Submucosal Fibroid

A submucosal fibroid is a smooth muscle tumour that lies just under the endometrium and projects into the uterine cavity. Types 0 and 1 lie mostly in the cavity and type 2 is more than half in the muscle.

• It is the fibroid type most likely to cause heavy menstrual bleeding and reduced fertility.
• It increases the risk of miscarriage.
• Hysteroscopic resection is first-line surgery for suitable lesions.

Heavy and prolonged menstrual bleeding, intermenstrual bleeding, dysmenorrhoea, anaemia, infertility and recurrent miscarriage.

• A normal or mildly enlarged uterus on examination; a prolapsing fibroid may appear at the cervix.
• Differential diagnosis: endometrial polyp, adenomyosis, endometrial hyperplasia, endometrial cancer, retained products of conception, intrauterine adhesions.
• Complications: severe anaemia, infertility, miscarriage, prolapse through the cervix, infection and degeneration.

Diagnosis is by ultrasound or saline infusion sonography, confirmed by hysteroscopy.

• Transvaginal ultrasound or saline infusion sonography to show the fibroid in the cavity.
• Hysteroscopy for direct view and classification.
• Pelvic MRI for multiple fibroids or unclear origin.
• Full blood count and ferritin; pregnancy test; cervical screening.
• Endometrial sampling for women aged 45 or over, or with risk factors for hyperplasia.

Control bleeding medically, and resect the fibroid hysteroscopically when it distorts the cavity or affects fertility.

• Supportive: menstrual diary; heat; iron-rich diet; counselling on fertility.
• Pharmacological: tranexamic acid 1 g oral 8-hourly for up to 4 days during heavy bleeding (maximum 4 g in 24 hours; reduce the dose in renal impairment; avoid in thromboembolism). Mefenamic acid 500 mg oral 8-hourly with food during menses. Norethisterone 5 mg oral 8-hourly from day 5 to day 26 of the cycle when heavy bleeding continues, or levonorgestrel 52 mg intrauterine system if the cavity is not distorted. Pre-operative shrinkage: leuprorelin 3.75 mg IM every 4 weeks for up to 3 months. Anaemia: ferrous sulphate 200 mg oral 8-hourly, continued for 3 months after haemoglobin normalises; iron sucrose 200 mg IV per dose for severe anaemia.
• Procedures: hysteroscopic resection (types 0 to 2) under anaesthesia, with fluid balance monitoring; myomectomy by laparoscopy or laparotomy for large fibroids; hysterectomy when fertility is complete; uterine artery embolisation in selected women.
• Special groups: in pregnancy manage conservatively and use paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); avoid tranexamic acid and GnRH analogues. In renal impairment reduce tranexamic acid to 15 mg/kg (usually 1 g) oral 12-hourly when creatinine is 120 to 249 micromol/L.
• Red flags: haemoglobin below 7 g/dL, heavy bleeding with shock, fever with foul discharge, rapid growth, postmenopausal bleeding.
• Follow-up: review at 6 weeks and 3 months; repeat ultrasound at 6 to 12 months; check haemoglobin and ferritin.