How it’s tested
With modern technology and imaging studies, we can pick up even the most minor (as in – nothing to get too worried about!) variances in a woman’s uterus shape and structure.
From the outside, your uterus is shaped like an upside-down pear: big at the top, skinny and tapered towards the bottom. To have a smooth egg implantation, the inside of your uterus should have a similar shape as well.
But sometimes a uterus develops a little abnormally. For example, two sides of the uterus can come together, cause the middle portion to “melt away”. Or your uterus can have a normal-appearing exterior, but “heart shaped” interior, with a dip extending from the top of the uterus (the “fundus”) into the cavity.
A minor dip like that is called an arcuate cavity. As it becomes longer, we call it subseptate. If the dip is over 1 cm in size, it’s sometimes called a “true septum” – like a wall dividing the two halves of your uterus. Although bigger dips are more serious, there’s actually no medical consensus yet on where the line between “normal” and “abnormal” should be drawn. In fact, the decision to label your dip “arcuate”, “subseptate” or “septum” isn’t standardized.
In any case, the trouble with these abnormalities is that they involve the “fundus”, the top of your uterus. That’s where eggs prefer to implant. So the longer the septate structure (the “dip”), the more difficult it is for blood to travel from the outside of your uterus to that part of your fundus. Eggs need that blood flow to implant, so there can be a reduced chance of implantation.
A regular transvaginal ultrasound or HSG (x-ray procedure) can reveal warning signs that there’s an arcuate, subseptate or septate. However, it can only truly be diagnosed by a sonohystogram or a hysteroscopy.
In this test, water is placed inside your uterus. This makes the two sides expand, which lets us clearly see the contours of the centre portion and whether there’s a dip.
With a “three-dimensional” sonohystogram, we can see the dip even more clearly. This version of the test will seem identical from your perspective, but it involves greater computer power in the ultrasound machine. It’s able to recreate a true three-dimensional image of your uterus!
This is a minor surgical procedure. It’s often done as an outpatient. Basically, a camera is placed through your cervix so the surgeon can look at the top of your fundus. If everything’s fine, they’ll see a fundus with natural appearing veins. If there’s a significant septum, the surgeon will see “tunneling” into each of the top corners of the uterine structure, with a fairly empty network of veins in the middle (in other words, it’ll show that it’s not receiving healthy blood flow).
How it’s treated
Treatment is pretty straightforward: a hysteroscopic resection. That means the extra tissue is removed from the dip. But it’s a delicate procedure, because the amount that needs to be removed is usually tiny! It’s measured in millimeters. However, you body will usually accept this removal, because such a small amount is being removed.
That said, we’re always cautious when suggesting this procedure. There are two risks:
- You could develop scar tissue right in the key location where the egg most needs to implant. That’s a serious risk that could harm your fertility.
- A resection could lead to a “perforation” (a small hole) in your uterus or fundus.
Even though these complications are actually pretty unlikely, the procedure is still quite controversial. Remember how we said that there’s no standard medical opinion on whether your “dip” is serious or not? That also means there’s no clear point at which surgery is necessary. Different doctors will have different options on when surgery is required – or whether it’s needed at all.
The good news is that for most women, a mild case will be considered relatively normal, and no surgery will be required.