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Findings: A hysterosalpingogram was performed on the patient. The ring-like opacity represents the right side of the patient's body. Following cannulation of the patient's cervix, contrast material was infused into the uterus. The uterus showed the presence of a body and right cornua. No abnormality in contour was visualized. Contrast subsequently filled the right fallopian tube with spillage into the peritoneal cavity.

There was no visualization of the left horn of the uterus or of the left fallopian tube. Physical exam was then performed showing the presence of only one cervix. These findings are consistent with a unicornuate unicollis uterus.

Diagnosis:Unicornuate, unicollis uterus.

Discussion: Uterine anomalies are consistent with anomalies of fusion of the paramesonephric ducts. Lack of fusion of the paramesonephric ducts in a localized area or along the length of the ducts cause different types of uterine malformations. Fusion is usually completed by the eighteenth week of fetal life. The incidence of malformations equals approximately 1 to 3%. Urinary tract abnormalities are found in approximately 20 to 50% of patients with uterine anomalies.

Total or partial failure of mullerian duct fusion represents approximately 75% of uterine anomalies. The first type of abnormality from this type of malformation is uterine didelphis. In this anomaly there are two vaginas, two cervices, and two uterine cavities. Each corpus of the uterus has its own fallopian tube. The second type of anomaly due to total or partial fusion of the mullerian ducts is a bicornuate uterus. In this type of anomaly there are two subtypes. The first subtype is uterus bicornis unicollis. This type of anomaly has one cervix, one vagina, and two uterine cornua. The second subtype is uterine bicornis bicollis. In this type of anomaly there are two horns of the uterus, two cervices, and one vagina. These patients with bicornuate uterus have repeated spontaneous abortions usually in the second or third trimester. Other abnormalities encountered in these patients are premature rupture of their membranes, premature labor, and malpresentation of the fetus (transverse).

Next are the malformations associated with arrested mullerian duct development. If the malformation is bilateral, uterine aplasia may be present. The lower portion of the vagina may be present as it arises from the urogenital sinus.

Approximately 3 to 6% of uterine anomalies are associated with unilateral arrest of mullerian duct formation. The so-called unicornuate uterus is associated with ipsilateral renal agenesis and infertility. These patients have a solitary fusiform uterine cavity with lateral deviation within the pelvis terminating in a single fallopian tube. This is the type of anomaly that we see in this patient.

Note should be made of the other abnormalities of uterine development. Nonresorption of the sagittal uterine septum may give rise to uterus septus (total) or uterus subseptus (partial).

The most common anomaly not associated with reproductive failure is the uterus arcuatus or (saddle-shaped) uterine fundus. These patients have an increased transverse diameter of the uterine cavity, a normal ultrasound examination, and normal external morphology.

References:
Beckman, C et al: Obstetrics and Gynecology. Williams and
Wilkins 1992.

Dahnert, W: Radiology Review Manual, Williams and Wilkins 1991.

Langman, J: Medical Embryology, Williams and Wilkins, 1990.

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