Physical sequelae of caesarean section

Best Practice & Research Clinical Obstetrics & Gynaecology Vol. 15, No. 1, pp. 49±61, 2001

doi:10.1053/beog.2000.0148, available online at http://www.idealibrary.com on

3 Physical sequelae of caesarean section Nicola Jackson

MA, MRCOG

Clinical Research Fellow and Hon. Specialist Registrar

Sara Paterson-Brown

MA, MRCOG, FRCS

Consultant Obstetrician and Gynaecologist Queen Charlotte's Hospital, Goldhawk Road, London, UK

The complications and recovery from caesarean section are dominated by the medical condition of the woman pre-operatively. Evidence regarding risks directly attributable to the caesarean section is scanty, and often derived from obstetric practice that di€ers from the current day. Mortality associated with the procedure is anything up to ®ve times that for vaginal delivery, with emergency caesarean section associated with almost twice the risk of elective procedures. Data regarding placenta praevia and placenta praevia-accreta come from population series where antibiotics were not routinely used for caesarean section, but there is no doubt that previous caesarean section increases the risk of both. Antibiotic and thromboprophylaxis at the time of caesarean section decrease morbidity in the index pregnancy, but can also reasonably be expected to reduce future pregnancy complications. Key words: caesarean section; maternal mortality; placenta praevia; placenta accreta; thromboembolism.

The number of caesarean sections performed each year continues to rise as a result of a variety of medical, legal and social pressures. The introduction of fetal heart rate monitoring1,2, concern over the safety of vaginal breech delivery3, fear of litigation4 and increasing in¯uence of maternal request all play a part.5,6 The main increase is in the number of elective operations, and maternal preference for an elective repeat caesarean section rather than undergoing a trial of scar accounts for a signi®cant proportion of these.5 Increasing rates of operative abdominal delivery mean that knowledge of the risks involved and the potential physical sequelae assumes greater importance, particularly in situations where there are no absolute contraindications to attempted vaginal delivery. Any assessment of sequelae of caesarean section has to take into account the in¯uence of the indication for the operation, or any underlying medical disorders that may have predisposed to that mode of delivery. Increasingly however, there is no medical indication for the caesarean section, with the mode of delivery depending purely on the informed choice of the woman and her partner. It is in precisely this situation, where adverse consequences of the caesarean are least acceptable, that the evidence from the literature is particularly scarce. 1521±6934/01/010049‡13 $35.00/00

c 2001 Harcourt Publishers Ltd. *

50 N. Jackson and S. Paterson-Brown

LIFE-THREATENING MATERNAL COMPLICATIONS Mortality and severe morbidity have long been associated with caesarean section7±11 and yet attributing such outcomes to the procedure itself is fundamentally ¯awed. Most studies are rather old and, as such, do not represent the risks associated with current anaesthetic or surgical techniques. Indeed, the evidence we have is so confounded by variables that in¯uence outcome in their own right that it is almost impossible to be precise about the two most important sequelae of caesarean section, namely, death and future risk of placenta praevia-accreta. The evidence available is nevertheless very useful, as long as these limitations are borne in mind.

Maternal mortality Lilford et al7 studied 263 075 maternities in Cape Town from 1975 to 1986 in which there were 108 maternal deaths (i.e. a maternal mortality rate of 40 per 100 000). This study suggested a fourfold higher risk of mortality associated with caesarean section compared to vaginal delivery when other contributing medical factors were excluded. The risk of death from caesarean section was approximately 1 in 4000, but this was in a population whose maternal mortality rate was four times higher than that in the United Kingdom at the time of the trial. Thus, such ®gures are helpful in comparison of caesarean section versus vaginal delivery, but cannot specify the risk of death from a caesarean section in di€erent populations with di€ering types of medical care. Sachs et al in the USA studied 84 maternal deaths (direct and indirect) from a total of 649 375 maternities (a maternal mortality rate of 11.7 per 100 000 live births).12 Although the mortality rate for all women delivered by caesarean section was twice as high as for those delivered vaginally, at 22.3 per 100 000 caesarean sections (compared to 10.8 per 100 000 vaginal births), the rate of mortality attributable to the caesarean section itself was lower, at 5.8 per 100 000 caesarean sections. This calculation included women who had been delivered by both elective and emergency caesarean sections. While the mortality rate associated with vaginal delivery included factors other than the vaginal delivery itself, Sachs concluded that the mortality due to a caesarean section was comparable to that associated with vaginal delivery. In the 1994±6 Report on Con®dential Enquiries into Maternal Deaths in the United Kingdom there were 134 deaths resulting from the pregnant state (Direct deaths).13 Of those who died after delivery, 50 had been delivered by caesarean section, compared to 38 who had been delivered vaginally. All the caesarean sections were carried out for obstetric indications or because of underlying or pre-existing disease and were dealt with in the relevant chapters of the Report. Indeed, this is the ®rst Report that has not dedicated a chapter to caesarean section deaths, re¯ecting these confounding variables. Unfortunately the total number of caesarean sections performed in the UK is not known, and therefore the absolute risks of caesarean section cannot be deduced. The current caesarean Section Sentinel Audit in the UK should help with these estimates and should provide guidance regarding future data collection. It is generally acknowledged that an emergency caesarean section is more hazardous for a woman than a planned elective procedure. This is borne out by the evidence7,9,13, which suggests di€erential death risks, particularly from sepsis and thromboembolism, of emergency compared to elective procedures. A relative risk of death attributable to the caesarean section of 1.7 (95% CI 0.5±6.0) has been reported for emergency compared to elective procedures.7

