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Assessment of menstrual blood loss in women referred for endometrial ablation
European Journal of Obstetrics & Gynecology and Reproductive Biology 57 (1994) 179-180
Assessment of menstrual blood loss in women referred for endometrial ablation M. Deeny*, J.A. Davis Stobhill Hospital NHS Trust, Glasgow G21 3UW. Scotland,
UK
Accepted 5 September 1994
Abstract
We measured menstrual blood loss in 54 women preferred for endometrial ablation on account of dysfunctional uterine bleeding. Patients’subjective assessmentof blood loss was assessed by visual analogue scores and by pictorial blood loss assessment charts. The former were not related to measured blood loss but the charts were a useful test for menorrhagia, with 88% sensitivity, 52% specificity and a false positive rate of 99%. Keywork
Endometrial ablation; Assessment; Menstrual loss
1. Introduction
Assessment of blood loss in women complaining of heavy periods usually relies on self-reporting of symptoms. The haemoglobin elution method of Hallberg and Nilsson [1] allows objective assessment of menstrual blood loss, but this is a cumbersome procedure. Higham et al. [2] have developed a pictorial calendar chart for recording menstrual loss, and validated this against the haemoglobin elution method. We report our experience of assessing menstrual loss in women referred for endometrial ablation using objective and subjective assessments. 2. Subjects and metbuds Fifty-three patients aged 30-52 years were studied. They were referred for endometrial ablation on account of dysfunctional uterine bleeding. Menstrual blood loss assessment was undertaken at least 2 months after stopping any therapy for menorrhagia, and prior to endometrial sampling. Objective assessment of menstrual blood loss (MBL) was performed according to the alkaline haematin method of Hallberg and Nilsson [I]. The women used their customary (uncoloured) sanitary material. Visual analogue scores (VAS) were obtained at the * Corresponding author. 002%2243/94/$07.00 0 1994 Elsevier SSDI 0028-2243(94)01967-C
initial clinic visit by asking the patient to score a IO-cm line to demonstrate how much trouble her periods caused her. Pictorial blood loss assessment charts (PBAC) as developed by Higham et al. [2] were kept by the patient during the cycle in which MBL was measured. The PBAC is a pictorial representation of blood loss, from which a numerical score is derived. For each subject, age, parity, height and weight were noted. Body mass index (BMI) was derived from the formula: mass (kg)/height2 (m). 3. Statistical analysis Median values and ranges were calculated for each of the variables age, parity, VAS, PBAC, MBL, BMI. Multiple regression analysis was performed with MEL by alkaline haematin method as the dependent variable. A receiver-operator characteristic (ROC) curve (Fig. 1) was plotted to demonstrate the accuracy of PBAC as a test for menorrhagia [3]. An ROC curve describes the diagnostic accuracy of a test [3,4]. It plots sensitivity against false positive rate. A test with no discriminatory power will have a straight line ROC curve as shown by the dotted line in Fig. 1. A test with good discriminatory power will give a high level of sensitivity at the expense of a small increase in the false positive rate, as shown by the thin line in Fig. 1.
Science Ireland Ltd. All rights reserved
180
M. Deeny, J. A. Davis / Eur. J. Obster. Gynerol.
Reprod.
Biol. 57 (1994)
179-180
100
sensitivity
1F .,’ .,,’ ,,,.
,,,’
,’
,I,’
04,’ I
0 -
20
40
60
80
100
false positive rate ROC curve no discriminatory power
~
good discriminatory power
Fig. I. ROC curve of PBAC taking MBL of 80 ml as true disease
4. Results
The age range of the patients was 30-52 years, with a median of 41 years. The median parity was 2, with a range of O-6. The median BMI was 26, with a range of 19-42.5. The group therefore tended to be overweight, with several patients in the grossly obese category (BMI greater than 30). The median VAS was 78 mm, with a range of 45-98 mm. The median PBAC score was 156, with a range of 30-714. The median menstrual blood loss was 73 ml, with range of lo-304 ml. Of the women, 47% had had MBL greater than 80 ml, which is objectively defined menorrhagia. This is a somewhat higher figure than is generally quoted for a group of women complaining of menorrhagia, and may reflect that this group consisted of women selected for surgery. The P values for multiple regression analysis on MBL were: age, 0.151; parity, 0.789; VAS, 0.724; PBAC, 0.001; BMI, 0.968. Thus, MBL was closely related to PBAC (P = 0.001). The visual analogue score did not appear to be related to MBL (P = 0.724). Obesity did not appear to be related to MBL (P = 0.968). However, obesity was a factor in the referral of some of these women for endometrial ablation as an alternative to hysterectomy for their complaint of heavy periods. Using a cut-off point of 100 (as used by Higham et al. [2]) to predict menstrual blood loss in excess of 80 ml, PBAC had a sensitivity of 88% and a specificity of 52%. The false positive rate was 59%.
