Interpretation of the Urinalysis and Urine Microscopy

AimsTo determine the rate of likely contaminated urine samples among urine specimens obtained by clean-catch method among under 3-month-olds screened for UTI in Children’s Emergency Department (CED), UHS between January...

Sepsis is the most common trigger for acute kidney injury (AKI) in critically ill patients. We sought to determine whether there are unique patterns to urine sediment in septic compared with non-septic AKI. Prospective two center cohort study of adult critically ill patients with septic and non-septic AKI, defined by the RIFLE criteria. Eligible patients had clinical, physiologic and laboratory data extracted. Blood and urine were sampled for urine biochemistry, microscopy and neutrophil gelatinase-associated lipocalin (NGAL). A urine microscopy score (UMS) was derived based on the observed quantification of renal tubular cells and casts in the sediment. The UMS was compared between septic and non-septic AKI and correlated with NGAL, worsening AKI, renal replacement therapy (RRT) and hospital mortality. Eighty-three patients were enrolled. Mean (SD) age was 64.3 (16.6) years, 60.2% were male, Charlson comorbidity score was 3.3 (2.8) and Acute Physiology and Chronic Health Evaluation II score was 21.4 (7.6). Septic AKI was present in 43 patients (51.8%). RIFLE class at enrollment was not different between groups (P = 0.43). Septic AKI was associated with higher UMS compared with non-septic AKI (P = 0.001). There was no correlation between UMS and fractional excretion of sodium (FeNa) or fractional excretion of urea (FeU). Elevated urine NGAL (uNGAL) correlated with higher UMS (P = 0.0003), while correlation with plasma NGAL was modest (P = 0.05). Worsening AKI occurred in 22.9% with no difference between septic and non-septic groups. A UMS score ≥ 3 was associated with increased odds of worsening AKI [adjusted odds ratio 8.0; 95% confidence intervals (CI), 1.03-62.5, P = 0.046]. For a UMS ≥3, sensitivity and specificity were 0.67 (95% CI, 0.39-0.86) and 0.95 (0.84-0.99) and positive and negative predictive values we re 0.80 (0.49-0.94) and 0.91 (0.78-0.96) for detecting worsening AKI, respectively. While there were no differences between septic and non-septic AKI, higher UMS correlated with need for RRT (15.7%, P = 0.02) and in-hospital death (30.1%, P = 0.01); however, this did not persist in multivariable analysis. Septic AKI is associated with greater urine microscopy evidence of kidney injury compared with non-septic AKI, despite similar severity of AKI. A UMS ≥ 3 correlated with higher uNGAL and was predictive of worsening AKI. Urine microscopy may have a complementary role for discerning septic from non-septic AKI, discriminating severity and predicting worsening AKI in critically ill patients.

A Simple Method for Selecting Urine Samples that Need Culturing

Although urine microscopy is an important step in the initial evaluation of a patient with kidney disease, internal medicine residents have minimal exposure to this technique during their training. The goal of this study was to understand knowledge of and attitudes toward urine microscopy among internal medicine residents and to implement virtual urine microscopy teaching sessions. A voluntary, anonymous, online survey was sent to all of the categorical internal medicine residents (n=131) training at the Icahn School of Medicine at Mount Sinai (ISMMS). The survey included 13 questions to assess attitudes toward, experience with, and clinical interpretation of urine microscopy specimens. In response to the survey results, we implemented virtual urine microscopy teaching sessions using video conferencing software that incorporated real-time urine sediment analysis with nephrology fellows and attending nephrologists. The survey response rate was 45% (59 of 131). Forty-seven percent (28 of 59) of respondents reported performing urine microscopy at least once during their training, and 75% (44 of 59) of respondents did not feel comfortable performing urine microscopy. The majority of residents (92%; 54 of 59) reported they felt urine microscopy was very helpful or somewhat helpful in the evaluation of patients with AKI. Overall, 41% of responses to clinical interpretation questions were considered correct. Following survey completion, virtual urine microscopy sessions were held monthly and well received by the participants. Our study found that internal medicine residents perceive urine microscopy as a helpful diagnostic tool, although lack the skills to perform and interpret urine microscopy sediments. Virtual educational sessions using video conferencing software are a technically feasible approach to teaching urine microscopy to internal medicine residents. Future studies include a study of the effect of these sessions on learning of urine microscopy. This article contains a podcast at https://www.asn-online.org/media/podcast/K360/2021_01_28_KID0006282020.mp3.