Physical sequelae of caesarean section 51

Haemorrhage Massive haemorrhage (blood loss 4 1000 ml) has been reported to occur in 7.3% of caesarean sections.14 It is particularly associated with placenta praevia, placental abruption and severe pre-eclampsia (especially with associated coagulation disorders) where the risk of requiring blood transfusion is increased.15,16 In the 1994±6 Report on Con®dential Enquiries into Maternal Deaths in the United Kingdom, 12 women died of haemorrhage ± three from bleeding associated with a placenta praevia, four from placental abruption and ®ve from bleeding from other causes.13 Two of the three women with placenta praevia had placenta percreta in association with a previous caesarean section scar. Three of the four women with placental abruption underwent caesarean section (the fourth died undelivered), but died from their pre-existing blood loss. None of them had previously had a caesarean section. Four out of the ®ve women who died from post-partum haemorrhage from other causes had been delivered by caesarean section and in two of these it was a repeat operation. No death from postpartum haemorrhage occurred after normal vaginal delivery. Once again, without knowing how many caesarean sections were done in this triennium the overall risk for this complication is unknown. The type of uterine incision used at caesarean section in¯uences the risk of haemorrhage: a classical uterine incision leads to a greater blood loss than a transverse lower segment incision.17 Increased blood loss at caesarean section should also be anticipated in any situation where the risk of uterine atony is increased, such as prolonged labour, multiple pregnancy, polyhydramnios or in the presence of multiple ®broids. Excessive blood loss may also be caused by surgical trauma to nearby blood vessels. This is usually due to inadvertent extension of the uterine angles damaging the vessels in the broad ligament and is particularly likely in second-stage caesarean sections or where there have been multiple previous caesarean sections and the lower segment is very thin. Vessel damage usually leads to overt bleeding, but occasionally occult loss can occur, causing a haematoma within the broad ligament. Thrombo-embolic disease Pregnancy increases the risk of thromboembolism sixfold. This risk increases by a further 2±20 times if delivery is by caesarean section, particularly if it is an emergency procedure.18 The indication for the caesarean also in¯uences this risk ± the woman may have been hospitalized and relatively immobile for some weeks prior to the delivery. Other factors such as maternal age, obesity and known hereditary thrombotic tendency are also important, but factors that are directly attributable to the caesarean section itself include excessive blood loss, dehydration and postoperative immobility, and all of these independently increase the risk of thromboembolism. One factor that may at least partially explain the increased risk of thrombosis after caesarean section is an increase in the platelet count. Reactive thrombocytosis has been shown to be associated with an increased risk of thrombosis and is more prominent after caesarean section than after vaginal delivery, even if the caesarean is uncomplicated.19 Anaemia, infection and postpartum haemorrhage increase the thrombocytosis further and are also known to be risk factors for thromboembolism.13,19 Thromboembolism is the major direct cause of maternal death in the United Kingdom, accounting for 36% of all such deaths.13 There were 25 postpartum deaths from pulmonary embolism in the United Kingdom between 1994 and 1996 and of

52 N. Jackson and S. Paterson-Brown

these 15 followed delivery by caesarean section. As with the ®gures for overall mortality rates it is dicult to assess the contribution to this risk from caesarean section alone, independent of other pre-existing risk factors ± of the ®fteen women who died only one did not have any other relevant risk factors and seven received no thromboprophylaxis. In 1995 the Royal College of Obstetricians and Gynaecologists published a Working Party Report on prophylaxis against thromboembolism.20 This was based on a consensus opinion, due to insucient robust evidence, and included a risk assessment pro®le for instituting thromboprophylaxis in patients undergoing caesarean section. Once women undergoing caesarean section are routinely assessed and given prophylaxis when indicated, the risk of thromboembolism should decrease, but the absolute risk is impossible to assess until the total number of caesarean sections in the UK is known. The incidence of non-fatal pulmonary embolism and deep venous thrombosis is not known, but estimates range from 0.05 to 0.1% of all pregnancies.21 There is a signi®cant long-term morbidity from venous insuciency, recurrent thrombosis or lung damage resulting in secondary pulmonary hypertension. Air and amniotic ¯uid embolism Although a rare complication that can only be diagnosed with certainty by the ®nding of fetal cells such as squames or hair in the maternal lungs at autopsy, there are several case reports of women su€ering amniotic ¯uid embolism during caesarean section.22,23 In the 1994±96 Con®dential Enquiries13 two of the 17 women who died from amniotic ¯uid embolism had undergone caesarean section prior to the onset of symptoms. Although the condition is usually fatal, two cases have been reported where women survived and went on to have a subsequent uncomplicated pregnancy after su€ering cardiopulmonary arrest presumed to be due to amniotic ¯uid embolism syndrome.24 Air embolism appears to be more common than amniotic ¯uid embolism during caesarean section25, and its e€ects may be subclinical.26 Nevertheless, air embolism can be fatal, particularly in the presence of an intracardiac septal defect. Predisposing factors include ruptured membranes and a prolonged uterine incision-to-delivery interval.27 Typical signs of air embolism are hypotension, hypoxia and decreased endtidal CO2 , and outcomes include cardiovascular collapse and extensive brain damage. Immediate therapy includes ¯ooding of the surgical ®eld with saline28, but the de®nitive treatment is with hyperbaric oxygen.29 Subsequent obstetric performance There is no doubt that caesarean section has a negative in¯uence on subsequent pregnancies and deliveries. Most importantly in the context of major morbidity is the increased incidence of placenta praevia and placenta accreta, with their attendant risks. Once again, we have the problem of risk estimates that are derived from caesarean sections performed for medical reasons when antibiotic prophylaxis was not routine, and therefore the risks quoted may well be overestimates. Placental abnormalities The presence of a uterine scar increases the risks of placenta praevia in a subsequent pregnancy.30,31 This may be because of impaired decidualization at the site of scarring, enabling the trophoblast to morbidly invade the myometrium, preventing placental

