Constipation, Tenesmus, & Painful Defecation Flashcards
What is the difference between tenesmus and dyschezia?
TENESMUS = ineffectual and painful defecation or urination, typically associated with colonic and urogenital disease
DYSCHEZIA = difficult or painful defecation, usually a result of anal and perianal disease
(typically used interchangeably)
What are the 7 major causes of constipation?
- neuromuscular dysfunction
- idiopathic megacolon - cats!
- mechanical - colonic or rectal obstruction
- inflammation
- metabolic or endocrine
- drugs - opioids decrease motility
- low fiber diet
What are the 2 major categories of colonic/rectal obstructions that can lead to constipation?
INTRALUMINAL - FB, masses (colorectal adenocarcinoma), strictures (atresia ani)
EXTRALUMINAL - external mass compressing colon (LN), pelvic fractures, pseudocorpostasis (feces cakes anal opening)
What 4 metabolic/endocrine diseases can cause constipation?
- hypokalemia, hypercalcemia
- obesity
- dehydration - CKD
- congenital hypothyroidism - dull, depressed, small
What 2 aspects of diet can cause constipation?
- low in fiber
- high in indigestible material - hair (long-haired animals), bones, mulch (dietary indiscretion - dogs)
What is the most common cause of constipation in cats? What are the most common clinical signs?
idiopathic megacolon common in middle-aged males - dysfunction of colonic smooth muscle
- reduced to absent bowel movements
- weight loss
- PE - colonic impaction, dehydration, abdominal pain
What are some possible physical exam findings in patients with constipation?
- impacted feces in colon
- dehydration
- abdominal pain
- intraabdominal masses or lymphadenopathy
- rectal mass, FB, or stricture
- perineal hernia
- abnormal pelvic canal
- neurologic disease
What 2 diagnostics are recommended for cases of constipation?
- CBC/chem/UA +/- T4 - r/o metabolic/endocrine disease
- abdominal radiographs - assess severity and extend of colonic impaction, assses for cause (FB, mass, pelvic fx)
How are radiographs used for assessing megacolon?
ratio of maximal diameter of the colon to L5 length
- <1.28 = normal
- > 1.48 = megacolon
How are AUS and colonoscopy used for assessing constipation?
AUS - intra/extraluminal masses, prostatomegaly
COLONOSCOPY - inflammatory lesions, masses, strictures, diverticula
What 5 treatments are recommended for constipation?
- rehydration
- removal of impacted feces - enema, manual, laxatives
- dietary change - fiber!
- laxatives + prokinetics - self-evacuation
- address underlying cause
What 4 substances can be used in enemas? What is typically avoided?
- warm water
- KY jelly
- lactulose
- dioctyl sodium sulfosuccinate (DSS) - stimulates movement
sodium phosphate (OTC human-grade) - can result in severe hyperphosphatemia, hypocalcemia, and hypernatremia
What are the 4 common types of laxatives?
- bulk forming
- emollient
- lubricant
- hyperosmotic
What bulk forming laxatives are recommended? How does it work?
FIBER (pumpkin, psyllium) - increases fecal water content and improves colonic motility
What are 3 types of hyperosmotic laxatives?
- poorly absorbed polysaccharides
- lactulose - stimulates colonic secretions and propulsive motility
- polyethylene glycols (PEG) - at home, chronic therapy = Miralax powder in food; in-hospital nasogastric tube CRI PEG3350 slow drip for defecation within 8 hours
What 2 diets are recommended in constipated patients?
- high fiber - bulk forming
- low residue - reduces fecal material, recommended for cats with no musculature to their colon where increased mass of feces is not helpful
What prokinetic is recommended for cases of constipation? When are they used? What is not used?
Cisapride (5HT4 agonist) - works lower in the GIT, enhances colonic motility
megacolon or refractory constipation/obstipation
Metoclopramide
What surgical procedure can be performed for refractory cases of constipation?
subtotal colectomy
What are the main 3 groups of differentials for tenesmus/dyschezia?
- colorectal disease - neoplasia, inflammation, infections (Histoplasma), obstruction (stricture, FB), rectal prolapse
- perianal disease - anal sacculitis, perianal fistula, neoplasia, hernia, atresia ani
- urogenital disease - prostatomegaly
What history is important to gather in cases of tenesmus/dyschezia?
- presence of GI or urogenital signs - duration and frequency
- timing - prior to defecation (obstruction), persistence after defecation (inflammation)
- diet - changes, indiscretion
- medications - opioids affect motility
- signalment - GSD and perianal fistulas, intact males and prostatomegaly
What is the most important part of the physical exam in cases of tenesmus/dyschezia?
careful abdominal, rectal, and perianal evaluation
- masses
- inflammation
- hernia
- fistulas
- stricture
- enlarged/firm bladder or prostate
What 4 diagnostics are commonly used for tenesmus/dyschezia?
- abdominal rads - fecal impation, extraluminal compression from masses, prostate, LNs, or pelvic abnormalities
- AUS - LNs, structural prostatic or urethral disease, thickening, mass
- FNA/biopsy of masses
- colonoscopy - masses, stricture, biopsies at areas of inflammation, neoplasia, or infection
What are the 2 most common colorectal neoplasias? How are they diagnosed?
- adenocarcinoma - dog
- lymphoma - cat
palpate rectal mass, thickening, or napkin ring narrowing
What benign growth is commonly found in the colorectal region?
benign adenomatous polyps - predunculated, focal, sessile tumors
How are colorectal neoplasia and polyps treated?
surgical removal
What is a rectal stricture? What are 3 possible causes of their formation?
narrowing of the rectal lumen by fibrous or proliferative tissue
- trauma
- inflammation
- tumors
How is rectal stricture diagnosed? Treated?
rectal exam or colonoscopy/proctoscopy
balloon dilation or surgery
What are perianal fistulas? What breed is most commonly affected?
chronic, progressive development of ulcerated draining tract in the perianal skin and associated structures around the anus
GSD –> most likely immune-mediated –> recommend immunotherapy
What are 4 parts to medical treatment of perianal fistulas? When is surgical treatment recommended?
- immunosuppression - Prednisone +/- Azathioprine, Cyclosporine, topical Tacrolimus
- antibiotics
- dietary change - hypoallergenic
- stool softeners - Miralax, lactulose
when medical management fails OR in addition to medical therapy
What are the 2 most common perianal tumors? What treatment is recommended for each?
- anal sac adenocarcinoma - hard, firm mass on anal sac diagnosed with FNA or biopsy, patient commonly presents with hypercalcemia of malignancy or metastasis –> surgical excision, radiation, chemotherapy
- perianal adenoma - more common in intact dogs –> surgical removal, castration
What are 3 possible infectious causes of colitis and proctitis?
- Histoplasmosis
- Prototheca
- bacterial
