British Journal of Obstetrics and Gynaecology May 1992, Vol. 99, pp. 364-367
OBSTETRICS
Intra-operative blood loss during elective lower segment caesarean section S. J . D U T H I E Senior Lecturer Department of Obstetrics and Gynaecology University of Liverpool Liverpool, UK A. GHOSH Senior Lecturer Department of Obstetrics and Gynaecology A. NG Senior Research Assistant Department of Obstetrics and G ynaecology P. C . H O Reader Department of Obstetrics and Gynaecology University of Hong Kong, Hong Kong
ABSTRACT Objective To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated wtih measured blood loss. Design Prospective observational study. Blood loss was measured in patients who underwent lower segment caesarean section in the course of routine hospital activity. Setting Tsan Yuk Hospital (Hong Kong), which is affiliated to the University of Hong Kong, 1990-1991. Subjects Forty women (mean age 29 years) with singleton pregnancies (mean gestation 38 weeks) delivered by elective lower segment caesarean section under general anaesthesia (mean birthweight 3177 g). Main outcome measure Intra-operative blood loss measured by the alkaline haematin method (intra-assay co-efficient of variation 2.2%). Results The mean measured blood loss was 487 ml (SE 40, range 164-1438). The mean estimated blood loss was 425 ml (SE 31) range 100-1300; mode 400). Observer error in estimating blood loss was higher if measured blood loss >600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level < 1O.Og/dl. Conclusion Blood loss at elective lower segment caesarean section was usually 4 0 0 ml and was estimated with reasonable accuracy. However, there was a tendency to under-estimate blood loss when the measured loss exceeded 600 ml.
In recent texts estimates of blood loss during elective lower segment caesarean section range from 600 ml (Beazley 1989) to 1000 ml (Letsky 1987). Earlier reports have been based on small numbers and heterogeneous groups of patients (Dieckmann & Daily 1935; Dieckmann & Stout 1950; Tatum 1953; Wilcox et al. 1959; Pritchard et al. 1962; Brant 1966). The methods used to determine blood loss were crude and often imprecise. More recently, sophisticated methods have been used to measure changes in plasma volume (Ueland 1976) but such measurements only provide an indirect assessment of the volume of circulating blood actually lost. By contrast, the use of a Stomacher Lab Blender (Model 3500, Seward Laboratories, London, UK) and alkaline haematin method for measurement of blood loss provide results which are accurate and reproducible (Newton et al. 1977; Shaw 1977; Duthie et al. 1990). We measured the intra-operative blood loss during elective lower segment caesarean section, performed by junior obstetricians, under general anaesthesia.
Subjects and methods Forty women (30 multiparae and 10 primiparae) were studied. All of them were delivered by elective lower segment caeCorrespondence to: Dr S. J. Duthie, Departmentof Obstetrics and and Gynaecology, University of Liverpool, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK.
sarean section between 38 and 40 weeks gestation under general anaesthesia. None of the women had hypertension, diabetes, anaemia, sepsis or meconium stained amniotic fluid. The operations were performed by an obstetrician who had either passed the MRCOG examination within the previous year or who was about to take the MRCOG examination. The latter were supervised by an obstetrician with the MRCOG qualification. Blood loss was measured using the alkaline haematin method (Newton et al. 1977; Shaw 1977; Duthie et al. 1990). One hour before the operation, 4 ml peripheral venous blood was collected from each woman for measurement of their haemoglobin level using the cyanmethaemoglobin method (Fairbanks 1976). During the operation the patient was draped with white linen and only white linen sanitary pads and gauze swabs were used. After the operation all the blood stained linen, sanitary pads, gauze swabs and blood clots were collected meticulously and placed in a cryovac plastic bag for blending. A 2 ml sample of the bloody fluid obtained by aspiration was collected for analysis and the total volume of bloody fluid aspirated was recorded. The operations were all performed using standard surgical techniques and instruments. The abdomen was opened using either a midline subumbilical incision or a Pfannenstiel incision. The uterus was opened using a transverse lower segment incision, the baby was born, the umbilical cord was clamped
364
B L O O D LOSS D U R I N G E L E C T I V E