Background: Urine culture is the gold standard in the diagnosis of urinary tract infection (UTI), but usually takes at least 48 hours and is expensive. Urine dipstick test and microscopy are useful for early diagnosis and initiation of treatment. The current study aims to assess the diagnostic value of dipstick and microscopy of urine in the diagnosis of UTI in comparison with culture.Methods: Children aged between 3 months-15 years of age, in whom UTI was suspected clinically were included in the study. Dipstick and microscopic examination of urine were done and compared with the urine culture. Results were analyzed using sensitivity, specificity, positive predictive value and negative predictive values.Results: Total of 104 children with clinical suspicion of UTI were evaluated in the study. The specificity of nitrite is 93.94%, leucocyte esterase 75.76%, urine dipstick test (nitrite and leukocyte esterase) 96.97% and urine microscopy is 50% when compared to urine culture.Conclusions: Urine dipstick test (nitrite and leukocyte esterase) and urine microscopy can be used as screening tests to rule out or rule in UTI. This would be useful clinically as treatment could be commenced in children pending culture reports.

Background: The accurate UTI diagnosis is crucial in the laboratory. Objective: The objective was to assess the sensitivity and specificity of the nitrite test, leukocyte esterase, both nitrite and leukocyte esterase, and urine microscopy in UTI diagnosis. Methodology: This was a cross-sectional study in which 100 adult patients, who were suspected to have UTI and did not receive antibiotics for at least 1 week, were included in this study performed in Shahabuddin Medical College and Hospital, Gulshan-2, Dhaka. Urine samples were collected and sent to laboratory for urine analysis and urine culture. Nitrite and leukocyte esterase dipsticks tests were done as well. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were measured for nitrite, leukocyte esterase, both nitrite and leukocyte esterase. Results: According to the results of the urine dipstick test, microscopy, and urine culture, nitrite was positive in 17.0% of the cases, leukocyte esterase was positive in 53.0% of the cases, both nitrite and leukocyte esterase were positive in 17.0% of the cases, urine microscopy was positive in 71.0% of the cases, and urine culture was positive in 41.0% of the cases. In the detection of urinary tract infections, the sensitivity, specificity, PPV, and NPV of leukocyte esterase were 87.8%, 71.2%, 67.9%, and 89.4% respectively, using urine culture as the gold standard test. Based on urine culture as gold standard test, the sensitivity, specificity, PPV, and NPV of both nitrite and leukocyte esterase were 34.1%, 94.9%, 82.4%, and 67.5% respectively, in detecting urinary tract infections. Conclusions: Efficacy of leukocyte esterase was found better in detecting UTI comparing nitrite test. Escherichia coli is the most common isolated organism. Bangladesh Journal of Medical Microbiology, July 2023;17(2):55-59

ABSTRACTBackgroundIsolated microhematuria (IMH) can signal hidden glomerular disease, necessitating detailed evaluations for potential kidney donors, including kidney biopsies. The optimal strategy for deciding on kidney biopsies remains unclear. While the British Transplant Society supports dipstick analysis, KDIGO focuses solely on urine microscopy. This study explored the correlation between kidney biopsy outcomes and results from dipstick urinalysis and urine microscopy in potential kidney donors.MethodsThis retrospective study encompassed all potential kidney donors who received kidney biopsies following a positive urine dipstick result for IMH, irrespective of whether red blood cells (RBCs) were found on urine microscopy. We performed sensitivity and specificity analyses to assess the effectiveness of microscopy and dipstick urinalysis in identifying histological abnormalities in the kidney biopsies.ResultsApproximately 49% of potential donors—133 out of 271—who had kidney biopsies due to positive dipstick tests showed negative results in urine microscopy for RBCs. In total, 168 donor candidates, or 62%, had abnormal findings in their biopsies, with nearly half of those diagnosed with immunoglobulin A nephropathy having negative urine microscopy results. Furthermore, 58% of potential donors with negative urine microscopy results—77 out of 133—also exhibited abnormal biopsy findings. The urine microscopy test displayed a sensitivity of 54.2% (95% confidence interval 46.6–61.5) and a specificity of 54.4% (95% confidence interval 44.8–63.7) for detecting abnormal biopsy results.ConclusionThis study highlighted a significant presence of donors with IMH with underlying glomerular lesions. Using urine microscopy showed limited sensitivity and specificity in identifying abnormal histopathological results. Relying solely on urine microscopy may miss critical pathologies like IgAN in prospective kidney donors. The persistence of IMH during dipstick urinalysis calls for kidney biopsy in potential donors. These findings suggest that our results be incorporated into future global guideline formulations.

