What causes left-sided pain under my ribs after colon preparation?

Left-Sided Pain Under Ribs After Colon Prep

Left-sided pain under the ribs following colonoscopy preparation is most commonly caused by colonic distension from the bowel cleansing process itself, splenic flexure spasm, or irritation of the colon from the preparation solution, and typically resolves within 24-48 hours without intervention. 1, 2

Understanding the Mechanism

The bowel preparation process causes several physiological changes that can produce left upper quadrant discomfort:

• Colonic distension and spasm occur as the preparation solution rapidly fills and cleanses the colon, with the splenic flexure (located under the left ribs) being particularly prone to gas trapping and spasm 1, 2

• Increased visceral sensitivity during bowel preparation is well-documented, with studies showing that patients experience heightened abdominal pain and nausea during the cleansing process, particularly those with higher anxiety levels 1

• Mucosal irritation from PEG-based solutions can cause transient inflammation, though these agents are preferred over sodium phosphate preparations which have been associated with more severe complications including aphthous ulceration 1

Expected Clinical Course

This pain should be self-limited and resolve within 1-2 days after completing the preparation. 1, 2

Common associated symptoms during and immediately after bowel prep include:

• Abdominal cramping and distension 2
• Nausea and vomiting (one of the most common complications) 2
• Acute diarrhea 2

Red Flags Requiring Immediate Evaluation

You should seek urgent medical attention if you experience any of the following:

• Severe, persistent, or worsening pain that doesn't improve after bowel movements or passage of gas 1, 3
• Fever (temperature >38°C/100.4°F), which could indicate diverticulitis or perforation 1
• Inability to pass gas or stool after the preparation is complete, suggesting possible obstruction 3
• Bloody stools beyond minor streaking 3
• Vomiting that prevents you from keeping down fluids 2
• Signs of dehydration including dizziness, decreased urination, or confusion 2

Differential Diagnosis to Consider

While most post-prep pain is benign, the left upper quadrant location raises specific considerations:

Splenic Flexure Syndrome

• Gas trapping at the splenic flexure (the sharp turn of the colon under the left ribs) is extremely common after bowel prep 1
• This typically improves with ambulation and passage of gas

Acute Diverticulitis

• Left lower quadrant pain with fever is the classic presentation, though pain can radiate upward 1
• The American College of Radiology identifies CT as the preferred imaging modality if diverticulitis is suspected, with sensitivity and specificity approaching 100% 1
• Uncomplicated diverticulitis can be managed without antibiotics in select patients without significant comorbidities or signs of sepsis 1

Rare but Serious Complications

• Colonic perforation from the preparation itself is exceedingly rare but presents with severe pain, fever, and peritoneal signs 2, 4
• Post-colonoscopy appendicitis occurs in approximately 3.8 cases per 10,000 procedures, though this typically presents in the right lower quadrant 4

Management Approach

For typical post-preparation discomfort:

• Ambulation helps mobilize trapped gas through the colon 1
• Over-the-counter analgesics (acetaminophen) can be used for mild pain 5
• Hydration to replace fluid losses from the preparation 2
• Time - most symptoms resolve within 24-48 hours 1, 2

Avoid NSAIDs initially if you're concerned about possible diverticulitis or mucosal injury, as these can theoretically worsen inflammation 1

When Imaging Is Indicated

CT imaging should be obtained if:

• Pain persists beyond 48 hours after preparation 1, 3
• Fever develops 1
• Pain is severe or progressively worsening 3
• Any red flag symptoms are present 3

The American College of Radiology specifies CT as the most appropriate imaging test for acute left-sided abdominal pain, with the ability to diagnose diverticulitis, perforation, abscess formation, and other serious pathology 1

Important Caveats

Studies show that patients with higher visceral sensitivity, anxiety, and pre-existing bowel symptoms experience more pain during bowel preparation - this doesn't necessarily indicate pathology but rather heightened perception of normal physiological processes 1

Female patients, younger patients, and those with lower BMI are more likely to experience discomfort during colonoscopy-related procedures, including the preparation phase 6

The pain location under the left ribs makes splenic flexure involvement most likely, as this is the anatomic location where the colon makes its sharpest turn and is most prone to gas trapping 1