Which Systemic Medications Can Improve the Thin Endometrium?

Transvaginal ultrasound assessment of endometrial thickness and echoic pattern is a part of standard monitoring before embryo transfer. Uterine pathology (adenomyosis, fibroids, and polyps), body habitus, uterine contractions, resolution of the ultrasound machine, inter- and intra-observer variability, and patient tolerance, may affect the accuracy of measurement. There is no exact definition of thin endometrium, and it is still controversial whether thin endometrium negatively affects pregnancy rates after embryo transfer. Common theoretical causes of thin endometrium include estrogen deficiency, medication such as clomiphene citrate, poor uterine blood flow, uterine fibroids, intrauterine adhesion, previous intrauterine surgery (including curettage), hydro-salpinges, and chronic endometritis. Suggested treatments are 1) Dietary supplements (e.g. L-arginine, and a high-protein diet) to provide protein that the body needs to thicken the endometrium or eat fruits high in nitric oxide (oranges, watermelons, and lemons) to increase blood supply to the uterus; 2) Increase the dose or use alternative routes of estrogen administration; 3) Use vasodilators (e.g. Sildenafil, Pentoxifylline, and low-dose aspirin) to increase uterine blood flow; 4) Hysteroscopy to lyse intrauterine adhesion; 5) Surgery to remove fibroids or hydro-salpinges; 6) Antibiotics to combat subclinical endometritis; 7) Life-style modification (enough sleep to recover and promote optimal tissue growth, and regular exercise to globally increase blood flow in the body); 8) Acupuncture to increase uterine blood flow; and 9) The use of platelet-rich plasma (PRP), granulocyte colony-stimulating factor (G-CSF), and stem cell to stimulate/regenerate endometrial stem cells. There is minimal evidence to support the use of any specific treatments to improve outcomes in patients with thin endometrium. In frozen embryo transfer, a natural cycle may be considered to avoid iatrogenic thinning of the endometrium. One should consider the cost and possible harm of the treatment before using an adjuvant to improve pregnancy outcomes in patients with a thin endometrium.