and cut and the placenta was born by controlled cord traction. The edges of the uterine incision were held using 4 Green Armytage forceps. As soon as the baby was born the mother was given 10 U oxytocin or 0.5 mg ergometrine intravenously. The angles of the incision were secured and the lower uterine segment was repaired using gauge 1 chromic catgut. The vesico-uterine fold of peritoneum was repaired using 2/0 chromic catgut. The abdominal incision was closed in layers using standard techniques. The time interval between incision and closure of the skin was recorded by the nursing officer in charge of the operating theatre. After the skin wound was cleaned and dressed the vagina was cleaned and any blood obtained was added to the cryovac bag. At the end of the operation the volume of blood loss was estimated visually by inspecting the gauze swabs, linen, sanitary pads and drainage bottle. A consensus was reached between the surgeon and the anaesthetist and the estimated blood loss was recorded in the woman’s case notes. The amniotic fluid was clear in all the women in the study. General anaesthesia was used for all the operations. The following anaesthetic agents were used: thiopentone sodium, succinylcholine, atracurium, 1% enflurane, nitrous oxide and oxygen, pethidine, atropine and neostigmine. After administration of the oxytocin or ergometrine as a bolus, an intravenous oxytocin infusion was used in all cases. Forty units of oxytocin were added to 500 ml 5% dextrose and infused at the rate of 10 u/h. The patients’ blood pressure, pulse rate and SaO, were monitored throughout the operations. The haemoglobin concentration was measured in each case on the second morning after delivery. A total of 2000 ml 5% (W/V) sodium hydroxide solution was added to each cryovac plastic bag containing blood stained linen, gauze swabs and sanitary pads. The bag was then placed in the Stomacher Lab Blender and processed at room temperature for 20 min (preparation A). Simultanenously, 100 ml 5% sodium hydroxide was added to a sample of 1 ml peripheral venous blood collected from the same patient (preparation B). After processing, a sample of the final mixture from each of the two preparations (A and B) was filtered and the absorbence of the clear supernatant was determined by spectrophotometry. Deviation of the absorbance at 550 nm with reference to the blank (Asso)was calculated. The volume of blood in the plastic bags, which represented the total amount of blood present in the stained linen and pads, was calculated from the following equation (Newton et al. 1977): Blood volume =
A,,, of eluate (preparation A) x 2000 A,,, of venous blood (preparation B) x 100
Also, 100 ml 5% sodium hydroxide was added to 1 ml of the aspirated fluid (preparation C). After processing, a sample of the mixture was filtered and the absorbance at 550 mm of the clear supernatant was measured. The volume of blood in the aspirate was obtained by the equation: Blood volume =
A,,, of eluate (preparation C) x Volume of aspirate A,,, of eluate (preparation B)
The total measured blood loss was obtained by adding together the volume of blood in each cryovac bag and the volume of aspirated blood. The intra-assay coefficient of variation for the
cs
365
measurement of blood volume by the alkaline-haematin method was 2.2%.
Results The mean age of the 40 patients was 29 years (SD 4.1, range 19-38), mean length of gestation at delivery was 38 weeks (SD 0.5) and the mean birthweight was 3177 g (SD 475, range 24004550). The mean duration of the operation was 50 min (SD 1.5). In 23 women (58%) the indication for caesarean section was a previous lower segment caesarean section and evidence of cephalo-pelvic disproportion, in 15 (38%) the indication was breech presentation with another complication (intrauterine growth retardation, prolonged pregnancy or unfavourable pelvis) and in 2 ( 5 % ) the indication was type 2 placenta praevia (posterior). The operation was performed through a transverse suprapubic incision in 19 women (47.5%), through a repeat transverse suprapubic incision in 7 (17.5%), through a midline incision in 9 (22.5%) and through a repeat midline incision in 5 (12.5%). After the birth of the infant, 10 women received a bolus dose of 0.5 mg of ergometrine and 30 a bolus dose of 10 U of oxytocin. All the infants were born in good condition and the amniotic fluid was clear in all cases. The mean measured blood loss was 487 ml (SE 40; range 164-1438). The mean estimated blood loss was 425 ml (SE 31; range 100-1300; mode 400). The relation between estimated blood loss and measured blood loss is shown in Fig. I . The women were stratified into five groups based on the difference between measured and estimated blood loss and the average blood loss in each group was calculated. Fig. 2 shows the five groups, their average blood loss and the number of women in each group. The difference between measured and estimated blood loss related to the measured blood loss is shown in Fig. 3. The mean pre-operative haemoglobin level was 12.1 g/dl (SE 0.21) and the mean postoperative haemoglobin level was 1 1.9 g/dl (SE 0.12). One woman, who had an estimated blood loss of 1300 ml (measured loss 1054 ml), received a blood transfusion immediately after the operation. Only one woman had a postoperative haemoglobin level < 10.0 g/dl; she had an estimated blood loss of 600 ml and a measured loss of 1438 ml.
