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Advances in amniotic fluid detection


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amniotic fluid detection

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Advances in amniotic fluid detection

  1. 1. Advances in Amniotic Fluid detection Dr. B. K. Iyer
  2. 2. The perception of PROM <ul><li>Sensation of wetness in 3rd trimester. </li></ul>Cause for concern? Urine Amniotic fluid leak PROM Source: James Alexander et al, Seminars in Perinatology, Vol 20, No 5, 1996: pp 369-374; Mercer et al, Am J Obstet Gynecol, 1999 Bacterial vaginosis PPROM
  3. 3. PROM overview Source: James Alexander et al, Seminars in Perinatology, Vol 20, No 5, 1996: pp 369-374; Mercer et al, Am J Obstet Gynecol, 1999 Premature ROM (PROM) Rupture of the amniotic sac and leakage of amniotic fluid beginning at least 1 hours before the onset of labor at any gestational age. (PPROM) is the rupture of membranes before 37 weeks of gestation. Occurs in 3 % of pregnancies & is responsible for 1/3 of preterm births 10% of pregnant women are diagnosed with PROM (responsible for 25- 30% of premature births
  4. 4. PPROM risks & complications Premature ROM (PROM) <ul><li>A history of PPROM, </li></ul><ul><li>Genital tract infection, </li></ul><ul><li>Antepartum bleeding, & </li></ul><ul><li>Cigarette smoking. </li></ul><ul><li>Maternal and neonatal infection, </li></ul><ul><li>Foetal distress </li></ul><ul><li>Preterm delivery, </li></ul><ul><li>Abruptio placenta, and </li></ul><ul><li>Cord prolapse. </li></ul><ul><li>Failure to identify patients with PROM can result in the failure to implement salutary obstetric measures </li></ul><ul><li>Infection precedes PPROM and is the serious side effect of PPROM. </li></ul><ul><li>Intra-amniotic infection of the chorion and amnion [chorioamnionitis] can harm the fetus and newborn </li></ul>Risk factors Complications
  5. 5. PPROM monitoring & management Premature ROM (PROM) <ul><li>Foetus surveillance: count fetal movement at least BID, 10 fetal movements in a 12-hours period. </li></ul><ul><li>Monitor the volume of amniotic fluid remaining in the amniotic sack </li></ul><ul><li>Check for Signs of stress on Foetal monitor </li></ul><ul><li>Try prevention of infection due to amniotic sac rupture. </li></ul><ul><li>Relieve psychological stress due to prolonged bed rest and possibility of premature birth </li></ul><ul><li>Bed rest and pelvic rest- to ↑ amniotic fluid reaccumulation and avoid infection </li></ul><ul><li>Induction of labor – to ↓ infection risk </li></ul><ul><li>Tocolytics – prophylactic tocolysis after PPROM has been shown to prolong latency </li></ul><ul><li>Corticosteroids – to reduce respiratory distress syndrome </li></ul><ul><li>Antibiotics – to prolong pregnancy, reduce chorioamniotis, neonatal sepsis, postpartum endometritis, intraventricular hemorrhage </li></ul>Monitoring Management
  6. 6. PPROM presentation & problems Premature ROM (PROM) <ul><li>PROM diagnosis AFTER 24 hours from its occurrence increases the chances of prenatal morbidity and mortality </li></ul><ul><li>Wrong and untimely PROM diagnosis constitute 2 independent risk factors of pre- & post- natal complications </li></ul>Clinical history suggestive of PPROM must be confirmed by visual inspection or laboratory tests to exclude other causes of wetness such as urinary incontinence, vaginal discharge, and perspiration Classic clinical presentation of PPROM is a sudden gush of clear or pale yellow fluid from the vagina Many women describe intermittent or constant leakage of small volumes of fluid or a sensation of wetness within the vagina or perineum
