![]() The lower the specificity of the diagnostic method being utilised, the higher the likelihood of false positives. The Implications of False Positives and False Negativesįalse positives occur when the diagnostic methodology indicates ROM when the membranes of the mother-to-be are in fact intact. ![]() Risk factors include infection, miscarriage, rupture of membranes, cramping and vaginal bleeding and the Amnio-Dye Test is seldom used in contemporary medical practice. ROM is confirmed by placing a tampon in the vagina and observing the tampon for the presence of blue dye. Once considered the gold standard for diagnosing ROM, the Amnio-Dye test requires an invasive amniocentesis and injection of a blue dye into the amniotic fluid. ![]() ![]() Ultrasound, however, is unable to detect small reductions of amniotic fluid, and marked reductions in levels may result from other clinical factors such as severe uteroplacental insufficiency. 3 UltrasoundĪlthough ultrasound alone is not diagnostic, it may be used to support a diagnosis as oligohydramnios (low amniotic fluid) is highly suggestive of ROM when combined with a characteristic history. The Fern Test has a reported sensitivity of 51% for women not in labour, and a specificity of 70%. False positives have been recorded as a result of fingerprints, and contamination with blood, semen or cervical mucus. The presence of amniotic fluid is determined by the appearance of a characteristic crystal pattern. The Fern Test requires the collection of cervicovaginal secretions which are then dried and examined under a microscope. 2 As a result the sensitivity of the Nitrazine test ranges from 90-97% and the specificity from 16-70%. Nitrazine paper is used to confirm only a change in the pH levels of cervicovaginal secretions within the naturally acidic environment of the vagina, and is associated with high false positive rates related to cervicitis, vaginitis, alkaline urine, and contamination with blood, semen or antiseptic agents. The Nitrazine/pH Test requires the use of a swab to collect cervicovaginal secretions. The efficacy of this method is compromised in cases where the leak of amniotic fluid is small, and the presence of vaginal infections such as cervicitis or vaginitis can lead to high false positive diagnoses. PoolingĪ speculum is used to visually determine the presence of a pool of amniotic fluid in the posterior vaginal fornix which is highly suggestive of amniorrhexis (rupture of membrane). The most commonly used conventional diagnostic for PROM is the sterile speculum examination (SSE). We are indebted to Dr Ross McQuivey, MD, for his clinical input. This article aims to provide an overview of the various diagnostic options available to clinicians and their comparative reliability in providing an accurate diagnosis of rupture of membranes (ROM). 1 Timely and accurate diagnosis allows for gestational age-specific interventions to optimise perinatal outcomes and minimise the risk of potential complications to both the mother and the foetus. PPROM is associated with three causes of neonatal death: prematurity, sepsis and pulmonary hypoplasia and there are maternal risks associated with chorioamnionitis. In the UK, pre-term premature rupture of membranes (PPROM) complicates only two percent of pregnancies, but is associated with 40% of preterm deliveries and can result in significant neonatal morbidity and mortality. PROM is defined as the spontaneous rupture of membranes prior to the onset of actual uterine contractions, and accurate diagnosis is crucial to allow timely and appropriate intervention. Once a rupture has occurred, the mother-to-be is at risk of going into labour irrespective of gestational age, and has an increased risk of developing infection. Biochemical changes that occur naturally during or just prior to labour reduce the integrity and elasticity of the membranes, rendering them vulnerable to rupture and thus contributing to the initiation of labour. The amniotic membrane protects the foetus and intact, healthy foetal membranes encourage an optimal pregnancy outcome. Premature rupture of membranes (PROM) is a significant complicating factor in contemporary obstetric practice. By: Articles 17 September 2012 Introduction
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