| Methods |
RCT.
November 2003 to December 2006.
Lehigh Valley Hospital Perinatal Testing Center. Pennsylvania, USA. |
| Participants |
Participants (N = 79)
“…women …with risk factors for spontaneous PTB were screened with serial transvaginal US beginning at 16 weeks' gestation”. “Risk factors for PTB included history of spontaneous PTB, second‐trimester pregnancy loss, previous cervical surgery (conization or loop excision), or documented uterine anomaly." "Also low‐risk, asymptomatic singleton pregnancies between 16 and 24 weeks' gestation were screened for evidence of cervical shortening with transabdominal ultrasound as part of routine anatomical survey.” “Patients with ultrasonographic evidence of short cervix, defined as transvaginal CL ≤ 25 mm, were offered enrolment into study".
Exclusion criteria
“…any known fetal chromosomal or structural anomaly, multiple gestation, known allergy to progesterone, ruptured membranes, vaginal bleeding, evidence of an active intra‐amniotic infection (diagnosed clinically or by amniocentesis), prolapse of endocervical membranes beyond the external cervical os, persistent uterine activity accompanied by cervical change, or an obstetrically indicated delivery.”
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| Interventions |
McDonald cerclage versus weekly intramuscular injections of 17 OHP‐C |
| Outcomes |
Primary: spontaneous preterm birth prior to 35 weeks' gestation.
Secondary: obstetrical complications and neonatal morbidity and mortality.
Obstetrical complications: included chorioamnionitis, abruption placentae, PPROM, need for a rescue procedure, days from study enrolment to delivery, and GA at delivery. Neonatal morbidity was stratified as follows: no morbidity was defined as no NICU admission and routine newborn care; mild morbidity was defined as NICU admission without severe morbidity; severe morbidity was defined as life threatening morbidity including respiratory distress syndrome requiring mechanical ventilation > 24 h, intraventricular haemorrhage, neonatal sepsis, or NEC. Perinatal death included any stillbirth or neonatal death during the study period
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| Notes |
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| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
“Randomisation was accomplished by computer generated assignment…”
“The randomisation sequence was secured by administrative stuff until enrolment was terminated.” |
| Allocation concealment (selection bias) |
Low risk |
“Assignments were concealed in sequentially numbered opaque envelopes by a coordinator not involved in screening, enrolment, or randomisation.”
“Randomisation was accomplished by handing out the sequentially numbered opaque envelopes.” |
| Blinding of participants and personnel (performance bias)
All outcomes |
High risk |
“Due to the intrinsic nature of the study design, there was no masking in this trial.” |
| Blinding of outcome assessment (detection bias)
All outcomes |
Unclear risk |
Not stated if outcome assessors were blinded |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
8/91 participants declined randomisation; no participants lost to follow‐up; 4/91 patients were excluded (2 PPROM, 2 positive amniocentesis); Analysis was intention‐to‐treat |
| Selective reporting (reporting bias) |
Unclear risk |
Study protocol not available |
| Other bias |
High risk |
Study was stopped early: “We anticipated randomising 160 patients to allow for attrition during the study. However, the trial was stopped early by the authors because 3 years of recruitment, an interim analysis showed no difference in outcome between treatment groups”.
No known baseline imbalance |
