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Short cervix on midtrimester USS screening: what outcome for the low risk population?
  1. C Alviani1,
  2. AL David1,2,
  3. J Braschi2,
  4. K Nicolaides1,
  5. A Kenyon1,2
  1. 1UCL Institute for Women's Health, London, UK
  2. 2University College Hospital London, London, UK


Introduction Screening pregnant women using midtrimester assessment of cervical length (CL) by trans-vaginal ultrasound identifies those at increased risk of preterm birth (PTB). The management of women with short CL and no other PTB risk factors remains unclear; cervical cerclage does not reduce the PTB risk, and the effect of progesterone on neonatal outcome is undetermined. Following the introduction of CL screening at University College Hospital, the authors report the outcome of low risk women with CL≤15 mm.

Methods From 1 January 2009 all women underwent a midtrimester CL assessment. The authors reviewed the outcome of singleton pregnancies for the following year after excluding women with no risk factors for PTB (previous PTB, cervical surgery, uterine anomaly).

Results Of 3408 pregnancies screened, 22 (0.64%) had a CL≤15 mm. 12 have complete outcome data (six ongoing pregnancies). 50% delivered at ≥37 weeks. Of those delivering <37 weeks the median (range) gestation was 25+5 weeks (18–35+1 weeks). 7/12 women had a fetal fibronectin test performed and all were negative. These women delivered at >35 weeks: median 38+4 weeks (35+1 to 40+0). CL in those delivering <37 weeks was not significantly different to those delivering ≥37 weeks (median CL 6.5 vs 9 mm). Emergency cervical cerclage was placed in three women (CL 2, 13 and 14 mm) who delivered at 23+6, 24+6 weeks and 35+1, respectively. Progesterone was prescribed in four women (31%) who delivered at >35 weeks.

Conclusion Over half the women with incidental CL≤15 mm on midtrimester ultrasound screening with no other PTB risk factors delivered after 35 weeks. This study supports conservative management of these women.

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