Distribution of tubal endometriosis

The left fallopian tube seems more prone to involvement by endometriosis

Key Points

Importance:

• In the current literature, tubal endometriosis has been reported less frequently than ovarian, sacral ligaments, and pelvic wall endometriosis.

Highlights:

• The incidence of left fallopian tube endometriosis is higher than that of right and bilateral fallopian tube endometriosis.
• The ampullar region of the tubes is statistically more affected by endometriosis when compared to the other parts of the fallopian tubes.

What's done here:

• A retrospective, cross-sectional, and single-center study investigates the distribution of tubal endometriosis in both tubal parts at the University of Guangxi, China.
• This research lasted 10 years and included sixty-three women who underwent tubal resection with or without a diagnosis of endometriosis during this period. 

Key Results:

• All 63 cases are histopathologically confirmed tubal endometriosis by salpingectomy.
• Thirty-three women underwent tubal resection with a previous diagnosis of endometriosis. In this group, the left, right, and bilateral fallopian tubal involvement were 44,12%, 38,23%, and 17,65% respectively.
• The indication for surgery was other than endometriosis (fibroids, uterine prolapse, hydrosalpinx, ovarian cysts, gynecological malignancy, etc.) in the remaining 29 women composed the non-EM group. 
• The non-EM group had a statistically different distribution of tubal endometriosis on the same sides of the tubes.
• The ampullary part of the tubes involved approximately half as much in the EM group, while it was around 75% in the non-EM group.
• Considering the entire study group, it was found that endometriosis was more common in the left fallopian tubes than in the right or bilateral fallopian tubes.
• Tubal ampullary involvement showed a higher incidence of endometriosis when compared to other parts of the fallopian tubes as well. 

Lay Summary

The incidence of tubal endometriosis was previously reported in a percentage of 4 to 11, but recent studies gave a prevalence up to 42.5 % which indicates the actual incidence of this disease is underestimated. 

Some studies in recent literature suggested that endometrioma as well as left deeply infiltrating endometriosis are more likely to occur on the left side, compared to the right. According to Sampson's theory, the explanation for this left-side involvement is related to the presence of the left sigmoid colon which could reduce the elimination of endometrial debris. 

Zheng et al. from the Department of Obstetrics and Gynecology, Fourth Affiliated Hospital of the Guangxi Medical University, China, aimed to investigate the distribution of tubal endometriosis in their tertiary clinic in a retrospective, and a cross-sectional study covering 10-year cases. Their primary interest is to identify the most common side of tubal endometriosis. The left Fallopian tubal involvement appeared to be more prominent than the right side and bilateral tubal endometriosis.

Secondly, the authors made comparisons of the endometriosis involvement between four parts of the fallopian tubes (interstitial, isthmic, ampullar, and fimbrial). Although there was no significant difference in incidence between ampullar and non-ampullary tubal endometriosis in the known endometriosis operated group, when the surgical indication was other than endometriosis, there was a higher incidence of ampullar tubal endometriosis.

Some previous studies claimed that tubal ligation and tubal fistula after the operation may be one of the causes of tubal endometriosis. If ligation has been made within 4 cm. from the uterine cornu, the tube might be dilated under internal pressure and cause a tubal fistula. With the retrograde menstrual flow, the glands and the stroma of the endometrium can penetrate the muscular layer before the tubal fistula.

This interesting study was recently published in the Journal of Obstetrics and Gynecological Research.

Research Source: https://pubmed.ncbi.nlm.nih.gov/35261117/