Discussion Previous reports on measured blood loss at caesarean section were based on groups of patients who were more heterogeneous than those in our study and the methods used to measure blood loss were not necessarily accurate. Dieckman & Daily (1935) found that the mean measured blood loss in 20 patients was 539 ml. They did not mention the type of anaesthesia used. Three of the operations were performed for placental abruption and five other emergency operations were performed during labour. The investigators used sponges soaked in acid and wrung out the fluid in the sponges by hand. Dieckman & Stout (1950) reported a mean blood loss of 618 ml in six patients who were delivered by caesarean section under spinal anaesthesia. Tatum (1953) investigated eight patients of whom one had an emergency caesarean section. Most of the oper-
366 s . J .
DUTHIE ET AL.
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2001
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/
@a
I
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800 1000 1200 1400 1600
Measured blood loss (ml)
Fig. 1. Relation between estimated and measured blood loss at lower segment caesarean section. The line represents values where measured blood loss equals estimated blood loss.
ations used local anaesthesia-a practice which is rarely used now. Using serial plasma volume measurements Tatum (1953) reported an average blood loss of 923 ml. Wilcox et al. (1959) reported an average blood loss of 1028 ml in 25 sections of which six were classical caesarean sections, four were emergency caesarean sections and four were undertaken between 32 and 36 weeks gestation. More recently, Pritchard (1962) studied 40 patients using 5'Cr-labelled red blood cells and estimated, without reference to details of surgical technique, oxytocics, the surgeon's level of training or duration of the operation, that the average blood loss at caesarean section was 930 ml. Ueland (1976) estimated a mean decrease of 1030 ml in blood volume from the start of' the operation to one hour postpartum. Brant (1966) distinguished between elective and emergency
m
caesarean sections and he measured blood loss meticulously in both situations. The average measured blood loss was 1068 ml in 22 elective sections and 1106 ml in 14 emergency sections. Ten of the 22 women delivered by elective section required blood transfusions either during or after the operation compared with only one of the 40 women in our study. An important finding in the study by Brant (1966) was that the surgeon under-estimated the volume of blood loss in 17 of the 20 elective sections where blood loss was estimated and in 13 of the 14 emergency sections. The ability of pregnant women to withstand blood loss at delivery is related to their blood volume and haemoglobin level, the volume of blood loss and any associated complications. There are large variations in the blood volume at term (Cope 1958), even when height and body weight are taken into account (Hytten & Paintin 1963). The prevention and management of anaemia and any other pregnancy associated complications are among the fundamental objectives of antenatal care. Accurate estimation of the volume of obstetric haemorrhage is also very important (Brant 1966; Brant 1967; Anonymous 1967). Because of the dispersion of blood lost at caesarean section, accurate estimation is often difficult (Wilcox 1959). We have shown that the difference between measured and estimated blood loss increases when the measured loss exceeds 600 ml, and also if the measured blood loss is lo00 ml in two (5%) and almost 1500 ml in one of them. Furthermore, blood loss at caesarean section is acute. We found that much of the blood loss took place between the time of incision and repair of the uterus but it was not possible, for practical reasons, to measure blood loss
r
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:;
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a
m
600 -
"
400 -
am
me
9
200 -
1600 1200 800 400 0 2 4 6 8 1012 14 16 1400 1000 600 200 Average blood loss (ml)
0No. of women
Fig. 2. Stratification of patients into five groups based on the difference between measured and estimated blood loss. The figure shows the difference between measured and estimated blood loss plotted against the average blood loss for each of the five groups and the number of patients in each group.
m.
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-200-
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Fig. 3. Difference between measured and estimated blood loss related to measured blood loss.
BLOOD LOSS D U R I N G ELECTIVE
from the uterus and from the anterior abdominal wall separately. The availability of blood for obstetric patients is potentially life saving (Stallworthy 19391and it is noteworthy that the triennial confidential enquiries into maternal deaths in England reported that haemorrhage foland Wales have lowing caesarean section is an important cause of maternal death (Department of Health 1991). In Hang Kong obstetric haemorrhage was the leading cause of maternal deaths between 1961 and 1985 (Duthie et al. 1989). Whilst we acknowledge that there are also risks associated with an allogenic blood transfusion (Roath 1991) we reiterate that crossmatched blood should be available during an elective or emergency caesarean section.