Physical sequelae of caesarean section 53 Table 1. Association of placenta praevia with number of previous caesarean sections.a Number of previous caesarean sections

Odds ratio (95% CI)

1 2 3 54

4.5 (3.6, 5.5) 7.4 (7.1, 7.7) 6.5 (3.6, 11.6) 44.9 (13.5, 149.5)

a

Adapted from the meta-analysis of Ananth et al (1997, American Journal of Obstetrics and Gynecology 177: 1071±1078).

Table 2. Association of placenta praevia and placenta praevia-accreta with previous caesarean section.a

Number of previous c/sections 0 1 2 3 54 Overall a

Total number of patients n ˆ 97 799 92 917 3820 850 183 29 97 799

Number with placenta praevia n ˆ 286 (% of total) 238 25 15 5 3 286

(0.26) (0.65) (1.8) (3.0) (10.0) (0.29)

Number with placenta accreta n ˆ 29 (% of total) 12 (0.01) 6 (0.16) 7 (0.82) 2 (1.09) 2 (6.9) 29 (0.03)

Proportion of placenta praevias with placenta accreta 5% 24% 47% 40% 67% 10%

Adapted from Clark et al (1985, Obstetrics and Gynecology 66: 89±92).

`migration' away from the cervix as the uterus grows and the lower segment develops. Women with a previous caesarean section have more than double the risk of a placenta praevia compared to women without.32 This risk increases with the number of previous caesarean sections (Table 1), and also with maternal age and parity independent of caesarean sections.30±33 The presence of a low-lying placenta is associated with signi®cant morbidity including ante- and post-partum haemorrhage, prolonged hospitalization and operative delivery.34 A placenta that is abnormally sited is also more likely to be abnormally adherent. In the study by Miller et al30 the incidence of placenta accreta increased from I in 20 000 (0.005%) in women without placenta praevia to almost 1 in 10 (9.3%) where the placenta was low, a relative risk of over 2000. Presence of a uterine scar also independently increases the risk of placenta accreta from 0.01% with no uterine scar to 0.25% if there is a history of at least one caesarean section.30 The combination of these two risk factors (uterine scar and placenta praevia) is associated with the highest risk of placenta accreta, particularly if the placenta is sited anteriorly over the scar. Again, the risk increases with the number of previous caesarean sections (Table 2). The clinical severity of the placenta praevia-accreta also increases if associated with a uterine scar. In the study by Clark et al31, 42% of the placenta praevia-accretas not associated with a uterine scar were amenable to conservative management, compared to 18% when a scar was present. Signi®cant morbidity and mortality occur with placenta accreta due to severe postpartum haemorrhage. Hysterectomy may be the treatment of choice in such cases, and reported incidences of such measures range from 50 to 82%.31,35

