What is fetal calprotectin and what is its clinical use?

Fecal Calprotectin in Pregnancy: A Non-Invasive Marker for IBD Disease Activity

Fecal calprotectin is a stool biomarker that measures intestinal inflammation and is used to screen for active inflammatory bowel disease (IBD) in pregnant women at preconception, during each trimester, and after delivery. 1

What is Fecal Calprotectin?

Fecal calprotectin is a calcium- and zinc-binding protein released by neutrophils during intestinal inflammation. 2 It serves as a non-invasive marker that can distinguish between active and quiescent IBD without requiring endoscopic procedures. 1

Clinical Use in Pregnancy

Primary Indication: IBD Monitoring

• Screening for active IBD disease should be performed by checking fecal calprotectin levels at preconception, during each trimester, and after delivery in all pregnant women with IBD. 1

• A cutoff level of 200 μg/g has a positive predictive value of 67-74% for detecting active disease activity. 1

• Fecal calprotectin is particularly useful because IBD symptoms during pregnancy can overlap with normal pregnancy symptoms, making clinical assessment challenging. 1

Why This Matters for Pregnancy Outcomes

• Active IBD during pregnancy increases risks of preterm birth, low birth weight, fetal growth retardation, hypertensive disease of pregnancy, and cesarean delivery. 1

• Maintaining disease remission throughout pregnancy is essential for optimal maternal and fetal outcomes. 1

• The non-invasive nature of fecal calprotectin testing allows for frequent monitoring without the risks associated with endoscopy or radiation exposure. 3

Important Clinical Caveats

When Fecal Calprotectin is NOT Useful

• Fecal calprotectin does NOT reflect fetal inflammatory status - studies show it is elevated in maternal circulation in conditions like preeclampsia but not in fetal serum, umbilical cord blood, or amniotic fluid. 4, 5

• Fecal calprotectin is elevated in pregnant women with active IBD but remains normal in healthy pregnant women without intestinal inflammation. 5

Complementary Testing

• When fecal calprotectin suggests active disease but further evaluation is needed, intestinal ultrasound (84% sensitivity, 98% specificity) or MRI without gadolinium should be considered rather than proceeding directly to endoscopy. 1

• Unsedated flexible sigmoidoscopy is preferred over colonoscopy if endoscopic evaluation becomes necessary for critical medical decision-making. 1

Practical Algorithm for Use

1. Baseline measurement: Check fecal calprotectin at preconception counseling visit 1

2. Serial monitoring: Repeat during first, second, and third trimesters 1

3. Interpretation:

   • <200 μg/g suggests quiescent disease
   • ≥200 μg/g indicates likely active inflammation requiring treatment adjustment 1

4. Postpartum follow-up: Recheck after delivery to assess disease status 1

5. Action on elevated levels: Optimize IBD therapy using the same medications as in non-pregnant patients (with specific exceptions for methotrexate, JAK inhibitors, and certain sphingosine-1-phosphate receptor modulators) 3