References Anonymous (1967) Estimation of blood loss in obstetrics (leading article). Br Med J 1, 38 I . Beazley J. M. (1989) Caesarean section. In Obstetrics (Turnbull A. Chamberlain G., eds) Churchill Livingstone, Edinburgh, 857-865. Brant H. A. (1 966) Blood loss at caesarean section. J Ohstet Gynaecol Brit Cwlth 73, 456459. Brant H. A. (1967) Precise estimation of postpartum haemorrhage: difficulties and importance. Br Med J 1, 398400. Cope I. (1958) Plasma and blood volume changes in late and prolonged pregnancy. .I Ohstet Gynuecol Brit Emp 65, 877. Department of Health (1991) Report of Confidential Enquiries into Maternal Deaths in the United Kingdom 1985-1987. Her Majesty's Stationery Office, London, p. 123. Dieckmann W. J. & Daily E. F. (1935) Blood loss during caesarean section. Am J Ohstet Gynecol 221-225. Dieckmann W. J. & Stout F. (1950) Insensible and total weight changes during labour, delivery and gynaecological operations. Am .I Ohstet Gynecol 59, 1021-1 028. Duthie S. J.. Ghosh A. & Ma H. K. (1989) Maternal mortality in Hong Kong 1961-1985. Br J Ohstet Gynuec,ol96,4-8. Duthie S. J., Yung G. L. K.. Dong Z. G., Chan S . Y. W. & Ma H. K.
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(1990) Discrepancy between laboratory determination and visual estimation of blood loss during normal delivery. Eur J Ohstet Gynuecol Reprod Biol 38, 119-124. Fairbanks v. F. (1976) Haemoglobin, haemoglobin derivatives and myoglobin. In Fundanzentals of Clinical Chemistry (Tietz N. W., ed,), W, B, Saunders, Philadelphia,pp, 41 Hytten F, E, & Paintin D, B, (1963) Increase in plasma volume during normal pregnancy. J Ohstet Gynaecol Brit Cwlrh 70,402407. Letskv E. A. (1987) , , Anaemia in obstetrics. In Prowess in Ohsterrii,s and Gynaecology (J. Studd, ed.), Vol. 6, Churchill Livingstone, Edinburgh, pp. 23-58. Ness P. M., Rourke M. E., Barrasso C., Luff R. D. &Johnson Jr., J. W. C. (1981) The efficacy of type and screen to reduce unnecessary cross matches for obstetric patients. A m .I Ohstet Gynei.ol 140, 661-664. Newton J., Barnard G. & Collins W. (1977). A rapid method for measuring menstrual blood loss using automatic extraction. C o m traceptiorz 16, 269-28 1. Pritchard J . A., Baldwin R. M., Dickey J. C., Wiggins K. M., Reed G. P. & Bruce D. M. (1962) Blood volume changes in pregnancy and the puerperium. Am .I Ohstet Gynecol84, 1271-1282. Roath S. (1991) Blood saving. Worth the trouble. Br iMcd .I 303, 659-660. Reisner L. S. (1983) Type and screen for caesarean section. A prudent alternative. Anaesthesiology 58, 476478. Shaw S. T. (1977) On quantifying menstrual blood loss. Contraception 6, 283-285. Stallworthy J. (1939) A plea for the freer use of blood transfusion in obstetrics. BY M e d J 1, 153-155. Tatum H. J. (1953) Blood volume variation during labour and early puerperium. Am J Ohstet Gynecol66,27-35. Ueland K. (1976) Maternal cardiovascular dynamics VI1. Intrapartum blood volume changes. Am J Ohstet Gynecol 126, 67 1-677. Wilcox C. F., Hunt A. B. & Owen C. A. (1959) The measurement of blood loss during caesarean section. Am .I Ohstet Gynecol 77, 772-779.
