Research Article: Screening for breech presentation using universal late-pregnancy ultrasonography: A prospective cohort study and cost effectiveness analysis

Date Published: April 16, 2019

Publisher: Public Library of Science

Author(s): David Wastlund, Alexandros A. Moraitis, Alison Dacey, Ulla Sovio, Edward C. F. Wilson, Gordon C. S. Smith, Jenny E. Myers

Abstract: BackgroundDespite the relative ease with which breech presentation can be identified through ultrasound screening, the assessment of foetal presentation at term is often based on clinical examination only. Due to limitations in this approach, many women present in labour with an undiagnosed breech presentation, with increased risk of foetal morbidity and mortality. This study sought to determine the cost effectiveness of universal ultrasound scanning for breech presentation near term (36 weeks of gestational age [wkGA]) in nulliparous women.Methods and findingsThe Pregnancy Outcome Prediction (POP) study was a prospective cohort study between January 14, 2008 and July 31, 2012, including 3,879 nulliparous women who attended for a research screening ultrasound examination at 36 wkGA. Foetal presentation was assessed and compared for the groups with and without a clinically indicated ultrasound. Where breech presentation was detected, an external cephalic version (ECV) was routinely offered. If the ECV was unsuccessful or not performed, the women were offered either planned cesarean section at 39 weeks or attempted vaginal breech delivery. To compare the likelihood of different mode of deliveries and associated long-term health outcomes for universal ultrasound to current practice, a probabilistic economic simulation model was constructed. Parameter values were obtained from the POP study, and costs were mainly obtained from the English National Health Service (NHS). One hundred seventy-nine out of 3,879 women (4.6%) were diagnosed with breech presentation at 36 weeks. For most women (96), there had been no prior suspicion of noncephalic presentation. ECV was attempted for 84 (46.9%) women and was successful in 12 (success rate: 14.3%). Overall, 19 of the 179 women delivered vaginally (10.6%), 110 delivered by elective cesarean section (ELCS) (61.5%) and 50 delivered by emergency cesarean section (EMCS) (27.9%). There were no women with undiagnosed breech presentation in labour in the entire cohort. On average, 40 scans were needed per detection of a previously undiagnosed breech presentation. The economic analysis indicated that, compared to current practice, universal late-pregnancy ultrasound would identify around 14,826 otherwise undiagnosed breech presentations across England annually. It would also reduce EMCS and vaginal breech deliveries by 0.7 and 1.0 percentage points, respectively: around 4,196 and 6,061 deliveries across England annually. Universal ultrasound would also prevent 7.89 neonatal mortalities annually. The strategy would be cost effective if foetal presentation could be assessed for £19.80 or less per woman. Limitations to this study included that foetal presentation was revealed to all women and that the health economic analysis may be altered by parity.ConclusionsAccording to our estimates, universal late pregnancy ultrasound in nulliparous women (1) would virtually eliminate undiagnosed breech presentation, (2) would be expected to reduce foetal mortality in breech presentation, and (3) would be cost effective if foetal presentation could be assessed for less than £19.80 per woman.

Partial Text: Undiagnosed breech presentation in labour increases the risk of perinatal morbidity and mortality and represents a challenge for obstetric management. The incidence of breech presentation at term is around 3%–4% [1–3], and fewer than 10% of foetuses who are breech at term revert spontaneously to a vertex presentation [4]. Although breech presentation is easy to detect through ultrasound screening, many women go into labour with an undetected breech presentation [5]. The majority of these women will deliver through emergency cesarean section (EMCS), which has high costs and increased risk of morbidity and mortality for both mother and child.

Recruitment to the POP study cohort is shown in Fig 2 and has been previously described [17]. Information about presentation at the 36-week scan was available for 3,879 women who delivered at the Rosie Hospital, Cambridge, UK; 179 of these had a breech presentation.

In a prospective cohort study of >3,800 women having first pregnancies, a presentation scan at approximately 36 wkGA identified the 4.6% of women who had a foetus presenting by the breech, and for more than half of these, breech presentation had not previously been clinically suspected. The majority of these women were ultimately delivered by planned cesarean section, some experienced labour before their scheduled date and were delivered by EMCS, and a small proportion had a cephalic vaginal delivery following either spontaneous cephalic version or ECV. No woman in the cohort had a vaginal breech delivery or experienced an intrapartum cesarean for undiagnosed breech. The low uptake of vaginal breech birth is likely to reflect the fact that this is a nulliparous population, and it is generally accepted that the risks associated with vaginal breech delivery are lower in women who have had a previous normal birth.



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