IUS in IBD & adverse pregnancy outcomes

May 7, 2024

Issue 09

Clinical Question

Does active IBD defined by intestinal ultrasound predict the risk of adverse pregnancy outcomes?

Editor’s Bottom Line

Features of disease activity on intrapartum intestinal ultrasound can predict adverse obstetric outcomes among women with IBD. More studies are needed to determine whether escalation of therapy during pregnancy improves those outcomes.

Reference

Prentice RE, Flanagan EK, Wright EK, et al. 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. Gastroenterology. Epub ahead of print March 25, 2025; https://www.sciencedirect.com/article

Synopsis

To assess whether active IBD detected on intestinal ultrasound (IUS) during pregnancy may predict adverse obstetric outcomes, researchers in Australia and the United States prospectively recruited 198 pregnant women with Crohn’s disease (CD) and 179 pregnant women with ulcerative colitis (UC) from three specialist centers in the two countries between 2017 and 2023.

Participants underwent clinical assessments and fecal calprotectin (FC) testing in each trimester and at six weeks postpartum. IUS was performed in the first (T1) or second (T2) trimester when referral timing allowed, with 234 women (62.1%) receiving at least one IUS during pregnancy.

The authors found that 36% of women had active disease on IUS. More than half of patients were exposed to biologics during pregnancy, with no significant difference in the rate of biologic use between those with active versus inactive disease on IUS.

On multivariable analysis, a maximal bowel wall thickness >6 mm on IUS in T2 was associated with a four-fold increased risk of prematurity (Risk Ratio [RR]: 4.01; 95% Confidence Interval [CI], 1.26–12.72; p=0.018) and a two-fold increased risk of low birth weight (RR: 2.19; 95% CI, 1.01–4.72; p=0.046). Additionally, hyperemia detected on IUS in T2 was associated with a three-fold increased risk of preeclampsia (RR: 3.46; 95% CI, 1.03–11.12; p=0.046). Each 1-mm increase in bowel wall thickness in T2 increased the risk of gestational diabetes (RR: 1.08; 95% CI 1.088–1.089; p<0.001).

The study also found poor agreement between clinical assessment tools (the Harvey Bradshaw Index or Simple Clinical Colitis Activity Index) and disease activity as measured by IUS and FC, particularly for CD patients (k=0.21–0.39.

Additionally, there was some disagreement between FC findings and IUS. For example, 16.1% (19) of the 118 participants who underwent both FC and IUS assessment in T1 had a normal FC but active disease on IUS, with 12 having CD with ileal involvement. Similarly, 14.2% (25) of 176 participants with both assessments in T2 had normal FC but active disease on IUS, with 20 having CD with ileal involvement.

Rates of adverse outcomes included preterm delivery in 5.9% of participants, low birth weight in 5.8%, preeclampsia in 6%, gestational diabetes in 12.2% and need for neonatal intensive or special care unit admission in 23.1%.

The authors noted the study was limited by variable protocol adherence, with only half of participants assessed with all three protocolized methods—clinical, FC and IUS—in T1 and T2. There were also a relatively low number of adverse obstetric outcomes.

Details

Study Design: Prospective cohort study
Funding: The Australian Government, the Gutsy Group, Ferring Pharmaceuticals, the National Health and Medical Research Council, Crohn’s Colitis Australia and St Vincent’s Hospital Melbourne.
Allocation: Not applicable
Setting: Multicenter
Level of Evidence: 2b