Disorders of the Intestines

Definition of diverticulosis

Herniation of mucosa + submucosa through muscularis propria at sites where vasa recta penetrate.

Most common location of diverticulosis

Sigmoid colon.

Risk factors for diverticulosis

Low‑fiber diet, high intracolonic pressure, Western diet, age.

Symptoms of diverticulosis

Usually asymptomatic (80%).

Pathophysiology of diverticulitis

Microperforation of diverticulum → localized inflammation contained by fat/omentum.

Presentation of diverticulitis

Progressive steady LLQ pain, fever, constipation/diarrhea; urinary symptoms possible; NO rectal bleeding.

Physical exam in diverticulitis

Focal LLQ tenderness.

Treatment of uncomplicated diverticulitis

Supportive care; antibiotics optional (new guidelines allow no antibiotics in select cases).

Complications of diverticulitis

Abscess, colovesical fistula, stricture, peritonitis.

Colovesical fistula symptoms

UTIs, pneumaturia, fecaluria.

Stricture symptoms

Constipation, distention, decreased stool caliber.

Pathophysiology of diverticular hemorrhage

Rupture of vasa recta over dome of diverticulum → arterial bleeding.

Presentation of diverticular hemorrhage

Abrupt painless hematochezia; large volume blood loss; no fever.

Diagnosis of diverticular hemorrhage

Colonoscopy (to confirm diverticula and exclude other causes).

Treatment of diverticular hemorrhage

Supportive care; IR embolization or surgery if persistent.

Celiac artery supplies

Stomach, liver, spleen, pancreas, proximal duodenum.

SMA supplies

Jejunum, ileum, cecum, ascending colon, proximal transverse colon.

IMA supplies

Distal transverse colon, descending colon, sigmoid colon, proximal rectum.

Watershed areas of gut

Splenic flexure (SMA/IMA), sigmoid colon.

Acute mesenteric ischemia causes

Embolus, thrombosis of SMA plaque, NOMI(Non Occlusive mesenteric ischemia) , mesenteric venous thrombosis .

Risk factors for embolic Acute Mesenteric Ischmia

Atrial fibrillation, recent MI, valvular disease.

Risk factors for thrombotic AMI

Atherosclerosis, smoking, PAD.

Presentation of acute mesenteric ischemia

Severe abdominal pain out of proportion to exam; rapid progression.

Treatment of Acute Mesenteric Ischemia

Heparin, IR embolectomy, stenting, papaverine for NOMI, surgery for necrosis.

Nonocclusive mesenteric ischemia (NOMI)

Low‑flow state with vasoconstriction; vessels patent.

Risk factors for Non-Occlusive Mesenteric Ischemia

Hypotension, CHF, vasopressors, cocaine, digitalis.

Presentation of Non-Occlusive Mesenteric Ischemia

Milder pain; may have distention or red/maroon stools; often overshadowed by cardiac issues.

Mesenteric venous thrombosis (MVT) presentation

Subacute abdominal pain for days–weeks; nausea/vomiting; rectal bleeding in 15%.

Risk factors for Mesenteric Venous Thrombosis

Hypercoagulable states (90%), DVT history (60%), abdominal infections, pancreatitis, cirrhosis, OCPs.

Treatment of Mesenteric Venous Thrombosis

Heparin → long‑term anticoagulation; thrombolysis; surgery if infarction.

Chronic mesenteric ischemia definition

Postprandial(after eating) intestinal angina due to atherosclerotic narrowing of ≥2 mesenteric arteries(SMA, IMA or Celiac).

Presentation of Chronic Mesenteric Ischemia (aka intestinal angina)

Postprandial pain 10–30 min after eating, lasting hours; sitophobia; weight loss.

Treatment of Chronic Mesenteric Ischemia

Endovascular stent or surgical bypass (SMA is key target).

Colonic ischemia (ischemic colitis) pathophysiology

Localized low‑flow state affecting watershed areas (splenic flexure, sigmoid).

Presentation of ischemic colitis

Sudden LLQ pain → red/maroon stools within 24 hrs; mild tenderness.

Diagnosis of ischemic colitis

CT (thickened colon), colonoscopy (segmental ulceration, rectal sparing).

Treatment of ischemic colitis

IV fluids, bowel rest, antibiotics; surgery if infarction or stricture.

Definition of Arteriovenous Malformations (AVMs)

Abnormal mucosal vessels with direct artery‑to‑vein connection (no capillary bed).

Locations of Arteriovenous Malformations (AVMs)

Right colon, small intestine; also stomach (GAVE).

Risk factors for Arteriovenous Malformations (AVMs)

Age, CKD, aortic stenosis.

Clinical effects of Arteriovenous Malformations

Iron‑deficiency anemia, occult or overt GI bleeding.

Treatment of AVMs

Oral iron, endoscopic therapy; bleeding worsened by anticoagulants.

Acute Mesenteric Ischemia, Chronic Mesenteric Ischemia, Colonic Ischemia

Gastric Antral Vascular Ectasia (GAVE)

“Watermelon stomach”; causes chronic GI bleeding and anemia. (GAVE me that watermelon)

Hereditary Hemorrhagic Telangiectasia (HHT)

Red dots on the lips: Autosomal dominant; mucocutaneous telangiectasias; AVMs in GI tract, lungs, CNS; recurrent epistaxis.