***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: Cervical injury is one of the most frequent complications of  suction curettage abortion  , yet little is known about its risk factors or prevention . In 15 438 suction curettage abortions carried out at less than or equal to 12 weeks ' gestation in hospitals in the USA from 1975 to 1978 the incidence of cervical injury requiring suturing was 1.03 per 100 abortions . Among factors potentially within the physician 's control , use of laminaria rather than rigid dilators for dilatation had a strong protective effect ( relative risk 0.19 ) , whereas performance of the abortion by a resident rather than an attending physician ( relative risk 2.0 ) and use of general rather than local anaesthesia ( relative risk 2.6 ) had detrimental effects on rates of cervical injury . Among other factors , a previous abortion had a protective effect ( relative risk 0.46 ) , whereas patient age less than or equal to 17 years had a detrimental effect ( relative risk 1.9 ) . Use of laminaria , performance of the abortion by an attending physician , and local anaesthesia together yield a 27-fold protective effect BACKGROUND Results from small-scale r and omized studies on the effectiveness of different preparations of nitric oxide donors in cervical priming before first trimester termination of pregnancies are not consistent . We compared sodium nitroprusside gel to misoprostol , the st and ard agent for cervical priming in this r and omized double-blinded controlled trial . METHODS Two hundred pregnant patients between 8 to 12 weeks admitted for surgical termination of pregnancy were recruited . They were r and omized into either 400 microg vaginal misoprostol and intracervical placebo gel , or 10 mg intracervical sodium nitroprusside gel and placebo tablets 3 h before the procedure . The baseline cervical dilatation and cumulative force required to dilate the cervix from 4 to 9 mm were measured with a tonometer . Blood pressure was measured and side effects were assessed . RESULTS The cumulative force to dilate the cervix from 4 to 9 mm was significantly higher in the sodium nitroprusside group , and the difference remained when a sub-group analysis was performed according to parity . Baseline cervical dilatation , duration of operation and operative blood loss were all in favour of misoprostol . Transient drop in blood pressure was observed after sodium nitroprusside treatment . CONCLUSIONS Intracervical sodium nitroprusside is not as effective as misoprostol in cervical priming Background . Vaginal administration of prostagl and in analogues as well as nitric oxide donors before first‐trimester surgical abortion has been shown to induce effective cervical ripening . In addition , nitric oxide donors , such as isosorbide mononitrate and nitroglycerin , have been associated with a patient‐friendly side‐effect profile when administered 3 h before the surgical procedure . We wanted to compare the cervical ripening effect and possible side effects of isosorbide mononitrate and the prostagl and in analogue misoprostol when self‐administered at bedtime the evening before surgical abortion . Methods . One hundred and twenty nulliparous women scheduled for suction termination of pregnancy in the first trimester were r and omly assigned to receive per vaginam either 40 mg of isosorbide mononitrate or 200 µg of misoprostol .  Sixty of the women were included for assessment of cervical ripening as well as evaluation of side effects . The other 60 women were recruited for assessment of side effects only . Cervical ripening was evaluated by measuring baseline cervical dilation and the cumulative force to dilate the cervix to 9 mm by means of a cervical tonometer . For assessment of side effects , the women were asked to complete a symptom question naire . Results . Cervical resistance was significantly higher in women treated with isosorbide mononitrate compared to misoprostol ( median cumulative force 73 versus 15 N ) . Common side effects of misoprostol  were abdominal pain ( 69 % ) , nausea ( 44 % ) , and vaginal bleeding ( 66 % ) , while in the isosorbide mononitrate group headache was frequently experienced ( 79 % ) . In both treatment groups , the frequency and intensity of side effects gradually increased during the