Introduction Iron deficiency anaemia (IDA) accounts for 4–13% of referrals to gastroenterology. The British Society of Gastronterology IDA guidelines recommend the investigation of the gastrointestinal (GI) tract, but not the renal tract. A single consultant led one stop IDA clinic was set up. As part of the evaluation of IDA, urine microscopy and an ultrasound or CT abdomen/pelvis (if used in lower GI tract examination) were performed to investigate for renal tract malignancies, alongside GI tract investigations. We aimed to demonstrate the yield of renal and GI tract malignancies in patients with IDA. Methods Patients with IDA or isolated hypoferritinaemia attending the clinic from 2013–2015 who underwent urine microscopy and an ultrasound or CT abdomen/pelvis alongside bidirectional GI investigations (Upper GI: gastroscopy/barium swallow/CT; lower GI: colonoscopy/barium enema/CT) were analysed. We described the yield of haematuria from urine microscopy and the yield of malignancy from renal and GI tract investigations. Results A total of 196 patients had renal tract investigations alongside bidirectional GI investigations (152 urinalysis/ultrasound, 44 urinalysis/CT). 6.1% (12/196) patients had microscopic haematuria. Four renal tract cancers were found: 2 from the haematuria group and 2 from the normal urine microscopy group. In the haematuria group, 2 bladder cancers were identified by CT and cystoscopy respectively. The latter patient was asymptomatic apart from gastroesophageal reflux and had no weight loss. He had a normal gastroscopy, colonoscopy and ultrasound abdomen. A cystoscopy was performed due to the persistent haematuria, which revealed a bladder cancer. In the normal urinalysis group, CT identified 1 prostate cancer and 1 renal cell carcinoma (RCC) where both patients presented with weight loss. The yield of renal tract malignancies in this cohort was 2.0% (4/196). The yield of GI malignancy was 3.1% (6/196) from bidirectional GI investigations in the same cohort of patients. All GI malignancies identified were colorectal cancers. Conclusion The ratio of renal: GI tract malignancies was 2:3 in this cohort. Urine microscopy identified 50% of renal tract cancers. Following the standard practice of bidirectional GI investigations for IDA, the 1 case of asymptomatic bladder cancer would have been missed had urine microscopy not been performed. Routine urine microscopy is easy and cheap to perform, and should be tested in all patients with IDA, and those with haematuria should have their renal tracts investigated. Routine renal tract ultrasound in the asymptomatic IDA patient is not indicated. Disclosure of Interest None Declared

Background:Diagnosis of urinary tract infection (UTI) can be challenging as symptoms are nonspecific. The gold standard for the diagnosis of urine culture is not easily available in resource constrained settings. Hence, the need for affordable point of care diagnostic test could be an inexpensive alternative for urine culture or microscopy. The objective of the study was to validate the urine dipstick test to detect UTI in a resource constrained primary care setting.Methods:A diagnostic accuracy study was conducted in a health center in an urban slum by Bangalore Baptist Hospital. We included 136 patients suspected to have UTI. Patients were asked to give urine samples for urine dipstick analysis, urine microscopy, and urine culture and validity of the dipstick was analyzed.Results:A total of 136 patients fulfilling the inclusion criteria were recruited. Nitrite had higher specificity than leukocyte esterase (95% vs. 73%). Positive predictive value for nitrite and leukocyte was 84% and 51%, respectively. A combination of fever, dysuria along with lower abdominal pain had higher specificity (92%). Most common organism that was isolated was E. coli (56%) followed by S. aureus (13%). E. coli was susceptible to nitrofurontoin.Conclusion:Urine dipstick could be used as a simple diagnostic test in a limited resource setting for a rapid diagnosis and initiation of empirical antibiotic therapy. Urine dipstick for nitrite has a good specificity.

