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Midwifery Sector News

New Diagnostic Test for Amniotic Leaks

Vaginal wetness is common during pregnancy. Around 20% of pregnant women report to hospital[1] or birth units reporting wetness. In most cases, it is harmless, resulting from urinary incontinence or changes to the vaginal secretions. However, dampness may indicate a rupture of the membranes.

Unless there is an obvious rupture, a speculum examination will be performed to determine if there is any pooling of amniotic fluid. It is not standard NHS practice to use acidity or Ferning tests to confirm any pooling is amniotic fluid. In around 50% of cases, the wetness is urine and women are sent home.[2] However current testing methods do not always detect small ruptures and hind leaks, which is of concern for all maternity and midwifery professionals as any leak of amniotic fluid increases the risk of a serious neonatal infection (1% compared to 0.5% for women with intact membranes) and early onset of labour in that 60% of women will go into labour within 24 hours.[3]


AmnioSenseTM, is a new evidence based test which has been proven to be as accurate as hospital-based examinations (Ferning test, sterile speculum examination and pH test). NICE approved, AmnioSense is a two-stage diagnostic polymer strip within the comfortable and familiar format of a panty-liner.  Each liner can be worn for up to 12 hours to ensure continuous monitoring and can detect as little as 100 microliters of amniotic fluid — the equivalent of 2 drops.

The strip changes colour from yellow to blue or green when it comes into contact with any fluid which has a pH of more than 6.5, as is the case with amniotic fluid.[4] Unlike a speculum examination, AmnioSense allows for constant monitoring and ensures small, difficult to diagnose ruptures, such as hind leaks, are detected. AmnioSense provides reassurance and peace of mind for pregnant women.


Several studies have confirmed the accuracy, sensitivity and ease of use of AmnioSense. Samples of amniotic fluid taken from 50 women, between 16 and 23 weeks gestation, who were undergoing checks for foetal abnormalities showed that in all cases the AmnioSense test gave a positive response to the presence of amniotic fluid. The results could be read for up to 12 hours,[5] which 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.

A further study involving 339 women attending hospital with unexplained vaginal wetness found that AmnioSense correctly detected 96% of cases where a leak of amniotic fluid was confirmed.[6] This study also demonstrated the results are clear enough to be interpreted accurately by pregnant women, with 97% alignment between subjects and healthcare professionals.

Another trial investigated the use of AmnioSense with 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 had been so concerned they went straight to the hospital.[7]

In all, 139 were eligible for the trial and were asked to wear the AmnioSense panty-liner for 20 minutes, or until they were aware of any dampness. After 10 minutes, the liner was checked by a midwife, who recorded the results. A second midwife, who was given no information about the findings, then carried out tests involving internal examination using a speculum to confirm whether or not there was a leak.

Comparisons confirmed that AmnioSense detected 98% of leaks caused by amniotic fluid and 67% that were not caused by amniotic fluid. Two out of five (38%) could have been diagnosed without the need for invasive investigation using a speculum — which itself can increase the risk of infection. While there were some false positives, a quarter of these were linked to the presence of bacteria or fungal infections, including candida, Group B Strep and staphyolococcus aureus.

The study, published in the Journal of Obstetrics and Gynaecology concluded with reference to AmnioSense: “If used in clinical practice, the reduction in the number of speculum examinations will substantially benefit women and service providers. All women with a positive test result require further investigation.”

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.[8]  Of the 34 women with suspected leaks, rupture of the membranes was confirmed in 10 cases and every one was correctly identified by the AmnioSense panty-liner.


Appraisal by the National Institute for Health and Care Excellence (NICE)[9] concluded AmnioSense is sufficiently accurate to exclude a leak of amniotic fluid, would avoid unnecessary speculum examinations and has the potential to generate cost savings. NICE concluded that 42% of these examinations would be unnecessary if AmnioSense were used as a simple prenatal triage measure to rule out leaks caused by vaginal mucus or urine. Based on the evidence, NICE has recommended the adoption of AmnioSense in the community.


The feedback I have had from women who have tried AmnioSense is that it can take some of the worry out of pregnancy by providing a simple and accurate home test to confirm whether or not their waters have broken. AmnioSense also provided them with peace of mind.

As a result, timely adoption of this simple technology – AmnioSense – would provide reassurance and clear benefits for both maternity and midwifery healthcare professionals and women with suspected SROM, PROM and P-PROM.

See for more information.


[1] The summary was published in Hygeia Foundation, Inc. and Institute for Perinatal Loss. Premature Rupture of the Fetal Membranes Vol.2 No.4

by Kunle Odunsi M.D., and Paolo Rinaudo, M.D. Yale-New Haven Hospital.

[2] Ref needed

[3] NICE Clinical guideline CG190 Intrapartum care for healthy women and babies.

[4] NICE Medical Technology Guidance on file

[5] Odeh M, Ophir E, Kesari-Shoham H, Maximovsky O, Bornstein J.

The AL-SENSE Test Is Reliable for Detection of Second Trimester Amniotic Fluid   International Journal of Clinical Medicine, 2011, 2, 307-309.

[6] Bornstein J, Ohel G, Sorokin Y, Reape KZ, Shnaider O, Kessary-Shoham H, Ophir E. Effectiveness of a novel home-based testing device for the detection of rupture of membranes. Am J Perinatol. 2009 Jan;26(1):45-50.

[7] Mulhair L, Carter J, Poston L, Seed P, Briley A. Prospective cohort study – AmnioSense Int J Obstet & Gynecol 2008

[8] Bornstein J Nonintrusive Diagnosis AL-SENSE Am J Printol 2006 on file