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Preterm birth affects up to 12.5% of all births and remains a significant burden to healthcare services, with an estimated health cost of more than £2.9 billion in the UK. Over the last 10 years, the identification of women at high risk of a preterm birth has been revolutionised by greater recognition of the impact of risk factors, such as cervical surgery, and the increased use of transvaginal ultrasound surveillance of cervical length during pregnancy.
This advance in ultrasound detection of women at risk of preterm birth has occurred at a time when new treatment options have been identified, to such an extent that we now appear to have several treatment options for short cervix, namely cervical cerclage,[6, 7] progesterone[8, 9] and Arabin cervical pessary, all of which appear, at least from the limited comparative data currently available, to be similarly efficacious. However, a note of caution must be sounded because of the recent controversies over intramuscular 17α-hydroxyprogesterone caproate.
A lack of formal guidance from bodies such as the Royal College of Obstetricians and Gynaecologists (RCOG) and the American College of Obstetricians and Gynecologists (ACOG) has hampered a clear approach to management. For example, RCOG suggests that high-risk women without a short cervix may be offered either serial sonographic assessment or expectant management, because of the high chance of delivery at >33 weeks in all high-risk groups.
Although preventative treatment options are well defined, the indications for when to treat are still hotly debated, with cut-offs for cervical length of 25 mm or 15 mm and centile charts all being used. Further controversies exist over the effectiveness of other management options, including fetal fibronectin testing, treatment of bacterial vaginosis, vaginal pH testing, the use of vaginal probiotics, aspirin and dietary advice, such as high oily fish intake.
The increasing complexity of management of these pregnancies has naturally led some units to develop dedicated preterm labour (PTL) clinics. This has occurred despite a recent Cochrane review which states that there is a paucity of evidence to support the benefits of a specialist PTL clinic.
It is noteworthy that neither RCOG nor ACOG has made any recommendation on the use of specialist PTL clinics. However, Whitworth et al. state that, despite a lack of proven cost-effectiveness, specialist clinics are here to stay, a statement which mirrors the introduction of a variety of specialised antenatal clinics in other areas (maternal medical disorders, multiple pregnancy).
This survey aimed to identify current practice within the UK, given the variety of management options and lack of good quality of guidelines. We hoped that clarification of the current provision would lead to the development of a more standardised approach to care, at least within the context of a social care system.
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The survey (Appendix S1) with a covering letter was mailed to each of the 210 NHS hospitals with a consultant obstetric unit in the UK (England, Wales, Scotland, Northern Ireland, Channel Islands and Isle of Man). The first round of questionnaires was sent in November 2012 and this was followed up by a second round in February 2013 to those units which had not responded to the initial invitation. If the unit did not have a specialist PTL clinic, the responder was thanked for their time and no further questions were necessary.
For those units with a specialist PTL clinic, further questions established the frequency of clinics, staffing and local protocols. Particular emphasis was placed on risk stratification and management options, including the use of transvaginal ultrasound, treatment options for a short cervix and other complementary investigations and advice. Finally, each unit was asked whether their clinical data was regularly audited and made available for external scrutiny.
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Of the initial 210 units identified, 12 responses were excluded as the unit no longer provided acute obstetrics, or had merged with other hospitals, leaving 198 hospitals for consideration. The survey was sent in two rounds in November 2012 and February 2013, achieving an overall response rate of 144/198 (73%).
Of the 144 responders, 48 units (33%) reported a delivery rate of >5000 per annum, 73 (51%) between 2500 and 5000, and 23 (16%) of <2500, with 19, three and one specialist PTL clinic, respectively. All specialist PTL clinics were located within England.
One unit with a specialist PTL clinic provided information about staffing and frequency, but failed to provide any information about their management policy, and was therefore excluded from the later analysis of clinic management. One unit performed screening tests on both high- and low-risk women, but was included in the analysis to demonstrate the range of clinical care offered. The staffing and skills mix is reported in Table 1.
Table 1. Staffing and organisation of specialist preterm labour clinics
| Staffing of preterm labour clinic || N = 23 |
|Lead clinician-university staff||7 (30%)|
|Lead clinician-NHS staff||16 (69%)|
|Designated midwife||11a (55%)|
| Cervical length assessment operator || N = 22 |
|Obstetric consultant||17 (77%)|
|Obstetric trainee||8 (36%)|
|Staff grade||2 (9%)|
|Research/clinical fellow||6 (27%)|
All units invited women with a history of previous preterm birth, although there was significant heterogeneity in what gestation constituted a clinically significant previous preterm birth (Table 2). Other indications for referral to a PTL clinic included previous preterm prelabour rupture of membranes (PPROM) (n = 20, 95%), uterine anomalies (n = 19, 90%), recurrent first trimester miscarriage (n = 1, 5%), recurrent second trimester miscarriage (n = 20, 95%) and previous cervical surgery (n = 20, 95%). The significance given to cervical surgery also varied, with some considering a single large loop excision of the transformation zone (LLETZ) as significant (n = 11, 52%), whereas others invited women with two (LLETZ) procedures (n = 20, 95%) or a cone biopsy (n = 20, 95%). The timing of appointments also varied significantly, with 11 (55%) clinics seeing women at <12 weeks for their initial appointment and all units seeing them before 20 weeks (Table 2).
