Predicting performance during clinical years from the new Medical College Admission Test

The results of a predictive validity study of the new Medical College Admission Test (MCAT) using criteria from the clinical years of undergraduate medical education are presented and discussed. The criteria included course grades and faculty ratings of clerks in internal medicine, surgery, obstetrics and gynecology, pediatrics, and psychiatry; scores on a comprehensive test of clinical knowledge (including patient management type examinations); and scores on Part II of the examinations of the National Board of Medical Examiners (NBME). While the validity coefficients of the MCAT with the Part II examinations ranged from .03 to .47, they were higher than those of undergraduate grade-point averages with the same criteria. The implications of the small-to-medium size validity coefficients for admissions are discussed.     

Macroscopic agglutination test for rapid diagnosis of human leptospirosis

A commercially available slide agglutination test (SAT) for the diagnosis of human leptospirosis was evaluated by comparing it to an immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and to the microscopic agglutination test (MAT). For all 108 patients, leptospirosis was diagnosed on the basis of a fourfold or greater increase in titer by MAT (seroconversion), and all but 1 of 245 controls were MAT negative (titers, <1:100). Both SAT and the IgM ELISA failed to detect one case of infection (sensitivity, 99%). Only 3 of 145 blood donors and none of the 100 patients with other illnesses were SAT positive (specificity, 99%). The overall results were similar for the three tests; however, SAT and ELISA were statistically more sensitive as initial screening tests. For 22% of the patients, the diagnosis of leptospirosis was made earlier by SAT than by MAT. SAT detected 27 (44%) of 62 MAT-negative patients with the first serum sample. ELISA and SAT had very similar results. Follow-up of patients for 1 year after the onset of symptoms showed a decreasing rate of positivity by SAT from the third month on. The rate of positivity by ELISA decreased more slowly, to about 67% by the end of the study. By MAT all patients were persistently reactive. SAT and ELISA seem to be convenient methods for the rapid and early screening for leptospirosis and could replace the less sensitive MAT. ELISA gives less subjective results than SAT and provides information on IgM kinetics, but it can be performed only by the more sophisticated laboratories. SAT is inexpensive, can be performed more quickly and more easily than ELISA, and could be used by the less well equipped laboratories.     

Pearson's fetal movement count (FMC) and antepartum fetal heart rate testing (AFHRT) for antepartum fetal well-being

To evaluate the accuracy of Pearson's fetal movement count (FMC) and antepartum fetal heart rate testing (AFHRT) in 380 high risk pregnancies at Rajavithi Hospital in 1994, the result of the 4 test FMC, AFHRT, FMC + AFHRT (serial test), and FMC + AFHRT (parallel test) were compared in sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false positive rate (FPR), false negative rate (FNR) and accuracy. All tests had equal specificity and FPR. FMC + AFHRT (serial test) had the highest value of sensitivity (66.67%) but lowest value of FNR, NPV and accuracy (33.33%, 40%, 72.73% respectively). PPV was 100 per cent in AFHRT and FMC + AFHRT (serial test). FMC might be used as a first line antepartum fetal well being screening test.     

Comparison of two tests and absorbance at 650 nm for assessing fetal lung maturity

The clinical performance of three rapidly performed tests--tap test, TDx Fetal Lung Maturity and amniotic fluid absorbance at 650 nm--in predicting fetal lung maturity were evaluated in 300 samples of clear amniotic fluid. In all cases, delivery occurred within three days of sample collection. Of the 300 newborns, 44 developed respiratory distress syndrome. For the tap test, the sensitivity (95.4%), specificity (82.8%), and predictive value for maturity (99.7%) and immaturity (48.9%) were comparable to those of the TDx fetal lung maturity test: sensitivity of 100%, specificity of 88.3%, and predictive value for maturity of 100% and immaturity of 53.1%. The specificity (68.4%) and predictive value for immaturity (34.7%) of amniotic fluid absorbance at 650 nm were significantly lower than for the TDx and tap tests, whereas no significant difference was found for sensitivity and prediction of maturity between amniotic fluid absorbance at 650 nm and the TDx and tap tests. Both the tap and the TDx tests appear to be useful in antenatal assessment of fetal lung maturity in terms of reliability, rapidity and uniformity.     

