men aged 35-54 with microhaematuria had no disease, decreasing to 26% between 55 and 74 years and to 5% in patients over 75.' Only 1% of the patients had neoplastic disease, and bladder cancer was found in only three patients (0-5%), all of whom were older than 75. Awareness is growing of IgA nephropathy and thin basement membrane nephropathy as common causes of microhaematuria," and benign renal microhaematuria with normal renal tissue may also be more common than previously realised. 6 Schramek et al suggested that determining the origin of the haematuria by phase contrast microscopy of the urinary sediment could be an important initial step in evaluating asymptomatic microhaematuria: dvsmorphic erythrocytes indicate a renal origin, whereas isomorphic cells (with smooth membranes) suggest a postrenal bleeding source such as bladder tumours.' Initial data support their claim that only non-dysmorphic microhaematuria need be investigated to detect bladder cancer. Thus time consuming, expensive, and invasive diagnostic procedures can be avoided in many patients by using this simple test. Other tests have also been reported to be able to determine the origin of haematuria. A SCHATTNER
Kaplan Hospital, Rehovot 76100, Israel I Plail R. Detecting bladder cancer. BMf
1990;301:567-8.
(22 September.) 2 Froom P, Ribak J, Benbassat J. Significance of microhaematuria in young adults. BM] 1984;288:20-2. 3 Mohr DN, Offord KP, Owen RA, Melton JL III. Asymptomatic microhaematuria and urologic disease: a population-based study. jAMA 1986;256:224-9. 4 Julian BA, Waldo FB, Rifai A, Mestecky J. IgA nephropathy, the most common glomerulonephritis worldwide. Am J Med 1988;84: 129-32. 5 l'iebosch ATA1G, Frederik PMN, Van Breda Vriesman PJC, et al. T'hin-basement-membrane nephropathy in adults with persistent haematuria. N Englj Med 1989;320:14-8. 6 Schramek P, Schuster FX, Georgopoulos M, Porpaczy P, Maier Al. Valuc of urinary erythrocyte morphology in assessment of symptomless microhaematuria. Lancet 1989;ii: 1316-9. 7 Shichiri M, Hosoda K, Nishio Y, et al. Red-cell-volume distribution curves in diagnosis of glomerular and non-glomerular haematuria. Lancet 1988;i:908-1 1.
Potassium and magnesium in essential hypertension SIR,-We agree with Drs Chris O'Callaghan and Laurence Howes' that potassium supplementation in our study' might have reversed the possible hvperglvcaemia and insulin resistance due to previous thiazide treatment. A complete multivariate analysis of the results, however, did not show any greater decrease in cholesterol concentrations in subjects receiving placebo in the early phase, hence we do not believe that there was a waning effect of thiazides on insulin resistance. Though glucose intolerance is a known phenomenon with thiazides, several reports have indicated that patients with high blood pressure are relatively glucose intolerant compared with normotensive patients." Several groups have shown that untreated patients with high blood pressure are also hyperinsulinaemic compared with normotensive patients." Thus it seems reasonable to conclude that resistance to insulin could be a characteristic of a certain proportion of patients with hypertension and that these abnormalities of glucose and insulin metabolism do not necessarily improve when hypertension is controlled by antihypertensive drugs.7 The potential role of potassium as a powerful determinant of cardiovascular morbidity and mortality is being extensively examined.' Potassium supplementation has been shown to prevent development of renal vascular lesions and decrease the rate of cerebral haemorrhage in rats,' and the protective effect of potassium on the vascular
BMJ VOLUME 301
1 DECEMBER 1990
sequelae of hypertension is greater than could be predicted by the reduction in blood pressure alone. Part of the effect could be due to potassium's hypocholesterolaemic effect. P S PATKI S G GOKHALE JAGMEET SINGH D S SHROTRI Bvramjee Jeejeebhoy Medical College and Sassoon General Hospitals, Pune-41 1007, India BHUSHAN PATWARDHAN Interdisciplinary School of Avurvedic Medicine, University of Poona, Pune-411 007, India 1 O'Callaghan C, Howes L. Potassium and magnesium in essential hypertension. BMJ 1990;301:1164. (17 November.) 2 Patki PS, Singh J, Golchale SV, Bulalch PM, Shrotri DS, Patwardhan B. Efficacy of potassium and magnesium in essential hypertension: a double blind, placebo controlled, crossover study. BMJ 1990;301:521-3. (15 September.) 3 Jarrett RJ, Keen H, McCartney M, et al. Glucose tolerance and blood pressure in two population samples: their relation to diabetes mellitus and hypertension. Int J Epidemiol 1978;7: 15-24. 4 Florey CduV, Uppal S, Lowy C. Relationship between blood pressure, weight, and plasma sugar levels in school children aged 9-12 years in Westland, Holland. BMJ 1976;i: 1368-71. 5 Lucas LP, Estigarribia JA, Darga LL, Reaven GM. Insulin and blood pressure in obesity. Hypertension 1985;7:702-6. 6 Modan M, Halkin H, Almog S, et al. Hyperinsulinemia: a link between hypertension, obesity and glucose intolerance. J Clin Invest 1985;75:809-17. 7 Shen DC, Sheih SM, Fuh M, Chen Y-D, Reaven GM. Resistance to insulin-stimulated glucose uptake in patients with hypertension. J Clin EndocrinolMetab 1988;66:580-3. 8 Packer M. Potential role of potassium as a determinant of morbidity and mortality in patients with systemic hypertension and congestive heart failure. Amj Cardiol 1990;65:45-5 IE. 9 Tobin L, Lange J, Ulm K, Wold L, Iwai J. Potassium reduces cerebral haemorrhage and death rate in hypertensive rats, evett when blood pressure is not lowered. Hypertension 1985;7(suppl 1): 1 10-4.
