National Rates of Uterine Rupture are not Associated with Rates of Previous Caesarean Delivery: Results from the Nordic Obstetric Surveillance Study

Obstetric emergencies as antecedents to neonatal hypoxic ischemic encephalopathy, does parity matter?

INTRODUCTION

Our aim was to investigate the risk of moderate to severe hypoxic ischemic encephalopathy (HIE) by obstetric emergencies, with focus on the distribution of obstetric emergencies by parity, taking the history of a previous cesarean into account.

MATERIAL AND METHODS

Population-based cohort study of 692 428 live births at ≥ 36 weeks of gestation in Sweden, 2009-2015. Data were retrieved by linking the Swedish Medical Birth Register with the Swedish Neonatal Quality Register. Therapeutic hypothermia served as surrogate for moderate to severe HIE. Logistic regression analysis was used to estimate associations between HIE and placental abruption, eclampsia, cord prolapse, uterine rupture, and shoulder dystocia, presented as adjusted odds ratios (aORs) with 95% CI.

RESULTS

An obstetric emergency occurred in 133/464 (29%) of all HIE cases, more commonly in the parous (overall 37%; 48% with and 31% without a previous cesarean) than in the nulliparous (21%). Among nulliparas, shoulder dystocia was the most common obstetric emergency with the strongest association with HIE (aOR 48.2; 95% CI 28.2-82.6). In parous women without a previous cesarean, shoulder dystocia was most common, but placental abruption had the strongest association with HIE. Among parous women with a previous cesarean, uterine rupture was the most prevalent obstetric emergency with the strongest association with HIE (aOR 45.6; 95% CI 24.5-84.6).

CONCLUSIONS

Obstetric emergencies are common among cases of moderate to severe HIE. The strong association with shoulder dystocia in nullipara, and with uterine rupture in women with previous cesarean deliveries, implies an opportunity for reducing the incidence of HIE.

The International Network of Obstetric Survey Systems study of uterine rupture: a descriptive multi-country population-based study

OBJECTIVE

International comparison of complete uterine rupture.

DESIGN

Descriptive multi-country population-based study.

SETTING

International.

POPULATION

International Network of Obstetric Survey Systems (INOSS).

METHODS

We merged individual data, collected prospectively in nine population-based studies, of women with complete uterine rupture, defined as complete disruption of the uterine muscle and the uterine serosa, regardless of symptoms and rupture of fetal membranes.

MAIN OUTCOME MEASURES

Prevalence of complete uterine rupture, regional variation and correlation with rates of caesarean section (CS) and trial of labour after CS (TOLAC). Severe maternal and perinatal morbidity and mortality.

RESULTS

We identified 864 complete uterine ruptures in 2 625 017 deliveries. Overall prevalence was 3.3 (95% CI 3.1-3.5) per 10 000 deliveries, 22 (95% CI 21-24) in women with and 0.6 (95% CI 0.5-0.7) in women without previous CS. Prevalence in women with previous CS was negatively correlated with previous CS rate (ρ = -0.917) and positively correlated with TOLAC rate of the background population (ρ = 0.600). Uterine rupture resulted in peripartum hysterectomy in 87 of 864 women (10%, 95% CI 8-12%) and in a perinatal death in 116 of 874 infants (13.3%, 95% CI 11.2-15.7) whose mother had uterine rupture. Overall rate of neonatal asphyxia was 28% in neonates who survived.

CONCLUSIONS

Higher prevalence of complete uterine ruptures per TOLAC was observed in countries with low previous CS and high TOLAC rates. Rates of hysterectomy and perinatal death are about 10% following complete uterine rupture, but in women undergoing TOLAC the rates are extremely low (only 2.2 and 3.2 per 10 000 TOLACs, respectively.) TWEETABLE ABSTRACT: Prevalence of complete uterine rupture is higher in countries with low previous CS and high TOLAC rates.