Mel L. Barclay

Gestational age assessment. I. analysis of individual clinical observations.

Accurate assessment of the estimated date of confinement is a cornerstone of obstetric care. Traditionally this date has been predicted from historical and clinical examinations; however, there have been few studies of the accuracy of such predictions. Multiple estimators of gestational age were examined in 418 patients who were delivered of infants weighting larger than or equal to 3,000 gm, following spontaneous onset of labor. Mean intervals from an event to delivery were calculated for last menstrual period (284.2 days), quickening (156.3 days), first audible fetal heart tones (136.2 days), uterine fundus at the umbilicus (140.8 days), and measurements of the fundal height. The variability in each of these estimators was examined and compared. The last menstrual period, if known with certainty, is the most accurate estimator, followed by the uterus at the umbilicus, first heard fetal heart tones, fundal height, and quickening.

A computer model of uterine contractions based on discrete contractile elements

Objective To predict uterine contraction waveforms using a microcomputer-based model of uterine activity based on discrete contractile elements, varying the shape of the model, total number of cells, and pacemaker locations. Methods The model is a hollow ovoid composed of discrete contractile elements (cells) that propagate electrical impulses, generate tension, and have defined contracting and refractory periods. Each cell contacts eight surrounding cells and propagates impulses iteratively from cell to cell. Contraction pressure is the sum of the tension contributions by contracting cells. Sample contraction waveforms were generated based on various numbers of cells organized in ovoids with long:short axis ratios of 1:1, 3:2, and 2:1, with one or two pacemakers at varying positions. Results Contraction waveforms are altered by altering the shape of the matrix, but not by increasing the number of contractile elements. The vertical placement of the pacemaker has a dramatic effect on the shape and symmetry of contractions, including the development of patterns characteristic of “dysfunctional” uterine contractions. Conclusion Abnormal uterine contraction patterns may result from pacemaker activity in unusual locations, such as mid-uterus. Further refinement of this computer model of uterine activity may contribute to a better understanding of the genesis of normal and abnormal intrauterine pressure waveforms and their relationship to the progress of labor.

Gestational age assessment: II. Prediction from combined clinical observations

Accurate assessment of the estimated date of confinement is a cornerstone of obstetric care. In an earlier report, we examined the time of occurrence of various historical and clinical estimators of gestational age in relation to the date of delivery. We now examine the possibility of combining multiple clinical estimators to improve the prediction of delivery date. Formulas for predicting delivery date from multiple clinical estimators were developed in a group of 418 patients who were delivered of infants weighing greater than or equal to 3,000 gm, after spontaneous onset of labor. These formulas were tested in a separate group of 107 patients who fulfilled similar criteria. In patients with a known last menstrual period, additional clinical information did not improve the prediction of delivery date; however, if the last menstrual period was uncertain or unknown, averaging the predicted delivery dates by several clinical examinations provided a prediction of delivery date as precise as if the last menstrual period were known.

Emergent behaviors in a deterministic model of the human uterus.

The human birth process is powered by uterine contractions that have observable patterns that depend on the physiology of muscular activity. We explored a previously designed model1 simulating the uterus to assess global contractile patterns. The model is a cellular automaton that simulates the complexities of uterine activity from a few simple rules of cellular interaction and uterine geometry. Multiple experiments using the cellular automaton involved different uterine shapes, cell numbers, and initial distributions of active and resting cells. Results demonstrate complex contraction patterns similar to those observed in human labor. At least 2 modes of behavior appear in the simulations, one consistent with effective labor and one not. Experiments with cellular automata provide insights into stereotypic and disordered labor patterns that produce patient discomfort without progress in labor. We hypothesize that complex uterine contraction patterns may have other roles in the preparation for labor and birth.

Effect of search experience on sustained MEDLINE usage by students

PURPOSE. While educators agree that medical students should learn to use MEDLINE for clinical application, there is a lack of consensus on an optimal level of exposure to this resource during training that will result in sustained usage. This study sought to identify the level of search experience (1) to increase the odds that the student searcher will continue to search MEDLINE in the absence of search assignments, and (2) to make an appreciable difference in the odds of retrieving items of relevance from the MEDLINE database. METHOD. Search frequencies of MEDLINE via the PaperChase interface by 184 fourth-year students (class of 1992) at the University of Michigan Medical School were analyzed using the log cross-product technique. The students were required to take the Comprehensive Clinical Assessment, an examination that included a search assignment, as they entered their fourth year of medical school. Their levels of MEDLINE use and their retrieval performances before the examination were compared with those achieved during the subsequent five months as fourth-year medical students. RESULTS. For those who searched an average of at least once a month during their first three years of medical school, there was a 7.38:1 chance that they would conduct three searches per month in the fourth year, compared with those who searched less frequently. The odds of retrieving at least one item of definite relevance were 8.27:1 for those who had searched at least one and one-half times per month before the search assignment. CONCLUSION. Searching once a month through the first few years of medical school provided an experience level that improved the odds that a student would continue to search MEDLINE. Data indicated that a history of a minimum of 1.5 online sessions per month increased the odds of retrieving relevant items to 8.27:1. Implications for educational strategy are clear.

Wave-form analysis of intrauterine pressure curves with methods and models developed in cardiac research

With the Hill model of muscle dynamics and a modified cardiac model, a series of computer programs have been generated which permit the description of certain aspects of uterine contractility and uterine function in human parturition. Patterns of labor relating to delivery outcome, dysfunctional uterine activity, and use of drugs are discussed with reference to the parameters measured in the study. Central tendencies among 70 spontaneous and induced labors (6,302 contractions) are presented and discussed. (Am. J. Obstet. Gynecol.

Using standardized patients to ensure that clinical learning objectives for the breast examination are met

No abstract available.

Performance on the radiology component of a critical clinical skills examination

RATIONALE AND OBJECTIVES Clinical competence certification is now required in some specialties in medicine. A Comprehensive Clinical Assessment (CCA) was created to test mastery of critical skills by students at the end of the 3rd year of medical school. METHODS The CCA is a series of stations that test skills the faculty consider important for all medical students (eg, breast examination, electrocardiogram reading, chest pain assessment, ophthalmology photographs). The radiology station was designed to evaluate imaging skills believed to be taught and learned in the core 3rd-year rotations. RESULTS External measures (National Board Examinations, grade point average, and overall score) of clinical performance of the 608 medical students who completed the CCA examination between 1991 and 1993 were found to be correlated with the radiology station scores. CONCLUSION The radiology station in the CCA examination is a reproducible measure of clinical performance.

A Computer Conference Format for Teaching Medical Ethics.

No abstract available.

The integration of computer conferencing into the medical school curriculum.

A computer conference was developed for use with students, faculty, and staff at a large state-funded medical school. The conference was intended to increase communication among these groups which study, work, and train at a variety of locations across the state. To date, 583 participants (91% are students, 6% are faculty, and 2% are staff) have discussed a variety of academic, ethical, social, and administrative issues. Conference use is required during the obstetrics-gynecology third year clerkship, and has also been used to evaluate courses and critique course examinations. The procedures for creating a computer conference, implementing its use in the curriculum, and evaluating its effectiveness are discussed.