Role of Imaging in Diagnosis of Female Infertility

Introduction:

Female infertility is a condition in which women cannot get pregnant after 12 months of unprotected sexual intercourse. Female infertility often results from problems with ovulation.

Uterine abnormalities are responsible for 10 percent of infertility, and tubal abnormalities contribute to 20 percent. Though hysterosalpingography is the gold standard imaging technique in diagnosing female infertility, ultrasonography is the first line imaging modality to detect the same.

What Are the Causes of Female Infertility?

Uterine Causes:

• Infections.

• Focal lesions.

• Congenital anomalies.

• Cervical stenosis.

• Intrauterine scar.

• Reduced uterine perfusion.

• Variation in endometrial thickness.

• Altered vascularity (blood supply).

Ovarian Causes:

• Stromal vascularity.

• Endometriosis - A painful condition in which tissues similar to the uterus lining grow outside the uterus.

• Follicular abnormalities.

• Ovulation abnormalities.

Tubal Causes:

• Obstruction.

• Infections.

What Is the Anatomy of Female Reproductive Organs?

• The female reproductive organs include the uterus, fallopian tubes, cervix, and a pair of ovaries. During the first six weeks of gestation, both female and male fetuses possess Mullerian and Wolffian ducts. Due to the presence of a Mullerian-inhibiting factor with a Y chromosome in males, the Mullerian ducts regress. The lack of Mullerian-inhibiting factor in the female fetus leads to regression of Wolffian ducts and growth of Mullerian ducts.

• Embryologically the cervix, uterus, fallopian tubes, and part of the vagina are formed by the fusion of the Mullerian ducts.

• Lack of fusion, partial resorption, or non-resorption of the mid-line septum results in Mullerian duct anomalies (MDA) that are often associated with infertility.

• The fallopian or uterine tubes are paired tubes that measure 10 to 12 centimeters that extend from the ovaries to the uterus. Each tube is made of four segments which are interstitial, isthmic, ampullary, and infundibular. These tubes are not visualized until they are surrounded by peritoneal fluid.

• The ovaries are paired, an ellipsoidal structure found in the ovarian fossa along the pelvic wall.

What Are the Risk Factors for Female Infertility?

• Age.

• Smoking.

• Weight - Obesity (overweight) or underweight.

• Alcohol.

• History of ectopic (outside the uterus) pregnancy.

• Sexually transmitted infections (STIs).

What Are the Different Types of Mullerian Duct Anomalies?

According to the American society of reproductive medicine system, the Mullerian duct anomalies are classified into:

• Class I - Uterine agenesis.

• Class II - Unicornuate uterus.

Unicornuate uterus refers to partial or complete hyperplasia of the Mullerian duct. It connects only with the coordinate fallopian tube.

• Class III - Diadelphys uterus.

It is a rare Mullerian duct anomaly that results from the partial fusion of the Mullerian duct, which includes duplication of the cervix, uterine cavity, and vagina.

• Class IV - Bicornuate uterus.

Bicornuate uterus refers to incomplete fusion of the uterovaginal canal.

• Class V - Septate uterus.

It indicates complete or partial failure of resorption of the septum.

• Class VI - Arcuate uterus.

It is formed by the complete resorption of the uterovaginal septum.

• Class VII or DES (diethyibestral) Induced - It appears as a hypoplastic T-shaped constricted uterus.

What Are the Imaging Techniques Used in the Diagnosis of Female Infertility?

Hysterosalpingography:

• Hysterosalpingography is the most common imaging tool used to visualize fallopian tubes and uterus to check for infertility. It can detect tubal patency, irregularity, occlusion, and peritubular defects. When the tubal occlusion occurs in the proximal part of the fallopian tube in the hysterosalpingogram, it should be differentiated from tubal spasm.

• Normally uterine cavity appears as a triangular contrast area with its base on top and the apex facing downward (caudally) like an inverted triangle. The uterine fundus appears as a concave or slightly convex structure on top.

• Hydrosalpinx refers to the occlusion of the ampulla of the fallopian tube in a hysterosalpingogram. It appears as an enlarged, tortuous, fluid-filled tube with the absence of intraperitoneal contrast spillage.

• The pelvic inflammatory disease appears as pelvic collection and tubo-ovarian mass. Uterine adhesion should be differentiated from the uterine fold, which appears as a longitudinal filling defect in a partially distended uterine cavity.

• Sonosalpingography shows endometrial lesions and also differentiates submucosal leiomyoma from the endometrial polyp. Endometrial polyp appears as an echogenic intracavitary mass.

Ultrasonography:

• Ultrasonography is the first choice of imaging modality used to detect female infertility. Sometimes color Doppler, three-dimensional, or four-dimensional scans may be combined with ultrasound.

• In ultrasonography, leiomyomas have variable appearances. Localized leiomyomas appear as hypoechoic well, defined heterogenous mass with hyperechoic calcification.

• Color doppler shows mild to moderate resistance to peripheral vascularity and differentiates it from adenomyoma with moderate peripheral vascularity.

• Transvaginal ultrasound is more effective than magnetic resonance imaging (MRI) in detecting leiomyoma. However, MRI is efficient in detecting the location, size, and numbers of fibroids pre-operatively.

Magnetic Resonance Imaging (MRI) Scan:

• Magnetic resonance Imaging is an excellent imaging choice to detect uterine anomalies that provide detailed images of the uterus and external contours of the uterus.

• MRI can detect endometriosis, adenomyosis, tubal disease, leiomyomas, ovarian disease, and Mullerian duct anomalies. It can also detect extra pelvic causes of female infertility, such as pituitary adenoma.

• The myometrial wall appears as low signal intensity in adenomyosis on T1 and T2 weighted images. In T2 weighted images, there is a diffuse or focal widening of junctional zone thickness of about 12 mm or more.

• In T2 weighted images, ectopic endometrium appears as high signal intensity areas.

• In MRI, submucosal fibroid appears as a sharply marginated mass with lower signal intensity than myometrium on T2 weighted images.

• In MRI bicornuate uterus is detected by an intercornual distance of more than four centimeters and an external fundal cleft of more than one centimeter.

• Septate uterus appears as a convex or minimally concave structure.

Conclusion:

Three-dimensional (3D) ultrasound images have 100% sensitivity in detecting septate uteri and 83 % sensitivity in detecting bicornuate uteri. Sonosalpingography shows higher sensitivity than hysterosalpingogram in the diagnosis of uterine adhesion, which appears as echogenic bands that cross the endometrial cavity. Sonosalpingography helps in the accurate assessment of location and number and acts as guidance for biopsy and excision. Submucosal leiomyoma appears as a hypoechoic mass destructing the normal endometrium. MRI shows 99% sensitivity in the differentiation of adenomyosis from leiomyoma in case of an enlarged uterus.