COVE R S TORY
check the position of babies, where simple abdominal palpation is less conclusive, and the Royal College of Obstetrics and Gynaecology recommends elective induction of labour at term for severely obese women.5
Ultrasound-guided regional anaesthesia and pain control Larger patients also present challenges for anaesthetists; carrying out IV and epidural insertions in very obese women is more problematic. If access can be evaluated by ultrasound before a woman is in the throes of active labour – at around 36-38 weeks – then it raises the success rate for these procedures should they be required once she is on the labour ward, for example, by knowing whether the epidural depth required is going to be 5 cm or 10 cm. Five to 10 years ago, it wasn’t essential for anaesthetists to be trained in neuraxial ultrasound techniques, but the need for these skills has increased with the ever- larger number of obese patients. If an obese woman has not had her back scanned prior to being in labour, anaesthetists will often carry out a quick landmark scan at the bedside before inserting the epidural, to improve the chances of success on the first attempt.6
High-risk anaesthetic patients also include women with a history of back or disc surgery, and ultrasound is useful in these
cases to explore the anatomy and assess the location of any scarring or metalwork that might impact on an epidural. In addition, ultrasound guidance can be used to place TAP blocks for pain control following a general anaesthetic for caesarean sections, as they have been shown to reduce the requirement for opioids post-op.
Scanning in the third trimester A significant proportion of the increase in ultrasound scans – monitoring growth or checking for viability when there is reduced fetal movement – can be attributed to the Saving Babies’ Lives care bundle, first drawn up in 2015 and updated in 2019, that aims to halve the rate of stillbirths in the UK by 2025. The first iteration of these guidelines resulted in a 35% increased referral rate for ultrasound examination from mothers reporting reduced fetal movements. The rate of stillbirths has reduced since then, with the second report in 20197
recommending
that growth scans continue after 36 weeks gestation, in the hope that ultrasound monitoring will help to spot babies who are growing normally until that point, but then do not grow as anticipated in the last few weeks.8 For most low-risk women their last scan is at 20 weeks, long before a baby settles into position for delivery, but studies have shown that universal scanning at 36 weeks
could also help to identify the 3- 4% of babies that are breeched. It is difficult to reliably confirm a breech presentation by abdominal palpation alone; research shows that this method is less than 70% accurate and approximately 20% of babies born in a breech position were not suspected. Planned caesarean delivery at term for breeched babies reduces the risk of perinatal morbidity and mortality. While better detection through ultrasound screening will increase the number of caesareans, it will also decrease the stress and complication of emergency sections.
The 36+ weeks scan premise is not yet an NHS pathway but is currently dictated by local decisions to resource and fund the huge increase in growth scans that it would create. The rise in quality and imaging capabilities of hand-carried ultrasound systems in the last few decades means that they could play an increasingly important role in easing this demand, perhaps sited away from the main central hospitals in community hubs. This model of care would be excellent for patients; a move towards continuity of care is encouraging rotation of midwives between the community and the labour ward. This would make teaching ultrasound skills and competency easier to manage, but would be hard to cost.
The new Mindray MX7 compact ultrasound system 14 l
WWW.CLINICALSERVICESJOURNAL.COM
An essential tool in the labour ward At present, a significant number of breeched presentations are first picked up as women are scanned on arrival to the labour ward as part of the admission assessment process, but presentation – cephalic or breech, face up or face down – is only the tip of the ultrasound iceberg in this setting. If a woman does go into labour before her due date, ultrasound will often be used instead of heart rate monitoring to check the baby throughout labour, as this is more reliable at picking up signs of distress in very premature babies. Examining the angle of progression and descent of the baby is also key for assessing slow and challenging labour, as information regarding the position of the baby is crucial to planning if and what instruments are to be used to aid vaginal delivery, or to decide to deliver the baby via caesarean section. While the use of ultrasound to guide instrumental deliveries is not mandatory, it is certainly recommended practice for most obstetricians now; however experienced the clinician, these are complicated procedures and medicolegally it’s a minefield if positioning is not accurate in the first place. For multiple babies too, ultrasound guidance is now considered to be the only safe way to manage vaginal delivery, by following the position of the babies and their progression through the birth canal. Most labour wards are equipped with the more compact, hand- carried, bedside ultrasound systems for these
AUGUST 2020
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