New agenda for general practice computing SIR,-I was encouraged and reassured by Dr Mike Pringle's editorial. ' Although, understandably, general practice systems were initially developed around labour saving facilities such as repeat prescribing and prevention recalls, this has not been the ideal background for the evolution of these systems. Clearly, the patient clinical record is most important in any general practice system as it enables the record content to be used to identify individual and groups of patients, perform audit, run repeat prescribing, and, indeed, begin to examine quality as well as quantity of care. Any clinically oriented system set up to help in patient management will always have the potential to examine aspects of both quantitative and qualitative care. The data record must remain flexible in terms of both content and method of input into the database. As Dr Pringle rightly points out conditions change rapidly in medicine, and it is important that users do not have recourse to support teams (who in our experience are often poor) or programmers who may not appreciate the need for continuing change. Evolving Hypertext systems may well provide one solution to the flexible data record problem as data transactions can be defined in many ways-structured form, blank page, table, or picture. Although producing offthe shelf general practice systems makes commercial sense, it is short sighted clinically. Each practice should expect to have its own unique system that contains the data and facilities appropriate to the staff of that practice. Inevitably there will be a core data set with core functions and facilities that will be common to most systems, permitting direct comparisons to be made. Introducing new ideas and concepts in relation to computer systems within the health service is far
from easy. Experience suggests that most users with little knowledge of the subject have tended to "stay with the pack" rather than look at more innovative (but more risky) systems. As the knowledge base increases within the profession this is likely to change. If the potential for improving patient care is to be exploited it is imperative that those at the leading edge of the computer technologies liaise closely not only with practitioners with an interest in computers but with groups, university and otherwise, with experience in developing clinically oriented systems within the health sector. MICHAEL WALKER University Computing Service (Medical Unit), Ninewells Hospital and Medical School, Dundee DD2 l UB 1 Pringle M. The new agenda for general practice computing. BMJ 1990;301:827-8. (13 October.)
Tubal pregnancy SIR, -Our findings support Professor James Owen Drife's statement that tests for human chorionic gonadotrophin in urine can exclude ectopic pregnancy in women with lower abdominal pain. ' Over the past nine months we have used the Tandem Icon II immunoenzymetric assay (Hybritech, San Diego, California) to detect urinary human chorionic gonadotrophin in women with abdominal pain suggestive of unruptured ectopic pregnancy. This semiquantitative assay, which can detect human chorionic gonadotrophin at concentrations as low as 2000 mIU/l, can be done at the bedside by the doctor admitting the patient to hospital and takes less than five minutes. During the study we estimated chorionic gonadotrophin concentrations in 350 women. Of these, 142 had a positive test result, 48 of whom were found to have an ectopic pregnancy at laparoscopy. The other 94 women in whom the test was positive were subsequently found to have threatened, complete, or incomplete abortions on ultrasonography. None of the 208 women who had a negative test result had an ectopic pregnancy. These results show that in diagnosing stable ectopic pregnancy a positive urine human chorionic gonadotrophin test result has a sensitivity of 100%, a specificity of 69%, a negative predictive value of. 100%, and positive predictive value of 34%. Similar results have been reported for estimation of serum chorionic gonadotrophin concentrations with the Tandem Icon assay.2 Thus the diagnosis of ectopic pregnancy can be excluded in a woman with abdominal pain if the Tandem Icon II human chorionic gonadotrophin assay produces a negative result, obviating the need for emergency diagnostic laparoscopy. When this assay is combined with ultrasonography, the need for laparoscopy is reduced further. Each assay costs approximately 65p and does not require a laboratory technician. We conclude that this is a highly cost effective screening test for women in whom an ectopic pregnancy is suspected. PAUL BYRNE ONOME OGUEH TOCHUKWU ONYEKWULUJE
Walsgrave Hospital,
Coventry CV2 2DX 1 Drife JO. Tubal (10 November.)
pregnancy.
