***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE The objective of the study was to assess cerclage to prevent recurrent preterm birth in women with short cervix . STUDY DESIGN Women with prior spontaneous preterm birth less than 34 weeks were screened for short cervix and r and omly assigned to cerclage if cervical length was less than 25 mm . RESULTS Of 1014 women screened , 302 were r and omized ; 42 % of women not assigned and 32 % of those assigned to cerclage  delivered less than 35 weeks ( P = .09 ) . In planned analyses , birth less than 24 weeks ( P = .03 ) and perinatal mortality ( P = .046 ) were less frequent in the cerclage group . There was a significant interaction between cervical length and cerclage . Birth less than 35 weeks ( P = .006 ) was reduced in the less than 15 mm stratum with a null effect in the 15 - 24 mm stratum . CONCLUSION In women with a prior spontaneous preterm birth less than 34 weeks and cervical length less than 25 mm , cerclage reduced previable birth and perinatal mortality but did not prevent birth less than 35 weeks , unless cervical length was less than 15 mm OBJECTIVE The aim of this study was to compare perinatal outcomes of patients with second-trimester ultrasonographic evidence of preterm dilatation of the internal os treated with cerclage  versus those of patients not treated with cerclage .  STUDY DESIGN From May 1998 through June 1999 patients with ultrasonographic evidence of preterm dilatation of the internal os between 16 and 24 weeks ' gestation were r and omly assigned to receive a McDonald cerclage or no cerclage .  Before r and om assignment all patients underwent amniocentesis and urogenital cultures and then received 48 hours of therapy with indomethacin and antibiotics . After treatment each patient was followed up as an outpatient with bed rest and weekly ultrasonographic evaluation . RESULTS Of the 61 patients 31 were r and omly assigned to cerclage and 30 were r and omly assigned to no cerclage . There were no differences between groups with respect to maternal demographic characteristics , risk factors for preterm birth , cervical measurements , rescue procedures , readmission , chorioamnionitis , and abruptio placentae . The mean gestational age at delivery ( 33.5 + /- 6.3 weeks ) and the perinatal death rate ( 12 . 9 % ) in the cerclage group were similar to the mean gestational age at delivery ( 34.7 + /- 4.7 weeks ; P = .4 ) and the perinatal death rate ( 10.0 % ; P = .9 ) in the no-cerclage group . CONCLUSION Treatment with McDonald cerclage of preterm dilatation of the cervix detected ultrasonographically during the second trimester did not improve perinatal outcomes Objective : To assess whether type of suture material affects cerclage efficacy for preterm birth ( PTB ) prevention . Methods : Secondary analysis of a multicenter trial of ultrasound-indicated cerclage for short cervical length ( CL ) , in which women with prior spontaneous PTB at 16–33 6/7 weeks , a singleton gestation and CL < 25 mm between 16–22 6/7 weeks , were r and omized to McDonald cerclage or no cerclage . Outcomes of women who underwent cerclage were analyzed by type of suture material , comparing polyester braided thread ( Mersilene ™ or Ethibond ™ ) to Mersilene tape ™ . Primary outcome was PTB < 35 weeks . Results : 138 women underwent McDonald cerclage :  84 ( 61 % ) received polyester braided thread and 46 ( 33 % ) Mersilene tape ™ . Eight ( 6 % ) received monofilament suture and were excluded from analysis . Rates of PTB < 35 weeks were similar , 35 % for polyester braided thread vs 24 % for Mersilene tape ™ ( p = .24 ) . Birth gestational age was also similar among the 2 groups ( p = .18 ) . Conclusion : Type of suture material may not affect ultrasound-indicated cerclage efficacy in high-risk women with short CL , but further study is needed . Polyester braided thread ( Mersilene ™ or Ethibond ™ ) and polyester braided Mersilene tape ™ seem to have similar efficacy OBJECTIVE To compare the effects of therapeutic cerclage and bed rest vs. just bed rest on cervical length and to relate these effects to the risk of preterm delivery . DESIGN Cervical length was measured in patients at high risk of cervical incompetence . When a cervical length < 25 mm was measured before 27 weeks ' gestation , r and omization for therapeutic cerclage and bed rest vs. just bed rest was performed . After r and omization , cervical length was measured weekly . For statistical analysis , t-test and Fisher 's exact tests were used and P < 0.05 was considered statistically significant . RESULTS Nineteen women were r and omly allocated to receive a therapeutic cerclage and bed rest  and 16 were allocated to receive bed rest only .  