Adnexal masses in early pregnancy

She is 32, and the sonographer has just spent a long time looking at her right ovary at the dating scan. The report says "complex adnexal mass, 7 cm, papillary projections". She has not had any pain. You can hear her holding her breath in the waiting room. The job at this station is to take a finding that the patient is convinced means cancer, characterise it confidently with the right tools, decide who to operate on and who to watch, and not be the clinician who adds a cancer label to a mass that would have resolved.[5][1]

Overview and definition

An adnexal mass in pregnancy is any ovarian, para-ovarian or tubal mass detected on imaging during pregnancy. The finding is common; the question is always the same: benign or malignant, watch or operate, and how to counsel without panic.[1][5]

• Incidence. Reported in roughly 1 to 6% of pregnancies — higher where routine first-trimester ultrasound is universal, lower where it is not.[1]
• Malignancy rate. Around 1% of adnexal masses that come to surgery in pregnancy are malignant — the overwhelming majority are benign.[1]
• Histology of operated masses. The mature cystic teratoma (dermoid) is the single most common pathology, accounting for about 36% of masses that come to surgery.[1]

The mass you are looking at is therefore overwhelmingly likely to be benign — but the small minority that are not, and the small minority that tort, are the whole reason this topic is examined.[1]

References11Show ledgerHide ledger

1. [1]Cagino K, Li X, Thomas C, et al. Surgical Management of Adnexal Masses in Pregnancy: A Systematic Review and Meta-analysis. J Minim Invasive Gynecol, 2021.PMID 33515746
2. [2]Timmerman D, Ameye L, Fischerova D, et al. Simple ultrasound rules to distinguish between benign and malignant adnexal masses before surgery: prospective validation by IOTA group. BMJ, 2010.PMID 21156740
3. [3]Van Calster B, Van Hoorde K, Valentin L, et al. Evaluating the risk of ovarian cancer before surgery using the ADNEX model to differentiate between benign, borderline, early and advanced stage invasive, and secondary metastatic tumours: prospective multicentre diagnostic study. BMJ, 2014.PMID 25320247
4. [4]Barreñada L, Ledger A, Dhiman P, et al. ADNEX risk prediction model for diagnosis of ovarian cancer: systematic review and meta-analysis of external validation studies. BMJ Med, 2024.PMID 38375077
5. [5]Barcroft J, Pandrich M, Del Forno S, et al. Evaluating use of two-step International Ovarian Tumor Analysis strategy to classify adnexal masses identified in pregnancy: pilot study. Ultrasound Obstet Gynecol, 2024.PMID 38787921
6. [6]Dvash S, Pekar M, Melcer Y, et al. Adnexal Torsion in Pregnancy Managed by Laparoscopy Is Associated with Favorable Obstetric Outcomes. J Minim Invasive Gynecol, 2020.PMID 31563614
7. [7]Rottenstreich M, Rotem R, Hirsch A, et al. Maternal and perinatal outcomes following laparoscopy for suspected adnexal torsion during pregnancy: a multicenter cohort study. Arch Gynecol Obstet, 2020.PMID 32889559
8. [8]Balinskaite V, Bottle A, Sodhi V, et al. The Risk of Adverse Pregnancy Outcomes Following Nonobstetric Surgery During Pregnancy: Estimates From a Retrospective Cohort Study of 6.5 Million Pregnancies. Ann Surg, 2017.PMID 27617856
9. [9]Rasmussen AS, Christiansen CF, Ulrichsen SP, et al. Non-obstetric abdominal surgery during pregnancy and birth outcomes: A Danish registry-based cohort study. Acta Obstet Gynecol Scand, 2020.PMID 31774546
10. [10]Ray JG, Vermeulen MJ, Bharatha A, et al. Association Between MRI Exposure During Pregnancy and Fetal and Childhood Outcomes. JAMA, 2016.PMID 27599330
11. [11]Moro F, Momi M, Ledger A, et al. External validation of ultrasound-based models for differentiating between benign and malignant adnexal masses: a nationwide prospective multicenter study (IOTA phase 6). Am J Obstet Gynecol, 2025.PMID 40653066