Caesarean Section at Full Dilatation and Risk of Major Obstetric Haemorrhage

V O’Dwyer, A Freyne, N Joyce, S Coulter-Smith
Rotunda hospital, Parnell Square, Dublin 1, Ireland

Abstract

The purpose of the study was to examine the risk factors for caesarean section (CS) at full dilatation and to assess the risk and management of haemorrhage. The study took place in a tertiary referral maternity hospital. Women who had a CS at full dilatation were included. Clinical and demographic details were recorded. There were 199 cases. The average age was 30.3 years and average BMI was 25.8kg/m2. There were 79.9 % (159) primigravidas and 20.1% (40) multigravidas. The average gestation at delivery was 39.4 weeks. Labour was induced in 46.9 % (92) and spontaneous in 53.8% (107). Oxytocin was used in 67.8 % (135). An instrumental delivery was attempted in 46.7 % (93). The rate of malposition was 46.5 % (92). The average birthweight was 3,629g and 9 babies weighed ≥4.5kg. The average estimated blood loss (EBL) was 665mls and 34 had EBL>1L. Most had an oxytocin infusion (141). Other uterotonic agents were used in 70 women. Seven women had blood transfusions. The highest rate of CS at full dilatation was in primigravidas due to malposition. There was a low rate of major obstetric haemorrhage.

Introduction
There has been a global increase in caesarean section rates. An American collaboration examined prevention of the first CS in an effort to reduce the overall CS rate1. A recent review of CS rates using the Robson criteria showed that women with a previous CS were an important determinant of the overall CS rate. Based on this finding the importance of avoiding unnecessary primary caesarean sections was again highlighted2. There has also been an increase in caesarean sections performed at full dilatation in the last decade in both Ireland and internationally3. The reason for this increase is multifactorial. It has coincided with a decline in the rate of instrumental delivery4. Studies have also shown that under use of oxytocin and lack of consultant presence affect the CS rate at full dilatation5. The maternal morbidity rate has become a marker of quality of care in modern obstetrics. In the last severe maternal morbidity in Ireland report, major obstetric haemorrhage was the commonest morbidity and the commonest indication for admission to the intensive care unit6. Interestingly, a review of trends and outcomes of postpartum haemorrhage (PPH) found that while PPH was increasing there was no associated increase in the maternal morbidity associated with PPH and CS, including blood transfusion7.

Methods
Women who had a caesarean section at full dilatation between January 2013 and December 2014 were included in the study. A caesarean section at full dilatation was defined as an emergency caesarean section at 10cm dilatation. Clinical and sociodemographic details were collected from patient records and from the Hospital’s computerized database. Details of labour and delivery were examined. Weighing swabs and measuring suction volume at the end of the caesarean section were used to calculate estimated blood loss. The reason for haemorrhage was obtained from the operative note in the patient records. Management of obstetric haemorrhage was obtained from the anaesthetic records and operative note in the patient records.

Maternal adverse outcomes including haemorrhage >500mls and major obstetric haemorrhage >1.5L were examined. Neonatal adverse outcomes including unexpected admission to the special care baby unit and arterial cord pH < 7.20 at birth were reviewed. The data was analysed using graph pad and a p value <0.05 was considered significant. The study was approved by the Hospital’s Research Ethics Committee.

Results
There were 199 caesarean sections at full dilatation during the two-year period. The delivery rate for these two years was 17,435 thus the rate of CS at full dilatation was 1.1%. The average age was 30.3 years and average BMI was 25.8kg/m2. There were 79.9% (159) primigravidas and 20.1% (40) multigravidas. The average gestation at delivery was 39.4 weeks. Labour was induced in 46.9% (92) and spontaneous in 53.8% (107). Oxytocin was used in 67.8% (135). Of the 135 women who had oxytocin half of these had labour induced and half had labour augmented with oxytocin. Epidural analgesia was used in 84.4% (168). An instrumental delivery was attempted in 46.7% (93). There were 18 forceps only, 44 vacuum only, 31 both vacuum and forceps deliveries attempted. There was a trend towards female obstetricians being more likely to attempt an instrumental delivery than male obstetricians (50% vs. 37%; p=0.28). There were 92 babies occipitoposterior and 51 occipitotransverse position at full dilatation. Indications listed for not attempting an instrumental delivery included malpresentation (13) and high head. The average birthweight was 3,629g, 59 babies weighed ≥4kg and 9 babies weighed ≥4.5kg.

