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Müllerian anomalies; Tubal anomalies; Absent tubal segment

Introduction

During the embryonic period, Müllerian duct development occurs through a mechanism of fusion in their distal portions. This results in the formation of the Fallopian tubes, uterus, cervix, and proximal third of the vagina. Disruption of the fusion mechanism can result in various developmental anomalies of the female internal genitalia, such as agenesis of the uterus or formation of a unicornuate, bicornuate, didelphic, septate, or arcuate uterus. This malformation can occur at any stage of Müllerian development and the resultant uterine anomalies can be of diverse types and shapes [1]. Fallopian tube anomalies are very rare and mainly include accessory ostia, multiple lumina, duplication, complete absence or partial atresia, or segmental deletion of different regions of the tube. They are usually reported in association with ipsilateral major uterine malformation. Isolated absence of a segment in a unilateral Fallopian tube is an extremely rare event. Here a rare case of an isolated segment of a Fallopian tube incidentally encountered in a fertile woman, during a myomectomy operation is reported. The etiological theories and potential hazards are discussed.

Case presentation

A 35-year-old lady, who has previous four pregnancies (two spontaneous vaginal deliveries and two first-trimester miscarriages) presented with menorrhagia due to intramural fibroid. She had no history of pelvic surgery or sexually transmitted disease.

At myomectomy operation, an interruption of the right Fallopian tube. There is a four-centimeter defect in the middle of the ampullary part of the tube. The proximal and distal ends are connected by a fibrotic band at the edge of the mesosalpinx. The proximal portion of the tube is seven centimeters in length while the distal part is four. The ipsilateral ovary is normal and active. The left ovary is active [2]. The left tube tube measures twelve centimeters and looks normal. Myomectomy was done and no intervention was done to the Fallopian tube as the patient had not consented to this intervention.

Discussion

Congenital abnormalities of the Fallopian tubes are extremely rare. Their true incidence is not known and very few cases have been reported in the literature in the form of case reports and small case series. They can be a complete, partial, or segmental absence or duplication, accessory ostia, tubes, multiple lumina, and diverticula. They are usually asymptomatic and are typically diagnosed incidentally during procedures for the evaluation and treatment of infertility. Most reported cases are unilateral and absent segments in both tubes are reported.

There are three theories for the etiology of the segmental absence of the fallopian tube. The first one is a defect in the development of the Müllerian and mesonephric systems that occurs in the local region of the genital ridge and caudal part. The second is an asymptomatic torsion of the adnexa during the fetal period [3]. The third is tubal maldevelopment caused by ischemia due to a vascular accident.

This case is most likely due to asymptomatic torsion as it is not associated with other Mullerian duct anomalies. Tubal maldevelopment caused by ischemia is a possible cause, but the absent segment is usually short. Asymptomatic segmental torsion of the Fallopian tube and/or ovarian pedicle may occur for uncertain reasons during adulthood, in childhood, or even during the fetal stages. Torsion may give rise to necrosis and autoamputation. This case differs from most reported cases in being a fertile woman. Her condition is asymptomatic, encountered incidentally during a surgical procedure not related to infertility [4-8]. This supports Yilmaz et al postulation that if the other tube is normal infertility problems may not emerge and these anomalies remain undiagnosed.

In this case, four pregnancies occur from fertilization of ovum from left ovary. Fertilization in the proximal part of the right tube is theoretically possible as intraperitoneal transmigration of spermatozoa from one ovary to the contralateral tube is documented. This gives rise to a potential risk of ectopic pregnancy. Furthermore, unilateral partial absence of a fallopian tube may potentially develop into hydrosalpinx and may negatively affect the function of the other tube or the pelvic microenvironment; with a negative effect on fertility.Unilateral tubal anomaly may negatively affect the function of the other tube or the pelvic microenvironment.

Therefore, although several studies have reported that the influence on ipsilateral ovarian function due to a decrease in blood flow after salpingectomy is still controversial.

Conclusion

Unilateral Segmental Absence of the Fallopian Tube is an extremely rare event, usually reported as incidental findings during procedures for infertility workups. We report such a case to document this condition in a fertile woman. As the condition does not affect fertility in this case, we assume there are an unknown number of fertile women with similar tubal anomalies undiagnosed.

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