54 N. Jackson and S. Paterson-Brown

The risk of placental abruption has also been reported to be higher in women with a previous caesarean section than in those without. Hemminki et al studied 7337 women who had had at least one caesarean section and compared the outcome in the subsequent pregnancy with that of 8227 controls.33 Thirty-six women in the previous caesarean group su€ered placental abruption (incidence of 4.9 per 1000) compared to 14 women in the control group (incidence of 1.7 per 1000), giving a relative risk of 2.9. Future deliveries Although many women who have had a caesarean section are able to attempt a vaginal delivery in the next pregnancy, up to 50% decline and undergo repeat caesarean section.36±38 Of those who do choose to labour, 60±85% will deliver vaginally and 51% will su€er a scar dehiscence.38,39 This subject is dealt with more fully in Chapter 5 of this issue. OTHER COMPLICATIONS CAUSING SIGNIFICANT MATERNAL MORBIDITY Infections Infections are the most common maternal complication after caesarean section and account for substantial postnatal morbidity and prolonged hospital stay.40 The incidence after emergency caesarean section is higher than that after an elective operation41, but reports vary when comparing caesarean section with vaginal delivery.38,42,43 However, much of the published evidence regarding incidence of post-operative infection is from studies where prophylactic antibiotics were not used routinely and which therefore misrepresent the true risk of post-operative infectious morbidity. Prophylactic antibiotics at the time of caesarean section have been conclusively shown to decrease the incidence of post-operative infection, and the conclusion of the Cochrane Reviewers was that further placebo-controlled trials of the e€ectiveness of antibiotics with caesarean section are not ethically justi®ed.44 Incidences of the commonest sites of infection in both the elective and the emergency situation are given in Table 3, along with the demonstrated decrease in incidence when prophylactic antibiotics are used. Factors that have been shown to increase the risk of infection after caesarean section include emergency delivery, diagnosis of labour preoperatively, length of labour, rupture of the membranes and its duration, number of vaginal examinations prior to delivery, anaemia, blood loss, obesity and diabetes.10,14,42 Anaemia The mean blood loss at caesarean section is greater than that after vaginal delivery and there is a larger drop in the post-natal haemoglobin in those women delivered by caesarean section. Haemodynamic compromise or symptomatic anaemia from a postpartum haemorrhage obviously requires transfusion, but in view of the attendant risks of infection and transfusion reactions, transfusions should not be given without good cause. Naef et al45 found a 6.4% incidence of transfusion in women undergoing caesarean section, but demonstrated that blood transfusion did not a€ect the length of post-operative hospital stay or incidence of post-operative infection or wound complications, despite signi®cantly increasing the post-transfusion haematocrit compared to the non-transfused group. Obviously, adequate haemoglobin concentration at the start of the operation is the ideal.

Physical sequelae of caesarean section 55 Table 3. Infectious complications associated with caesarean section, and the e€ect of prophylactic antibiotic use.a

Infection

Nature of caesarean section

Incidence of infection (%) Antibiotics used

Control group

Odds ratio (95% CI)

Fever

Elective Emergency Total

8.6 16.0 14.4

23.1 38.4 33.9

0.32 (0.22, 0.48) 0.31 (0.25, 0.39) 0.33 (0.29, 0.38)

Urinary tract

Elective Emergency Total

3.1 3.7 5.3

5.2 8.8 9.4

0.40 (0.16, 1.00) 0.37 (0.25, 0.53) 0.51 (0.42, 0.62)

Wound

Elective Emergency Total

4.3 2.5 3.6

7.0 7.6 9.4

0.71 (0.39, 1.30) 0.32 (0.22, 0.46) 0.36 (0.30, 0.43)

Endometritis

Elective Emergency Total

1.7 10.3 7.6

6.5 27.6 20.7

0.24 (0.11, 0.49) 0.29 (0.24, 0.36) 0.29 (0.26, 0.33)

Serious maternal morbidity/death

Elective Emergency Total

0.7 0.8 0.9

0 4.1 2.6

3.78 (0.04, 353.5) 0.25 (0.11, 0.56) 0.38 (0.24, 0.61)

a

Reproduced from Smaill & Hofmeyr (2000, The Cochrane Library, issue 2; Oxford: Update Software).

RARE OR MINOR MATERNAL ISSUES Urinary tract damage Surgical trauma to the bladder occurs most commonly during re¯ection of the bladder o€ the lower anterior uterine wall46, but the bladder may also be damaged while entering the abdominal cavity, especially if there are adhesions from previous surgery or if a urinary catheter has not been passed prior to surgery. Vesical damage increases in incidence with the number of previous abdominal deliveries (overall rate 0.1± 0.3%46±48), but it should be immediately recognizable and, with correct management, long-term complications are rare.49 Damage to a ureter is a rare complication of caesarean section with an incidence of between 0.03 and 0.1%.46,47,50 It is usually caused by inadvertent lateral extension of the uterine incision with ligation of the ureter while trying to achieve haemostasis. In contrast to accidental cystotomy, ureteric injury is often not diagnosed until the postoperative period. It should be suspected if the patient has persistent loin pain, persistent abdominal distension with or without ileus, unexplained haematuria and/or watery vaginal discharge, particularly if the caesarean section is known to have been dicult.49 The method of ureteric repair depends on the site and nature of the injury and should be undertaken as soon as recognized in conjunction with a urologist. Gastrointestinal tract sequelae Damage to the bowel during caesarean section is very rare, with an incidence of about 0.05%.49 The bowel may be damaged during abdominal entry, particularly in the presence of intra-abdominal adhesions and in an emergency situation. Small injuries to both small and large bowel can usually be repaired primarily, without the need for