Mean cervical lengths and mean gestational ages before r and omization were comparable between both groups , overall 19.8 mm and 20.7 weeks . Cervical length was measured again at a mean gestation of 22.1 weeks . Mean cervical length ( 31 mm ) was significantly ( P < 0.0001 ) longer after cerclage than after bed rest only ( 19 mm ) . A cervical length > or = 25 mm was measured in 22 of the 35 included women , 16 in the cerclage group and six in the bed-rest group ( P = 0.006 ) . Of these 22 women , only one delivered before 34 weeks ' gestation , which was significantly less frequent than six out of 13 women with a cervical length < 25 mm ( P = 0.006 ) . CONCLUSIONS Therapeutic cerclage with bed rest increases cervical length more often than bed rest alone . A postintervention cervical length > or = 25 mm reduces the risk of preterm delivery in women at high risk of cervical incompetence and a preintervention cervical length < 25 mm OBJECTIVE The study was undertaken to measure cerclage location within the cervix and to determine whether placement closer to the internal os is related to perinatal outcome . STUDY DESIGN We analyzed data collected during a r and omized trial of cervical cerclage versus no cerclage that was conducted at Lehigh Valley Hospital between May 1998 and June 2001 in women with ultrasound findings of short cervix less than 25 mm or funneling between 16 and 24 weeks ' gestation . Women who were r and omly assigned to the cerclage arm had cervical measurements performed before cerclage , including dilation of the internal os , depth of membrane prolapse into the endocervical canal , cervical length below any funnel ( distal length ) , and total cervical length ( including any funnel ) . Measurements obtained after cerclage placement included the distance from external os to cerclage ( A ) , and a repeat of the same four measurements . The distance from the external os to the cerclage ( A ) was divided by the total cervical length ( B ) and a cerclage to cervical length ratio ( A/B ) was calculated . The relationship between these measurements and gestational age at birth was assessed by linear regression analysis . RESULTS Of 150 patients enrolled , 74 received a McDonald cerclage suture . Mean distal cervical length was 1.9+/-0.9 cm before and 2.9+/-1.0 cm after cerclage ( P=.001 ) . The mean distance between the cerclage and external os ( A ) was 1.8+/-0.6 cm ; the total cervical length after cerclage ( B ) was 3.6+/-0.9 cm . The mean cerclage to cervical length ratio ( A/B ) was 0.5+/-0.1 . Linear regression analysis did not demonstrate a correlation between either the cerclage to external os measurement ( A ) or the cervical length ratio ( A/B ) and gestational age at birth ( R(2)=0.0006 and 0.008 , P=.8 and .6 , respectively ) . CONCLUSION The length of the cervix below the level of cerclage is not related to duration of pregnancy in women treated with cerclage  because of ultrasound evidence of cervical effacement Internal os cerclage for cervical incompetence was performed in 90 patients who had previous McDonald procedure failure ( 70 patients ) or had unfavorable cervical anatomy ( short or lacerated cervix ) for primary McDonald type cerclage ( 20 patients ) . Two different techniques were used : the Shirodkar operation ( n = 44 ) with Mersilene b and , and a simpler new technique ( n = 46 ) . The new technique is characterized by anterior colpotomy for exposure of the internal os , and a 0.6 mm nylon suture encircling the cervix to be tied high in the posterior fornix . The pregnancy outcome for both groups was similar . Late abortions of 8.7 and 11 % and premature deliveries of 13 and 18 % occurred in the new technique and the Shirodkar groups , respectively . The removal of