Received 20 June I991 A i w p t e d 20 January 1992
OBSTETRICS
Intra-operative blood loss during elective lower segment caesarean section S. J . D U T H I E Senior Lecturer Department of Obstetrics and Gynaecology University of Liverpool Liverpool, UK A. GHOSH Senior Lecturer Department of Obstetrics and Gynaecology A. NG Senior Research Assistant Department of Obstetrics and G ynaecology P. C . H O Reader Department of Obstetrics and Gynaecology University of Hong Kong, Hong Kong
ABSTRACT Objective To measure intra-operative blood loss at elective lower segment caesarean section and to compare estimated wtih measured blood loss. Design Prospective observational study. Blood loss was measured in patients who underwent lower segment caesarean section in the course of routine hospital activity. Setting Tsan Yuk Hospital (Hong Kong), which is affiliated to the University of Hong Kong, 1990-1991. Subjects Forty women (mean age 29 years) with singleton pregnancies (mean gestation 38 weeks) delivered by elective lower segment caesarean section under general anaesthesia (mean birthweight 3177 g). Main outcome measure Intra-operative blood loss measured by the alkaline haematin method (intra-assay co-efficient of variation 2.2%). Results The mean measured blood loss was 487 ml (SE 40, range 164-1438). The mean estimated blood loss was 425 ml (SE 31) range 100-1300; mode 400). Observer error in estimating blood loss was higher if measured blood loss >600 ml. One patient received a blood transfusion and another had a post-operative haemoglobin level < 1O.Og/dl. Conclusion Blood loss at elective lower segment caesarean section was usually 4 0 0 ml and was estimated with reasonable accuracy. However, there was a tendency to under-estimate blood loss when the measured loss exceeded 600 ml.
In recent texts estimates of blood loss during elective lower segment caesarean section range from 600 ml (Beazley 1989) to 1000 ml (Letsky 1987). Earlier reports have been based on small numbers and heterogeneous groups of patients (Dieckmann & Daily 1935; Dieckmann & Stout 1950; Tatum 1953; Wilcox et al. 1959; Pritchard et al. 1962; Brant 1966). The methods used to determine blood loss were crude and often imprecise. More recently, sophisticated methods have been used to measure changes in plasma volume (Ueland 1976) but such measurements only provide an indirect assessment of the volume of circulating blood actually lost. By contrast, the use of a Stomacher Lab Blender (Model 3500, Seward Laboratories, London, UK) and alkaline haematin method for measurement of blood loss provide results which are accurate and reproducible (Newton et al. 1977; Shaw 1977; Duthie et al. 1990). We measured the intra-operative blood loss during elective lower segment caesarean section, performed by junior obstetricians, under general anaesthesia.
Subjects and methods Forty women (30 multiparae and 10 primiparae) were studied. All of them were delivered by elective lower segment caeCorrespondence to: Dr S. J. Duthie, Departmentof Obstetrics and and Gynaecology, University of Liverpool, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK.
sarean section between 38 and 40 weeks gestation under general anaesthesia. None of the women had hypertension, diabetes, anaemia, sepsis or meconium stained amniotic fluid. The operations were performed by an obstetrician who had either passed the MRCOG examination within the previous year or who was about to take the MRCOG examination. The latter were supervised by an obstetrician with the MRCOG qualification. Blood loss was measured using the alkaline haematin method (Newton et al. 1977; Shaw 1977; Duthie et al. 1990). One hour before the operation, 4 ml peripheral venous blood was collected from each woman for measurement of their haemoglobin level using the cyanmethaemoglobin method (Fairbanks 1976). During the operation the patient was draped with white linen and only white linen sanitary pads and gauze swabs were used. After the operation all the blood stained linen, sanitary pads, gauze swabs and blood clots were collected meticulously and placed in a cryovac plastic bag for blending. A 2 ml sample of the bloody fluid obtained by aspiration was collected for analysis and the total volume of bloody fluid aspirated was recorded. The operations were all performed using standard surgical techniques and instruments. The abdomen was opened using either a midline subumbilical incision or a Pfannenstiel incision. The uterus was opened using a transverse lower segment incision, the baby was born, the umbilical cord was clamped
364
B L O O D LOSS D U R I N G E L E C T I V E
