Fallopian tubes can become blocked by scar tissue, fluid buildup, or adhesions from a range of causes, with pelvic infections being the most common. A blockage in one or both tubes prevents an egg from reaching the uterus, which is one of the leading causes of difficulty getting pregnant. Understanding what creates these blockages helps clarify what testing and treatment options look like.
Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is the most frequent cause of blocked fallopian tubes. It happens when sexually transmitted bacteria, most often chlamydia or gonorrhea, travel upward from the vagina into the uterus, fallopian tubes, or ovaries. The infection triggers inflammation that, if untreated, produces scar tissue and pockets of infected fluid (abscesses) inside the reproductive tract. That scar tissue can partially or fully seal off the inside of one or both tubes.
What makes PID particularly damaging is that many people don’t realize they have it. Chlamydia in particular often causes no symptoms at all, so the infection can quietly scar the tubes over months or years. Even a single episode of PID raises the risk of tubal blockage, and repeated infections compound the damage significantly. The scar tissue also destroys the tiny hair-like structures lining the tubes that help guide an egg toward the uterus, so even a tube that isn’t fully blocked may not function properly.
Endometriosis
Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus, often on the ovaries, fallopian tubes, and surrounding pelvic surfaces. This misplaced tissue responds to hormonal cycles just like the uterine lining does, thickening and breaking down each month. Over time, the repeated inflammation creates adhesions, which are bands of scar tissue that can bind organs together, distort the shape of the tubes, or block them entirely. Even when a tube isn’t physically sealed shut, endometriosis-related adhesions can kink or compress it enough to prevent an egg from passing through.
Abdominal and Pelvic Surgery
Any surgery in the abdomen or pelvis carries a risk of adhesion formation, and those adhesions can involve the fallopian tubes. Roughly 75% of diagnosed adhesions form as a direct result of abdominal surgery. Open surgeries (those using a single large incision rather than small keyhole incisions) are the biggest culprit, with adhesions developing in more than 90% of cases. Laparoscopic procedures carry a somewhat lower risk, but adhesions can still form.
The surgeries most likely to affect the tubes are those performed nearby: cesarean sections, operations on the colon or rectum, ovarian cyst removal, and appendectomy, especially when the appendix has ruptured and caused widespread inflammation. Multiple surgeries compound the risk, because each procedure creates new opportunities for scar tissue to form and attach to the tubes or surrounding structures. Emergency surgeries, where there’s less time for careful tissue handling, also tend to produce more adhesions.
Hydrosalpinx: Fluid-Filled Tubes
A hydrosalpinx is a specific type of blockage where one end of the fallopian tube seals shut and the tube fills with fluid, swelling into a sausage-like shape. It typically develops as a consequence of one of the other causes on this list, most commonly a prior infection or surgery. The tube becomes blocked at the end closest to the ovary, trapping fluid inside.
A hydrosalpinx doesn’t just prevent eggs from traveling through. The fluid it contains can flow backward into the uterus, creating an environment that’s hostile to a developing embryo. This is why hydrosalpinx reduces the success of IVF as well: even when the tube is bypassed entirely and an embryo is placed directly in the uterus, the leaking fluid can interfere with implantation. For this reason, removing or clipping a fluid-filled tube before IVF is a common recommendation.
Ectopic Pregnancy
An ectopic pregnancy, where a fertilized egg implants inside the fallopian tube instead of the uterus, can damage or destroy the tube. If the tube ruptures, emergency surgery is usually required to remove part or all of it. Even when the ectopic pregnancy is caught early and treated with medication or a tube-preserving surgery, the episode itself often leaves scar tissue that narrows or blocks the tube.
The recurrence rate tells the story of how much damage these events cause. After one ectopic pregnancy, the chance of another is about 15%. After two, that climbs to roughly 30%. Studies have found no significant difference in recurrence rates whether the ectopic pregnancy was treated with medication or surgery, which suggests the underlying tubal damage, not the treatment method, is what drives the risk. Interestingly, tube-preserving surgery (salpingostomy) is actually associated with higher rates of recurrent ectopic pregnancy compared to full tube removal, likely because the repaired tube retains its damaged lining.
Other Causes
Several less common conditions can also block or damage fallopian tubes. Tuberculosis that spreads to the reproductive tract is a significant cause in parts of the world where TB is prevalent. Uterine fibroids that grow near the point where the tube meets the uterus can physically obstruct the opening. Mucus plugs or tissue debris can cause blockages at the part of the tube closest to the uterus; these are sometimes temporary and may clear on their own or during diagnostic testing.
Inflammatory conditions like Crohn’s disease, diverticulitis, and even a severe bout of appendicitis can trigger pelvic inflammation and adhesions that affect the tubes, even though the original problem had nothing to do with the reproductive system.
How Blockages Are Diagnosed
The standard test is a hysterosalpingogram (HSG), where dye is injected through the cervix and an X-ray shows whether it flows freely through both tubes. If the dye stops partway or doesn’t enter a tube at all, that indicates a blockage. The procedure takes about 15 to 30 minutes and can cause cramping similar to menstrual pain.
An ultrasound-based alternative called HyCoSy uses contrast fluid and ultrasound imaging instead of X-rays. A large analysis of 1,340 patients across 24 studies found that HyCoSy correctly identified open tubes 89% of the time and correctly identified blocked tubes 93% of the time. Newer 3D/4D versions using microbubble contrast performed even better, matching the sensitivity of MRI-based testing while offering higher specificity (94% versus 82%). In practice, either imaging method provides reliable results, and the choice often depends on what’s available at your clinic.
Laparoscopy, a surgical procedure using a small camera inserted through the abdomen, remains the most definitive way to evaluate the tubes. It lets a surgeon see adhesions, endometriosis, and structural damage that imaging alone might miss. It’s typically reserved for cases where imaging results are unclear or when a procedure to treat the blockage is planned at the same time.
Treatment Options
Treatment depends on where the blockage is, what caused it, and whether one or both tubes are affected. For blockages near the uterine end of the tube, a procedure called tubal cannulation can often restore flow. A thin wire or catheter is threaded through the uterus and into the blocked portion of the tube to open it. Success rates are high: in one comparative study, at least one tube was successfully reopened in 86% to 92% of patients, and about 29% achieved pregnancy without needing IVF afterward.
For blockages at the far end of the tube (near the ovary), or for tubes damaged by hydrosalpinx, surgical repair is more complex and less reliably successful. The surgery involves opening the sealed end of the tube and folding it back, but re-blockage is common because the underlying tissue damage persists. When tubal damage is severe, bilateral, or caused by extensive scarring, IVF bypasses the tubes entirely by retrieving eggs directly from the ovaries and transferring embryos into the uterus.
If only one tube is blocked and the other is healthy, many people conceive without any intervention. You ovulate from alternating ovaries in a roughly random pattern, so a single open tube on either side can catch an egg released from the ovary on the opposite side, though the chances per cycle are lower than with two functioning tubes.