HY lecture notes:
Sitz bath is the answer for Tx of anal fissure, which occurs posterior in the midline below the pectinate line –> can present with adjacent skin tag (why I don’t know, but I’ve seen it on the surgery NBME) –> described as exquisitely and extraordinarily painful to the point that the patient will refuse the rectal exam –> vignette will often say a rectal exam cannot be performed.
For Hirschsprung –> Dx = abdominal x-ray (AXR) looking for obstruction, followed by rectal manometry, followed by definitive rectal biopsy.
They’ll tell you a young child (age can range from neonates up until age ~10ish [there are varying severities apparently based on the degree of neural crest cell non-migration]) has chronic constipation + passes one string-like stool every four days despite maximum fiber + laxative therapy; they’ll also say there’s no stool palpable in the rectal vault. Answer sequence should go: AXR –> rectal manometry –> confirmatory biopsy.
AXR in Hirschsprung will show multiple loops of dilated small bowel with air-fluid levels, which suggests a distal bowel obstruction.
Don’t order an abdominal x-ray unless you’re looking for gas, which may be used to diagnose a potential obstructive pathology (e.g., Hirschsprung) or conditions such as toxic megacolon. It can also be used for pneumatosis intestinalis, which is air in the bowel wall / portal vein seen in necrotizing enterocolitis (generally neonates born <32 weeks gestation). Obstipation is inability to pass stool and flatus. This is often an indication for an AXR secondary to the suspicion of obstruction.
For hiatal hernia, do a CXR showing an air fluid-level posterior to the cardiac silhouette, and then a barium swallow will show the proximal stomach herniating through the esophageal hiatus, and then definitive Dx is made via endoscopy.
Charcot triad for cholangitis –> fever + RUQ/epigastric pain + jaundice
Primary biliary cirrhosis –> woman 20s-50s with high direct bilirubin + high ALP + high cholesterol + diffuse pruritis + usually has personal Hx of autoimmune disease (or in the family) –> autoimmune diseases go together, meaning if a patient has one (e.g., RA, IBD, SLE), then he or she has increased risk of another. Dx with anti-mitochondrial antibodies, followed by confirmatory liver biopsy.
Diabetic gastroparesis = new-onset “GERD” in a diabetic with severe disease such as peripheral neuropathy up to the knees or peripheral edema due to renal failure. Pathophys is sorbitol-induced myelin damage of the nerves of the GI tract, leading to delayed gastric emptying (can also cause both diarrhea + constipation; I’ve seen both) –> the wrong answer is “trial of PPIs” based on the assumption this is regular GERD; you nee to identify this as diabetic gastroparesis –> first step is endoscopy to rule out physical obstruction –> if endoscopy negative, do a gastric-emptying scintigraphy –> if it shows delayed gastric emptying, this confirms the diagnosis. The Tx is smaller meals –> if insufficient and they want a medication, choose metoclopramide. Erythromycin (which agonizes motilin receptors) may be added after metoclopramide.
Empyema = pus in a previously existing space (i.e., pleural space or peritoneal space).
Abscess = pus in a place where there wasn’t a pre-existing cavity (e.g., your forearm).
USMLE wants you to know for empyema that it doesn’t just happen randomly. It happens as a result of worsening pneumonia:
Pneumonia –> progresses to parapneumonic effusion –> empyema.
Parapneumonic effusion is an exudative pleural effusion (increased LDH, protein, WBCs; low glucose in the setting of infective exudates). Low pH of the fluid (<7.1) is the most important indicator of a potential progression to empyema. This is really HY.
For empyema and abscess, always, always, always drain the fluid/pus before giving Abx. Even if you’re like, “Well yeah we’d drain, but wouldn’t we at least start the patient on Abx first?” No. We always drain first.
If skin abscess, the collection will need to be kept open to the air by stuffing it with sterile gauze, which will gradually be pulled out a little each day, until the space has closed. If you’re learning this for the first time, that might sound really weird, but it’s not and is HY. If you drain an abscess and then the area is sealed over or sutured shut via primary intention, bacterial proliferation may not cease.
Primary closure means sutured closed; secondary closure means kept open and allowed to close on its own, leading to worse scar formation, but as we said, the latter has its utility.