Usefulness of angiotensin converting enzyme inhibitors in the diagnosis of renovascular hypertension. III. Evaluation of the validity of the captopril test and the reno-scintigraphic captopril test in the diagnosis of renovascular hypertension according to accepted criteria

The aim of the study was to evaluate diagnostic validity of captopril test and scintigraphic test before and after captopril for the detection of renovascular hypertension (RVH) according to applied criteria. Employing blood pressure response to captopril as a criteria sensitivity was 37.0%, specificity 92.1%, positive predictive value 75.0% and negative predictive value 70.2% in the captopril test. Applying plasma renin activity (PRA) response to captopril as a criteria sensitivity was 92.5%, specificity 100%, positive predictive value 100% and negative predictive value 96.0% in the same test. Renin captopril test has excellent sensitivity and positive predictive value, is easy to perform and inexpensive and therefore may be a useful screening test for RVH in unselected population. With the own criteria used, captopril renoscintigraphy detected RVH with 87.5% sensitivity, 91.7% specificity, 87.5% positive predictive value and 91.7% negative predictive value. Captopril renoscintigraphy is an accurate diagnostic test for the identification of RVH in a clinically selected high-risk population. Common evaluation of both tests does not improve their accuracy in diagnosis of RVH.     

Evaluating the predictive validity of MCAT scores across diverse applicant groups

PURPOSE: To examine the predictive validity of MCAT scores, alone and in combination with other preadmission data, for medical students grouped by race/ethnicity and sex. METHOD: This study included two samples: 1,109 students who entered in 1992 any of the 14 medical schools participating in the MCAT Predictive Validity Study; and all 11,279 students who entered medical school in 1992 and took the USMLE Step 1 in June 1994. Criterion measures included each student's cumulative GPA in the first two years of medical school and his or her pass/fail status on Step 1. Differential predictive validity was examined by comparing prediction errors across racial/ethnic and sex groups. For cumulative GPA; residuals were compared, and for Step 1, classification errors were studied. RESULTS: The patterns of prediction errors observed across the groups indicated that, on average, (1) no difference between the sexes in prediction errors was evident; (2) performances of the three racial/ethnic minority groups tended to be overpredicted, with significant findings for Asians and Hispanics; and (3) Caucasians' performance tended to be underpredicted, although the magnitude of this underprediction was quite small. When USMLE Step 1 scores were the criterion for success in medical school, the majority of errors were overprediction errors. CONCLUSION: The authors caution that although MCAT scores, alone and in combination with undergraduate GPA, are good predictors of medical school performance, they are not perfect. The authors encourage future research exploring additional predictor variables, such as diligence, motivation, communication skills, study habits, and other relevant characteristics. Similarly, they indicate that high grades and Step 1 scores are not the only indicators of success in the medical profession and call for studies examining other important qualities, such as integrity, interpersonal skills, capacity for caring, willingness to commit to lifelong learning, and desire to serve in underserved areas.     

Is urine leukocyte esterase test a useful screening method to predict Chlamydia trachomatis infection in women?

We evaluated the use of the leukocyte esterase test (LET) on first-catch urine specimens from women as a screening test to predict infection with Chlamydia trachomatis. For diagnosis, we used Abbott's ligase chain reaction (LCR) on urine specimens and isolation by tissue culture (TC) on cervical brushes. Of 4,053 women attending sexually transmitted disease and family planning clinics, 4.3% (n = 174) were positive by TC and 5.9% (n = 239) were positive by LCR. When LET was compared to TC, the sensitivity, specificity, positive predictive value, and negative predictive value were 54.0, 67.0, 6.8, and 97.0%, respectively. The corresponding performance of LET versus LCR was 53.1, 67.3, 10.1, and 95.8%. Almost half of the laboratory-confirmed chlamydial infections were negative by LET. The low specificity probably reflects multiple causes of pyuria in women and results in a low positive predictive value. LET is neither sensitive nor specific as a predictor of chlamydial infection and cannot be recommended for use as a screening test for C. trachomatis with first-catch urine samples from females from low- or moderate-prevalence populations.     