the suture was generally difficult in the Shirodkar group and in eight patients analgesia and sedation were required . In the new technique group , the removal was easier and in only one patient was sedation required ( p less than 0.0001 ) . Severe vaginal discharge was found in 52 % of the Shirodkar patients and none in the other group . Apparently the monofilament nylon suture prevented this side effect . It seems that the new technique is simpler to perform , involves fewer side effects , the removal of the suture is easier , and it is as effective as the Shirodkar procedure OBJECTIVE To determine the effectiveness of cerclage pessary in the prevention of  preterm birth in asymptomatic Chinese women with a short cervix at 20 to 24 weeks . METHODS Low-risk women carrying singleton pregnancies were screened with transvaginal ultrasound , and those with a cervical length < 25 mm at 20 to 24 weeks were recruited into a r and omized controlled trial , comparing the prophylactic use of cerclage pessary with expectant management . The analysis was by intent-to-treat . The primary outcome measure was preterm delivery before 34 weeks . RESULTS Among 4438 screened women , 203 women ( 4.6 % ) met the inclusion criteria and 108 ( 58 % ) consented for the study . A total of 53 and 55 women were allocated to pessary and control groups , respectively . There was no difference in background demographics , including the mean cervical length ( 19.6 mm versus 20.5 mm ) and the mean gestational age at r and omization ( both 21.9 weeks ) . Delivery before 34 weeks occurred in 9.4 % and 5.5 % ( p = 0.46 ) in the pessary and the control groups , respectively . No differences in major side effects were noted between the groups . CONCLUSION In our population , < 5 % had a cervical length of less than 25 mm at 20 to 24 weeks ' gestation . The prophylactic use of cerclage pessary did not reduce the rate of preterm delivery before 34 weeks AIM To compare the effectiveness of the double cervical cerclage method versus the single method in women with recurrent second-trimester delivery . METHOD In this r and omized clinical trial , we included 33 singleton pregnancies suffering from recurrent second-trimester pregnancy loss ( ≥2 consecutive fetal loss during second-trimester or with a history of unsuccessful procedures utilizing the McDonald method ) , due to cervical incompetence . Patients were r and omly assigned to undergo either the classic McDonald method ( n = 14 ) or the double cerclage method ( n = 19 ) . The successful pregnancy rate and gestational age at delivery was also compared between the two groups . RESULTS The two study groups were comparable regarding their baseline characteristics . The successful pregnancy rate did not differ significantly between those who underwent the double cerclage method or the classic McDonald cerclage method ( 100 % vs 85.7 % ; P = 0.172 ) . In the same way , the preterm delivery rate ( < 34 weeks of gestation ) was comparable between the two study groups ( 10.5 % vs 35.7 % ; P = 0.106 ) . Those undergoing the double cerclage method had longer gestational duration ( 37.2 ± 2.6 vs 34.3 ± 3.8 weeks ; P = 0.016 ) . CONCLUSION The double cervical cerclage method seems to provide better cervical support , as compared with the classic McDonald cerclage method , in those suffering from recurrent pregnancy loss , due to cervical incompetence The pregnant women at higher risk of preterm labor , referred to the perinatal clinic of Kosar University Hospital in Urmia district of Iran , were enrolled into a parallel r and omized clinical trial . In the investigational arm of the clinical trial , a double cervical cerclage procedure was performed addition to McDonald cerclage . In the control group however , only McDonald cerclage was performed .  Extreme preterm labor ( GA < 33 weeks ) was the primary endpoint of this clinical trial . Age , gestational age at cerclage time , and gravidity were not found to be statistically different between the groups . Means of gestational age were 37.4 and 36.2 weeks , respectively , for the 
    Output:
    
Cervical cerclage reduces the risk of preterm birth in women at high-risk of preterm birth and probably reduces risk of perinatal deaths .