Intestinal ultrasound in pregnancyMust knowUC and CD · Pregnancy
Active Inflammatory Bowel Disease on Intestinal Ultrasound During Pregnancy Is Associated With an Increased Risk of Adverse Pregnancy and Neonatal Outcomes Independent of Clinical and Biochemical Disease Activity
Prentice RE, et al.
Gastroenterology 2025 · PMID 40147617 (PubMed, opens in a new tab) · doi 10.1053/j.gastro.2025.03.016 (full paper, opens in a new tab)
| Outcome | Estimate (confidence interval) | P |
|---|---|---|
| Maximal bowel wall thickness above 6 mm on ultrasound | ||
| Preterm birth (primary) | 4.01 (95% CI 1.26–12.72) | P=0.018 |
| Low birth weight (primary) | 2.19 (95% CI 1.01–4.72) | P=0.046 |
| Hyperaemia on ultrasound | ||
| Pre-eclampsia (primary) | 3.46 (95% CI 1.03–11.12) | P=0.046 |
The lower bounds for low birth weight and pre-eclampsia sit just above 1: the direction is clear, the size of the risk is not.
Source: Prentice 2025, abstract. Log-binomial regression among participants scanned in pregnancy (234 had an ultrasound).
Structured abstract
BackgroundActive IBD in pregnancy is linked with adverse outcomes, but symptom scores are unreliable in pregnancy and colonoscopy is usually avoided, so it was unclear how best to judge disease activity before birth.
MethodsInternational prospective cohort study (3 specialist IBD pregnancy services, 2017–2023); not randomised. 377 patients. Primary endpoint: Association between ultrasound disease activity and adverse pregnancy and neonatal outcomes (log-binomial regression); agreement between clinical, calprotectin and ultrasound activity.
ResultsPrimary result. Maximal bowel wall thickness above 6 mm in the second trimester: preterm birth RR 4.01 (95% CI 1.26–12.72; P=0.018) and low birth weight RR 2.19 (1.01–4.72; P=0.046). Second-trimester hyperaemia: pre-eclampsia RR 3.46 (1.03–11.12; P=0.046).
Take-homeIn pregnancy, inflammation seen on intestinal ultrasound was associated with preterm birth, low birth weight and pre-eclampsia independently of symptoms and calprotectin; consider ultrasound to monitor IBD antenatally.
| Patients | 377 |
|---|---|
| Population | Pregnant people with IBD (198 with Crohn's disease). Clinical scores and faecal calprotectin each trimester and 6 weeks postpartum; 234 had intestinal ultrasound in the first or second trimester. |
| Comparison | Pregnancies with vs without active disease on intestinal ultrasound (bowel wall thickness, hyperaemia) |
| Published | Prentice RE, et al. Gastroenterology 2025;169:647–62. |
Key points
- These associations were independent of clinical activity and faecal calprotectin.
- Agreement between clinical scores (Harvey-Bradshaw Index, Simple Clinical Colitis Activity Index) and ultrasound or calprotectin activity was weak, especially in Crohn's disease.
- Greater second-trimester bowel wall thickness was also associated with gestational diabetes.
- Ultrasound was done in the first or second trimester when referral timing allowed, so not every participant had a scan.
Limitations
- Observational; it shows association, not that treating ultrasound activity improves outcomes.
- Specialist centres with ultrasound expertise; confidence intervals are wide.
- Ultrasound timing was opportunistic (first or second trimester when referral allowed); third-trimester scans were not studied.
Commentary
Clinical scores are unreliable in pregnancy: nausea, bowel habit changes and anemia overlap with IBD symptoms, and colonoscopy is usually avoided. This cohort shows that intestinal ultrasound, which is safe and needs no preparation or sedation, detects inflammation that matters for the baby.
How to use it: where intestinal ultrasound is available, a first- or second-trimester scan can confirm remission or uncover active disease that symptoms miss, and can support a decision to escalate therapy. Escalation decisions in pregnancy should still weigh the safety data for each drug (see PIANO).
Whether ultrasound-guided treatment changes pregnancy outcomes has not been tested in a randomised trial.
Journal club
Design
International prospective cohort study (3 specialist IBD pregnancy services, 2017–2023); not randomised. 377 patients.
Primary result. Maximal bowel wall thickness above 6 mm in the second trimester: preterm birth RR 4.01 (95% CI 1.26–12.72; P=0.018) and low birth weight RR 2.19 (1.01–4.72; P=0.046). Second-trimester hyperaemia: pre-eclampsia RR 3.46 (1.03–11.12; P=0.046).
Validity and applicability
- Observational; it shows association, not that treating ultrasound activity improves outcomes.
- Specialist centres with ultrasound expertise; confidence intervals are wide.
- Ultrasound timing was opportunistic (first or second trimester when referral allowed); third-trimester scans were not studied.
Where it sits now
In pregnancy, inflammation seen on intestinal ultrasound was associated with preterm birth, low birth weight and pre-eclampsia independently of symptoms and calprotectin; consider ultrasound to monitor IBD antenatally.
- PIANO (2021): Biologics and thiopurines, alone or together, did not increase pregnancy or infant harms; active disease did, so continue effective therapy through pregnancy.
- Anti-TNF levels in newborns (2016): At birth, infliximab levels in the newborn are about twice the mother's and adalimumab levels are similar or slightly higher; both take months to clear (infliximab longest), which matters for live vaccines; combination with a thiopurine raised infant infection risk.
Questions for discussion
- Ultrasound was done only when referral timing allowed. How might that selection bias the associations?
- Several ultrasound measures and outcomes were tested. How would you weigh P values close to 0.05 with wide confidence intervals?
- If a second-trimester scan shows a thick bowel wall in a patient who feels well and has a normal calprotectin, would you escalate therapy? What evidence would you want first?