Mullerian duct anomalies are caused by abnormal formation, fusion or resorption of paired para-mesonephric ducts.(1) The incidence varies amongst general population with normal reproductive function vis a vis infertility patients. Unicornuate uterus constitutes around 20 % of Mullerian duct anomalies. Isolated unicornuate uterus is the most common with a reported frequency of 35%. When a rudimentary horn is present, it is non-cavitary in 33%, cavitary non-communicating in 22% and cavitary communicating in 10 %. (2) Most of these patients are asymptomatic until menarche or until pregnancy. They often present in pregnancy with recurrent abortions, ectopic pregnancy, intra uterine growth retardation or preterm labor. (3) Pregnancy in non-communicating rudimentary horn is possible by trans-peritoneal migration of sperm or fertilized ovum. It occurs in approximately 1 out of 76,000 pregnancies. The risk of uterine rupture is 50 to 90%, with most ruptures (approximately 80%) occurring by the end of the second trimester (4). We report here a case of young parous female who presented in the emergency with clinical features of ectopic pregnancy and later was found to have a unicornuate uterus with non-communicating cavitary rudimentary horn with hematometra.
24 year old lady with previous one caesarean delivery presented in emergency with severe pain in left lower abdomen since one day. She had spotting for two days before the onset of pain. Her previous cycle was two months ago and was also slightly painful. Patient had received multiple oral and injectable pain killers. She was pale, hypotensive with a BP of 90/60 mm Hg and had tachycardia of 110per/min. Abdomen was soft with slight guarding in left iliac fossa. On per vaginum examination cervix was firm, uterus anteverted and normal in size. A 3×3 cm tender mass was felt in left adnexa adjacent to uterus. Ultrasound was suggestive of a left adnexal complex mass of 4.9 x 4.0 x 4.4 cm with a fluid fluid level with small amount of free fluid seen in Pelvis suggestive of left ectopic pregnancy or endometriotic cyst. Serum b-HCG was in the normal range ruling out ectopic pregnancy. Patient was stabilized with IV fluids and injectable pain killers. MRI done for further evaluation was suggestive of a well-defined hypo intense mass in close vicinity to the uterine wall with central fluid fluid level measuring 5.1 x 4.8 cm suggestive of a uterine anomaly with dilated left uterine horn with collected blood inside. Hysteroscopy was suggestive of single uterine cavity with only right tubal ostia. Absence of second cavity ruled out bicornuate uterus. A dilator was left in the uterine cavity for identification and exploratory laparotomy done. On exploration two uterine bodies visualized one measuring 4 X 4 cm and other around 6 X 6 cm. One fallopian tube attached to each body of uteri. The normal cavity identified with the help of dilator and other cavity opened up. Endometrial cavity with blood inside and non-communicating with the normal uterine cavity identified. Diagnosis of unicornuate uterus with non-communicating cavitary rudimentary horn made. Rudimentary horn with the endometrial cavity excised and uterine wall repaired using vicryl suture.
The female reproductive organs develop at approximately the sixth week of gestation from the paired müllerian (paramesonephric) ducts, which fuse to create the uterus, cervix, and upper two-thirds of the vagina. Failure of fusion or normal development or incomplete medial wall resorption of the müllerian ducts can result in a variety of congenital uterine anomalies. In 1979, Buttram and Gibbons (5) developed a classification system of müllerian duct anomalies based on the degree of failure of normal development. Updated in 1988 by the American Society of Reproductive Medicine, this classification system remains in use today and separates uterine anomalies into 7 classes based on embryology (Table 1)
Table1. American Society of Reproductive Medicine Classification of Mullerian Anomalies
I Uterovaginal hypoplasia and agenesis
II Unicornuate uterus
III Uterus didelphys
IV Bicornuate uterus
V Septate uterus
VI Arcuate uterus
VII Uterine anomalies related to diethylstilbestrol exposure Unicornuate uterus is
This a rare case of non-communicating rudimentary horn of a unicornuate uterus (class IIb Mullerian duct anomaly based on the classifications of the American Society of Reproductive Medicine 1988) which probably became functional after many years of menarche. The case highlights the clinical and radiological challenge posed in such atypical presentation of Mullerian anomalies. Most of these patients present in pregnancy with associated complications like recurrent abortions, intrauterine growth retardation, preterm labor etc. This patient underwent a normal pregnancy upto term and underwent elective caesarean in view of breech presentation (malpresentations being common in uterine anomalies). Though the patient did have mild dysmenorrhea since menarche but surprisingly pain was never of such severe intensity. Probably the endometrium in rudimentary horn got stimulated after pregnancy. This time she had severe pain because of distension of uterine cavity and because of which she presented in a clinical state like of ectopic pregnancy.
Once a diagnosis of rudimentary horn is made, the treatment is surgery. Majority of cases present in pregnancy and if undiagnosed early can lead to spontaneous rupture and possible catastrophic consequences. The surgical management is challenging as there are high chances of severe hemorrhage resulting from well fused horns or morbidly adherent placenta. Laparoscopy can be considered in case of early pregnancy.
Rudimentary horn mimicking ectopic pregnancy as in this case are difficult to diagnose and challenging to treat. This case alerts clinicians and sonographers in our environment to the possibility of a uterine anomaly