A UK study looked at 157 women attending the antenatal unit at St Thomas’ Hospital in London with a suspected leak of amniotic fluid. Some had been referred to the unit by their GP or midwife, while others were so concerned they had gone straight to the hospital*. In all, 139 women between 18 and 24 weeks’ gestation, were eligible for the trial.
These women were asked to wear the AmnioSense panty-liner for 20 minutes, or until they were aware of any dampness. Ten minutes after they removed the panty-liner, when any colour change had stabilised, it was checked by a midwife, who recorded the results. A second midwife, who was given no information about the findings, then carried out a speculum examination to try to detect any pooling of amniotic fluid.
Comparisons confirmed that AmnioSense detected 98% of leaks caused by urine and harmless vaginal discharges and 67% of cases where there was a leak of amniotic fluid.
Crucially, two out of five cases of rupture (38%) could have been diagnosed without the need for an invasive speculum examination; a quarter of the ‘false’ positives were subsequently linked to the presence of bacteria or fungal infections; rupture was retrospectively identified in two women and seven went on to deliver within 3 days — suggesting AmnioSense has greater sensitivity and accuracy than speculum examination.
The study, published in the International Journal of Obstetrics and Gynaecology concluded: “If used in clinical practice, the reduction in the number of speculum examinations will substantially benefit women and service providers.”
Another study reviewing AmnioSense compared results from 103 women, aged 18 to 45, attending the labour and delivery ward of a university-affiliated hospital in Israel. A third had suspected leaks, rupture was confirmed in another third and the remaining third had no symptoms and provided a control group. Of the 34 women with suspected leaks, rupture of the membranes was confirmed in 10 cases and everyone was correctly identified by the AmnioSense panty-liner.
Of six ‘false’ positives identified in the AmnioSense group, four were found to have bacterial vaginosis and two went into labour shortly after speculum examinations.
The investigators concluded that AmnioSense is: “A highly sensitive, non-intrusive method for use in ruling out the possibility of PROM. It is also capable of differentiating PROM from urinary incontinence or vulvo-vaginal candidiasis, thereby avoiding misdiagnosis, unnecessary treatment, and interventions, which reduces patient anxiety and lowers costs.”
* Mulhair L Prospective cohort study - AmnioSense Int J Obstet & Gynecol 2008