Premature Rupture Of Membrane

PREMATURE MEMBRANE 1

Background The definition of premature rupture of membrane (PROM) is rupture of membranes before the onset of labor. When membrane rupture occurs before 37 weeks of gestation, it is referred to as preterm PROM. Premature rupture of membranes can result from a wide array of pathologic mechanisms acting individually or in concert ( Ventura SJ, Martin JA, Curtin SC, Mathews,1997)

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The gestational age at membrane rupture has significant implications regarding the etiology and consequences of PROM. Management may be dictated by the presence of overt intrauterine infection, advanced labor, or fetal compromise. When such factors are not present, especially with preterm PROM, other interventions may have a significant impact on maternal and infant morbidity. An accurate assessment of gestational age and knowledge of the maternal, fetal, and neonatal risks are essential to appropriate evaluation, counseling, and management of patients with PROM. Etiology Membrane rupture may occur for a variety of reasons. At term, weakening of the membranes may result from physiologic changes combined with shearing forces created by uterine contractions ( French JI, McGregor JA,1996). Intrauterine infection has been shown to play an important role in preterm PROM, especially at earlier gestational ages (McGregor JA, French JI,1997 ). Factors associated with an increase in PROM include lower socioeconomic status, sexually transmissible infections, prior preterm delivery especially due to PROM, vaginal bleeding, cervical conization, and cigarette smoking during pregnancy (Harger JH, Hsing AW, Tuomala RE, Gibbs RS, Mead PB, Eschenbach DA, et al,1989). Uterine distention (hydramnios, twins), emergency cervical cerclage, prior antepartum antibiotic treatment, and preterm labor also may be associated with PROM. In many cases, however, PROM may occur in the absence of recognized risk factors. Term Premature Rupture of Membranes At term, PROM complicates approximately 8% of pregnancies and is generally followed by the onset of labor and delivery. In a large randomized trial, half of women with PROM who were managed expectantly delivered within 5 hours, and 95% delivered within 28 hours of membrane rupture (Gold RB, Goyert GL, Schwartz DB, Evans MI, Seabolt LA,1990 ). Other studies have reported similar rates (Wagner MV, Chin VP, Peters CJ, Drexler B, Newman LA;1989). The most significant maternal risk of term PROM is intrauterine infection, a risk that increases with the duration of membrane rupture (Hannah ME, Ohlsson A, Farine D, Hewson SA, Hodnett ED, Myhr TL, et al. ,1996 ). Fetal risks associated with PROM include umbilical cord compression and ascending infection. Preterm Premature Rupture of Membranes Regardless of management or clinical presentation, birth within 1 week is the most likely outcome of any patient with PROM prior to term. A review of 13 randomized trials reported that approximately 75% of patients with preterm PROM who were managed expectantly delivered within 1 week (Mercer BM, Arheart KL,1995 ). The earlier in gestation that PROM occurs, the greater the potential for pregnancy prolongation. With expectant management, 2.8-13% of women can anticipate cessation of fluid leakage (Mercer BM,1992 ). Of women with preterm PROM, clinically evident intraamniotic infection occurs in 1360% and postpartum infection occurs in 2-13% (Vergani P, Ghidini A, Locatelli A, Cavallone M, Ciarla I, Cappellini A, et al. , 1994). The incidence of infection increases with decreasing gestational age at membrane rupture (Hillier SL, Martius J, Krohn M, Kiviat N, Holmes KK, Eschenbach DA,1988 ) and increases with digital vaginal examination (Schutte MF, Treffers PE, Kloosterman GJ, Soepatmi,1983) with

