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Multicenter Study
. 2014 Nov 5:349:g6223.
doi: 10.1136/bmj.g6223.

Risk of preterm delivery with increasing depth of excision for cervical intraepithelial neoplasia in England: nested case-control study

Alejandra Castanon  1 , Rebecca Landy  1 , Peter Brocklehurst  2 , Heather Evans  3 , Donald Peebles  2 , Naveena Singh  4 , Patrick Walker  3 , Julietta Patnick  5 , Peter Sasieni  6 ; PaCT Study Group
Collaborators, Affiliations
Multicenter Study

Risk of preterm delivery with increasing depth of excision for cervical intraepithelial neoplasia in England: nested case-control study

Alejandra Castanon et al. BMJ. .

Erratum in

  • BMJ. 2014;349:g7406. Chin, S [corrected to China, S]

Abstract

Objective: To determine the association between depth of excision of cervical intraepithelial neoplasia and risk of preterm birth.

Design: Case-control study nested in record linkage cohort study.

Setting: 12 hospitals in England.

Participants: From a cohort of 11 471 women with at least one histological sample taken at colposcopy and a live singleton birth (before or after colposcopy), 1313 women with a preterm birth (20-36 weeks) were identified and frequency matched on maternal age at delivery, parity, and study site to 1313 women with term births (38-42 weeks).

Main outcome measures: Risk of preterm birth and very/extreme preterm birth by depth of excisional treatment of the cervical transformation zone.

Results: After exclusions, 768 preterm births (cases) and 830 term births after colposcopy remained. The risk of preterm birth was no greater in women with a previous small (<10 mm) excision (absolute risk 7.5%, 95% confidence interval 6.0% to 8.9%) than in women with a diagnostic punch biopsy (7.2%, 5.9% to 8.5%). Women with a medium (10-14 mm) (absolute risk 9.6%; relative risk 1.28, 0.98 to 1.68), large (15-19 mm) (15.3%; 2.04, 1.41 to 2.96), or very large (≥ 20 mm) excision (18.0%; 2.40, 1.53 to 3.75) had a higher risk of preterm delivery than those with small excision. The same pattern was seen in 161 women with very/extremely preterm births (20-31 weeks) and with increasing volume excised. Most births were conceived more than three years after colposcopy, and the risk of preterm delivery did not seem to depend on time from excision to conception.

Conclusions: The risk of preterm birth is at most minimally affected by a small excision. Larger excisions, particularly over 15 mm or 2.66 cm(3), are associated with a doubling of the risk of both preterm and very preterm births. The risk does not decrease with increasing time from excision to conception. Efforts should be made to excise the entire lesion while preserving as much healthy cervical tissue as possible. Close obstetric monitoring is warranted for women who have large excisions of the cervical transformation zone.

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Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: support for the submitted work as described above; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

None
Fig 1 Inclusions in and exclusions from study
None
Fig 2 Sensitivity analyses and sub-analyses. Solid squares: relative risk of preterm birth for women with small excisions (<10 mm) relative to punch biopsy only. Open squares: relative risk of preterm birth with increasing depth of excision, excluding women with unknown depth. LLETZ=large loop excision of the transformation zone
See this image and copyright information in PMC

Comment in

References

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