and cut and the placenta was born by controlled cord traction. The edges of the uterine incision were held using 4 Green Armytage forceps. As soon as the baby was born the mother was given 10 U oxytocin or 0.5 mg ergometrine intravenously. The angles of the incision were secured and the lower uterine segment was repaired using gauge 1 chromic catgut. The vesico-uterine fold of peritoneum was repaired using 2/0 chromic catgut. The abdominal incision was closed in layers using standard techniques. The time interval between incision and closure of the skin was recorded by the nursing officer in charge of the operating theatre. After the skin wound was cleaned and dressed the vagina was cleaned and any blood obtained was added to the cryovac bag. At the end of the operation the volume of blood loss was estimated visually by inspecting the gauze swabs, linen, sanitary pads and drainage bottle. A consensus was reached between the surgeon and the anaesthetist and the estimated blood loss was recorded in the woman’s case notes. The amniotic fluid was clear in all the women in the study. General anaesthesia was used for all the operations. The following anaesthetic agents were used: thiopentone sodium, succinylcholine, atracurium, 1% enflurane, nitrous oxide and oxygen, pethidine, atropine and neostigmine. After administration of the oxytocin or ergometrine as a bolus, an intravenous oxytocin infusion was used in all cases. Forty units of oxytocin were added to 500 ml 5% dextrose and infused at the rate of 10 u/h. The patients’ blood pressure, pulse rate and SaO, were monitored throughout the operations. The haemoglobin concentration was measured in each case on the second morning after delivery. A total of 2000 ml 5% (W/V) sodium hydroxide solution was added to each cryovac plastic bag containing blood stained linen, gauze swabs and sanitary pads. The bag was then placed in the Stomacher Lab Blender and processed at room temperature for 20 min (preparation A). Simultanenously, 100 ml 5% sodium hydroxide was added to a sample of 1 ml peripheral venous blood collected from the same patient (preparation B). After processing, a sample of the final mixture from each of the two preparations (A and B) was filtered and the absorbence of the clear supernatant was determined by spectrophotometry. Deviation of the absorbance at 550 nm with reference to the blank (Asso)was calculated. The volume of blood in the plastic bags, which represented the total amount of blood present in the stained linen and pads, was calculated from the following equation (Newton et al. 1977): Blood volume =
A,,, of eluate (preparation A) x 2000 A,,, of venous blood (preparation B) x 100
Also, 100 ml 5% sodium hydroxide was added to 1 ml of the aspirated fluid (preparation C). After processing, a sample of the mixture was filtered and the absorbance at 550 mm of the clear supernatant was measured. The volume of blood in the aspirate was obtained by the equation: Blood volume =
A,,, of eluate (preparation C) x Volume of aspirate A,,, of eluate (preparation B)
The total measured blood loss was obtained by adding together the volume of blood in each cryovac bag and the volume of aspirated blood. The intra-assay coefficient of variation for the
cs
365
measurement of blood volume by the alkaline-haematin method was 2.2%.
Results The mean age of the 40 patients was 29 years (SD 4.1, range 19-38), mean length of gestation at delivery was 38 weeks (SD 0.5) and the mean birthweight was 3177 g (SD 475, range 24004550). The mean duration of the operation was 50 min (SD 1.5). In 23 women (58%) the indication for caesarean section was a previous lower segment caesarean section and evidence of cephalo-pelvic disproportion, in 15 (38%) the indication was breech presentation with another complication (intrauterine growth retardation, prolonged pregnancy or unfavourable pelvis) and in 2 ( 5 % ) the indication was type 2 placenta praevia (posterior). The operation was performed through a transverse suprapubic incision in 19 women (47.5%), through a repeat transverse suprapubic incision in 7 (17.5%), through a midline incision in 9 (22.5%) and through a repeat midline incision in 5 (12.5%). After the birth of the infant, 10 women received a bolus dose of 0.5 mg of ergometrine and 30 a bolus dose of 10 U of oxytocin. All the infants were born in good condition and the amniotic fluid was clear in all cases. The mean measured blood loss was 487 ml (SE 40; range 164-1438). The mean estimated blood loss was 425 ml (SE 31; range 100-1300; mode 400). The relation between estimated blood loss and measured blood loss is shown in Fig. I . The women were stratified into five groups based on the difference between measured and estimated blood loss and the average blood loss in each group was calculated. Fig. 2 shows the five groups, their average blood loss and the number of women in each group. The difference between measured and estimated blood loss related to the measured blood loss is shown in Fig. 3. The mean pre-operative haemoglobin level was 12.1 g/dl (SE 0.21) and the mean postoperative haemoglobin level was 1 1.9 g/dl (SE 0.12). One woman, who had an estimated blood loss of 1300 ml (measured loss 1054 ml), received a blood transfusion immediately after the operation. Only one woman had a postoperative haemoglobin level < 10.0 g/dl; she had an estimated blood loss of 600 ml and a measured loss of 1438 ml.
