Endo Belly: What Is It and Why Does It Happen?-A Narrative Review

Abstract

Endometriosis is a chronic inflammatory disease where endometrial-like lesions settle outside the uterus, resulting in extensive inflammatory reactions. It is a complex disease that presents with a range of symptoms, with pain and infertility being the most common. Along with severe dysmenorrhea, cyclic and acyclic lower abdominal pain, cyclic dysuria and dyschezia, dyspareunia, and infertility, there are also nonspecific complaints that can cause confusion and make endometriosis the chameleon among gynecological diseases. These symptoms include unspecific intestinal complaints, cyclic diarrhea, but also constipation, nausea, vomiting, and stomach complaints. It appears that in addition to general bowel symptoms, there are also specific symptoms related to endometriosis such as cyclic bloating of the abdomen, known as endo belly. During the second half of the menstrual cycle leading up to menstruation, the abdomen becomes increasingly bloated causing discomfort and pain due to elevated sensitivity of the intestinal wall. Patients with endometriosis exhibit a reduced stretch pain threshold of the intestinal wall. Here, we review the endo belly, for the first time, pathophysiology and the influence of other diseases (such as irritable bowel syndrome-IBS), microbiome, hormonal levels, inflammation, and diet on the presentation of this condition.

Keywords: diet; endometriosis; enteric nervous system; intestinal disorder; irritable bowel syndrome; microbiome.

Figure 1

Photos (a,b) show two patients with pronounced endo belly, which usually occurs in the second half of the cycle.

Figure 2

The interplay of local and systemic factors in abdominal inflammatory processes in the pathogenesis of endometriosis. The local inflammatory processes, metabolome, and estrobolome in the intestine can have systemic effects that contribute to the development of endometriosis. The pathophysiological concept underlying here is intricate and complex. Retrograde menstruation causes an increase in the number of endometrial cells and cellular debris in the pelvis, leading to a proinflammatory response that releases cytokines and growth factors. The body’s natural immune response is insufficient to break down these cells, resulting in the development of ectopic lesions. At the same time, the release of cytokines and growth factors can also disrupt gut function, causing dysbiosis. Dysbiosis may also affect intestinal epithelial cell function, stem cell activity, and the estrobolome, resulting in increased permeability that causes immunologic imbalance and low-grade systemic inflammation. This cycle can continue, with endometriosis lesions and dysbiosis exacerbating each other.

Figure 3

Alterations in IBS-associated complaints in the course of the menstrual cycle.