BMJ7
1990;301:1057-8.
2 Byrne P, Ashley E, Bates G, et al. The value of ultrasound and non-quantitative hCG estimation in the diagnosis of ectopic pregnancy. Lancet 1989;i:386-7.
SIR, -We support the concept of more conservative treatment of tubal pregnancy as proposed by Professor James Owen Drife.' He mentioned local injection of methotrexate for unruptured tubal pregnancy, but there is also evidence that local
1279
Kaplan Hospital, Rehovot 76100, Israel I Plail R. Detecting bladder cancer. BMf
1990;301:567-8.
(22 September.) 2 Froom P, Ribak J, Benbassat J. Significance of microhaematuria in young adults. BM] 1984;288:20-2. 3 Mohr DN, Offord KP, Owen RA, Melton JL III. Asymptomatic microhaematuria and urologic disease: a population-based study. jAMA 1986;256:224-9. 4 Julian BA, Waldo FB, Rifai A, Mestecky J. IgA nephropathy, the most common glomerulonephritis worldwide. Am J Med 1988;84: 129-32. 5 l'iebosch ATA1G, Frederik PMN, Van Breda Vriesman PJC, et al. T'hin-basement-membrane nephropathy in adults with persistent haematuria. N Englj Med 1989;320:14-8. 6 Schramek P, Schuster FX, Georgopoulos M, Porpaczy P, Maier Al. Valuc of urinary erythrocyte morphology in assessment of symptomless microhaematuria. Lancet 1989;ii: 1316-9. 7 Shichiri M, Hosoda K, Nishio Y, et al. Red-cell-volume distribution curves in diagnosis of glomerular and non-glomerular haematuria. Lancet 1988;i:908-1 1.
Potassium and magnesium in essential hypertension SIR,-We agree with Drs Chris O'Callaghan and Laurence Howes' that potassium supplementation in our study' might have reversed the possible hvperglvcaemia and insulin resistance due to previous thiazide treatment. A complete multivariate analysis of the results, however, did not show any greater decrease in cholesterol concentrations in subjects receiving placebo in the early phase, hence we do not believe that there was a waning effect of thiazides on insulin resistance. Though glucose intolerance is a known phenomenon with thiazides, several reports have indicated that patients with high blood pressure are relatively glucose intolerant compared with normotensive patients." Several groups have shown that untreated patients with high blood pressure are also hyperinsulinaemic compared with normotensive patients." Thus it seems reasonable to conclude that resistance to insulin could be a characteristic of a certain proportion of patients with hypertension and that these abnormalities of glucose and insulin metabolism do not necessarily improve when hypertension is controlled by antihypertensive drugs.7 The potential role of potassium as a powerful determinant of cardiovascular morbidity and mortality is being extensively examined.' Potassium supplementation has been shown to prevent development of renal vascular lesions and decrease the rate of cerebral haemorrhage in rats,' and the protective effect of potassium on the vascular
BMJ VOLUME 301
1 DECEMBER 1990
sequelae of hypertension is greater than could be predicted by the reduction in blood pressure alone. Part of the effect could be due to potassium's hypocholesterolaemic effect. P S PATKI S G GOKHALE JAGMEET SINGH D S SHROTRI Bvramjee Jeejeebhoy Medical College and Sassoon General Hospitals, Pune-41 1007, India BHUSHAN PATWARDHAN Interdisciplinary School of Avurvedic Medicine, University of Poona, Pune-411 007, India 1 O'Callaghan C, Howes L. Potassium and magnesium in essential hypertension. BMJ 1990;301:1164. (17 November.) 2 Patki PS, Singh J, Golchale SV, Bulalch PM, Shrotri DS, Patwardhan B. Efficacy of potassium and magnesium in essential hypertension: a double blind, placebo controlled, crossover study. BMJ 1990;301:521-3. (15 September.) 3 Jarrett RJ, Keen H, McCartney M, et al. Glucose tolerance and blood pressure in two population samples: their relation to diabetes mellitus and hypertension. Int J Epidemiol 1978;7: 15-24. 4 Florey CduV, Uppal S, Lowy C. Relationship between blood pressure, weight, and plasma sugar levels in school children aged 9-12 years in Westland, Holland. BMJ 1976;i: 1368-71. 5 Lucas LP, Estigarribia JA, Darga LL, Reaven GM. Insulin and blood pressure in obesity. Hypertension 1985;7:702-6. 6 Modan M, Halkin H, Almog S, et al. Hyperinsulinemia: a link between hypertension, obesity and glucose intolerance. J Clin Invest 1985;75:809-17. 7 Shen DC, Sheih SM, Fuh M, Chen Y-D, Reaven GM. Resistance to insulin-stimulated glucose uptake in patients with hypertension. J Clin EndocrinolMetab 1988;66:580-3. 8 Packer M. Potential role of potassium as a determinant of morbidity and mortality in patients with systemic hypertension and congestive heart failure. Amj Cardiol 1990;65:45-5 IE. 9 Tobin L, Lange J, Ulm K, Wold L, Iwai J. Potassium reduces cerebral haemorrhage and death rate in hypertensive rats, evett when blood pressure is not lowered. Hypertension 1985;7(suppl 1): 1 10-4.