Discussion Previous reports on measured blood loss at caesarean section were based on groups of patients who were more heterogeneous than those in our study and the methods used to measure blood loss were not necessarily accurate. Dieckman & Daily (1935) found that the mean measured blood loss in 20 patients was 539 ml. They did not mention the type of anaesthesia used. Three of the operations were performed for placental abruption and five other emergency operations were performed during labour. The investigators used sponges soaked in acid and wrung out the fluid in the sponges by hand. Dieckman & Stout (1950) reported a mean blood loss of 618 ml in six patients who were delivered by caesarean section under spinal anaesthesia. Tatum (1953) investigated eight patients of whom one had an emergency caesarean section. Most of the oper-
366 s . J .
DUTHIE ET AL.
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73
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2001
I / V 0
/
@a
I
I
I
200
400
600
I
I
I
I
1
800 1000 1200 1400 1600
Measured blood loss (ml)
Fig. 1. Relation between estimated and measured blood loss at lower segment caesarean section. The line represents values where measured blood loss equals estimated blood loss.
ations used local anaesthesia-a practice which is rarely used now. Using serial plasma volume measurements Tatum (1953) reported an average blood loss of 923 ml. Wilcox et al. (1959) reported an average blood loss of 1028 ml in 25 sections of which six were classical caesarean sections, four were emergency caesarean sections and four were undertaken between 32 and 36 weeks gestation. More recently, Pritchard (1962) studied 40 patients using 5'Cr-labelled red blood cells and estimated, without reference to details of surgical technique, oxytocics, the surgeon's level of training or duration of the operation, that the average blood loss at caesarean section was 930 ml. Ueland (1976) estimated a mean decrease of 1030 ml in blood volume from the start of' the operation to one hour postpartum. Brant (1966) distinguished between elective and emergency
m
caesarean sections and he measured blood loss meticulously in both situations. The average measured blood loss was 1068 ml in 22 elective sections and 1106 ml in 14 emergency sections. Ten of the 22 women delivered by elective section required blood transfusions either during or after the operation compared with only one of the 40 women in our study. An important finding in the study by Brant (1966) was that the surgeon under-estimated the volume of blood loss in 17 of the 20 elective sections where blood loss was estimated and in 13 of the 14 emergency sections. The ability of pregnant women to withstand blood loss at delivery is related to their blood volume and haemoglobin level, the volume of blood loss and any associated complications. There are large variations in the blood volume at term (Cope 1958), even when height and body weight are taken into account (Hytten & Paintin 1963). The prevention and management of anaemia and any other pregnancy associated complications are among the fundamental objectives of antenatal care. Accurate estimation of the volume of obstetric haemorrhage is also very important (Brant 1966; Brant 1967; Anonymous 1967). Because of the dispersion of blood lost at caesarean section, accurate estimation is often difficult (Wilcox 1959). We have shown that the difference between measured and estimated blood loss increases when the measured loss exceeds 600 ml, and also if the measured blood loss is lo00 ml in two (5%) and almost 1500 ml in one of them. Furthermore, blood loss at caesarean section is acute. We found that much of the blood loss took place between the time of incision and repair of the uterus but it was not possible, for practical reasons, to measure blood loss
r
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:;
u
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a
m
600 -
"
400 -
am
me
9
200 -
1600 1200 800 400 0 2 4 6 8 1012 14 16 1400 1000 600 200 Average blood loss (ml)
0No. of women
Fig. 2. Stratification of patients into five groups based on the difference between measured and estimated blood loss. The figure shows the difference between measured and estimated blood loss plotted against the average blood loss for each of the five groups and the number of patients in each group.
m.
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-200-
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400
600
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800 1000 1200 1400 1600
Measured blood loss (ml)
Fig. 3. Difference between measured and estimated blood loss related to measured blood loss.
BLOOD LOSS D U R I N G ELECTIVE
from the uterus and from the anterior abdominal wall separately. The availability of blood for obstetric patients is potentially life saving (Stallworthy 19391and it is noteworthy that the triennial confidential enquiries into maternal deaths in England reported that haemorrhage foland Wales have lowing caesarean section is an important cause of maternal death (Department of Health 1991). In Hang Kong obstetric haemorrhage was the leading cause of maternal deaths between 1961 and 1985 (Duthie et al. 1989). Whilst we acknowledge that there are also risks associated with an allogenic blood transfusion (Roath 1991) we reiterate that crossmatched blood should be available during an elective or emergency caesarean section.
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Received 20 June I991 A i w p t e d 20 January 1992
