Written by Community Midwife Emma Herbert
AmnioSense is a new, evidence-based non-invasive test for detecting amniotic fluid. It has been analysed and tested by several independent clinical studies and reviews, all confirming its efficacy and accuracy.
It has been proven to be as accurate as hospital-based examinations* and the National Institute for Health and Clinical Excellence (NICE) concluded that using AmnioSense alongside appropriate changes to clinical practice in the community should be encouraged.
The product, which takes the form of a panty-liner contains a two-stage diagnostic polymer strip that can tell if a pregnant woman is leaking amniotic fluid. Amniotic fluid has a pH of 6.7 or more, and if the strip comes into contact with a moisture with a pH of more than 6.5 it will turn a blue-green colour. Urine has a pH of between 4 and 8, so can cause a colour change, but ammonia causes a reagent to return the liner to its original colour within 10 minutes. If the result is caused by amniotic fluid the blue-green colour will remain for at least two hours. Using AminoSense means that both healthcare professionals and the expectant mother can be confident that any leaks of amniotic fluid will be quickly identified.
A few of the studies demonstrating the efficacy and accuracy of AmnioSense include;
- In its conclusion, NICE also reported that AmnioSense is sufficiently accurate to exclude a leak of amniotic fluid, would avoid unnecessary speculum examinations and has the potential to generate cost savings. Based on the evidence, NICE has recommended the adoption of AmnioSense within clinical practice in the community.
- The proof of principle test showed AmnioSense was 100% effective at identifying amniotic fluid. This was demonstrated beyond doubt by using samples of amniotic fluid taken from 50 women, between 16 and 23 weeks gestation, who were undergoing checks for foetal abnormalities. In all cases, the AmnioSense test gave a positive response to the presence of amniotic fluid: 100% accuracy. Perhaps more importantly, the results could be read for up to 12 hours, even though the manufacturer has adopted a very conservative approach and advises the test remains stable for at least two hours. This is important in a real-world setting as a woman could carry out the test at home, and still have time to get to her midwife or healthcare provider and show them the result while it was still reliable.
- A further study involving 339 women attending hospital with unexplained vaginal wetness found that AmnioSense correctly detected 154 of the 161 cases where a leak of amniotic fluid was confirmed. Writing in the American Journal of Perinatology, the researchers described AmnioSense as a, “Highly sensitive, non-intrusive method to detect the presence of amniotic fluid.”
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 some were so concerned they had gone straight to the hospital. In all, 139 between 18 and 24 weeks’ gestation, were eligible for the trial and these women were asked to wear the AmnioSense panty-liner for 20 minutes, or until they were aware of any dampness. The panty-liner was then reviewed for 10 minutes, for any colour change to stabilise, before being 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 identify any pooling of amniotic fluid and high vaginal swabs were taken in 103 out of 139 cases. Comparisons confirmed that AmnioSense detected 98% of leaks caused by leak of amniotic fluid and 67% of cases where there was urine and/or harmless vaginal discharge.
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.
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.”
The studies show that there are several potential applications for AminoSense, including using it in triage, to identify ‘leaks’ which are caused by urinary incontinence or an increase in harmless vaginal secretion, and to reserve speculum examination only for those women who have a positive result using the AmnioSense test.
As the NICE technology appraisal points out, this would save 42% of the speculum examinations currently carried out to determine whether or not there is a rupture of the membranes.
Find out more at www.amniosense.co.uk
 Marwan Odeh and Borstein J AL-SENSE IJCM20110300017_39572450
 Marwan Odeh and Borstein J AL-SENSE IJCM20110300017_39572450
 Effectiveness of a novel home-based testing device for the detection of rupture of membranes. Bornstein J, Ohel G, Sorokin Y, Reape KZ, Shnaider O, Kessary-Shoham H, Ophir E. Am J Perinatol. 2009 Jan;26(1):45-50.
 Mulhair L Prospective cohort study – AmnioSense Int J Obstet & Gynecol 2008
*When compared to the most common tests performed in hospital; sterile speculum examination, microscopic ferning test and pH paper test.
 Bornstein J Nonintrusive Diagnosis AL-SENSE Am J Printol 2006 on file
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