Ovarian Tumours and Fibroids in Pregnancy

Authored by , Reviewed by Dr John Cox | Last edited | Meets Patient’s editorial guidelines

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The incidence of ovarian and adnexal masses in pregnancy appears to be increasing in line with the expanding use of antenatal ultrasound:[1]

  • The majority of such masses do not cause problems and most are functional cysts of the corpus luteum that have not undergone full involution. They usually resolve by the second trimester of pregnancy.
  • Persisting adnexal masses can lead to complications and may (rarely) require emergency or elective surgical resection (the optimal surgical window being around 16 to 20 weeks of gestation).

Type of mass

Benign ovarian tumours are extremely common:

  • Functional ovarian cysts.
  • Benign cystic teratomas.
  • Serous or mucinous cystadenomas.
  • Fibromas.

All ovarian cancers are rare and usually low-stage/low-grade:[2]

  • Germ cell tumours.
  • Borderline ovarian tumours.
  • Epithelial tumours.
  • Sex-cord stromal tumours.

Evidence suggests that there is an increased risk of pregnancy loss associated with the presence of uterine fibroids in early pregnancy, especially submucosal and intramural fibroids.[3]One review suggests that fibroids are probably more common than thought in pregnancy but cause fewer problems than expected:[4]

  • One longitudinal study found a complication rate of 4 in 72 affected pregnancies.[5]
  • There is a generally held belief that fibroids grow during pregnancy but longitudinal studies have shown that this happens rarely.[5]
  • If they do enlarge, it is usually during early pregnancy.[4]
  • Submucosal fibroids have the strongest association with poor pregnancy outcomes; evidence that intramural and subserosal fibroids affect fecundity is inconclusive.[6]
  • Fibroids are common, occurring in as many as 10% of pregnancies, with a higher incidence in African-American women.[7]Since their incidence increases with increasing age, they may be becoming more common in pregnancy as women delay childbearing.[8]
  • Ultrasound scanning detects an adnexal mass in about 1 in 200 early pregnancies.
  • Clinically detectable adnexal masses are thought to affect about 1 in 1,500 pregnancies.
  • The vast majority of these adnexal masses do not persist beyond the second trimester.
  • Ovarian malignancy is very rare at approximately 7 cases per 10,000 pregnancies in one series.[9]
  • Most adnexal masses and fibroids are detected coincidentally during routine antenatal ultrasound.
  • A small proportion of both pathologies may be large enough to detect clinically during bimanual palpation of the uterus.
  • The mass may also cause complications (see list under 'Complications', below) and the patient then presents with symptoms caused by this.
  • For ovarian tumours, the main question is whether the tumour is benign or malignant.
  • Uterine fibroids (once visualised by ultrasound scanning) are unlikely to be confused with other pathologies.

The investigation of choice for uterine or ovarian masses in pregnancy is detailed ultrasound scanning including Doppler:[10]

  • This indicates the size, location, appearance and likelihood of any problems, to assist decisions on management. Morphological criteria can identify benign ovarian cysts compared with malignant masses relatively accurately.
  • Ovarian tumour markers are used mainly to monitor disease status during treatment, rather than as a diagnostic test, due to low specificity. Several markers can be elevated due to pregnancy itself - eg, CA 125, beta human chorionic gonadotrophin (beta-hCG) - and their use in pregnant cancer patients is not recommended.[11]
  • In confirmed malignancy, investigations to stage the tumour, such as MRI scanning of the pelvis, may be used but CT and positron emission tomography (PET) should be avoided.[11]

Ovarian masses

  • If the mass is thought to be benign and unlikely to cause complications, expectant management and follow-up scans are recommended.
  • There is little evidence to support the use of laparoscopic surgery in the management of presumed benign ovarian tumours.[12]
  • Surgery after 15 weeks of gestation is indicated for large (greater than 5-10 cm in diameter) and/or symptomatic tumours and those that appear highly suspicious for malignancy (solid or mixed solid and cystic) on ultrasound.[13]
  • Surgery should never be postponed, if deemed to be crucial, particularly once the time of 25 weeks of gestation has been reached.[11]
  • The extent of surgery is decided by the intraoperative findings showing whether the tumour is benign/malignant:
    • Conservative surgery is indicated for benign masses/borderline ovarian tumours.
    • More extensive surgery (including staging biopsies) is indicated for confirmed higher-grade malignancies.
  • Chemotherapy may be given from the second trimester of pregnancy but is associated with an increased risk of obstetric and fetal problems, including intrauterine growth restriction, premature labour and premature rupture of the membranes. Etoposide, used in the treatment of germ cell tumours, has been specifically associated with myelosuppression in the newborn.[11]

Uterine fibroids

  • Most fibroids cause no problems during pregnancy and observation is all that is required.[4]
  • Diffuse uterine fibroids can be successfully treated conservatively to achieve a successful pregnancy outcome.[14]
  • Intractable fibroid pain unresponsive to medical treatments is an indication for myomectomy, as is a large fibroid (≥5 cm) located in the lower uterine segment.
  • Fibroids are not normally operated upon in the first or second trimester other than in an emergency.
  • Myomectomy should not normally be carried out at the time of caesarean section except in emergency, as there is a high morbidity due to haemorrhage, although there is emerging evidence that it can be a safe procedure for large (>5cm) myomas in carefully selected cases if performed by an experienced surgeon.[8]However, a Cochrane review failed to find evidence to confirm that myomectomy improves subsequent fertility, which is the usual indication for myomectomy at the time of caesarean section.[15]
  • Bilateral uterine artery embolisation (UAE) immediately after caesarean delivery may be effective in decreasing postpartum blood loss and minimising the risk of myomectomy or hysterectomy.[16]

Ovarian masses[1]

  • Torsion presenting as acute abdomen.
  • Rupture presenting as acute abdomen.
  • Obstruction of labour.
  • Preterm labour.
  • Malignant transformation causing peritoneal spread (may lead to ascites and peripheral oedema).