Taking the low (stretch) road

Helicobacter pylori infection can be detected by several invasive tests based on gastroscopy and by noninvasive methods such as serologic assays. Noninvasive tests can be used not only in addition to invasive tests but also by themselves to screen for H. pylori infection in patients who are not in urgent need of endoscopy. Lately, rapid qualitative serologic tests have been developed. In the present study, the accuracy of a novel rapid whole-blood test, Pyloriset Screen, detecting immunoglobulin G (IgG) and IgA antibodies against H. pylori was evaluated. A total of 207 consecutive adult outpatients referred for upper endoscopy were enrolled. Gastric biopsy specimens were taken from the antrum and corpus for histologic examination and rapid urease testing. Cultures were available for 113 patients. Serum samples collected from all patients were tested for H. pylori antibodies by two enzyme immunoassays (EIAs) (Pyloriset EIA and an in-house EIA), a rapid latex agglutination test (Pyloriset Dry), and Pyloriset Screen. Patients were considered H. pylori positive if helicobacters were seen on histologic examination (77 patients) or, if in combination with histologically verified (although helicobacter-negative) gastritis, their IgG antibody titers were elevated in the two EIAs (five patients). The Pyloriset Screen test had a sensitivity of 95%, a specificity of 94%, a positive predictive value of 91%, and a negative predictive value of 97%. Among 63 patients under the age of 45 years, the Pyloriset Screen test did not miss a single H. pylori diagnosis, and only 1 patient had a false-positive result. Pyloriset Screen could be used reliably to screen for H. pylori infection.     

Evaluation on non invasive diagnostic tests for the second look in epithelial ovarian cancer

OBJECTIVE: To determine the usefulness of diagnostic tests performed before a second look laparotomy in patients with epithelial ovarian cancer. STUDY DESIGN: Thirty-three patients with epithelial ovarian cancer attended at Fundación Jiménez Díaz from 1984 to 1995 were studied. All patients initially underwent cyto-reducing surgery, followed by at least six platinum-based chemotherapy cycles. Prior to second look laparotomy all patients were evaluated by computerized tomography (CT) of the pelvis and abdomen, CA-125, pelvic-abdominal echography and gynecologic examination. To evaluate sensitivity, specificity, positive predictive value and negative predictive value for each test contingency tables were used. RESULTS: Eleven out of the 33 second look patients (33%) had histologic or cytologic evidence of disease. Six out of the eleven positive second look had a positive CT prior to second look (sensitivity of 55%). CT showed lack of disease in 21 out of the 22 negative second look cases (specificity 95%). Positive and negative predictive values of the test were 86% and 81%, respectively. Nine cases out of the 28 who had a CA-125 obtained had a positive second look. Four out of these nine patients had an increased CA-125 value (sensitivity 44%, specificity 95%, positive predictive value 80% and negative predictive value 78%). Sensitivity, specificity, positive predictive value and negative predictive value of physical examination and echography were 36%, 100%, 100%, 76% and 27%, 95%, 75%, 72%, respectively. On the other hand, sensitivity, specificity, positive predictive value and negative predictive value of all tests taken together were 64%, 91%, 78% and 83%, with a rate of false-negative results of 17% and a rate of false-positive results of 22%. CONCLUSION: Pelvic-abdominal computerized tomography, CA-125, pelvic-abdominal echography and gynecologic examination can be an alternative to second look laparotomy for the diagnosis of persistence or recurrence of the disease in patients with epithelial ovarian cancer.     

Assessment of corticosteroid-induced alkaline phosphatase isoenzyme as a screening test for hyperadrenocorticism in dogs

Quantitative determination of the corticosteroid-induced isoenzyme of alkaline phosphatase (CAP) was evaluated as a screening test for hyperadrenocorticism (HAC) in dogs. A series of 40 dogs with HAC (CAP range, 96 to 14,872 U/L), 30 clinically normal dogs (CAP range, 0 to 38 U/L), and 80 dogs with various diseases (non-HAC) and without history of exogenous glucocorticoid exposure for a minimum of 60 days (CAP range, 0 to 1163 U/L) were used to evaluate the test. Sensitivity and specificity of CAP was calculated at various cutoff points for absolute CAP activity and for CAP activity expressed as a percentage of total alkaline phosphatase activity. A cutoff point of 90 U/L was selected as optimal for use of this assay as a screening test for HAC. A prevalence survey then was done of all canine serum samples submitted to our diagnostic laboratory over a 3-month period, to calculate the predictive values of a positive and a negative test result in a clinical population and to determine the relative frequency and magnitude of CAP activity in dogs that had received glucocorticoids. The predictive values of a positive and a negative test result at the 90 U/L cutoff value were 21.43% (95% confidence limits, 8.3 to 40.95%) and 100% (95% confidence limit > 96%), respectively. It was concluded that CAP isoenzyme activity, determined by routine biochemical analysis by an automated levamisole-inhibition assay, could function as a screening test for HAC; however, the predictive value of a positive test result was too low to recommend the assay as a diagnostic test.(ABSTRACT TRUNCATED AT 250 WORDS)     

Opening up in the classroom: Effects of expressive writing on graduate school entrance exam performance.