56 N. Jackson and S. Paterson-Brown

diversion, while larger injuries, particularly to small bowel, may require resection. All such repairs should be performed in conjunction with a bowel surgeon. As with any abdominal surgical procedure there is a risk of post-operative ileus, particularly if adhesions require division, if there is much handling of the bowel, if blood remains within the abdominal cavity or if the caesarean section was performed under general anaesthetic. Most cases settle with conservative management and have been shown to do so more quickly if the peritoneum has not been closed at operation.51,52 A history of caesarean section increases the risk of subsequent intra-abdominal adhesions and adhesion-related small bowel obstruction, although this increase is smaller than that associated with other abdominal operations.53 The incidence of small bowel obstruction after caesarean section was estimated at 1 in 2000 caesarean deliveries, while that after abdominal hysterectomy was 1 in 60 hysterectomies.53 Closure of the peritoneum was shown to increase the incidence of intestinal adhesions and, therefore, obstruction.53,54 Any increase in intra-abdominal adhesions increases the risks from any subsequent abdominal operations. Subsequent fertility Information regarding subsequent fertility after caesarean section is limited, and is frequently confounded by the indication for the initial caesarean section. An association has, however, been demonstrated between caesarean section and lowered fertility, subsequent miscarriage and possibly ectopic pregnancy, as well as the placental complications discussed earlier. In Aberdeen, Hall et al55 studied future fertility in 22 948 women having their ®rst singleton live birth between 1964 and 1983. The group who had delivered by caesarean section had the lowest proportion of women with a further pregnancy and the highest proportion that were sterilized (Table 4). Women who had undergone an instrumental delivery had proportions intermediate between those who had had a caesarean section and those who had delivered normally, suggesting that psychological factors may play a role in subsequent fertility rates.55,56 Hall et al also showed that the number of pregnancies ending in miscarriage was signi®cantly higher in the caesarean section group (Table 4). These ®ndings were similar to those of Hemminki in an earlier study57 and to those of a small, more recent study by Jolly, questioning 750 women by post.56 The results of studies investigating e€ect of caesarean section on subsequent ectopic pregnancy vary, but it appears that the small increase in relative risk is con®ned to women with more than one previous pregnancy (relative risk 1.54).33 Convalescence Early recovery from a caesarean section is more prolonged than from an uncomplicated vaginal delivery. Restricted mobility has implications for the woman's ability to look after her new baby as well as any older children. Minor morbidity several weeks after delivery is common, however, and is irrespective of the mode of delivery.58 In the postnatal survey by Glazener et al58 87% of women at 8 weeks and 76% at 2±18 months perceived themselves as having at least one health problem. One-half to two-thirds of these women required subsequent treatment. Although several minor complaints were more likely early in the recovery period, by 2 months or more post-delivery the only persistent health problem signi®cantly more likely to occur after caesarean section was high blood pressure (®ve out of 65 women). Conversely, women who had

Physical sequelae of caesarean section 57 Table 4. Future fertility and outcome by mode of ®rst delivery.a Mode of delivery in ®rst birth SVD n ˆ 14 448 Subsequent event

Instrumental n ˆ 6507

C/section n ˆ 1993

n

(%)

n

(%)

n

(%)

None Sterilization

5319 241

(36.8) (1.7)

2677 124

(41.1) (1.9)

999 54

(50.1) (2.7)

Pregnancy Birth Miscarriage

8888 7745 672

(61.5) (87.1) (7.6)

3706 3197 306

(57.0) (86.2) (8.3)

940 793 94b

(47.2) (84.4) (10.0)

a b

Adapted from Hall et al (1989, British Journal of Obstetrics and Gynaecology 96: 1297±1303). C/Section versus SVD P 5 0.01; c/section versus instrumental delivery P 5 0.05.

required assisted vaginal delivery had signi®cantly more problems than those delivered normally or by caesarean section up to 18 months post-delivery. NEONATAL COMPLICATIONS Caesarean section avoids the risks of labour and vaginal delivery, including intrapartum death, hypoxia and birth trauma. As such it is often viewed as the safest mode of delivery for the baby. However, successful labour and vaginal delivery confer advantages over babies delivered by caesarean section in terms of respiratory function, and especially in relation to lung maturation in the premature infant. Elective caesarean section is associated with an increased risk of transient tachypnoea of the newborn (TTN) and respiratory distress syndrome (RDS) when compared to a trial of labour.59 This risk of respiratory morbidity in babies born by elective caesarean section is dependent on gestation, with a signi®cant reduction in neonatal respiratory morbidity for each advancing week of gestation from 37 to 40 weeks in babies born by elective caesarean section60 (Table 5). Unfortunately this trial did not distinguish between TTN and RDS, but nevertheless the data lend support to delaying truly elective caesarean sections until 39 completed weeks of gestation, when the risk of respiratory compromise is 52%. Fetal laceration is more likely to occur with an operative than a non-operative delivery. It is probably under-reported as most lacerations are minor and heal without special treatment and without signi®cant scarring or morbidity for the neonate.61 At caesarean section it is more common with a breech presentation (6% incidence) than when the vertex is presenting (1.4%). Care should be taken on entering the uterus particularly if the operating ®eld is obscured by blood, and blunt dissection should be employed where necessary. There is recent evidence associating mode of delivery with childhood and adult behaviour patterns and stress responses. Taylor et al reported that stress (salivary cortisol) and crying response to inoculation at 8 weeks was related to method of delivery.62 Those born by operative vaginal delivery demonstrated the greatest response by crying longest, while those born by elective caesarean section cried least. Jacobson and Bygdeman63 showed that adults prone to violent suicide were more likely to have had a traumatic birth (instrumental delivery, internal version, meconium