In primigravidas, the mean gestation at delivery was 40 weeks and 50% (80) had labour inducted. Of these women, 15% (12) had prostaglandin and artificial rupture of membranes but not oxytocin. The remaining 85% (68) had oxytocin to induce labour. Of the 79 spontaneously laboring primigravidas 65% (51) had oxytocin. Thus 76.3% (172) of primigravidas had oxytocin in labour. Ninety percent (143) had epidural analgesia. An instrumental delivery was attempted in 48% (76); 13 forceps only, 40 vacuum only and 23 both vacuum and forceps. There were 80 babies occipitoposterior and 45 occipitotransverse position at full dilatation. The average birthweight was 3,678g, 53 babies weighed ≥4kg and 5 babies weighed ≥4.5kg.

In multigravidas, the mean gestation at delivery was 39 weeks and 33% (13) had labour inducted. Of these women, 5 had prostaglandin and artificial rupture of membranes and seven had oxytocin to induce labour. Of the spontaneous labouring multigravidas 5 had oxytocin. Sixty-five percent (26) had epidural analgesia. An instrumental delivery was attempted in 455 (18); 5 forceps only, 8 vacuum and 5 both vacuum and forceps. There were 12 babies occipitoposterior and 7 occipitotransverse position at full dilatation. The average birthweight was 3436g, 7 babies weighed ≥4kg and one baby weighed ≥4.5kg. The average estimated blood loss (EBL) was 665mls, 50% had EBL >500mls and 7 had EBL >1.5L. Of the seven women with an EBL >1.5L, 5 were primigravidas and two were multigravidas. Most had an oxytocin infusion (141). Other uterotonic agents were used in 70 women including syntometrine (17), misoprostol (44), carboprost (9). One multigravida had a uterine balloon inserted and one multigravida had a B-lynch suture. In 33 cases there was an angle extension; 30 of these had an EBL >500mls and 6 had an EBL >1.5L. Seven women, 6 of whom were primigravidas, had a blood transfusion. There were no peripartum hysterectomies. The indication for delivery was suspected fetal distress in 71 cases. Of these babies, 37 had an arterial pH <7.20, two had an arterial pH <7.0 at delivery. There were 4 babies unexpectedly admitted to the special care baby unit.

Discussion
Our study showed that the highest rate of caesarean section at full dilatation was in primigravidas due to malposition. There was a low rate of major obstetric haemorrhage. However, there was a high rate of postpartum haemorrhage >500mls and more than a third of women needed more than one uterotonic agent. Caesarean section for dystocia in labour can be caused by inefficient uterine activity, fetal macrosomia and fetal malposition. A recent article showed that malposition was common in women who underwent CS at full dilatation8. Appropriate use of oxytocin, especially in primigravidas can correct dystocia in the first stage of labour. Furthermore, a study showed that oxytocin in the second stage of labour was associated with a higher rate of spontaneous vaginal delivery in primiparous women with a baby in the occipitoanterior position9. Haemorrhage is a common complication of CS with rates of 5-10% associated with an EBL >1L10. The risk of haemorrhage has been shown to reduce with oxytocin prophylaxis and treatment of uterine atony11. The NICE guideline recommends a bolus 5iu oxytocin slow intravenous injection to encourage contraction of the uterus and to decrease blood loss12. A randomised control trial also showed that addition of an oxytocin infusion to the standard oxytocin bolus reduced the need for further uterotonic agents and, when the operator was junior, also reduced the incidence of major obstetric haemorrhage13. While there was a low rate of maternal and fetal morbidity in our study it is important to remember that CS at full dilatation is a potentially difficult procedure with higher risks than other CS. The routine use of oxytocin infusion should be considered in addition to the standard bolus to reduce the risk of haemorrhage.

Conflict of interest
The authors have no conflict of interest to declare.

Correspondence:
Vicky O’Dwyer, National Maternity Hospital, Holles street, Dublin 2
Tel: 01-6373100
Email: vickyodwyer@hotmail.com

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