Our study sought to determine whether experimental disclosure could improve exam performance and psychological health in students taking a graduate school entrance exam. Students preparing for the GRE, MCAT, LSAT, or PCAT were randomly assigned to write expressively about their upcoming exam or to a neutral writing condition. Participants completed measures of depressive symptoms and test anxiety before and after writing, and exam scores were collected. The experimental disclosure group had significantly higher test scores and significantly lower pre-exam depressive symptoms than the neutral writing group. Although benefits for depressive symptoms were found in expressive writers regardless of exam type, the advantage of expressive writing for test performance was only observed in students taking the MCAT or LSAT. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

MCAT is not required for in vitro polyketide synthesis in a minimal actinorhodin polyketide synthase from Streptomyces coelicolor

BACKGROUND: It has been proposed that Streptomyces malonyl CoA: holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. RESULTS: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar AC:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. CONCLUSIONS: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.     

Utility of the Bard BTA test in detecting upper urinary tract transitional cell carcinoma

OBJECTIVES: The Bard BTA test has been shown in early studies to be useful in diagnosing transitional cell carcinoma (TCC) of the bladder. However, the utility of this test has not been evaluated for TCC of the upper urinary tract. We therefore evaluated the clinical utility of the BTA test for upper urinary TCC. METHODS: We tested 71 specimens from the ureter and/or renal pelvis in 22 patients with a history or clinical suspicion for TCC and 9 patients with benign disorders. RESULTS: When compared to cytologic diagnoses, BTA had a sensitivity of 65%, a specificity of 40% (when correlated with clinical history), a false-positive rate of 33%, and a false-negative rate of 62%. The test had a positive predictive value of 83% and a negative predictive value of 32%. CONCLUSIONS: The BTA does not have any clinical value in detecting upper urinary tract TCC.     

Leptospirosis: an ignored cause of acute renal failure in Taiwan

Leptospirosis, caused by a spirochete, is the most common zoonosis in domestic or wild animals. Animals excrete infected urine in soil or water and may cause human infections through abrased wound, mucosa, conjunctiva, or by swallowing contaminated water. Clinical presentations of leptospirosis are mostly subclinical. Five to ten percent of leptospirosis are fatal, causing fever, hemorrhage, jaundice, and acute renal failure (Weil's syndrome). Leptospirosis has been ignored as a cause of acute renal failure in Taiwan. We report two patients with leptospirosis who presented with high fever, abdominal pain, jaundice, and acute renal failure. Patient 1 died on day 12 of admission of multiple organ failure associated with pancytopenia, hypogammaglobulinemia, and reactive hemophagocytosis. Leptospirosis was recognized after death. Patient 2 was admitted with similar presentations 2 weeks later. Penicillin and doxycycline were given early in the course, and azotemia, jaundice, respiratory failure, and aseptic meningitis gradually improved. Renal biopsy showed interstitial nephritis. Several tubular clearance tests showed proximal tubular defect with severe bicarbonate wasting (FeHCO3- 20.9%) and incomplete type II renal tubular acidosis without affecting the distal nephron. After 80 days of treatment, this patient was discharged with recovery of conscious level and renal function. This is the first leptospirosis patient with detailed tubular functional and morphological studies of the kidney. Diagnosis of leptospirosis was made by microscopic agglutination test (MAT) for antibody to leptospira and by polymerase chain reaction (PCR) for leptospira DNA in blood and urine (interrogans serogroup australis in case 1 and Leptospira borgpetersenii serogroup ballum in case 2). Because active surveillance has resulted in 13 cases diagnosed as leptospirosis islandwide thereafter, underestimation and ignorance of leptospirosis as a cause of acute renal failure may occur in Taiwan. Therefore, an area with a low leptospirosis incidence may actually have a very high incidence. Leptospirosis should be suspected in febrile patients with jaundice and renal failure when pathogens cannot be identified by traditional culture for microorganisms.     