58 N. Jackson and S. Paterson-Brown Table 5. Incidence of respiratory morbidity according to mode of delivery and gestation.a Gestation (weeks) 37 38 39 40 41 a

Mode of delivery

Number of women

Number of babies with respiratory morbidity

Elective c/section Vaginal delivery Elective c/section Vaginal delivery Elective c/section Vaginal delivery Elective c/section Vaginal delivery Elective c/section Vaginal delivery

366 1507 1063 3728 505 6955 243 10 299 164 6089

27 19 45 26 9 22 1 53 1 30

Rate/1000 (95% CI) 74 13 42 7 18 3 4 5 6 5

(49±106) (8±20) (31±56) (5±10) (8±34) (2±5) (0±23) (4±7) (0±34) (3±7)

Adapted from Morrison et al (1995, British Journal of Obstetrics and Gynaecology 102: 101±106).

stained liquor) than their non-suicidal siblings. Maternal use of sedatives and opiate analgesia during labour was also lower in those subsequently committing suicide, but there was no di€erence in the incidence of delivery by emergency caesarean section between the two groups. SUMMARY Caesarean section is becoming increasingly safe, and in some situations is preferable to attempted vaginal delivery. There is no doubt that it is associated with signi®cant morbidity for both mother and infant but this must be placed in context, with the risks of caesarean being compared to those risks associated with labour and vaginal delivery. Furthermore, the comparison should include those risks of awaiting labour64,65, as well as the consequences of instrumental delivery. The gap is closing, with operative vaginal delivery increasingly recognized as being associated with problems. Regional analgesia together with routine antibiotics and appropriate thromboprophylaxis for all women undergoing caesarean section should be followed up with robust prospective studies to assess the true, current risks of this increasingly common and popular method of delivery. In particular, maternal mortality and the incidence of placental problems in future pregnancies must be established. Practice points . antibiotic prophylaxis should be routine for all caesarean sections . all women undergoing caesarean section should have their risk pro®le assessed and appropriate thromboprophylaxis instigated . true elective caesarean sections should be delayed until 39 completed weeks of gestation, when the risk of neonatal respiratory morbidity is under 2% . risk factors for massive obstetric haemorrhage should be anticipated and appropriate measures taken to minimize these risks . placenta accreta should be anticipated in any woman with a previous caesarean section and a placenta praevia

Physical sequelae of caesarean section 59

Research agenda . each unit should systematically collect data regarding caesarean sections performed within their hospital . the ideal regimen for thromboprophylaxis, in terms of prevention of thromboemboli compared to peri-operative morbidity from wound haematomas, is still to be de®ned . long-term follow-up of women undergoing caesarean section after routine antibiotic prophylaxis is needed to determine the risk of placenta praeviaaccreta in subsequent pregnancies

REFERENCES 1. Leveno K, Cunningham F, Nelson S et al. A prospective comparison of selective and universal fetal heart rate monitoring in 34,995 pregnancies. New England Journal of Medicine 1986; 315: 615±619. 2. Sta€ord R. The impact of non-clinical factors on repeat caesarean section. Journal of the American Medical Association 1991; 265: 59±63. 3. Thorpe-Beeston JG, Ban®eld PJ & Saunders NJS. Outcome of breech delivery at term. British Medical Journal 1992; 305: 746±747. 4. Francome C, Savage W, Churchill H & Lewison H. Caesarean birth in Britain. London: Middlesex University Press, 1993. 5. Eftekhar K & Steer P. Women choose caesarean section. British Medical Journal 2000; 320: 1072. 6. Jackson N & Irvine L. The in¯uence of maternal request on the elective caesarean section rate. Journal of Obstetrics and Gynaecology 1998; 18: 115±119. * 7. Lilford RJ, van Coeverden de Groot HA, Moore PJ & Bingham P. The relative risks of caesarean section (intrapartum and elective) and vaginal delivery: a detailed analysis to exclude the e€ects of medical disorders and other acute pre-existing physiological disturbances. British Journal of Obstetrics and Gynaecology 1990; 97: 883±892. 8. van Coeverden de Groot HA. Maternal and perinatal mortality associated with caesarean section in Cape Town (letter). South African Medical Journal 1985; 68: 450. 9. Moldin P, Hokegard KH & Nielsen TF. Cesarean section and maternal mortality in Sweden 1973±1979. Acta Obstetricia et Gynecologica Scandinavica 1984; 63: 7±11. 10. Nielsen TF & Hokegard KD. Postoperative cesarean section morbidity: a prospective study. American Journal of Obstetrics and Gynecology 1983; 146: 911±915. 11. Amirikia H, Zarewych B & Evans TN. Caesarean section: a 15-year review of changing incidence, indications, and risks. American Journal of Obstetrics and Gynecology 1981; 140: 81±90. *12. Sachs BP, Yeh J, Acker D et al. Cesarean section-related maternal mortality in Massachusetts, 1954±1985. Obstetrics and Gynecology 1988; 71: 385±388. *13. Department of Health. Why Mothers Die. Report on Con®dential Enquiries into Maternal Deaths in the United Kingdom. London: The Department of Health, 1998. 14. van Ham MA, van Dongen PW & Mulder J. Maternal consequences of caesarean section. A retrospective study of intra-operative and postoperative maternal complications of caesarean section during a 10-year period. European Journal of Obstetrics, Gynecology and Reproductive Biology 1997; 74: 1±6. 15. Maxwell CN. Blood transfusion and caesarean section. Australian and New Zealand Journal of Obstetrics and Gynaecology 1989; 29: 121±123. 16. Imberti R, Preseglio I, Trotta V et al. Blood transfusion during cesarean section. A 12 years' retrospective analysis. Acta Anaesthesiologica Belgica 1990; 41: 139±144. 17. Lao TT, Halpern SH, Crosby ET & Huh C. Uterine incision and maternal blood loss in preterm caesarean section. Archives of Gynecology and Obstetrics 1993; 252: 113±117. 18. Nelson-Piercy C. Thromboembolic disease. In Handbook of Obstetric Medicine, pp 30±44. Oxford: Isis Medical Media Ltd, 1997. 19. Atalla RK, Thompson JR, Oppenheimer CA et al. Reactive thrombocytosis after caesarean section and vaginal delivery: implications for maternal thromboembolism and its prevention. British Journal of Obstetrics and Gynaecology 2000; 107: 411±414.