  7. 7. PPROM diagnostic difficulties Optimal method for PROM diagnosis is controversial & PROM diagnosis is difficult when Candida vaginitis or bacterial vaginosis are also possible causes of vaginal discharge that can mimic PROM The classic ‘‘gush of fluid’’ does not occur There is spotting The fluid leak is slow Urinary incontinence occurs in the 3 rd trimester <ul><li>Wetness in a pregnant woman [eagerly waiting to meet her baby] leaves her anxious & helpless, running to hospital every time she senses wetness </li></ul><ul><li>Over 20% of women reaching the hospital with sensation of wetness are sent home as this wetness is diagnosed to be due to urine. </li></ul><ul><li>On the other hand, many women, for whom wetness is caused by amniotic leak interpret it as urine and avoid visiting the hospital, which may lead to harm for both mother & baby. </li></ul>
  8. 8. Current diagnostic approaches
  9. 9. PPROM diagnostic approaches Current methods of PROM diagnosis on suspicion include: <ul><li>Although normal vaginal pH is 3.5 to 4.5, amniotic fluid pH is above 6.0. </li></ul><ul><li>A false -ve nitrazine test can occur when there is only a tiny amount of fluid leak, such as in chronic membrane rupture or so-called high rupture of the membranes </li></ul>USG Speculum examination to visualize fluid collection in the posterior fornix, mainly while the patient is asked to cough Microscopic techniques include the identification of fetal lanugo hair or the microscopic detection of a crystallization pattern (ferning test) Litmus paper or nitrazine indicator to determine the pH of fluid obtained from the vaginal pool during speculum examinations Amnio-Dye Infusion
  10. 10. PPROM diagnostic approaches Speculum examination <ul><li>Pooling is the best method of confirming PPROM as direct observation of amniotic fluid emerging from cervical canal or pooling in vaginal fornix </li></ul>Accuracy Basis Technique Drawbacks <ul><li>Visualization of an amniotic pool in the posterior fornix of the vagina </li></ul><ul><li>Subjective </li></ul><ul><li>Speculum exam is required. Urine, semen, and other fluids can easily be mistaken for amniotic fluid and vice versa. </li></ul>Source: Contemp Ob/GYN, Sept 15 2005, Joong Shin Park and Errol R. Norwitz
  11. 11. PPROM diagnostic approaches Ferning <ul><li>A confirmatory test is the presence of Arborization pattern (crystallization) of dry amniotic fluid as seen through a microscope </li></ul>Accuracy Basis Technique Drawbacks <ul><li>Fluid from the posterior vaginal fornix is swabbed onto a glass slide & allowed to dry for 10 minutes. </li></ul><ul><li>Amniotic fluid produces a delicate ferning pattern, in contrast to the thick and wide arborization pattern of dried cervical mucus </li></ul><ul><li>False positive results are 5-30% </li></ul><ul><li>False negative results are 12.9% </li></ul><ul><li>Sensitivity 51.4% (no labor) </li></ul><ul><li>Specificity 70.8% (no labor) </li></ul><ul><li>Speculum exam is required to collect the sample. </li></ul><ul><li>Needs microscope </li></ul><ul><li>False +ves from slide contamination with fingerprints or semen & cervical mucus contamination. </li></ul><ul><li>False -ve due to dry swabs, contamination with blood / discharge. </li></ul>Source: Contemp Ob/GYN, Sept 15 2005, Joong Shin Park and Errol R. Norwitz
  12. 12. PPROM diagnostic approaches Ultrasound <ul><li>USG looks at the size of the uterus </li></ul>Accuracy Basis Technique Drawbacks <ul><li>Ultrasound can detect oligohydramnios, suggesting loss of amniotic fluid due to membrane rupture </li></ul><ul><li>Not a reliable screening test if used alone. Used only to help confirm diagnosis </li></ul><ul><li>Time-consuming. Requires equipment and expertise. Can only detect significant loss of amniotic fluid. Can’t confirm cause of fluid loss. Not all hospital facilities have ultrasound expertise easily accessible on a 24/7 basis. </li></ul>Source: Contemp Ob/GYN, Sept 15 2005, Joong Shin Park and Errol R. Norwitz