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appropriate management risk ofmaternal sequelae are uncommon. Fetal malpresentation is increased with preterm PROM. Abruptio placentae affects 4-12% of pregnancies with preterm PROM (Ananth CV, Savitz DA, Williams MA,1996). The most significant risks to the fetus after preterm PROM are complications of prematurity. At all gestational ages prior to term, respiratory distress has been reported to be the most common complication (Fanaroff AA, Wright LL, Stevenson DK, Shankaran S, Donovan EF, Ehrenkranz RA, et al,1995)other serious forms of morbidity, including necrotizing enterocolitis and intraventricular hemorrhage, also are associated with prematurity but are less common nearer to term. The presence of maternal infection poses the additional risk of neonatal infection. Infection, cord accident, and other factors contribute to the 1-2% risk of antenatal fetal demise after preterm PROM (Mercer BM, Arheart KL,1995). Midtrimester Premature Rupture of Membranes Premature rupture of membranes occurring before and around the time of neonatal viability often is referred to as midtrimester PROM. Premature rupture of membranes at 16-26 weeks of gestation complicates almost 1% of pregnancies ( . Schucker JL, Mercer BM,1999). e the 1970s, delivery in the second trimester was generally associated with neonatal death resulting from complications of prematurity. Primarily because of advances in neonatal intensive care over the past two decades, neonates are surviving at increasingly younger gestational ages. Currently, overall infant survival after delivery at 24-26 weeks of gestation is reported to be between 50% and 75% (Kilpatrick SJ, Schlueter MA, Piecuch R, Leonard CH, Rogido M, Sola A.,1997).survival rates in pregnancies complicated by PROM are comparable but decreased in the presence of infection or deformations. A small number of patients with midtrimester PROM will have an extended latency period. In a review of 12 studies evaluating patients with midtrimester PROM, the mean latency period ranged from 10.6 to 21.5 days ( Schucker JL, Mercer BM,1997).Although delivery occurred within 1 week of membrane rupture in 57% of patients, in 22% of patients pregnancy continued for 1 month. Most studies of midtrimester PROM have been retrospective and include only those patients amenable to expectant management. Patients usually are excluded from analysis in the presence of labor, infection, prolapsed membranes, and fetal demise, thus potentially exaggerating the latency period to delivery and deceptively decreasing the apparent maternal and infant morbidity. Reported maternal complications of midtrimester PROM include intraamniotic infection, endometritis, abruptio placentae, retained placentae, and postpartum hemorrhage. Maternal sepsis is a rare but serious complication reported to affect approximately 1% of cases (Schucker JL, Mercer BM,1997). The incidence of stillbirth subsequent to PROM at 16-25 weeks of gestation ranges from 3.8% to 21.7% (Bengtson JM, VanMarter LJ, Barss VA, Greene MF, Tuomala RE, Epstein MF,1989).compared with 0-2% with PROM at 30-36 weeks of gestation (Cox SM, Leveno KJ,1995). This increased rate of death may be explained by increased susceptibility of the umbilical cord to compression or of the fetus to hypoxia and intrauterine infection. Alternatively, this finding may reflect the lack of intervention for fetal compromise prior to neonatal viability. The fetal survival rate subsequent to PROM at less than 24 weeks of gestation

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has been reported to be about 30%, compared with a 57% survival rate with rupture at 24-26 weeks of gestation (Schucker JL, Mercer BM,1997). Several trials have described outcomes of survivors after PROM at 16-26 weeks of gestation (Morales WJ, Talley T.,1993).Although up to 69% of these neonates were reported as having normal neurologic development, these results may be biased by a lack of follow-up. Generalized developmental delay, delayed motor development, and other less frequent complications, including cerebral palsy, chronic lung disease, blindness, hydrocephalus, and mental retardation, also were reported to occur. A variety of conditions that are associated with fetal lung compression or oligohydramnios or both can result in pulmonary hypoplasia. Reported risks of pulmonary hypoplasia after PROM at 16-26 weeks of gestation vary from less than 1% to 27% (Moretti M, Sibai BM.,1988). Pulmonary hypoplasia rarely occurs with membrane rupture subsequent to 26 weeks of gestation, presumably because alveolar growth adequate to support postnatal development already has occurred (.van Eyck J, van der Mooren K, Wladimiroff JW,1990). Prolonged oligohydramnios also is associated with in utero deformation including abnormal facies (ie, low-set ears and epicanthal folds) and limb positioning abnormalities. When leakage of amniotic fluid occurs after amniocentesis, the outcome is better than after spontaneous preterm PROM. In one study of 603 women who had second-trimester amniocentesis for prenatal diagnosis of genetic disorders, seven women (1.2%) experienced PROM, and leakage stopped in all with conservative management ( Gold RB, Goyert GL, Schwartz DB, Evans MI, Seabolt LA,1989).

