In addition to the endometrium and cervix, the shape and competency of the uterine fundus must be considered. Anomalies of mullerian fusion and fibroids have been suggested to result in the inability of implantation or growth of the pregnancy. It is difficult to postulate how abnormalities of the uterus can cause infertility except through abnormal blood flow leading to poor implantation and subsequent placentational factor. Indeed, evidence that does exist relates infertility to large fibroids suggesting tubal factor infertility. Mullerian fusion abnormalities resulting in a uterine septum or bicornuate uterus are largely associated with recurrent miscarriage rather than the ability to conceive. A possible exception to this is the intramural fibroid larger than 4 cm. These fibroids appear to adversely effect implantation after in vitro fertilization with intracytoplasmic sperm injection and embryo transfer. However, clinical evidence regarding an in vivo effect is lacking. (23.1)
Historical clues of an abnormal uterus are rare. Occasionally, patients with incomplete mullerian fusion may have dysmenorrhea, but the symptom itself is so nonspecific that the physician is not likely to alter either diagnosis or therapeutic course. An abnormal uterus caused by large myomas may present with heavy bleeding, urinary urgency and frequency from pressure on the bladder and constipation from partial rectal occlusion.
A bimanual pelvic examination will reveal large fibroids. The bicornuate uterus is not often felt. However, a compete uterus didelphys will be revealed by a vaginal and cervical examination.
Uterine fibroids may be diagnosed by ultrasound (Figure 5). Their imposition on the endometrial cavity may be illustrated by hysterosalpingogram and confirmed by hysteroscopy. Ultrasound is less valuable in diagnosing mullerian anomalies, but hysterosalpingogram will identify the abnormal uterus (Figures 6,7,8) . MRI is often helpful in identifying both fibroids and the type of mullerian anomaly found on hysterosalpingogram (Figure 9).
Figure 5. Transverse sonographic image of the uterus demonstrating overall enlargement and multiple leiomyomata.
Figure 6. Hysterosalpingogram of a normal uterus. Note the normal appearing intrauterine cavity with bilateral tubal spillage of contrast.
Figure 8. Hysterosalpingogram of a uterine anomaly. With HSG, a septum versus a bicornuate uterus cannot be distinguished.
The septate uterus can be differentiated from the bicornuate uterus by laparoscopy on MRI. Both laparoscopy and hysteroscopy will identify fibroids and their location in the uterus and pelvis. If fibroids interfere with tubal pick-up of oocytes, mechanical infertility will result. Similarly, fibroids impinging on the endometrial cavity may interfere with implantation and placentation.
Uterine fibroids may be treated by myomectomy. Depending on the location of the fibroid, hysteroscopic or laparoscopic removal may be possible. Otherwise laparotomy is necessary. Treatment of the fibroid with a GnRH agonist will shrink the fibroid, but as soon as the agonist is discontinued and estrogen activity resumes, the fibroid will return to at least its original size (24).
Uterine artery embolisation leading to fibroid necrosis has been introduced as a non-surgical treatment. However this is not recommended for the woman who has not completed her childbearing. First, the effect on uterine and endometrial function is unknown, and second, the technique is associated with ovarian dysfunction in approximately 14% of patients. (24.1) Premature ovarian failure from embolization into the ovarian arterial system and compromised ovarian blood flow has been reported in 15% of patients older than 44 years.(24.3) More recently, MRI-guided focused ultrasound therapy has been suggested to incrementally destroy the tissue and lead to partial necrosis of fibroids even as large as 4 cm. (24.4) However, subsequent fertility has not yet been tracked.
Myomectomy is indicated when the myomas result in bleeding severe enough to cause anemia, when pressure is placed on the bladder to cause urinary tract infections, or when pressure on the bowel results in constipation. It is less clear whether myomectomy improves fertility and, in fact, may even result in pelvic adhesions and lead to tubal factor infertility (25). Myomas which impinge or are present within the endometrial cavity probably cause spontaneous abortion, but evidence proving this causation is difficult to find. Even harder to prove is the efficacy of myomectomy resulting in an increase in term pregnancy.