This study was designed to compare urine microscopy and the Griess test as screening tests for asymptomatic bacteriuria (AB) in pregnancy, using urine culture as a gold standard. Urine microscopy, Griess test and urine culture were carried out on urine samples from 483 antenatal women. AB was detected by urine culture in 30 (6.8%) of the patients. The Griess test and urine microscopy were found to have a sensitivity of 63.3% and 60%, specificity of 99.5% and 83.6%; and positive predictive value of 90.5% and 21.1% respectively. Most of the infections missed by the Griess test were either <100,000 colony count on culture or caused by gram positive cocci. The cost of the Griess test was only one tenth of that of urine microscopy. The Griess test is a simple and inexpensive test that when compared to urine microscopy has equal sensitivity, and better specificity and positive predictive value for the detection of AB in pregnancy than urine microscopy.

Acute kidney injury (AKI) is a common and adverse complication following non-cardiac surgery. Evidence have shown urine microscopy could help early detection, differentiating the causes and predicting the progression of AKI. However, little evidence is available on AKI after non-cardiac surgery. Thus, we investigated the association between urine microscopy and severe AKI in critically ill patients after non-cardiac surgery. This was a single-center prospective cohort study. The primary outcome was severe AKI, defined as stage 2 or 3 according to maximal KDIGO criteria within 7 days following non-cardiac surgery. Urine microscopy immediately, 6 and 12 hours after surgical intensive care unit (SICU) admission were examined and graded by a urine microscopy score (UMS) based on the observed quantification of renal tubular cells and casts in the sediment. Then, multivariate Logistic regression models were used to analyze the associations between UMS and postoperative severe AKI. From May 20, 2019 to November 24, 2020, 661 patients were enrolled with 147 patients (22.2%) developing postoperative severe AKI. Multivariate Logistic regression model showed elevated UMS (≥1) 6 and 12 hours after SICU admission were independently associated with postoperative severe AKI (OR 2.200, 95% CI: 1.182-4.095, P=0.013 and OR 2.949, 95% CI: 1.657-5.248, P<0.001, respectively). Furthermore, higher UMS 6 hours after SICU admission demonstrated correlation with greater risk of severe AKI with OR 3.887 (95% CI: 1.430-10.563) for UMS ≥3 and OR 2.429 (95% CI: 1.237-4.770) for UMS =1-2. The specificity and sensitivity of UMS ≥1 for severe AKI was 93.8% (95% CI: 91.7-95.9%) and 15.6% (95% CI: 9.7-21.5%), respectively. While the negative and positive predictive value was 79.5% (95% CI: 76.3-82.7%) and 41.8% (95% CI: 28.8-54.8%), respectively. In addition, patients with higher UMS (≥3, 1-2 and 0) had significantly more postoperative complications and longer SICU stay; and they also showed a trend toward other adverse postoperative outcomes. Early urine microscopy was independently associated with severe AKI in critically ill patients following non-cardiac surgery with higher UMS related to greater risk. ClinicalTrials.gov identifier: NCT03880110.

This study compares the performance of urine dipstick alone with urine microscopy and with both tests combined as a screen for urinary tract infection (UTI) in febrile infants aged 1 to 90 days. We queried the Intermountain Healthcare data warehouse to identify febrile infants with urine dipstick, microscopy, and culture performed between 2004 and 2011. UTI was defined as >50 000 colony-forming units per milliliter of a urinary pathogen. We compared the performance of urine dipstick with unstained microscopy or both tests combined ("combined urinalysis") to identify UTI in infants aged 1 to 90 days. Of 13 030 febrile infants identified, 6394 (49%) had all tests performed and were included in the analysis. Of these, 770 (12%) had UTI. Urine culture results were positive within 24 hours in 83% of UTIs. The negative predictive value (NPV) was >98% for all tests. The combined urinalysis NPV was 99.2% (95% confidence interval: 99.1%-99.3%) and was significantly greater than the dipstick NPV of 98.7% (98.6%-98.8%). The dipstick positive predictive value was significantly greater than combined urinalysis (66.8% [66.2%-67.4%] vs 51.2% [50.6%-51.8%]). These data suggest 8 febrile infants would be predicted to have a false-positive combined urinalysis for every 1 infant with UTI initially missed by dipstick screening. Urine dipstick testing compares favorably with both microscopy and combined urinalysis in febrile infants aged 1 to 90 days. The urine dipstick test may be an adequate stand-alone screen for UTI in febrile infants while awaiting urine culture results.