blems [5]. It is possible that the advent of endoscopic surgery will broaden the indications for surgery for menorrhagia, and Coulter [6] advises that the profession should practise audit in this field. In this series we demonstrated that 47% of the women experienced excessive menstrual loss as defined by Hallberg and Nilsson [l]. They had a functional abnormality, despite the absence of any endometrial disease, endometrial polyps, or intracavitary or submucous libroids. We found PBAC to be a useful test for menorrhagia, although less specific than Higham et al. found it to be [2]. This may reflect our investigation of 53 individual women, rather than their report of 55 cycles in 30 women, which may have introduced bias in the comparison of PBAC to MBL. It is also possible that our less rigorous control of the sanitary material used contributed to our different lindings. In the original study, Higham and her colleagues used a specific brand and absorbency of sanitary towel and tampon, which were supplied to the subjects for their menstrual collections. In most clinical situations, the gynaecologist will not have the resources to supply sanitary material to women for the measurement of PBAC, so we felt it was worthwhile evaluating the technique in the more common clinical situation where the woman will be using the sanitary material she has purchased herself. In this latter situation, we have shown that PBAC does provide a sensitivity of 88% and a specificity of 52% in predicting menstrual loss in excess of 80 ml. However, the plotting of the ROC curve indicates that PBAC has only intermediate discriminatory power in detecting excessive menstrual loss. Chard and Lilford [4] recommend the plotting of an ROC curve to demonstrate the discriminatory power of a test, rather than merely quoting specificity, sensitivity, false positive and false negative rates. Our data endorse the use of PBAC in assessing menstrual blood loss in women complaining of heavy periods, but we would recommend the retention of the alkaline haematin method as the ‘gold standard’. References ill 121 [31 141
5. Discussion The objective assessment of menorrhagia remains a challenge. Menstrual disorders are a common cause of referral for specialist opinion. A considerable surgical workload is generated in consequence of menstrual pro-
[51
Hallberg L, Nilsson L. Determination of menstrual blood loss. Stand J Clin Lab Inv 1964; 16: 244-248. Higham JM, O’Brien PMS, Shaw RW. Assessment of menstrual blood loss using a pictorial chart. Br J Obstet Gynaecol 1990; 9-l: 734-139. Swets JA. Measuring the accuracy of diagnostic systems. Science 1988; 2401 1285-1293. Chard T, Lilford RJ. How useful is a test? In: JWW Studd. ed. Progress in obstetrics and gynaecology, vol. 9. Edinburgh: Churchill Livingstone, 1991.
Coulter A, Bradlow J, Agass M, Martin-Bates C, Tulloch A. Outcomes of referrals to gynaecology outpatient clinics for menstrual problems: an audit of general practice records. Br J Obstet Gynaecol 1991; 98: 789-796. with endometrial resection. 161 Coulter A. Managing menorrhagia Lancet 1993: 341: 1185-l 186.
Assessment of menstrual blood loss in women referred for endometrial ablation M. Deeny*, J.A. Davis Stobhill Hospital NHS Trust, Glasgow G21 3UW. Scotland,
UK
Accepted 5 September 1994
Abstract
We measured menstrual blood loss in 54 women preferred for endometrial ablation on account of dysfunctional uterine bleeding. Patients’subjective assessmentof blood loss was assessed by visual analogue scores and by pictorial blood loss assessment charts. The former were not related to measured blood loss but the charts were a useful test for menorrhagia, with 88% sensitivity, 52% specificity and a false positive rate of 99%. Keywork
Endometrial ablation; Assessment; Menstrual loss
1. Introduction
Assessment of blood loss in women complaining of heavy periods usually relies on self-reporting of symptoms. The haemoglobin elution method of Hallberg and Nilsson [1] allows objective assessment of menstrual blood loss, but this is a cumbersome procedure. Higham et al. [2] have developed a pictorial calendar chart for recording menstrual loss, and validated this against the haemoglobin elution method. We report our experience of assessing menstrual loss in women referred for endometrial ablation using objective and subjective assessments. 2. Subjects and metbuds Fifty-three patients aged 30-52 years were studied. They were referred for endometrial ablation on account of dysfunctional uterine bleeding. Menstrual blood loss assessment was undertaken at least 2 months after stopping any therapy for menorrhagia, and prior to endometrial sampling. Objective assessment of menstrual blood loss (MBL) was performed according to the alkaline haematin method of Hallberg and Nilsson [I]. The women used their customary (uncoloured) sanitary material. Visual analogue scores (VAS) were obtained at the * Corresponding author. 002%2243/94/$07.00 0 1994 Elsevier SSDI 0028-2243(94)01967-C
initial clinic visit by asking the patient to score a IO-cm line to demonstrate how much trouble her periods caused her. Pictorial blood loss assessment charts (PBAC) as developed by Higham et al. [2] were kept by the patient during the cycle in which MBL was measured. The PBAC is a pictorial representation of blood loss, from which a numerical score is derived. For each subject, age, parity, height and weight were noted. Body mass index (BMI) was derived from the formula: mass (kg)/height2 (m). 3. Statistical analysis Median values and ranges were calculated for each of the variables age, parity, VAS, PBAC, MBL, BMI. Multiple regression analysis was performed with MEL by alkaline haematin method as the dependent variable. A receiver-operator characteristic (ROC) curve (Fig. 1) was plotted to demonstrate the accuracy of PBAC as a test for menorrhagia [3]. An ROC curve describes the diagnostic accuracy of a test [3,4]. It plots sensitivity against false positive rate. A test with no discriminatory power will have a straight line ROC curve as shown by the dotted line in Fig. 1. A test with good discriminatory power will give a high level of sensitivity at the expense of a small increase in the false positive rate, as shown by the thin line in Fig. 1.