treatment interval . Conclusions . Misoprostol induced a more pronounced cervical ripening than isosorbide mononitrate , but both regimens were associated with a high frequency of side effects OBJECTIVE To compare the efficacy and safety of vaginal applications of three different principles of cervical priming prior to first trimester curettage , isosorbide mononitrate ( ISMN ) , misoprostol and Dilapan-S , a hygroscopical cervical dilator . STUDY DESIGN Pregnant women with missed abortion between 6 and 12 gestational weeks were included and r and omly assigned to receive either 80 mg ISMN vaginal gel ( group 1 ) or 200 microg of misoprostol vaginal gel ( group 2 ) or Dilapan-S , a hygroscopical cervical dilator ( group 3 ) , for cervical ripening before curettage . Outcome parameters were cervical dilation at the time of operation and maximum dilation reached with Hegar 's dilator and the degree of difficulty in mechanical dilation as well as safety and side effects of the preparations . RESULTS Sixty-five pregnant women with missed abortion were included and assigned to the three study groups ( n=22 for group 1 , n=22 for group 2 , n=21 for group 3 ) . Misoprostol vaginal gel and Dilapan-S were significantly more effective than ISMN vaginal gel in cervical dilation reached with priming ( p<0.005 and p<0.005 ) and in the degree of difficulty in cervical dilation assessed by the surgeon ( p<0.001 and p<0.01 ) . Mild discomfort was indicated by all patients after Dilapan insertion , whereas no patient complained about discomfort after misoprostol or ISMN insertion ( p<0001 ) . Three patients suffered from mild hypotension and headache after ISMN treatment , and two had increased vaginal bleeding due to uterine atony during surgery ( p<0.05 ) . CONCLUSION A vaginal gel of ISMN is less effective for cervical ripening prior to first trimester curettage compared to misoprostol vaginal gel or Dilapan-S. The latter could be an effective and safe alternative to prostagl and in priming avoiding preoperative contractions caused by prostagl and in preparations OBJECTIVE To evaluate the efficacy of isosorbide mononitrate ( IMN ) for cervical ripening  prior to first trimester surgical termination of pregnancy . METHODS A prospect i ve , double-blind , r and omized , placebo-controlled trial . Women scheduled for surgical termination of a nonviable fetus before 12 weeks of gestation from October 2008 to June 2009 were enrolled and r and omly assigned to receive either 20 mg vaginally of IMN ( n=24 ) or a placebo ( n=24 ) 4 hours before suction evacuation . Cervical dilation before evacuation was assessed with 10-mm Hegar dilators followed by smaller sizes that were measured until the instrument passed freely through the internal os . Cervical dilation , adverse effects , termination complications , and patient satisfaction were the main outcomes . RESULTS Mean cervical dilation was not significantly different between the IMN and placebo groups ( 6.29+/-0.99 mm vs 5.71+/-1.04 mm ; P=0.05 ) . Mean operative time did not differ between the groups ( 16+/-0.07 min vs 18+/-0.06 min ; P=0.55 ) , nor did patient satisfaction measured by visual analogue scale ( 7.04+/-1.68 vs 6.54+/-1.22 ; P=0.24 ) . CONCLUSION IMN was comparable to placebo in terms of efficacy and patient satisfaction for cervical priming prior to first-trimester termination of pregnancy Objective To assess the efficacy of oral and vaginal misoprostol as cervical priming agents administered 1 hour before first trimester surgical termination of pregnancy Objective : The objective of this study was to compare NO-donor isosorbide mononitrate to misoprostol , both applied as vaginal tablets for cervical ripening prior to first trimester curettage in patients with missed abortion . Material s and methods : Thirty women with missed abortion were assigned after a r and om list to be treated either with 200 μg gemeprost ( Cytotec , Pfizer , Germany ) or with 40 mg isosorbide mononitrate for cervical priming at least 3 h before curettage . Vaginal bleeding or the intracervical presence of products of conception was documented . The largest number of Hegar ’s dilator , which could be introduced without difficulty and the largest number of Hegar ’s dilator at which cervical dilation was performed and the ease of