Anal Fistula During Pregnancy: Is It Harmful to the Baby, and When to Treat It?

When a pregnant patient comes to me with fistula symptoms, my first job before the examination is to ease her anxiety — because the question on her mind is clear, and it isn't really about the anal area: "Will something happen to my baby?" Let me give you the answer up front and clearly: no. A fistula is a localized tunnel that has nothing to do with any structure connecting mother and baby. It poses no direct threat to your pregnancy, your delivery, or your baby. Our job during pregnancy isn't to treat it — it's to manage the process comfortably and safely for you.

Why does pregnancy trigger fistula flare-ups?

The fistula itself doesn't originate from pregnancy, but pregnancy can bring an existing or silently waiting fistula onto the stage. Three mechanisms are at work: the hormone progesterone slows the bowel and increases constipation; the growing uterus puts pressure on the vessels and tissues around the anal area; and the immune system is naturally somewhat suppressed during pregnancy. Constipation + pressure + lowered defenses — this trio can turn a silent tunnel into one that speaks up with discharge and soreness.

Are the symptoms different during pregnancy?

No; the classic triad is the same — discharge that stains underwear, soreness that worsens with sitting, and an opening in the skin that won't close. What complicates things during pregnancy is that these symptoms get confused with the far more common hemorrhoids; since nearly half of pregnant women experience hemorrhoids, people assume "it's probably just piles" and the fistula gets overlooked. I've explained how to tell them apart in this article; when in doubt, the examination decides — and examination during pregnancy is completely safe and requires no preparation.

Treatment during pregnancy: what's done, what's postponed?

Our rule is clear, and it matches the international approach: a fistula is not given definitive treatment during pregnancy — it is managed. Because laser or surgical closure carries an anesthesia and medication burden, it's planned for after delivery. The one exception is an abscess: if one develops during pregnancy, it isn't left waiting — it's safely drained under local anesthesia. This small procedure relieves the mother, prevents the infection from spreading, and carries no added risk for the baby.

After delivery, we don't rush, but we don't let it slide either: once the postpartum period is over, we plan definitive treatment for a suitable window based on your breastfeeding schedule. Laser treatment (FiLaC) is a same-day procedure, making it the most practical option for new mothers; the effect of sedation on breastfeeding is short-lived, and we plan accordingly.

Safe relief at home

Things you can do during pregnancy with complete peace of mind: a warm sitz bath two to three times a day for 10-15 minutes (comfortably warm, plain water); a fiber + water routine that tackles constipation at its root (vegetables and fruit, whole grains, at least 2 liters of water a day — already recommended during pregnancy); cleaning with water after a bowel movement and patting, not rubbing, dry. Breaking up long periods of sitting with short walks helps both the fistula and your overall comfort during pregnancy.

As for what not to do — pregnancy raises the bar here: do not use any painkiller, cream, or suppository on your own decision. Even medications thought to be safe during pregnancy can have restrictions depending on the stage; every medication decision should be made jointly with your obstetrician. Internet remedies (garlic, vinegar, baking soda) can burn the skin even in people who aren't pregnant — they're not even worth discussing during pregnancy.

Can I have a vaginal delivery?

In most cases, yes. The presence of a fistula is not, on its own, a reason for a C-section. The decision is based on two things: how close the tunnel is to the birth canal and perineum, and whether there's active inflammation. For a fistula near the perineum with active discharge, we evaluate the mode of delivery together with your obstetrician; not leaving this joint decision to the last month of pregnancy is reassuring for everyone. Rectovaginal fistula, which can also occur in women, is a separate topic that has a closer bearing on the delivery plan.

When is it an emergency?

During pregnancy, the following should not be left waiting: a fever above 38°C (100.4°F), a throbbing swelling that grows within hours, spreading redness. This suggests an abscess is developing — seek care the same day, both for your comfort and to contain the infection. Drainage is safe during pregnancy; being afraid and waiting only makes things worse.

Frequently asked questions

Can the fistula transmit germs to the baby?

No. A fistula is a localized route of inflammation; it has no anatomical connection to the uterus, the placenta, or the baby.

Can an MRI be done for the fistula during pregnancy?

If necessary, yes — MRI doesn't involve radiation and is considered safe during pregnancy. However, an examination is usually sufficient during pregnancy; we generally save the MRI for the definitive treatment plan after delivery.

Can I have laser treatment while breastfeeding?

Yes, with planning. The procedure is same-day; depending on the type of anesthesia used, a short pump-and-wait window is enough. You don't need to stop breastfeeding.

How long after delivery should I get treated?

There's no strict timeframe; once the postpartum period is over, generally from the 2nd-3rd month onward, we choose the right window together. What matters is not postponing it for years with a "once the baby is a bit older..." attitude — a tunnel left waiting can branch out.

My symptoms disappeared completely during pregnancy; am I cured?

Most likely not — it has entered a silent phase. Get a postpartum examination anyway; if the tunnel is still there, that calm period is exactly the most comfortable time to resolve it.

Sources

• American Society of Colon and Rectal Surgeons (ASCRS), fascrs.org
• American College of Obstetricians and Gynecologists (ACOG), acog.org
• NHS — patient information on Anal Fistula, nhs.uk

Don't face this on your own during pregnancy; the examination is safe, and together we'll build a plan tailored to you. Levent: 444 8 623.