1/6/20, 9:43:15 PM
Compare Results
New File:
Old File:
First Aid for the USMLE Step 1 2020, Thirtieth
FA 2019.pdf
versus edition-1.pdf
44 pages (293.11 MB)
46 pages (109.99 MB)
1/5/20, 12:57:57 PM
1/5/20, 12:52:18 PM
BY u/verified-idiot
To the only girl i've ever loved, to soufia.
BLUE new in FA 2020
YELLOW text of FA 2019 was edited; the note box next to the yellow highlight will
show the difference between them the old text and the new text of FA 2020
Some pages might look scary! because of note boxes and highlighting , but it is
not, my recommendation for you is to study your book and after than look for the
new stuff and edits.. I DONT recommend comparing while you are studying since
it will consume your time.
Go to First Change (page 1)
file://NoURLProvided[1/6/20, 9:43:15 PM]
,HIGH-YIELD SYSTEMS
Gastrointestinal
“A good set of bowels is worth more to a man than any quantity of brains.” ` Embryology 358
—Josh Billings
` Anatomy 360
“Man should strive to have his intestines relaxed all the days of his life.”
—Moses Maimonides ` Physiology 371
“All right, let’s not panic. I’ll make the money by selling one of my livers. I ` Pathology 376
can get by with one.”
—Homer Simpson ` Pharmacology 398
When studying the gastrointestinal system, be sure to understand the
normal embryology, anatomy, and physiology and how it is affected in
the various pathologic diseases. Study not only what a disease entails,
but also its specific findings, so that you can differentiate between two
similar diseases. For example, what specifically makes ulcerative colitis
different than Crohn disease? Also, it is important to understand bile
metabolism and which lab values increase or decrease depending on the
disease process. Be comfortable with basic interpretation of abdominal
x-rays, CT scans, and endoscopic images.
357
,358 SEC TION III GASTROINTESTINAL `G̀ASTROINTESTINAL—EMBRYOLOGY
``
GASTROINTESTINAL—EMBRYOLOGY
Normal Foregut—esophagus to duodenum at level of pancreatic duct and common bile duct insertion
gastrointestinal (ampulla of Vater).
embryology Midgut—lower duodenum to proximal 2/3 of transverse colon.
Hindgut—distal 1/3 of transverse colon to anal canal above pectinate line.
Midgut development:
6th week—physiologic herniation of midgut through umbilical ring
10th week—returns to abdominal cavity + rotates around superior mesenteric artery (SMA),
total 270° counterclockwise
Ventral wall defects Developmental defects due to failure of rostral fold closure (eg, sternal defects [ectopia cordis]),
lateral fold closure (eg, omphalocele, gastroschisis), or caudal fold closure (eg, bladder exstrophy).
Gastroschisis Omphalocele
ETIOLOGY Extrusion of abdominal contents through Failure of lateral walls to migrate at umbilical
abdominal folds (typically right of umbilicus) ring persistent midline herniation of
abdominal contents into umbilical cord
COVERAGE Not covered by peritoneum or amnion A ; Surrounded by peritoneum B (light gray shiny
“the guts come out of the gap (schism) in the sac); “abdominal contents are sealed in the
letter G” letter O”
ASSOCIATIONS Not associated with chromosome abnormalities; Associated with congenital anomalies (eg,
favorable prognosis trisomies 13 and 18, Beckwith-Wiedemann
syndrome) and other structural abnormalities
(eg, cardiac, GU, neural tube)
A B
Congenital umbilical Failure of umbilical ring to close after physiologic herniation of the midgut. Small defects usually
hernia close spontaneously.
, GASTROINTESTINAL `G̀ASTROINTESTINAL—EMBRYOLOGY SEC TION III 359
Tracheoesophageal Esophageal atresia (EA) with distal tracheoesophageal fistula (TEF) is the most common (85%)
anomalies and often presents as polyhydramnios in utero (due to inability of fetus to swallow amniotic fluid).
Neonates drool, choke, and vomit with first feeding. TEFs allow air to enter stomach (visible on
CXR). Cyanosis is 2° to laryngospasm (to avoid reflux-related aspiration). Clinical test: failure to
pass nasogastric tube into stomach.