IntroductionUrinary tract infections (UTI) are a serious bacterial infection in infants presenting to emergency departments (ED). Current guidelines have not identified a White Blood Cell (WBC) cut off in urine...

HIV-1 infection disproportionately affects women in sub-Saharan Africa, where areas of high HIV-1 prevalence and Schistosoma haematobium endemicity largely overlap. Female genital schistosomiasis (FGS), an inflammatory disease caused by S. haematobium egg deposition in the genital tract, has been associated with prevalent HIV-1 infection. Elevated levels of the chemokines MIP-1α (CCL-3), MIP-1β (CCL-4), IP-10 (CXCL-10), and IL-8 (CXCL-8) in cervicovaginal lavage (CVL) have been associated with HIV-1 acquisition. We hypothesize that levels of cervicovaginal cytokines may be raised in FGS and could provide a causal mechanism for the association between FGS and HIV-1. In the cross-sectional BILHIV study, specimens were collected from 603 female participants who were aged 18–31 years, sexually active, not pregnant and participated in the HPTN 071 (PopART) HIV-1 prevention trial in Zambia. Participants self-collected urine, and vaginal and cervical swabs, while CVLs were clinically obtained. Microscopy and Schistosoma circulating anodic antigen (CAA) were performed on urine. Genital samples were examined for parasite-specific DNA by PCR. Women with FGS (n=28), defined as a positive Schistosoma PCR from any genital sample were frequency age-matched with 159 FGS negative (defined as negative Schistosoma PCR, urine CAA, urine microscopy, and colposcopy imaging) women. Participants with probable FGS (n=25) (defined as the presence of either urine CAA or microscopy in combination with one of four clinical findings suggestive of FGS on colposcope-obtained photographs) were also included, for a total sample size of 212. The concentrations of 17 soluble cytokines and chemokines were quantified by a multiplex bead-based immunoassay. There was no difference in the concentrations of cytokines or chemokines between participants with and without FGS. An exploratory analysis of those women with a higher FGS burden, defined by ≥2 genital specimens with detectable Schistosoma DNA (n=15) showed, after adjusting for potential confounders, a higher Th2 (IL-4, IL-5, and IL-13) and pro-inflammatory (IL-15) expression pattern in comparison to FGS negative women, with differences unlikely to be due to chance (p=0.037 for IL-4 and p<0.001 for IL-5 after adjusting for multiple testing). FGS may alter the female genital tract immune environment, but larger studies in areas of varying endemicity are needed to evaluate the association with HIV-1 vulnerability.

Urine examination has been employed in clinical practice as the most common screening laboratory method for early detection of urinary tract infections (UTIs) or renal disorder. This study was undertaken to ascertain the usefulness of urine macroscopy and microscopy as vital screening procedure for diagnosing UTI among antenatal patients in a teaching hospital in Awka, Nigeria. Freshly voided midstream urine specimens of 269 pregnant women were collected and examined using macroscopic, microscopic and culture methods. The sensitivity, specificity, positive predictive value and negative predictive value of urine colour, and microscopic features were compared with urine culture in diagnosis of UTI. Statistical analysis was done using SPSS and Epi info® and P-value was set at &lt;0.05 significant level. One hundred and seven specimens showed positive urine cultures. Out of these 107 specimens, 60 (56.1%) also had deviation from normal urine colour and 77(72%) were positive on urine microscopy. Macroscopic examination showed that a significant relationship exists between urine colour and positive urine culture (p=0.0001). The sensitivity and specificity of urine colour with respect to UTI were 56.7% and 67.9% respectively. Urine microscopy revealed that the positive features had a significant relationship with positive urine culture (p= 0.000). Pyuria alone showed the specificity and positive predictive value of 100% each. The sensitivity, specificity, positive predictive value and the negative predictive value of combination of positive microscopic features were 72%, 64.8%, 57.5% and 77.8% respectively. Examination of colours and microscopic features of urine are therefore vital in predicting urinary tract infection.