mechanical dilation was assessed . Results : There were no significant differences in cervical ripeness before procedure nor in ease of dilation . In the misoprostol group , the cervical canal was more dilated before any procedure ( median of Hegar ’s dilator 6 vs. 5 ) and after dilation ( median of Hegar ’s dilator 11 vs. 10 ) , although this difference was not significant . Vaginal bleeding occurred in two patients in each group . Products of conception were only found in the cervix of one patient of the misoprostol group . Synopsis : Vaginal application of isosorbidemononitrate in cervical priming prior to curettage abortion is as effective as vaginal application of misoprostol Aim The present study was undertaken to compare the efficacy of isosorbide mononitrate ( IMN ) and misoprostol for  cervical ripening in termination of pregnancy between 8 and 12 weeks . Material s and methods This prospect i ve r and omized single blind study enrolled 40 women with singleton pregnancy seeking surgical termination of pregnancy between 8 and 12 weeks of gestation . They were divided into two groups — group I received IMN 40 mg while group II received misoprostol 40 mg vaginally , 3 h prior to suction and evacuation . All women were monitored for effects of cervical ripening and adverse effects . Results The mean sizes of dilators that could be negotiated without any resistance was 5.9 ± 1.33 in group I and 8.6 ± 0.94 in group II ( p < 0.001 , 95 % CI 0.58 , 0.41 ) . The mean dilator sizes at which resistance was first encountered was 6.9 ± 1.37 in group I and 9.9 ± 1.23 in group II ( p < 0.001 , 95 % CI 0.60 , 0.54 ) . The mean blood loss was 61.5 ± 13.86 ml in group I and 36.25 ± 12.80 ml in group II ( p < 0.001 , 95 % CI 6.07 , 5.63 ) . Headache was the most common adverse effect seen with IMN use . Conclusion The results show that IMN has a definite role and better safety profile than misoprostol in first trimester cervical ripening , although misoprostol is more effective and causes less blood loss OBJECTIVE To compare the efficacy of a nitric oxide donor ( isosorbide mononitrate ) and a prostagl and in E1 analogue ( misoprostol ) for cervical priming before suction termination of pregnancy . METHODS This was a r and omized , double blind , placebo-controlled trial . One hundred twenty-six healthy women requesting termination of pregnancy between 9 and 12 weeks ' gestation were recruited . Women were r and omized into three groups : control , isosorbide mononitrate , and misoprostol . All women were given moistened intravaginal study drugs ( placebo , 40 mg of isosorbide mononitrate , or 400 μg of misoprostol ) 4–6 hours before suction evacuation . Side effects were assessed 3 hours after drug administration . The cervical dilatation and the cumulative force required to dilate the cervix to 8 mm were measured by a cervical tonometer before suction evacuation . Operative blood loss was measured after sieving off the products of gestation . RESULTS There were no differences in the baseline cervical dilatation , cumulative force , and operative blood loss between the isosorbide mononitrate and placebo groups . However , women in the misoprostol group had a significantly greater cervical dilatation , required less cumulative force , and had less blood loss than women in the isosorbide mononitrate or control group . The majority ( more than 80 % ) of women in all three groups found their cervical priming agents acceptable . CONCLUSION Intravaginal isosorbide mononitrate was less effective than misoprostol in cervical ripening before suction termination of pregnancy Nitric oxide ( NO ) has been found to be involved in the processes of cervical ripening . In a r and omized , placebo-controlled study , cervical softening by an intracervical application of sodium nitroprusside , one of the most clinical ly potent and effective NO donor agents , was evaluated . A total of 36 primigravid women undergoing pregnancy termination between 9 and 12.5 weeks were enrolled . In one series , 18 patients 
    Output:
    
NO donors were more effective in cervical ripening when compared with placebo or no treatment .
NO donors are superior to placebo or no treatment , but inferior to prostagl and ins for first-trimester cervical ripening , and associated with more side effects