Women who underwent gastric band surgery to lose weight reported significant improvements in urinary function and quality of life after the operation, according to research published in the January issue of the urology journal BJUI.

However, men undergoing the procedure did not enjoy the same significant urinary function improvements as the women. They also reported that erectile function was slightly worse after surgery, unlike studies following non-surgical weight loss where sexual function actually improved.

Researchers surveyed 176 patients - 142 women and 34 men - who had undergone laparoscopic gastric banding surgery (LGB) at a single centre in Newcastle, Australia.

"We were keen to see what effect weight loss surgery had had on the patients' sexual and urinary functions, as these are common problems in people who are very obese" says study lead Dr Weranja Ranasinghe from the Department of Urology at Austin Hospital in Melbourne.

"Just under two-thirds of the women (65 per cent) and 24 per cent of the men had some urinary incontinence, while the majority of the men (83 per cent) had erection problems before surgery."

Estimates suggest that 1.6 billion adults worldwide are overweight and 400 million are obese. In 2007-8, 68 per cent of men and 55 per cent of women in Australia were overweight or obese. In Europe alone, obesity accounts for up to eight per cent of healthcare costs and up to 13 per cent of deaths.

"Gastric band surgery is increasingly being used to tackle the most severe cases of obesity, because carrying excess weight increases the risk of life-threatening conditions such as heart disease, high blood pressure and diabetes" says Dr Ranasinghe.

"However it is still regarded as a last resort by many surgeons, after non-surgical options like diet and exercise have failed, and there is limited data to show its effect on sexual and urinary function."

All the patients who had undergone surgery in the last ten years were invited to take part in the study and equal percentages of men and women agreed, providing the researchers with data on 34 males and 142 females. The average time that had elapsed since their surgery was just under 32 months.

The women had an average age of just under 48 years and the men averaged just under 53. The women averaged 118kg before surgery and the men averaged 146kg.

Weight loss following surgery was similar for both sexes, averaging just over 23kgs for the men and just under 23kgs for the women. However the women had a slightly higher BMI loss than the men (8.3 versus 7.5).

Key findings of the study included:

* The women in the study reported that weight loss had led to significant improvements in their urinary problems, possibly due to a reduction in intra-abdominal pressure, as soon as three to four months after surgery. And every kilogram lost led to a slight improvement in their quality of life score.

* Although women reported an overall improvement in urinary function, urge incontinence worsened. However, the authors say that this condition can be caused by a number of factors and the deterioration may be down to the time elapsed since surgery, not the weight loss.

* The men in the study did not show any improvement when it came to urinary function and the authors suggest that raised intra-abdominal pressure may not affect male urinary problems in the same way as females.

* Despite the men's significant weight-loss, the overall scores for erectile and orgasmic function declined over time. Age was not a factor in this reduction. This is at odds with the findings of other studies following non-surgical weight loss where sexual function actually improved.

"Urinary incontinence is common in people who are very obese and this study shows that gastric band surgery did improve the majority of urinary problems in women, with the exception of urge incontinence" concludes Dr Ranasinghe. "Our results highlight an added benefit of weight loss surgery, apart from the known improvements in cardiovascular mortality and diabetes risk etc.

"However the anticipated improvement in the men's sexual function, which has been observed in studies on non-surgical weight loss, did not materialise. In fact, the men in our study reported that their erection and orgasm problems worsened after surgery.

"A number of factors could have influenced this decline in sexual function after surgery. Our study looked at the short-term results of sexual function and these problems may improve in the long term. There is always a dip in sexual function after any form of surgery, due to psychological issues and fluctuating hormone levels. It is likely, therefore, that sexual function will improve over time.

"It is clear from our study that further research is needed to investigate the effects of gastric band surgery on urinary and sexual function, as such problems can be very distressing and cause a number of health and quality of life issues for patients."

The collaborative study also drew on the expertise of urology surgeon Mr Raj Persad from Bristol Royal Infirmary, UK, and upper gastrointestinal surgeon Dr Tim Wright from John Hunter Hospital, Australia, as well as the School of Medicine and Public Health at the University of Newcastle, Australia.