AmnioSense for unexplained vaginal wetness in pregnancy

Stringer and Hornbuckle (2016)

Study size, design and location

Poster abstract of an observational study reporting outcomes of 148 symptomatic pregnant women over 20 weeks of pregnancy after using AmnioSense as a SROM screening tool.

Australia.

Intervention and comparator(s)

AmnioSense (under an alternative brand name, AL‑SENSE).

Key outcomes

39 women had a positive AmnioSense test result, 36 of whom had a diagnosis confirmed within 48 hours resulting in a sensitivity of 94.7%. The remaining 109 received negative results. There were 90 women with negative results who were discharged. Of these, 6 women re-presented within 12 hours, 2 were subsequently diagnosed with SROM resulting in a specificity of 97.2%. No adverse events recorded. Compared with a retrospective group, using AmnioSense resulted in 39 minutes less in the assessment unit.

Strengths and limitations

This study has reasonable sample size and reports the number of confirmed positive diagnoses and adverse events after using AmnioSense. The study does not compare direct use of the technology with standard screening tools, and sample demographics were not reported. Sensitivity and specificity of AmnioSense were not reported. Retrospective comparisons can be confounded by uncontrolled variables. The study was done in Australia so results may not be generalisable to the UK.

Bornstein et al. (2009)

Study size, design and location

A blinded, repeated measures study evaluating the reliability of Vision ALD in identifying leaking amniotic fluid in 339 pregnant women over 16 weeks of pregnancy.

Israel and US.

Intervention and comparator(s)

Vision ALD (previous version of technology under alternative brand name, AmniScreen).

Standard diagnosis including visualisation of vaginal pooling, crystallisation and nitrazine testing.

Key outcomes

Vision ALD displayed a sensitivity of 96% (154/161) and a specificity of 84% (125/148). Overall, agreement between the patient's interpretation of the Vision ALD result and the healthcare professional was 97%.

Strengths and limitations

The study was a large, multicentre, blinded study comparing the results of the Vision ALD with current standard of care diagnostic techniques. Results of the technology were interpreted by the patient and a healthcare professional who was blinded to the subject's interpretation. This design allows for generalisability for patient use. Confidence intervals have not been calculated. The study uses an earlier version of the technology and was conducted outside of the UK so results may not be generalisable. This study was supported by the company.

Mulhair et al. (2009)

Study size, design and location

A blinded, repeated measures, prospective cohort study comparing the outcomes of Vision ALD and a speculum examination in 139 women between 18 and 42 weeks of pregnancy.

UK.

Intervention and comparator(s)

Vision ALD (previous version of technology under alternative brand name, AmnioSense).

Speculum examination.

Key outcomes

Vision ALD correctly identified intact membranes in 52 women and ruptured membranes in 58 women. Vision ALD resulted in 28 false positives, 7 of which were associated with a positive high vaginal swab result. There was 1 woman who had a false negative result. Vision ALD showed a sensitivity of 98% (58/59; 95% CI 91 to 100) and specificity of 65% (52/80; 95% CI 54 to 75).

Strengths and limitations

This study is a well-designed comparator study. The outcomes measures of prevalence, sensitivity and specificity are relevant to the evaluation of the technology. The study was appropriately powered and was done in the UK. There was a higher percentage of Caucasian subjects in the cohort compared with the population and subgroups were insufficiently powered for analyses. The study was done in a clinical setting and is not generalisable to home use. This study was done using an earlier version of the technology.

Bornstein et al. (2006)

Study size, design and location

103 women attending a labour and delivery ward were categorised into 3 groups: positive control, negative control and study group. The diagnostic efficacy of Vision ALD was tested in each group and compared with standard care diagnostic procedures.

Israel.

Intervention and comparator(s)

Vision ALD (previous version of technology under alternative brand name, AL‑SENSE).

Standard diagnosis including visualisation of vaginal pooling, crystallisation and nitrazine testing.

Key outcomes

In the study group (n=34), Vision ALD had a sensitivity of 100% (10/10; 95% CI 69.15 to 100) and a specificity of 75% (18/24; 95% CI 65.47 to 93.24) in detecting PROM. In the positive control group (n=42), all women correctly had a positive result using the technology. In the negative control group (n=27), Vision ALD correctly identified 23 of 25 negative cases, 2 women of the 27 had ruptured membranes. The overall agreement between the Vision ALD test result and the clinical diagnosis was 82.35%.

Strengths and limitations

The study compares use of the Vision ALD liner with relevant clinical diagnosis. Appropriate outcome measures were reported. The technology was tested across a range of clinical presentations. The study was done with an earlier version of the technology and was done in Israel so results may not be generalisable to the UK. The study was partially supported by a grant from the company.

Abbreviations: CI, confidence interval; PROM, premature rupture of membranes; SROM, spontaneous rupture of membranes; Vision ALD, vision amniotic lead detector.