New agenda for general practice computing SIR,-I was encouraged and reassured by Dr Mike Pringle's editorial. ' Although, understandably, general practice systems were initially developed around labour saving facilities such as repeat prescribing and prevention recalls, this has not been the ideal background for the evolution of these systems. Clearly, the patient clinical record is most important in any general practice system as it enables the record content to be used to identify individual and groups of patients, perform audit, run repeat prescribing, and, indeed, begin to examine quality as well as quantity of care. Any clinically oriented system set up to help in patient management will always have the potential to examine aspects of both quantitative and qualitative care. The data record must remain flexible in terms of both content and method of input into the database. As Dr Pringle rightly points out conditions change rapidly in medicine, and it is important that users do not have recourse to support teams (who in our experience are often poor) or programmers who may not appreciate the need for continuing change. Evolving Hypertext systems may well provide one solution to the flexible data record problem as data transactions can be defined in many ways-structured form, blank page, table, or picture. Although producing offthe shelf general practice systems makes commercial sense, it is short sighted clinically. Each practice should expect to have its own unique system that contains the data and facilities appropriate to the staff of that practice. Inevitably there will be a core data set with core functions and facilities that will be common to most systems, permitting direct comparisons to be made. Introducing new ideas and concepts in relation to computer systems within the health service is far
from easy. Experience suggests that most users with little knowledge of the subject have tended to "stay with the pack" rather than look at more innovative (but more risky) systems. As the knowledge base increases within the profession this is likely to change. If the potential for improving patient care is to be exploited it is imperative that those at the leading edge of the computer technologies liaise closely not only with practitioners with an interest in computers but with groups, university and otherwise, with experience in developing clinically oriented systems within the health sector. MICHAEL WALKER University Computing Service (Medical Unit), Ninewells Hospital and Medical School, Dundee DD2 l UB 1 Pringle M. The new agenda for general practice computing. BMJ 1990;301:827-8. (13 October.)
Tubal pregnancy SIR, -Our findings support Professor James Owen Drife's statement that tests for human chorionic gonadotrophin in urine can exclude ectopic pregnancy in women with lower abdominal pain. ' Over the past nine months we have used the Tandem Icon II immunoenzymetric assay (Hybritech, San Diego, California) to detect urinary human chorionic gonadotrophin in women with abdominal pain suggestive of unruptured ectopic pregnancy. This semiquantitative assay, which can detect human chorionic gonadotrophin at concentrations as low as 2000 mIU/l, can be done at the bedside by the doctor admitting the patient to hospital and takes less than five minutes. During the study we estimated chorionic gonadotrophin concentrations in 350 women. Of these, 142 had a positive test result, 48 of whom were found to have an ectopic pregnancy at laparoscopy. The other 94 women in whom the test was positive were subsequently found to have threatened, complete, or incomplete abortions on ultrasonography. None of the 208 women who had a negative test result had an ectopic pregnancy. These results show that in diagnosing stable ectopic pregnancy a positive urine human chorionic gonadotrophin test result has a sensitivity of 100%, a specificity of 69%, a negative predictive value of. 100%, and positive predictive value of 34%. Similar results have been reported for estimation of serum chorionic gonadotrophin concentrations with the Tandem Icon assay.2 Thus the diagnosis of ectopic pregnancy can be excluded in a woman with abdominal pain if the Tandem Icon II human chorionic gonadotrophin assay produces a negative result, obviating the need for emergency diagnostic laparoscopy. When this assay is combined with ultrasonography, the need for laparoscopy is reduced further. Each assay costs approximately 65p and does not require a laboratory technician. We conclude that this is a highly cost effective screening test for women in whom an ectopic pregnancy is suspected. PAUL BYRNE ONOME OGUEH TOCHUKWU ONYEKWULUJE
Walsgrave Hospital,
Coventry CV2 2DX 1 Drife JO. Tubal (10 November.)
pregnancy.
BMJ7
1990;301:1057-8.
2 Byrne P, Ashley E, Bates G, et al. The value of ultrasound and non-quantitative hCG estimation in the diagnosis of ectopic pregnancy. Lancet 1989;i:386-7.
SIR, -We support the concept of more conservative treatment of tubal pregnancy as proposed by Professor James Owen Drife.' He mentioned local injection of methotrexate for unruptured tubal pregnancy, but there is also evidence that local
1279
