Uterine fibroids and endometrial polyps are frequent findings which may interfere with embryo implantation regardless of how conception occurs. The diagnosis of uterine abnormalities relies upon pelvic examination and several imaging tests: 1. ultrasound, 2. HSG x-ray; 3. saline infusion sonohysterogram (SIS); 4. MRI.
The location of fibroids is often more important than their size or number. Fortunately, the most problematic fibroids occur within the uterine cavity and can usually be removed with hysteroscopy, a minor surgical procedure performed on an outpatient basis.
Fibroids arise from the muscle layer of the uterus. The pictures below show a large submucous fibroid being resected with an electric loop. The patient had a successful spontaneous conception shortly after surgery.
Submucous fibroid
With regard to fertility the location of a fibroid matters the most. Intramural fibroids within the wall of the uterus are most common but their exact impact on the cavity may be the key consideration for pregnancy. Subserosal fibroids, as pictured below at laparoscopy, have little, if any, impact on the chance of a successful pregnancy.
Two subserosal fibroids outside the uterus
In rare cases multiple fibroids and surgeries to remove them may damage the uterus to the point that a successful pregnancy cannot be achieved. In such situations gestational surrogacy may be advisable.
Endometrial polyps arise from the gland layer lining the uterine cavity. Large polyps can be apparent on vaginal ultrasound (upper picture) while smaller polyps usually are readily seen on saline infusion sono-hysterogram (SIS, lower picture). Hysteroscopic removal of all polyps is recommended before IVF and other advanced treatments.
Inborn (congenital) abnormalities of uterine shape are relatively common. Septate uterus contains 2 small cavities within a unified uterine body (see images below) and is associated with recurrent miscarriages. Uterus unicornis is another congenital abnormality in which only one half of the womb develops in association with a single tube and frequently a kidney abnormality as well.
Other uterine abnormalities include scarring (Asherman’s syndrome) from infection in conjunction with pregnancy and narrowing of the cervical canal (stenosis) which can make embryo transfer difficult. Most of these conditions can be corrected through outpatient hysteroscopy.
Ultrasound of a septate uterus (S=septum, C=cavities)
Hysteroscopic view of septum at arrow and 2 cavities in upper panel;
unified uterine cavity after incision of septum in lower panel