Science Ireland Ltd. All rights reserved
180
M. Deeny, J. A. Davis / Eur. J. Obster. Gynerol.
Reprod.
Biol. 57 (1994)
179-180
100
sensitivity
1F .,’ .,,’ ,,,.
,,,’
,’
,I,’
04,’ I
0 -
20
40
60
80
100
false positive rate ROC curve no discriminatory power
~
good discriminatory power
Fig. I. ROC curve of PBAC taking MBL of 80 ml as true disease
4. Results
The age range of the patients was 30-52 years, with a median of 41 years. The median parity was 2, with a range of O-6. The median BMI was 26, with a range of 19-42.5. The group therefore tended to be overweight, with several patients in the grossly obese category (BMI greater than 30). The median VAS was 78 mm, with a range of 45-98 mm. The median PBAC score was 156, with a range of 30-714. The median menstrual blood loss was 73 ml, with range of lo-304 ml. Of the women, 47% had had MBL greater than 80 ml, which is objectively defined menorrhagia. This is a somewhat higher figure than is generally quoted for a group of women complaining of menorrhagia, and may reflect that this group consisted of women selected for surgery. The P values for multiple regression analysis on MBL were: age, 0.151; parity, 0.789; VAS, 0.724; PBAC, 0.001; BMI, 0.968. Thus, MBL was closely related to PBAC (P = 0.001). The visual analogue score did not appear to be related to MBL (P = 0.724). Obesity did not appear to be related to MBL (P = 0.968). However, obesity was a factor in the referral of some of these women for endometrial ablation as an alternative to hysterectomy for their complaint of heavy periods. Using a cut-off point of 100 (as used by Higham et al. [2]) to predict menstrual blood loss in excess of 80 ml, PBAC had a sensitivity of 88% and a specificity of 52%. The false positive rate was 59%.
blems [5]. It is possible that the advent of endoscopic surgery will broaden the indications for surgery for menorrhagia, and Coulter [6] advises that the profession should practise audit in this field. In this series we demonstrated that 47% of the women experienced excessive menstrual loss as defined by Hallberg and Nilsson [l]. They had a functional abnormality, despite the absence of any endometrial disease, endometrial polyps, or intracavitary or submucous libroids. We found PBAC to be a useful test for menorrhagia, although less specific than Higham et al. found it to be [2]. This may reflect our investigation of 53 individual women, rather than their report of 55 cycles in 30 women, which may have introduced bias in the comparison of PBAC to MBL. It is also possible that our less rigorous control of the sanitary material used contributed to our different lindings. In the original study, Higham and her colleagues used a specific brand and absorbency of sanitary towel and tampon, which were supplied to the subjects for their menstrual collections. In most clinical situations, the gynaecologist will not have the resources to supply sanitary material to women for the measurement of PBAC, so we felt it was worthwhile evaluating the technique in the more common clinical situation where the woman will be using the sanitary material she has purchased herself. In this latter situation, we have shown that PBAC does provide a sensitivity of 88% and a specificity of 52% in predicting menstrual loss in excess of 80 ml. However, the plotting of the ROC curve indicates that PBAC has only intermediate discriminatory power in detecting excessive menstrual loss. Chard and Lilford [4] recommend the plotting of an ROC curve to demonstrate the discriminatory power of a test, rather than merely quoting specificity, sensitivity, false positive and false negative rates. Our data endorse the use of PBAC in assessing menstrual blood loss in women complaining of heavy periods, but we would recommend the retention of the alkaline haematin method as the ‘gold standard’. References ill 121 [31 141
5. Discussion The objective assessment of menorrhagia remains a challenge. Menstrual disorders are a common cause of referral for specialist opinion. A considerable surgical workload is generated in consequence of menstrual pro-
[51
Hallberg L, Nilsson L. Determination of menstrual blood loss. Stand J Clin Lab Inv 1964; 16: 244-248. Higham JM, O’Brien PMS, Shaw RW. Assessment of menstrual blood loss using a pictorial chart. Br J Obstet Gynaecol 1990; 9-l: 734-139. Swets JA. Measuring the accuracy of diagnostic systems. Science 1988; 2401 1285-1293. Chard T, Lilford RJ. How useful is a test? In: JWW Studd. ed. Progress in obstetrics and gynaecology, vol. 9. Edinburgh: Churchill Livingstone, 1991.
Coulter A, Bradlow J, Agass M, Martin-Bates C, Tulloch A. Outcomes of referrals to gynaecology outpatient clinics for menstrual problems: an audit of general practice records. Br J Obstet Gynaecol 1991; 98: 789-796. with endometrial resection. 161 Coulter A. Managing menorrhagia Lancet 1993: 341: 1185-l 186.