biofilm in the wounds after cleansing with both solutions. CONCLUSIONS: The results of this study indicate that both PHMB and saline solution are effective in reducing the bacterial load in venous leg ulcers. However, bacterial biofilm was present after cleansing with both solutions. These findings provide important evidence regarding effectiveness of 2 common wound cleansers on bacterial presence in wounds.

Are large clinical trials in orthopaedic trauma justified?

BACKGROUND: The objective of this analysis is to evaluate the necessity of large clinical trials using FLOW trial data. METHODS: The FLOW pilot study and definitive trial were factorial trials evaluating the effect of different irrigation solutions and pressures on re-operation. To explore treatment effects over time, we analyzed data from the pilot and definitive trial in increments of 250 patients until the final sample size of 2447 patients was reached. At each increment we calculated the relative risk (RR) and associated 95% confidence interval (CI) for the treatment effect, and compared the results that would have been reported at the smaller enrolments with those seen in the final, adequately powered study. RESULTS: The pilot study analysis of 89 patients and initial incremental enrolments in the FLOW definitive trial favored low pressure compared to high pressure (RR: 1.50, 95% CI: 0.75-3.04; RR: 1.39, 95% CI: 0.60-3.23, respectively), which is in contradiction to the final enrolment, which found no difference between high and low pressure (RR: 1.04, 95% CI: 0.81-1.33). In the soap versus saline comparison, the FLOW pilot study suggested that re-operation rate was similar in both the soap and saline groups (RR: 0.98, 95% CI: 0.50-1.92), whereas the FLOW definitive trial found that the re-operation rate was higher in the soap treatment arm (RR: 1.28, 95% CI: 1.04-1.57). CONCLUSIONS: Our findings suggest that studies with smaller sample sizes would have led to erroneous conclusions in the management of open fracture wounds. TRIAL REGISTRATION: NCT01069315 (FLOW Pilot Study) Date of Registration: February 17, 2010, NCT00788398 (FLOW Definitive Trial) Date of Registration: November 10, 2008.

BET 1: Is routine irrigation of a cutaneous abscess necessary?

A short cut review was carried out to establish whether the addition of irrigation of the abscess cavity improved outcomes after incision and drainage of a cutaneous abscess. One paper presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this paper are tabulated. It is concluded that in adult patients with cutaneous abscesses routine irrigation during incision and drainage does not improve clinical outcomes.

A Prospective, Randomized, Controlled Clinical Trial to Assess Use of 2% Lidocaine Irrigation to Prevent Abdominal Surgical Site Infection.

Surgical site infections (SSI) are the third most common nosocomial infection, increasing morbidity and mortality rates of patients as well as their costs of care, but longer-term follow up studies and data are limited. Lidocaine, in addition to being a readily available and accessible local anesthetic, is known to have bacteriostatic properties. A prospective, descriptive, controlled, randomized clinical trial was conducted among patients scheduled to undergo abdominal sur- gery in the general surgical unit of a Mexican hospital. The purpose of the study was to assess the incidence of SSIs in general and to compare the 30-day postoperative infection outcomes of saline irrigation to saline irrigation followed by 2% lidocaine application before skin closure in wounds grade II to IV per the Centers for Disease Control and Prevention surgical wound classi cation. All patients received systemic antibiotics before surgery. Eighty-four (84) patients (40 men and 44 women; mean age 49.02 ± 19.9 years, range 18-92 years), 39 in the control and 45 in the experimental group, completed the 30-day follow-up without experiencing nonsurgery-related complications. The overall incidence of SSIs (speci cally, seromas and abscesses) was 17.86%; the incidence of abscess formation was 7.14%. The overall incidence of SSIs in the lidocaine group was 8.89% compared to 28.2% in the saline only group (P = .02); the relative risk was 1.8 (P = .02; 95% CI 1.19-2.74) and 0.45 (P = .02; 95% CI 0.19-1.06) in the saline and lidocaine groups, respectively. Hemoglobin and albumin levels were signi cantly lower in patients who did compared to those who did not develop an SSI (P = .02 and .04, respectively). No signi cant SSI rate differences were seen between patients who did and did not have a drain placed. In patients who developed an abscess, Escherichia coli was the most prevalent bacteria and present in 40% of collected uid. While carefully controlled clinical studies are needed, lidocaine appears to be a viable option to decrease the incidence of SSI if applied as irrigation before wound closure in patients undergoing abdominal surgery.

Treatment of open fractures of the hand in the emergency department.