  13. 13. PPROM diagnostic approaches Nitrazine <ul><li>Confirmed by pH testing of vaginal fluid, which is done with nitrazine paper </li></ul>Accuracy Basis Technique Drawbacks <ul><li>Amniotic fluid is alkaline and turns Nitrazine pH indicator blue. Amniotic fluid has a pH range of 7.0-7.7 compared to the normally acidic vaginal pH of 3.8 to 4.2 </li></ul><ul><li>False positive results are up to 17.4% </li></ul><ul><li>False negative results are 12.9% </li></ul><ul><li>Sensitivity 90.7% </li></ul><ul><li>Specificity 77.2% </li></ul><ul><li>False +ve can be due to the presence of alkaline fluids in the vagina such as blood, seminal fluid or infections as Trichomonas BV, alkaline urine. </li></ul><ul><li>False -ve can occur when leaking is intermittent or the amniotic fluid is diluted by other vaginal fluids. </li></ul>Source: Contemp Ob/GYN, Sept 15 2005, Joong Shin Park and Errol R. Norwitz
  14. 14. PPROM diagnostic approaches Amnio-Dye Infusion <ul><li>Documenting leakage of dye into the vagina. </li></ul>Accuracy Basis Technique Drawbacks <ul><li>Instillation of dilute indigo carmine into the amniotic cavity and confirmation of rupture of membranes by documenting dye leakage &staining of tampon within 20-30 minutes </li></ul><ul><li>“ Gold Standard” for diagnosis of rupture of membranes </li></ul><ul><li>Accurate, but expensive & highly invasive (requires amniocentesis) which is associated with risk to pregnancy including bleeding, infection, latrogenic rupture of membranes, and loss of pregnancy (approximately 1 in 270). </li></ul>Source: Contemp Ob/GYN, Sept 15 2005, Joong Shin Park and Errol R. Norwitz
  15. 15. PPROM diagnostic approaches Conclusions “ Nitrazine and Ferning tests indicated that these tests have high inaccuracy rates, which increase progressively when more than one hour has elapsed since the rupture of the membranes, and become unreliable after 24 hours. It is concluded that in cases of prolonged PROM these tests provide no better diagnostic information than that obtained by simple clinical evaluation.” Reference 3 Reference 1 Reference 2 “ We note that the fern test is neither sensitive nor specific enough for diagnostic determination of premature rupture of membranes. We recommend against routinely providing fern testing alone for the detection of ruptured membranes.” “ We note that the pH / nitrazine test when applied to patients suspected of having PROM, the test does not appear to be sufficiently sensitive or specific enough for diagnostic determination of premature rupture of membranes.” Source: Trovo S. et al.Minerva Ginecol.1998;50(12):519-512 Source: NACB. Laboratory Medicine Practice Guidelines 2007. p 142-143.
  16. 16. PPROM diagnostic problems Current methods Time / labor/material costs (speculum, microscope, etc.) Sub-clinical / Silent cases Labor intensive Invasive or inaccurate <ul><li>Misdiagnosed ROM has caused unwarranted patient transfers </li></ul><ul><li>Safety & satisfaction of patient often compromised </li></ul><ul><li>Cost of unwarranted use of medications when false +ve ROM diagnosis is made. </li></ul><ul><li>Cost of potentially life-long complications when false-negative ROM diagnosis is made. </li></ul>Not detectable by ANY of the prevalent methods (aside from dye instillation that is rarely done)
  17. 17. PPROM diagnostic problems Search for new diagnostic methods Developed test systems had high rates of false results Since 1970s, multiple proteins of amniotic fluid have been discovered like Placental Alpha Microglobulin-1 PAMG-1, Alpha Feta Protein (AFP), Fetal Fibronectin (fFn), etc. that have high concentration in amniotic fluid, while having smaller concentration in blood serum However, wide range and variance of concentrations in different patients noticed with overlapping of levels in amniotic fluid with its levels in the background <ul><li>Women with high background concentration of the given antigen may test false +ve even with intact fetal membranes. </li></ul><ul><li>On the contrary, women with unusually low antigen concentration in the background and small ROM may test false-negative. </li></ul>UNRESOLVED PROBLEMS IN TESTING FOR ROM: No accurate test No easy to use test No home prescription test