60 N. Jackson and S. Paterson-Brown 20. RCOG. Report of a Working Party on Prophylaxis against Thromboembolism in Gynaecology and Obstetrics. London: Royal College of Obstetricians and Gynaecologists, 1995. 21. Gates S & Brocklehurst P. Prophylaxis for venous thromboembolic disease in pregnancy and the early postnatal period (Protocol for a Cochrane Review). In The Cochrane Library (Issue 2). Oxford: Update Software, 2000. 22. Cluroe AD. Delayed paradoxical air embolism following Caesarian section for placenta previa ± a case history. Pathology 1994; 26: 209±211. 23. Margarson MP. Delayed amniotic ¯uid embolism following caesarean section under spinal anaesthesia. Anaesthesia 1995; 50: 804±806. 24. Clark SL. Successful pregnancy outcomes after amniotic ¯uid embolism. American Journal of Obstetrics and Gynecology 1992; 167: 511±512. 25. Lew TW, Tay DH & Thomas E. Venous air embolism during cesarean section: more common than previously thought. Anesthesia and Analgesia 1993; 77: 448±452. 26. Handler JS & Bromage PR. Venous air embolism during cesarean delivery. Regional Anaesthesie 1990; 15: 170±173. 27. Matthews NC & Greer G. Embolism during caesarean section. Anaesthesia 1990; 45: 964±965. 28. Lowenwirt IP, Chi DS & Handwerker SM. Nonfatal venous air embolism during cesarean section: a case report and review of the literature. Obstetrical and Gynecological Survey 1994; 49: 72±76. 29. Mushkat Y, Luxman D, Nachum Z et al. Gas embolism complicating obstetric or gynecologic procedures. Case reports and review of the literature. European Journal of Obstetrics, Gynecology and Reproductive Biology 1995; 63: 97±103. 30. Miller DA, Chollet JA & Goodwin TM. Clinical risk factors for placenta previa-placenta accreta. American Journal of Obstetrics and Gynecology 1997; 177: 210±214. *31. Clark SL, Koonings PP & Phelan JP. Placenta previa/accreta and prior cesarean section. Obstetrics and Gynecology 1985; 66: 89±92. 32. Ananth CV, Smulian JC & Vintzileos AM. The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis. American Journal of Obstetrics and Gynecology 1997; 177: 1071±1078. 33. Hemminki E & Merilainen J. Long-term e€ects of cesarean sections: ectopic pregnancies and placental problems. American Journal of Obstetrics and Gynecology 1996; 174: 1569±1574. 34. Groom KM & Paterson-Brown S. Placenta praevia and placenta accreta ± a review of aetiology, diagnosis and management. Maternal and Fetal Medicine Review 2000 (in press). 35. Zaki ZM, Bahar AM, Ali ME et al. Risk factors and morbidity in patients with placenta previa accreta compared to placenta previa non-accreta. Acta Obstetricia et Gynecologica Scandinavica 1998; 77: 391±394. 36. Joseph GF Jr, Stedman CM & Robichaux AG. Vaginal birth after cesarean section: the impact of patient resistance to a trial of labor. American Journal of Obstetrics and Gynecology 1991; 164: 1441±1444, discussion 1444±1447. 37. Lau TK, Wong SH & Li CY. A study of patients' acceptance towards vaginal birth after caesarean section. Australian and New Zealand Journal of Obstetrics and Gynaecology 1996; 36: 155±158. *38. McMahon MJ, Luther ER, Bowes WA Jr & Olshan AF. Comparison of a trial of labor with an elective second cesarean section. New England Journal of Medicine 1996; 335: 689±695. 39. Learman LA, Evertson LR & Shiboski S. Predictors of repeat cesarean delivery after trial of labor: do any exist? Journal of the American College of Surgeons 1996; 182: 257±262. 40. Henderson EJ & Love EJ. Incidence of hospital-acquired infections associated with caesarean section. Journal of Hospital Infection 1995; 29: 245±255. 41. Hillan EM. Postoperative morbidity following caesarean delivery. Journal of Advanced Nursing 1995; 22: 1035±1042. 42. Irion O, Hirsbrunner Almagbaly P & Morabia A. Planned vaginal delivery versus elective caesarean section: a study of 705 singleton term breech presentations. British Journal of Obstetrics and Gynaecology 1998; 105: 710±717. 43. Obwegeser R, Ulm M, Simon M et al. Breech infants: vaginal or cesarean delivery? Acta Obstetricia et Gynecologica Scandinavica 1996; 75: 912±916. *44. Smaill F & Hofmeyr GJ. Antibiotic prophylaxis for cesarean section. In The Cochrane Library (Issue 2). Oxford: Update Software, 2000. 45. Naef RW III, Washburne JF, Martin RW et al. Hemorrhage associated with cesarean delivery: when is transfusion needed? Journal of Perinatology 1995; 15: 32±35. 46. Eisenkop SM, Richman R, Platt LD & Paul RH. Urinary tract injury during cesarean section. Obstetrics and Gynecology 1982; 60: 591±596. 47. Rajasekar D & Hall M. Urinary tract injuries during obstetric intervention. British Journal of Obstetrics and Gynaecology 1997; 104: 731±734. 48. Yao XY. [Sequelae in 4122 cases of cesarean section]. Chung Hua Fu Chan Ko Tsa Chih 1990; 25: 15±17, 61.