Table 2. Indication for referral and general management structure of specialist preterm labour (PTL) clinics
|Indication for referral to PTL clinic||N = 21a (%)||Initial clinic appointment||N = 20b (%)|
|Previous preterm birth||21 (100)||≤12 weeks||11 (55)|
|Previous PPROM||20 (95)||12–14 weeks||3 (15)|
|1 × LLETZ||11 (52)||15–16 weeks||2 (10)|
|2 × LLETZ||20 (95)||17–18 weeks||2 (10)|
|Cone biopsy||20 (95)||19–20 weeks||1 (5)|
|Uterine anomalies||19 (90)||As soon as referred||1 (5)|
|Recurrent first trimester loss||1 (5)|
|Recurrent second trimester loss||20 (95)|
| Gestation of previous preterm birth ||N = 21a (%)|| Frequency of follow-up || N = 22 (%) |
|<37 weeks||3 (14)||Every 2 weeks||4 (18)|
|<35 weeks||1 (5)||Every 4 weeks||1 (5)|
|<34 weeks||10 (48)||Based on clinical findings||17 (77)|
|<32 weeks||5 (24)|
|<28 weeks||2 (10)|
Thirteen units (59%) initiated treatment with a cervical length of <25 mm, whereas two units used a cut-off of 15 mm (9%). A further four units (18%) used a variety of different cut-off measurements for treatment, and three units (14%) used a cervical normogram (Table 3).
Table 3. Cervical length measurement deemed to be sufficiently significant to require primary treatment
| Cervical length at treatment || N = 22 |
|<25 mm||13 (59%)|
|<15 mm||2 (9%)|
|Centile charts||3 (14%)|
| Primary treatment choice || N = 22 |
|Cervical cerclage||10 (45%)|
|Vaginal progesterone||4 (18%)|
|Arabin cervical pessary||1 (4%)|
|Multiple therapiesa||5 (22%)|
|Dependent on clinical picture||2 (9%)|
The most commonly used primary treatment for asymptomatic women with ultrasound-detected short cervix was cervical cerclage (n = 10, 45%). However, both vaginal progesterone pessaries (n = 4, 18%) and Arabin cervical pessary (n = 1, 5%) were also used. Some units treated with multiple modalities (n = 5, 23%), which included a combination of cervical cerclage with vaginal progesterone (two units), cervical cerclage with intramuscular progesterone (one unit), cervical cerclage with rectal progesterone (one unit) and vaginal progesterone with Arabin cervical pessary (one unit). If we include units that used multiple therapies, primary treatment involved cervical cerclage in 14 units (64%), vaginal progesterone in seven units (31%), Arabin cervical pessary in two units (9%) and rectal and intramuscular progesterone in one unit (5%) each.
Thirteen units (59%) regularly assessed vaginal flora, seven units (32%) used fetal fibronectin and three units (14%) utilised the cervical stress test, whereas no units routinely assessed vaginal acidity as part of their management strategy. If bacterial vaginosis was diagnosed, nine units (45%) treated with vaginal clindamycin, three units (15%) with oral clindamycin, seven units (35%) with metronidazole and two units (10%) did not treat bacterial vaginosis (Table 4).
Table 4. Other assessments and additional advice routinely conducted within specialist preterm labour clinics
|Other assessments||N = 22 (%)||Additional advice||N = 22 (%)|
|Vaginal flora||13 (59)||Restricting physical activity||10 (45)|
|Vaginal acidity||0||Sick leave||6 (27)|
|Cervical stress test||3 (14)||Refraining from sexual intercourse||9 (41)|
|Fetal fibronectin||7 (32)||Nutrition||6 (27)|
|None of the above||5 (23)||Bed rest||0|
|No further advice given||8 (36)|
| Management of bacterial vaginosis ||N = 20a (%)|| Gestational age at discharge || N = 22 (%) |
|Vaginal clindamycin||9 (45)||24 weeks||1 (5)|
|Oral clindamycin||3 (15)||28 weeks||9 (41)|
|Oral metronidazole||7 (35)||30 weeks||1 (5)|
|We do not treat bacterial vaginosis||2 (10)||34 weeks||8 (36)|
|Until delivery||3 (14)|
An array of additional advice was given to women managed within specialist PTL clinics, which included restricting physical activity (n = 10, 46%), avoidance of sexual intercourse (n = 9, 41%), stopping work (n = 6, 27%) and dietary advice (n = 6, 27%) (Table 4). However, eight units (36%) did not routinely give any additional advice.
After a diagnosis of short cervix, women were followed up within the specialist PTL clinic until 24 weeks (n = 1, 5%), 28 weeks (n = 9, 41%), 30 weeks (n = 1, 5%), 34 weeks (n = 8, 36%), 37 weeks or until delivery (n = 3, 14%) (Table 4). Outcomes from women seen within the specialist PTL clinic were routinely audited by 17 units (77%), but the information from only four units (18%) was publicly available.