29 Dec 2011
By: JOAN CHEW
It used to be that a woman giving birth by caesarean section (C-section) would be fully anaesthetised, waking up only when it was all over.
These days though, more women are choosing to stay conscious so they can participate in the delivery of their babies.
Thomson Medical Centre reported 75 per cent of women undergoing C-section deliveries this year chose regional anaesthesia over general anaesthesia, up from 61 per cent in 2006. More than 2,500 women have C-sections at the private obstetrics centre a year.
Doctors in other private practices also noted a similar trend.
Dr Law Wei Seng, a consultant obstetrician and gynaecologist at Pacific Healthcare Specialist Centre, said nine in 10 women undergoing C-section now opt for regional anaesthesia, up from about six in 10 women a decade ago.
The proportion is also nine in 10 now at the Obstetrics & Gynaecology Centre at Paragon Medical, up from seven in 10 about 15 years ago, said its medical director, Dr Chee Jing Jye.
At KK Women’s and Children’s Hospital (KKH), about 85 per cent of the 1,800 women who had a C-section last year had regional anaesthesia, a trend that has stayed constant in the last five years, said a spokesman. Figures before that at KKH are not available.
While patients have the last say on the type of anaesthesia they prefer, the trend towards regional anaesthesia has been driven in the last decade by doctors who have been encouraging women to choose a regional block as a safer option over general anaesthesia.
Dr Chong Jin Long, president of the College of Anaesthesiologists, said pregnancy changes a woman’s biological make-up.
The weight gain from carrying a foetus results in a higher basal metabolic rate, which is the rate at which the body uses energy and oxygen to perform vital body processes such as breathing.
As a result, pregnant women can develop hypoxia, or oxygen deficiency, more quickly than other patients – a problem that is exacerbated when a person is put under general anaesthesia, added Dr Chong, who practises at Mount Alvernia Hospital.
This is because drugs used to suppress the part of the brain that controls consciousness also affects ventilation by muting the breathing reflex.
Associate Professor Ong Biauw Chi, head and senior consultant at the department of anaesthesiology at Singapore General Hospital (SGH), said muscle tone in the pharynx is also lost temporarily and the tongue tends to fall backwards, both of which obstruct the airway and cause breathing difficulties.
In addition, a patient’s cough reflex, which usually works to get rid of secretions such as saliva and mucus, is impaired when general anaesthesia is used. These secretions then accumulate and obstruct the airway.
These issues can usually be solved by passing a tube down the airway to provide mechanical ventilation to the woman, but this is not easy to do for pregnant women because of pregnancy-linked physiological changes, doctors said.
Dr Law said pregnant women tend to have narrow airways because of an increase in fat tissue in the airway from hormonal changes and the occurrence of water retention.
She is also predisposed to regurgitating her stomach contents due to the pressure of the enlarged uterus on the stomach, he added.
Dr Chong said that under general anaesthesia, a pregnant woman would temporarily lose function of the sphincter muscle that prevents gastric juices from flowing back up. As a result, the acid may inadvertently enter the lungs and cause pneumonitis, a potentially fatal lung infection.
Overseas studies show that as many as 2 per cent of all maternal deaths in the 1960s was the result of backflow of acid into the lungs.
After thinking through the risks, Madam Marcia Norman, a 29-year-old housewife, changed her mind about having general anaesthesia for the birth of her third child.
On Dec 16, she gave birth to her daughter by C-section at SGH. She had regional anaesthesia and felt no pain.
She recalled: “I was awake to see my baby girl being delivered and hear her cries. And I had her by my side almost immediately afterwards.”
But while doctors may encourage mothers to choose a regional block over general anaesthesia for various reasons, they say general anaesthesia is very safe and women should not worry about choosing it.
Associate Professor Ti Lian Kah, senior consultant at the department of anaesthesia at National University Hospital, said surgery under general anaesthesia becomes fatal usually because of an underlying condition or a complication of the pregnancy, and not from anaesthetic use.
In fact, when there is immediate threat to the life of the foetus or mother and an emergency C-section is required, doctors may still use general anaesthesia.
This is because surgery can begin quicker when general anaesthesia is induced.
A study in the Journal Of Obstetrics And Gynaecology published in July 2006 showed that the mean delay in time between induction of anaesthesia and surgery was nine minutes longer in the regional anaesthesia (18.5 minutes) group as compared to the general anaesthesia (9.5 minutes) group.
But the use of regional anaesthesia during emergency C-section did not lead to a significant decrease in Apgar score, a test which reflects newborn babies’ state of health. A baby who scores seven or above on the test one minute after birth is considered healthy.
As general anaesthesia is safe, some women prefer it.
Mrs Thanamalar Prabhu, a 37-year-old special education teacher, chose to be asleep the three times that she gave birth by C-section.
She has a two-week-old baby and two girls aged three and five.
She said: “I’d rather not be aware of what is happening.”
Email: joanchew@sph.com.sg
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