Examination of the uterine junctional zone (JZ), located in the inner myometrium, is crucial for diagnosing abnormalities such as adenomyosis and endometriosis. It's also necessary for successful intracytoplasmic sperm injection (ICSI) outcomes. Learning how to properly assess the uterine junctional zone may help physicians predict ICSI success in patients.
Examining the Junctional Zone in Uterus
Adenomyosis is when endometrial tissue grows within the muscle in the junctional zone; endometriosis is when endometrial tissue grows outside the uterus. The two conditions can occur separately, but most of the time, patients experience adenomyosis and endometriosis together. Both adenomyosis and endometriosis may cause symptoms such as dysmenorrhea, dyspareunia and pelvic pain.
When a physician suspects either adenomyosis or endometriosis, the first step toward a diagnosis is an examination of the uterine junctional zone. While previously limited to expensive MRI examinations, according to a review published in Human Reproduction Update, diagnosis can now be accomplished with a low-cost transvaginal ultrasound.
According to a review published in the Journal of Ultrasound in Medicine, if sonographic examination reveals that the uterus is enlarged or the endometrial lining in the uterine junctional zone is greater than 12 mm, adenomyosis is the likely diagnosis. The timing during a patient's cycle is crucial, as the junctional zone may appear thicker during menstruation and cause a false positive for adenomyosis.
If the patient does have adenomyosis, the junctional zone will have experienced repeated microtrauma — lining injury and subsequent lining repair — resulting in a thick appearance throughout the menstrual cycle. Endometriosis might be the diagnosis if the frequency of oxytocin-dependent uterine contractions visible through ultrasound is significantly higher than normal for a non-pregnant patient.
Impact of Uterine Junctional Zone Thickness on ICSI
Measuring the junctional zone in the uterus may prove useful in detecting possible adenomyosis or endometriosis during ICSI. A study published in the Open Journal of Obstetrics and Gynecology found that the thicker the junctional zone, the less likely ICSI would result in successful implantation. More specifically, a study published in the EuropeanJournal of Obstetrics, Gynecology, and Reproductive Biology found that patients with a uterine junctional zone thickness of less than 2.7 mm were significantly more likely to become pregnant than patients with a thickness above this threshold.
According to a study published in Obstetrics and Gynaecology, the presence of adenomyosis can also impact natural implantation by changing the muscular peristalsis that transports sperm and oocytes. This change may at least partially explain a patient's infertility, and point to ICSI as the best method for achieving pregnancy.
The accuracy of JZ examination and other measurements is still largely dependent on the skill of the physician. Criteria are currently being developed to help standardize the diagnostic process and offer clinicians a more dependable way to diagnose adenomyosis and other potential causes of infertility.
