Bloody Diarrhea in Pregnancy

Differential Diagnosis

1. Infectious Causes (most common cause acutely)

2. Inflammatory Bowel Disease (IBD) Flare

• Approximately one-third of pregnant patients with active UC or Crohn disease will flare during pregnancy - the same annual risk as in non-pregnant women.
• Active disease at conception tends to remain active; inactive disease tends to remain inactive.
• Disease first presenting in pregnancy is typically diagnosed in the first trimester and is not more severe than in non-pregnant individuals.
• UC patients relapse more often during pregnancy than Crohn disease patients.

Severe ulcerative colitis on endoscopy - Creasy & Resnik's Maternal-Fetal Medicine

3. Other Causes

• Hemorrhoids / anorectal disease - very common in pregnancy due to constipation and increased venous pressure; frank blood on toilet paper
• Ischemic colitis - uncommon but possible
• Colorectal polyp or malignancy - rare but must not be missed
• Preeclampsia / HELLP - can cause hepatic hemorrhage but rarely presents as bloody diarrhea per se

Initial Assessment

• Gestational age
• Duration and character of bleeding (bright red vs. dark/maroon, volume, admixed with stool vs. on top)
• Fever, tenesmus, abdominal cramping
• Recent antibiotic use (C. difficile risk)
• Travel history (tropical infections)
• Known IBD diagnosis
• Dietary history, sick contacts

• Vital signs (fever, tachycardia, hypotension = alarm features)
• Abdominal exam for peritonism
• Anorectal examination

• Stool culture, C. difficile PCR/toxin, ova and parasites
• Stool microscopy (white cells = inflammatory; red cells)
• FBC, CRP, albumin, electrolytes, renal function
• Blood cultures if systemically unwell
• Pelvic ultrasound to confirm fetal wellbeing

For a known IBD patient with new diarrhea during pregnancy: always rule out C. difficile infection before starting any new immunosuppressive therapy. - Creasy & Resnik's Maternal-Fetal Medicine, p. 1571

Management

Infectious Diarrhea

• Oral/IV rehydration is the cornerstone
• Avoid antimotility agents in bloody/inflammatory diarrhea
• Antibiotics when indicated:
  • Shigella: azithromycin (preferred in pregnancy) or ceftriaxone
  • Campylobacter: azithromycin
  • C. difficile: oral vancomycin (preferred) or metronidazole (acceptable; low teratogenic risk per safety data)
  • STEC O157:H7: antibiotics generally avoided (risk of precipitating HUS)
  • Listeria/Salmonella bacteremia: ampicillin

IBD Management in Pregnancy

• Methotrexate (teratogenic - stop ≥6 months before conception)
• Thalidomide (teratogenic)
• Ozanimod (stop ≥6 months before conception)

Fulminant Colitis / Severe IBD Flare in Pregnancy

• IV high-dose corticosteroids
• IV antibiotics (broad spectrum)
• Cyclosporine as salvage therapy
• Biological therapies (anti-TNF)
• Surgical indications are the same as in non-pregnant patients - do not delay
• Bowel surgery carries risk of premature labor, maternal and fetal mortality
• Subtotal colectomy preferred over total colectomy to preserve future fertility
• If fulminant colitis occurs after 28 weeks: consider synchronous cesarean section + subtotal colectomy

Mode of Delivery

• Cesarean section performed in up to 44% of IBD patients (higher than general population)
• Cesarean delivery is recommended for active perianal disease; individual assessment otherwise

Endoscopy in Pregnancy

• Elective endoscopy should be deferred to the postpartum period
• Nonemergent but necessary procedures should ideally be done in the second trimester
• Endoscopy is acceptable if the clinical need (e.g., suspected severe colitis, malignancy) outweighs risk
• Flexible sigmoidoscopy is generally preferred over full colonoscopy in pregnancy when feasible

Fetal Outcomes

• Active IBD is associated with increased risk of preterm birth, low birth weight, and small for gestational age
• No increased risk of congenital anomalies from IBD itself
• Quiescent IBD at conception: pregnancy expected to proceed without increased complications
• Severe/untreated infectious diarrhea risks: dehydration, electrolyte imbalance, fetal compromise

Summary: Red Flags Requiring Urgent Escalation

• High fever + profuse bloody stool = consider severe infectious colitis or IBD flare
• Signs of peritonism = risk of perforation - urgent surgical review
• Hemodynamic instability
• Worsening despite 24-48h of appropriate therapy
• New fetal distress