Thin Endometrium

The endometrium (uterine lining) must reach an adequate thickness — typically at least 7 mm and ideally 8–10 mm — to support implantation. A thin endometrium is often due to inadequate estrogen stimulation, prior uterine surgery (Asherman's syndrome), or poor endometrial blood flow.

On transvaginal ultrasound, both thickness and trilaminar (triple-line) pattern are assessed. A thin or non-trilaminar endometrium may prompt dose adjustments of estrogen, extended priming, or use of adjuvant therapies such as sildenafil vaginal suppositories, low-dose aspirin, or intrauterine PRP infusion.

Severe Asherman's syndrome (intrauterine adhesions from D&C or infection) requires hysteroscopic adhesiolysis before embryo transfer.