Serial pulmonary function tests in the diagnosis of P. carinii pneumonia

The predictive value of serial versus isolated measurements of transfer factor for carbon monoxide (TLCO) in the diagnosis of pneumocystis carinii pneumonia (PCP) in a cohort of 474 HIV-1 seropositive patients, with all stages of HIV disease, was evaluated. Two groups of patients were studied, one group with serial lung function measurements (Group 1) and another with only a single set of measurements (Group 2). During the study period 118 patients performing serial tests developed a respiratory illness of which 58 were performing monthly and 60 three monthly measurements of lung function (Group 1). In 36 patients from Group 1, where PCP was diagnosed, monthly lung function tests showed a decrease in TLCO from 68% (+/- 3.2) (SEM), (8 weeks prior to illness), to 44% (+/- 2.5) predicted normal at presentation, whereas in 22 patients who did not have PCP, TLCO fell from 71% (+/- 4.5) to 57% (+/- 3.1). TLCO was thus reduced to lower values in these with PCP than in those without PCP (p < 0.05). A fall of TLCO of 5% from initial values when used as predictive for presence of PCP had a sensitivity of 75% and a specificty of 28% (positive predictive value 56%; negative predictive value 48%). TLCO was < 70% predicted in 72/78 patients with PCP who performed only single lung function tests (Group 2), which gave a sensitivity of 92% and a specificity of 71% as a diagnostic test for PCP when compared with the cohort as a whole. The positive predictive value was 34%, negative predictive value was 98%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies on the early serodiagnosis of leptospirosis by dot-ELISA

Thirty serum samples of patients with early leptospirosis from whom cultures of leptospira were positive were tested by dot-enzyme linked immunosorbent assay (dot-ELISA) and microscopical agglutination test (MAT). The results showed that the positive rate of dot-ELISA (40%) was higher than that of MAT (13.3%). One-hundred and ninety-eight serum samples from patients with clinical diagnosis of early leptospirosis were tested by dot-ELISA, MAT and blood culture. The results showed that the positive rate of dot-ELISA (64.6%) was higher than that of blood culture (15.2%) and MAT (14.1%). The longer the time of the illness, the lower the positive rate of the blood culture. However, the positive rate of dot-ELISA was stable in different stages of the illness.     

The evaluation of a dipstick test for Plasmodium falciparum in mining areas of Venezuela

A field trial comparing a dipstick test, an antigen-capture test detecting trophozoite-derived histidine-rich protein-II, and the quantitative buffer coat (QBC) (acridine orange staining technique) assay for the detection of Plasmodium falciparum was carried out on a population of 1,398 suspected malaria patients in gold mining areas of Venezuela. Sensitivity, specificity, and positive predictive values were higher for the dipstick test than for the acridine orange staining compared with the thick blood smear. The sensitivity for the dipstick method was 86.7% (95% confidence interval [CI] = 82-90%), the specificity was 99.3% (95% CI = 98.5-99.7%), and the positive predictive value was 97.1% (95% CI = 94-98%) as compared with the thick blood smear. The sensitivity for acridine orange staining was 82.2% (95% CI = 77-86%), the specificity was 98.5% (95% CI = 97.6-99.1%), and the positive predictive value was 94.1% (95% CI = 90-97%); with a P. falciparum asexual parasitemia higher than 21 parasites/microliter, the dipstick was 100% sensitive, when parasitemia was 10-20/microliter, sensitivity was 88%, and when parasitemia was less than 10/microliter, it was only 13.4%. The dipstick assay meets the criteria for an appropriate, rapid, and reliable test for the diagnosis of P. falciparum and has advantages over the acridine orange staining method. Nonetheless, its effectiveness seems limited in areas with low prevalence and among patients with low levels of parasitemia.     

