The majority of low-grade pre-invasive lesions of cervix (low-grade squamous intraepithelial lesions, LSIL).will regress spontaneously over 2 years and immediate treatment may not be necessary. According to the Hong Kong College of Obstetricians and Gynaecologists (HKCOG), if a low-grade lesion is confirmed by colposcopy and biopsy, the patient can be observed and followed up with HPV testing or co-testing at 12 months, irrespective of age. This randomized controlled study is to determine whether high-intensity focused ultrasound (HIFU) treatment of low-grade pre-invasive lesions of cervix, can cause regression of these lesions in more patients within a specific time when compared to observation as a standard management according to HKCOG Guidelines. All eligible patients will be randomized in a 1:1 ratio into 2 groups: high-intensity focused ultrasound (HIFU) or Observation group. Background information of the patients such as age, parity, body mass index, smoking status and the presence of chronic medical disease will be collected. All patients with cervical HR-HPV status will be tested. Patients randomized into HIFU group will receive HIFU treatment within 2 weeks after randomization. Those randomized into Observation group will have no intervention. All patients will attend follow-up at 6 and 12 months after randomization, during which cervical smear for cytology (with cytopathologists blinded to the treatment group) and HR-HPV testing will be performed. The rate of cytological LSIL regression and HR-HPV clearance rates at 6 and 12 months in both groups will be analyzed. Patients will be referred back to colposcopy clinic for repeat colposcopy if needed according to HKCOG Guidelines. At the 12-month follow-up visit, if referral to repeat colposcopy is not needed, patients will be referred back to their primary care physicians, Department of Health Family Health Service, Family Planning Association or other primary care centres for follow-up cervical smears.

Inclusion Criteria:

1. Pre-menopausal women aged 18 years old or above.
2. Women had satisfactory colposcopy for abnormal cervical smear with positive HR-HPV test, with histologically confirmed diagnosis of cervix LSIL or CIN1.

Exclusion Criteria:

1. Women who are pregnant or breast feeding at the time of planned HIFU treatment.
2. Women without HR-HPV, or previously treated for CIN or cervical cancer.
3. Women not able to attend follow up.
4. Women with evidence of acute genital tract infection.
5. Women with significant autoimmune diseases, immunodeficiency diseases, severe cardiac, hepatic, renal, and coagulation dysfunctions.
6. Women not able to give consent.

Participants be considered withdrawn from study or excluded from analysis

1. Formally recruited into the study but withdraw from the study after randomization.
2. Do not attend both follow-up appointments.

Women had satisfactory colposcopy for abnormal cervical smear with positive HR-HPV test, with histologically confirmed diagnosis of cervix LSIL or CIN1.

not yet decided