14. Screening in pregnancy

Cervical screening during pregnancy is a special circumstance, as additional consideration needs to be given for the wellbeing of the fetus. The incidence of cervical cancer in pregnancy is low, with estimates in the literature ranging from 3.3 to 26 cases per 100,000 births.[1][2] However, early-stage cervical cancer may be more frequently encountered by clinicians caring for women during their pregnancy due to higher age-specific incidence rates in the 30–39 year age group, compared with younger ages,[3] and more women delaying pregnancy.[4] Although most cases of cervical abnormalities are likely to be asymptomatic and identified through screening, it is important to consider non-obstetric causes when a pregnant women reports vaginal bleeding (see Chapter 18. Investigation of abnormal vaginal bleeding).[5]

Approximately five per cent of pregnant women will have abnormal cervical cytology.[6] It is strongly recommended that, routine antenatal care should include cervical screening when this is due or overdue. For some women, pregnancy may be the first, or only, opportunity for cervical screening and cervical cancer is more likely to be diagnosed in never screened or under-screened women.[3] For pregnant women who accept their cervical screening specimen being collected by a practitioner the tool of choice should be a broom type brush, as the endocervical(cytobrush) brush is not recommended. The use self-collection of a vaginal sample for HPV testing is not contraindicated during pregnancy, and pregnant women should be offered the choice of either a practitioner or self-collected sample.

Conservative management of high-grade squamous intraepithelial lesions (HSIL) is recommended during pregnancy.[7] Colposcopy is performed to exclude the presence of invasive cervical cancer, to confirm the presence of pre-invasive disease and reassure the pregnant woman that it is safe to continue with her pregnancy. When HSIL is diagnosed during pregnancy, treatment can be delayed until after delivery[8] because progression of cervical intraepithelial neoplasia (CIN) to invasive disease during pregnancy is rare, with a range of 0–3% of cases.[9][10][11][8][12] Almost all cases are microinvasive and amenable to curative treatment.

Postpartum regression of CIN lesions is common.[10][13][14] A meta-analysis of studies found that women treated for CIN during pregnancy were at an increased risk of preterm birth (< 37 weeks) and premature rupture of membranes, compared with women with untreated CIN who gave birth before treatment.[15] However, when invasive disease is suspected or confirmed in pregnancy, expert management by a gynaecologic oncologist is required due to the increased risk of poor pregnancy outcomes.

General literature review evidence

A general literature search was conducted to identify recent studies reporting on the natural history of cervical dysplasia during pregnancy and its management.

The available evidence consists of only small studies, with somewhat diverse findings for the natural history of progression and regression of HSIL or histologically confirmed HSIL identified during pregnancy.[10][11][16][17][13][14][18][19] Microinvasive or invasive disease was identified in a small number of cases, most of which were diagnosed post partum.[10][11][16][12][19]

There is evidence to support the safety of colposcopy[10][8][13][14] and biopsy[16] during pregnancy. Biopsy of the cervix in pregnancy is associated with a small risk of excessive bleeding from the cervical biopsy site, but is considered otherwise safe.[16][12][10]

The findings are summarised in the Technical report.

Flowchart 14.1. Management of a LBC prediction of HSIL in pregnancy

Biopsy is not recommended in pregnancy but may be required, especially when there is suspicion of invasive disease. There is evidence that it is safe to biopsy the cervix during pregnancy, although there may be a risk of excess bleeding.[16][12][10] However, the risk of an undiagnosed cervical cancer in pregnancy outweighs the risk of bleeding from a biopsy.

Deferring treatment of pre-invasive high grade lesions during pregnancy will prevent possible complications of pregnancy loss and excessive bleeding. There is a small risk of progression to invasive cervical cancer during pregnancy, although an Australian case series showed no cases of progression.[20] Most commonly, this will be microinvasive disease, rather than a clinically apparent cancer.

See Chapter 5. Benefits, harms and cost-effectiveness of screening in the renewed NCSP.

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Clinical practice

The recommendations are consistent with current clinical practice. However changes to the cervix in pregnancy make colposcopic assessment more challenging. Although the squamocolumnar junction and the transformation zone (TZ) are more exposed during pregnancy, complete visualisation of all four quadrants of the cervix is often hindered by oedema, cyanosis, vaginal wall protrusion and thick mucus production.[9] Although colposcopy is safe to perform during pregnancy, an experienced colposcopist should perform the examination owing to the difficulty in differentiating between changes occurring as a result of pregnancy and those due to cervical pathology. A lack of experience could potentially lead to an overestimation of the severity of dysplasia, a mistaken diagnosis of invasive disease and unnecessary investigation during pregnancy.[21]

Resourcing

No additional costs are anticipated.

Barriers to implementation

None.

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Figure 14.1. Cyto-broom: recommended for use in pregnant women to collect a cervical screening specimen

Image source: Australian Centre for the Prevention of Cervical Cancer

Figure 14.2. Endocervical brush: NOT recommended for use

Image source: Australian Centre for the Prevention of Cervical Cancer

Figure 14.3. Self-collection swab

Image source: Australian Centre for the Prevention of Cervical Cancer

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