Uterine fibroids

Most women with fibroids have uneventful pregnancies; however, evidence does suggest an association with:[17]

Large submucosal and retroplacental fibroids have the greatest risk of complications.[4]

The outcome is very good for the majority of patients with fibroids and ovarian masses during pregnancy.

  • Elective surgery for an adnexal mass in the second trimester appears to be safe for both the woman and her baby.[19]
  • Where surgical intervention for fibroids is needed, outlook is good, especially for elective surgery; there is, however, a higher caesarean section rate in women who undergo myomectomy during pregnancy, due to concerns over uterine rupture.[17]
  • Prognosis in cases of ovarian malignancy is related to tumour histology and stage but one series shows 70% maternal survival and relatively good fetal outcomes:[9]
    • Earlier diagnosis gave a better prognosis.
    • A worse prognosis was associated with the presence of ascites.

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Further reading and references

  1. Giuntoli RL 2nd, Vang RS, Bristow RE; Evaluation and management of adnexal masses during pregnancy. Clin Obstet Gynecol. 2006 Sep49(3):492-505.

  2. Leiserowitz GS, Xing G, Cress R, et al; Adnexal masses in pregnancy: how often are they malignant? Gynecol Oncol. 2006 May101(2):315-21. Epub 2005 Nov 28.

  3. Cook H, Ezzati M, Segars JH, et al; The impact of uterine leiomyomas on reproductive outcomes. Minerva Ginecol. 2010 Jun62(3):225-36.

  4. Ouyang DW, Economy KE, Norwitz ER; Obstetric complications of fibroids. Obstet Gynecol Clin North Am. 2006 Mar33(1):153-69.

  5. Neiger R, Sonek JD, Croom CS, et al; Pregnancy-related changes in the size of uterine leiomyomas. J Reprod Med. 2006 Sep51(9):671-4.

  6. Klatsky PC, Tran ND, Caughey AB, et al; Fibroids and reproductive outcomes: a systematic literature review from conception to delivery. Am J Obstet Gynecol. 2008 Apr198(4):357-66. doi: 10.1016/j.ajog.2007.12.039.

  7. Laughlin SK, Baird DD, Savitz DA, et al; Prevalence of uterine leiomyomas in the first trimester of pregnancy: an ultrasound-screening study. Obstet Gynecol. 2009 Mar113(3):630-5. doi: 10.1097/AOG.0b013e318197bbaf.

  8. Kwon DH, Song JE, Yoon KR, et al; The safety of cesarean myomectomy in women with large myomas. Obstet Gynecol Sci. 2014 Sep57(5):367-72. doi: 10.5468/ogs.2014.57.5.367. Epub 2014 Sep 17.

  9. Zhao XY, Huang HF, Lian LJ, et al; Ovarian cancer in pregnancy: a clinicopathologic analysis of 22 cases and review of the literature. Int J Gynecol Cancer. 2006 Jan-Feb16(1):8-15.

  10. Glanc P, Salem S, Farine D; Adnexal masses in the pregnant patient: a diagnostic and management challenge. Ultrasound Q. 2008 Dec24(4):225-40.

  11. Cancer, pregnancy and fertility: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up; European Society for Medical Oncology (2013)

  12. Bunyavejchevin S, Phupong V; Laparoscopic surgery for presumed benign ovarian tumor during pregnancy. Cochrane Database Syst Rev. 2013 Jan 311:CD005459. doi: 10.1002/14651858.CD005459.pub3.

  13. Marret H, Lhomme C, Lecuru F, et al; Guidelines for the management of ovarian cancer during pregnancy. Eur J Obstet Gynecol Reprod Biol. 2010 Mar149(1):18-21. Epub 2009 Dec 29.

  14. Purohit R, Sharma JG, Singh S; A case of diffuse uterine leiomyomatosis who had two successful pregnancies after Fertil Steril. 2011 Jun95(7):2434.e5-6. Epub 2011 May 5.

  15. Metwally M, Cheong YC, Horne AW; Surgical treatment of fibroids for subfertility. Cochrane Database Syst Rev. 2012 Nov 1411:CD003857. doi: 10.1002/14651858.CD003857.pub3.

  16. Liu WM, Wang PH, Tang WL, et al; Uterine artery ligation for treatment of pregnant women with uterine leiomyomas who are undergoing cesarean section. Fertil Steril. 2006 Aug86(2):423-8. Epub 2006 Jun 8.

  17. Lee HJ, Norwitz ER, Shaw J; Contemporary management of fibroids in pregnancy. Rev Obstet Gynecol. 2010 Winter3(1):20-7.

  18. King R, Overton C; Management of fibroids should be tailored to the patient. Practitioner. 2011 Mar255(1738):19-23, 2-3.

  19. Telli E, Yalcin OT, Ozalp SS, et al; Surgical intervention for adnexal masses during pregnancy. BMJ Case Rep. 2013 Jun 282013. pii: bcr2013010324. doi: 10.1136/bcr-2013-010324.