Physical sequelae of caesarean section 61 49. Davis JD. Management of injuries to the urinary and gastrointestinal tract during cesarean section. Obstetrics and Gynecology Clinics of North America 1999; 26: 469±480. 50. Onuora VC, al Ariyan R, Koko AH et al. Major injuries to the urinary tract in association with childbirth. East African Medical Journal 1997; 74: 523±526. 51. Hull DB & Varner MW. A randomized study of closure of the peritoneum at cesarean delivery. Obstetrics and Gynecology 1991; 77: 818±821. 52. Irion O, Luzuy F & Beguin F. Nonclosure of the visceral and parietal peritoneum at caesarean section: a randomised controlled trial. British Journal of Obstetrics and Gynaecology 1996; 103: 690±694. 53. Al-Took S, Platt R & Tulandi T. Adhesion-related small-bowel obstruction after gynecologic operations. American Journal of Obstetrics and Gynecology 1999; 180: 313±315. 54. Stricker B, Blanco J & Fox HE. The gynecologic contribution to intestinal obstruction in females. Journal of the American College of Surgeons 1994; 178: 617±620. 55. Hall MH, Campbell DM, Fraser C & Lemon J. Mode of delivery and future fertility. British Journal of Obstetrics and Gynaecology 1989; 96: 1297±1303. 56. Jolly J, Walker J & Bhabra K. Subsequent obstetric performance related to primary mode of delivery. British Journal of Obstetrics and Gynaecology 1999; 106: 227±232. 57. Hemminki E. E€ects of cesarean section on fertility and abortions. Journal of Reproductive Medicine 1986; 31: 620±624. 58. Glazener CM, Abdalla M, Stroud P et al. Postnatal maternal morbidity: extent, causes, prevention and treatment. British Journal of Obstetrics and Gynaecology 1995; 102: 282±287. 59. Hook B, Kiwi R, Amini SB et al. Neonatal morbidity after elective repeat cesarean section and trial of labor. Pediatrics 1997; 100: 348±353. *60. Morrison JJ, Rennie JM & Milton PJ. Neonatal respiratory morbidity and mode of delivery at term: in¯uence of timing of elective caesarean section. British Journal of Obstetrics and Gynaecology 1995; 102: 101±106. 61. Smith JF, Hernandez C & Wax JR. Fetal laceration injury at cesarean delivery. Obstetrics and Gynecology 1997; 90: 344±346. 62. Taylor A, Fisk NM & Glover V. Mode of delivery and subsequent stress response. Lancet 2000; 355: 120. 63. Jacobson B & Bygdeman M. Obstetric care and proneness of o€spring to suicide as adults: case ± control study. British Medical Journal 1998; 317: 1346±1349. 64. Hilder L, Costeloe K & Thilaganathan B. Prolonged pregnancy: evaluating gestation-speci®c risks of fetal and infant mortality. British Journal of Obstetrics and Gynaecology 1998; 105: 169±173. 65. Cotzias CS, Paterson-Brown S & Fisk NM. Prospective risk of unexplained stillbirth in singleton pregnancies at term: population based analysis. British Medical Journal 1999; 319: 287±288.