Current guidelines suggest early surgical treatment of open fractures. This rule in open hand fractures is not well supported and may be unpractical. Furthermore, desirable debridement and washout can be obtained in the emergency department (ED). The purpose of this study was to evaluate the relationship between the level of contamination, quality of washout in the emergency room, and the development of infection. Sixty-one patients with open fractures of the hand were retrospectively reviewed for demographic and fracture characteristics, and other complications. The infection rate was 14.8%. Contamination was present in 43 patients (70.5%). One thousand milliliters or more were used to obtain a grossly clean wound in 43 patients (70.5%). No significant relationship was found between fracture type, finger involved, hand dominance, comorbidities, and development of infection. The amount of fluid used for washout was significantly related to infection (P = 0.047), whereas wound contamination was not (P = 0.259). Type of oral antibiotic was significantly related to infection (P = 0.039). The level of contamination was not a significant factor in predicting infection, whereas the amount of fluid used for washout and the oral antibiotic type were significant factors in preventing infection. Since administration of intravenous antibiotics and thorough wound cleansing can be performed on open hand fractures in the ED under adequate anesthesia, most open fractures in the hand do not need to be treated early in the operating theater.

Normal saline versus heparin for patency of central venous catheters in adult patients - a systematic review and meta-analysis.

BACKGROUND: Heparin saline (HS) is theoretically superior to normal saline (NS) for maintaining the patency of central venous catheters (CVCs), but the comparative efficacy of them remains controversial. The aim of this systematic review and meta-analysis was to assess the efficacy of NS versus HS in the maintenance of the patency of CVCs in adult patients. METHODS: We searched PubMed, Embase and the Cochrane library databases. Randomized controlled trials (RCTs) evaluating the use of NS vs. HS to maintain the permeability of CVCs among adult patients were included in our meta-analysis. References of relevant papers were reviewed manually. No language restriction was applied. Non-human studies were excluded. Pooled relative risk (RR) was calculated using a Mantel-Haenszel random-effects model. We also performed subgroup analysis examining the effect of the duration of catheter placement on the outcome. All statistical tests were two-sided using a significance level of 0.05. RESULTS: Ten RCTs involving 7875 subjects (with analysis at patient, catheter, lumen and line access level) were included in this meta-analysis. Whether in terms of pooled or local analysis (RR with 95% confidence interval spans 1), NS can be equally, if not more effective, in keeping the CVCs open. Of studies reporting secondary outcomes (maneuver needed, heparin-induced thrombocytopenia, haemorrhage, central venous thrombosis and catheter-related bloodstream infection), heparinised saline was shown not to be superior to non-heparinised solution. Subgroup analysis in patients with short vs long term CVC placement was consistent with the main outcome partly and in particular for maintenance of catheter patency in patients with a long-term placement i.e. >30 days, the RR was 0.97 (n = 6589; 95% CI = 0.76 to 1.23; P = 0.796). However, for patients in whom the catheter was in place for <30 days, the RR was 1.52 (n = 1286; 95% CI = 1.02 to 2.27; P = 0.041). CONCLUSIONS: Based on the results of this meta-analysis, HS is not superior to NS in reducing CVCs occlusion. But in the short term, the use of HS is slightly superior to NS for flushing catheters from a statistical point of view.

The usefulness of uterine lavage and acute phase protein levels as a diagnostic tool for subclinical endometritis in Icelandic mares.

BACKGROUND: Endometritis is a common problem in a broodmare practice, often leading to infertility. The diagnosis is based on several methods such as cytology, bacteriology and histopathology; however the outcome of these methods may be inconclusive even when used together. The objectives of this study were: (1) to investigate the usefulness of acute phase proteins as an additional diagnostic tool for diagnosis of subclinical endometritis in mares and (2) to evaluate the association between macroscopic changes in uterine flushes and inflammation of the uterus. Materials were collected from 53 Icelandic mares with subclinical endometritis. Endometrial swabs and uterine lavage for cytological and bacteriological examinations and two endometrial biopsies were taken. Blood samples were collected 12-24 h after ovulation to determine the concentrations of serum amyloid A and haptoglobin in the 53 subfertile mares and, for comparison, from 20 non-pregnant mares that later conceived. RESULTS: Twenty-five mares were classified as positive for endometritis based on endometrial biopsy, which was used as the 'gold standard'. We observed a correlation between cloudy efflux in the lavage and (1) polymorphonuclear cell (PMN) infiltration of the endometrium (P = 0.031), (2) positive cytology in samples obtained by cotton swabs (P = 0.019) and uterine lavage (P = 0.011), and (3) positive microbiology from samples obtained by cotton swabs (P = 0.001) and uterine lavage (P = 0.047). The degree of agreement between PMN infiltration and positive cytology from samples taken by cotton swabs and uterine lavage was fair to moderate. We found no association between the concentration of acute phase proteins and infiltration of the endometrium by PMNs, or with positive results of cytological and microbiological examinations. CONCLUSIONS: Measurement of serum amyloid A and haptoglobin was not proven useful for diagnosis of subclinical endometritis in Icelandic mares. Macroscopic changes in the fluid collected by lavage were not consistently indicative of infection, but when present they indicate inflammation in the uterus with a high probability.