Endogenous adenosine attenuates long-term depression and depotentiation in the CA1 region of the rat hippocampus

We describe a series of 144 cases of leptospirosis diagnosed in 1989 in New Caledonia. The incidence rate was 90 per 100,000 person-years, with a specific mortality rate of 4% patients. Those affected (100 males, 44 females) were mainly aged 20 to 40 years. Incidence in rural areas (112 per 100,000 person-years) was seven times higher than in urban settlements. Two periods with higher incidence were noticed corresponding to highest rainfall. Twenty-nine of the cases occurred in individuals with professions commonly associated with leptospirosis. Contacts with rats, dogs and ditch or river water were the most frequently mentioned. The clinical expression of the disease was polymorphic: 60% of the patients had mild symptoms, 40% were acute forms including Weil's disease. Of 57 hospitalized, 23% were admitted with an initial diagnosis of dengue, and 37% with leptospirosis. Main clinical syndromes were: icterus and/or renal syndrome in 50% of patients, cardiac syndrome in 65%, acute myalgies in 58% and pulmonary syndrome in 50%. Although hemorrhages were uncommon (17%), 40% of the cases demonstrated thrombocytopenia (< 50,000/m3). Pancreatic involvement with hyperamylasemia was evidenced in 50% of cases. Twelve serogroups of Leptospira were implicated, Icterohaemorragiae predominated (41%), but was not associated with severe forms. In New Caledonia, like in all tropics, leptospirosis must be considered as an environmental diseases, professional activities being just an additional risk factor. Use of serology as a reliable tool for confirmation of cases in areas of high environmental contamination is discussed.     

Anesthetic drug interactions. Quarterly update

The aim of this study was to compare the diagnostic accuracy of an optical immunoassay (STREP B OIA, Biostar) to direct plating and broth-enhanced culture for the detection of group B streptococcus (GBS) colonization of the lower genital tract in pregnant women. GBS cultures from the lower genital tract were obtained in a prospective fashion using a dual swab transport system from patients with risk factors for perinatal GBS infection. One swab was used to inoculate a trypticase soy agar plate with 5% sheep blood (TSA) and then placed in Lim broth. The other swab was used to perform the Strep B OIA. Growth of GBS by either direct plating or broth-enhanced culture was used as the gold standard for determining GBS colonization. Of the 524 women in the study, 90 women had positive cultures (either TSA or Lim broth). The sensitivity, specificity, positive predictive value, and negative predictive value of the Strep B OIA were 47% (42/90), 96% (416/434), 70% (42/60), 90% (416/464). The sensitivity, specificity, positive predictive value, and negative predictive value of the TSA were 61% (55/90), 100% (434/434), 100% (55/55), 93% (434/469). The sensitivity, specificity, positive predictive value, and negative predictive value of Lim broth were 97% (87/90), 100% (434/434), 100% (87/87), and 97% (434/437). The sensitivity of the Strep B OIA to detect light GBS colonization and heavy GBS colonization, as determined by the TSA, was 53% (19/36) and 90% (17/19), respectively. The Strep B OIA and direct agar plate culture appear to be of limited clinical value due to their poor sensitivities. This study also demonstrates the need to use a selective medium such as Lim broth when assessing for GBS colonization of the lower genital tract.     

Residents'' corner. Answer to case of the month #58. Megacystis-microcolon-intestinal hypoperistalsis syndrome

The aim of this study was to compare the predictive value of umbilical artery Doppler velocimetry in women in the supine position with that in women in the complete left lateral position as a screening test for abnormal obstetric outcomes. Umbilical artery resistance index (RI) was measured at 27-29 weeks and 35-37 weeks in 202 pregnant women. The measurements were performed with the mother in the supine position in 100 cases (supine group), and in the complete left lateral position in 102 cases (lateral group). Predictive values of the tests for abnormal outcomes (small for gestational age, fetal distress, pregnancy-induced hypertension) were compared between both groups. When abnormal RIs were defined as being greater than the 90th centile in the supine group, the sensitivities for any of the abnormal outcomes at 27-29 weeks were 18% in the supine group and 6% in the lateral group; the positive predictive values were 30% and 25%, respectively. For measurement at 35-37 weeks, the sensitivity and positive predictive value were 29% and 45%, respectively in the supine group, and 0% in both cases in the lateral group. When abnormal RIs were defined as being greater than the 90th centile in the lateral group, the sensitivities at 27-29 weeks were 41% in the supine group and 6% in the lateral group; the positive predictive values were 44% and 8%, respectively. At 35-37 weeks, the sensitivity and positive predictive value were 53% and 43% in the supine group, and 6% and 8% in the lateral group. Umbilical artery Doppler velocimetry when the mother was in the complete left lateral position was of little value as a screening test. However, when the mother is in the supine position, it may serve as a kind of stress test and disclose latent obstetric abnormalities in certain cases.