Risk Of Uterine Rupture After Previous Caesarean Section

Main Category: Women's Health / Gynecology
Also Included In: Pregnancy / Obstetrics
Article Date: 25 Mar 2010 - 2:00 PDT


A Norwegian study to be published in BJOG: An International Journal of Obstetrics and Gynaecology has found that for women with previous caesarean section, the risk of uterine rupture was 8 times higher after trial of labour (TOL)1 than at repeated elective caesarean section. Induction of labour (using prostaglandins) was associated with the highest risk of uterine rupture.

Uterine rupture is a rare obstetric complication associated with severe maternal and perinatal morbidity and mortality. Previous caesarean section is the main risk factor for uterine rupture. Because the rate of caesarean section is increasing worldwide, there are an increasing number of mothers with previous caesarean section, with consequent higher risk of uterine rupture.

Considerable debate has surrounded birth choices for women with previous caesarean section, comparing the risks and benefits of vaginal birth after previous caesarean section (VBAC) with those of elective repeat caesarean section. This study sought to determine the risk factors for uterine rupture after previous caesarean section, comparing TOL (resulting in VBAC or failed VBAC), with repeat caesarean section.

In Norway, there is a relatively high rate of TOL with vaginal births in 51% of mothers with previous caesarean section. This provided a good basis for studying uterine rupture among mothers with different starts to birth2 after previous caesarean section.

This study reviewed all mothers giving birth in Norway from January 1999 to June 2005, using data from the Medical Births Registry of Norway. The study identified 18 794 mothers with previous caesarean section, giving birth to a total of 19 057 infants. 11 954 mothers attempted TOL (63.6%) and 6840 had prelabour caesarean section (36.4%).

Among the 18 794 mothers, there were 94 uterine ruptures (five ruptures per thousand women). The risk of uterine rupture was 8 times higher after TOL than at repeated elective caesarean section. The highest risk was after induction of labour, especially using prostaglandins, where the risk was up to 12.6 times higher.

Uterine ruptures after trial of labour resulted in significantly higher risk of serious consequences for both mother and newborn. These risks included serious bleeding, exposure to general anaesthesia, hysterectomy, and increased perinatal death and brain injury due to severe asphyxia of the newborn. The authors underline that the absolute number of these serious outcomes was low.

Lead author, Dr. Iqbal Al-Zirqi, from the University of Oslo and National Resource Centre for Women's Health in Norway, said "Uterine rupture can not be prevented completely, even with planned repeated caesarean section, although the risks of serious consequences at this type of delivery are minimal, compared with ruptures occurring after trial of labour. Not recommending trial of labour to mothers with higher risk for failed attempt at vaginal birth after previous caesarean section might reduce the rate of uterine rupture.

"Induction should be discouraged in mothers with previous caesarean section, as it carried the highest risk, and most catastrophic consequences, of uterine rupture for both mother and neonate. If needed, mechanical induction should be used instead of medical induction by prostaglandins."

Michael Marsh, BJOG deputy editor-in-chief, said "This study adds to a growing body of evidence on the risks and benefits of vaginal birth after caesarean section. Women should be aware that although trial of labour was associated with greater risk of uterine rupture, as compared to arranged repeat caesarean section, the absolute risk of uterine rupture is low.

"The study does, however, caution against the use of medical induction of labour for women with previous caesarean section. Further research is needed in order to determine the best ways of inducing labour after a previous caesarean section."

Notes

BJOG: An International Journal of Obstetrics and Gynaecology is owned by the Royal College of Obstetricians and Gynaecologists (RCOG) but is editorially independent and published monthly by Wiley-Blackwell. The journal features original, peer-reviewed, high-quality medical research in all areas of obstetrics and gynaecology worldwide. Please quote 'BJOG' or 'BJOG: An International Journal of Obstetrics and Gynaecology' when referring to the journal and include the website: http://www.bjog.org as a hidden link online.

1 Trial of labour was defined as an attempt of labour that either resulted in vaginal birth after previous caesarean section (VBAC), or resulted in emergency caesarean section after labour start (failed VBAC).

2 Start of birth was categorised into: elective prelabour caesarean section (defined as planned caesarean section performed before onset of labour), emergency prelabour caesarean section (defined as emergency caesarean section before onset of labour), spontaneous labour onset and induced labour onset. Elective and emergency prelabour caesarean section constituted prelabour caesarean section, whereas spontaneous and induced labour constituted trial of labour.

Reference

Al-Zirqi I, Stray-Pedersen B, Forsén L, Vangen S. Uterine rupture after previous caesarean section. BJOG 2010; DOI: 10.1111/j.1471-0528.2010.02533.x.

Source
Royal College of Obstetricians and Gynaecologists

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