References 1. Ventura SJ, Martin JA, Curtin SC, Mathews TJ. Report of final natality statistics, 1995. Monthly vital statistics report; vol 45, no. 11, supp. Hyattsville, Maryland: National Center for Health Statistics, 1997 2. French JI, McGregor JA. The pathobiology of premature rupture of membranes. Semin Perinatol 1996;20:344-368

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3. McGregor JA, French JI. Evidence-based prevention of preterm birth and rupture of membranes: infection and inflammation. J SOGC 1997;19:835852 4. Harger JH, Hsing AW, Tuomala RE, Gibbs RS, Mead PB, Eschenbach DA, et al. Risk factors for preterm premature rupture of fetal membranes: a multicenter case-control study. Am J Obstet Gynecol 1990;163:130-13 5. Gold RB, Goyert GL, Schwartz DB, Evans MI, Seabolt LA. Conservative management of second trimester post-amniocentesis fluid leakage. Obstet Gynecol 1989;74:745-747 6. Hannah ME, Ohlsson A, Farine D, Hewson SA, Hodnett ED, Myhr TL, et al. Induction of labor compared with expectant management for prelabor rupture of the membranes at term. N Engl J Med 1996;334:1005-1010 7. Wagner MV, Chin VP, Peters CJ, Drexler B, Newman LA. A comparison of early and delayed induction of labor with spontaneous rupture of membranes at term. Obstet Gynecol 1989;74:93-97 8. Mercer BM, Arheart KL. Antimicrobial therapy in expectant management of preterm premature rupture of the membranes. Lancet 1995;346:1271-1279 9. Mercer BM. Management of premature rupture of membranes before 26 weeks' gestation. Obstet Gynecol Clin North Am 1992;19:339-351 10. Vergani P, Ghidini A, Locatelli A, Cavallone M, Ciarla I, Cappellini A, et al. Risk factors for pulmonary hypoplasia in second-trimester premature rupture of membranes. Am J Obstet Gynecol 1994;170:1359-1364 11. Hillier SL, Martius J, Krohn M, Kiviat N, Holmes KK, Eschenbach DA. A case-control study of chorioamnionic infection and histologic chorioamnionitis in prematurity. N Engl J Med 1988;319:972-978 12. Morales WJ. The effect of chorioamnionitis on the developmental outcome of preterm infants at one year. Obstet Gynecol 1987;70:183-186 13. Schutte MF, Treffers PE, Kloosterman GJ, Soepatmi S. Management of premature rupture of membranes: the risk of vaginal examination to the infant. Am J Obstet Gynecol 1983;146:395-400 14. Ananth CV, Savitz DA, Williams MA. Placental abruption and its association with hypertension and prolonged rupture of membranes: a methodologic review and meta-analysis. Obstet Gynecol 1996;88:309-31 15. Fanaroff AA, Wright LL, Stevenson DK, Shankaran S, Donovan EF, Ehrenkranz RA, et al. Very-low-birth-weight outcomes of the National Institute of Child Health and Human Development Neonatal Research Network, May 1991 through December 1992. Am J Obstet Gynecol 1995; 173:1423-1431 16. Schucker JL, Mercer BM. Midtrimester premature rupture of the membranes. Semin Perinatol 1996;20:38 17. Kilpatrick SJ, Schlueter MA, Piecuch R, Leonard CH, Rogido M, Sola A. Outcome of infants born at 24-26 weeks' gestation: I. Survival and cost. Obstet Gynecol 1997;90:803-808 18. Moretti M, Sibai BM. Maternal and perinatal outcome of expectant management of premature rupture of the membranes in midtrimester. Am J Obstet Gynecol 1988;159:390-396

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19. Bengtson JM, VanMarter LJ, Barss VA, Greene MF, Tuomala RE, Epstein MF. Pregnancy outcome after premature rupture of the membranes at or before 26 weeks' gestation. Obstet Gynecol 1989;73:921-926 20. Cox SM, Leveno KJ. Intentional delivery versus expec- tant management with preterm ruptured membranes at 30-34 weeks' gestation. Obstet Gynecol 1995;86:875-879 21. Mercer BM, Crocker LG, Boe NM, Sibai BM. Induction versus expectant management in premature rupture of the membranes with mature amniotic fluid at 32 to 36 weeks: a randomized trial. Am J Obstet Gynecol 1993;169:775-782 22. Morales WJ, Talley T. Premature rupture of membranes at <25 weeks: a management dilemma. Am J Obstet Gynecol 1993;168:503-507 23. van Eyck J, van der Mooren K, Wladimiroff JW. Ductus arteriosus flow velocity modulation by fetal breathing movements as a measure of fetal lung development. Am J Obstet Gynecol 1990;163:558-566

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