In H-type, the fistula resembles the letter H. In pure EA, CXR shows gasless abdomen.
Trachea Esophagus Tracheoesophageal
fistula
Esophageal
atresia
Normal anatomy Pure EA Pure TEF EA with distal TEF
(atresia or stenosis) (H-type) (most common)
Gastric
bubble
Normal Gasless stomach Prominent gastric bubble
Intestinal atresia Presents with bilious vomiting and abdominal distension within first 1–2 days of life.
A
Duodenal atresia—failure to recanalize. Abdominal x-ray A shows “double bubble” (dilated
stomach, proximal duodenum). Associated with Down syndrome.
Jejunal and ileal atresia—disruption of mesenteric vessels (typically SMA) ischemic necrosis of
fetal intestine segmental resorption: bowel becomes discontinuous. X-ray shows dilated loops of
small bowel with air-fluid levels.
Hypertrophic pyloric Most common cause of gastric outlet obstruction in infants (1:600). Palpable olive-shaped mass in
stenosis epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ∼ 2–6 weeks old.
A
More common in firstborn males; associated with exposure to macrolides.
Results in hypokalemic hypochloremic metabolic alkalosis (2° to vomiting of gastric acid and
stomach
pyloric wall subsequent volume contraction).
Ultrasound shows thickened and lengthened pylorus A .
ic
lor el
Treatment: surgical incision of pyloric muscles (pyloromyotomy).
py ann
c h
Compare Results
New File:
Old File:
First Aid for the USMLE Step 1 2020, Thirtieth
FA 2019.pdf
versus edition-1.pdf
44 pages (293.11 MB)
46 pages (109.99 MB)
1/5/20, 12:57:57 PM
1/5/20, 12:52:18 PM
BY u/verified-idiot
To the only girl i've ever loved, to soufia.
BLUE new in FA 2020
YELLOW text of FA 2019 was edited; the note box next to the yellow highlight will
show the difference between them the old text and the new text of FA 2020
Some pages might look scary! because of note boxes and highlighting , but it is
not, my recommendation for you is to study your book and after than look for the
new stuff and edits.. I DONT recommend comparing while you are studying since
it will consume your time.
Go to First Change (page 1)
file://NoURLProvided[1/6/20, 9:43:15 PM]
,HIGH-YIELD SYSTEMS
Gastrointestinal
“A good set of bowels is worth more to a man than any quantity of brains.” ` Embryology 358
—Josh Billings
` Anatomy 360
“Man should strive to have his intestines relaxed all the days of his life.”
—Moses Maimonides ` Physiology 371
“All right, let’s not panic. I’ll make the money by selling one of my livers. I ` Pathology 376
can get by with one.”
—Homer Simpson ` Pharmacology 398
When studying the gastrointestinal system, be sure to understand the
normal embryology, anatomy, and physiology and how it is affected in
the various pathologic diseases. Study not only what a disease entails,
but also its specific findings, so that you can differentiate between two
similar diseases. For example, what specifically makes ulcerative colitis
different than Crohn disease? Also, it is important to understand bile
metabolism and which lab values increase or decrease depending on the
disease process. Be comfortable with basic interpretation of abdominal
x-rays, CT scans, and endoscopic images.
357
,358 SEC TION III GASTROINTESTINAL `G̀ASTROINTESTINAL—EMBRYOLOGY
``
GASTROINTESTINAL—EMBRYOLOGY
Normal Foregut—esophagus to duodenum at level of pancreatic duct and common bile duct insertion
gastrointestinal (ampulla of Vater).
embryology Midgut—lower duodenum to proximal 2/3 of transverse colon.
Hindgut—distal 1/3 of transverse colon to anal canal above pectinate line.
Midgut development:
6th week—physiologic herniation of midgut through umbilical ring
10th week—returns to abdominal cavity + rotates around superior mesenteric artery (SMA),
total 270° counterclockwise
Ventral wall defects Developmental defects due to failure of rostral fold closure (eg, sternal defects [ectopia cordis]),
lateral fold closure (eg, omphalocele, gastroschisis), or caudal fold closure (eg, bladder exstrophy).
Gastroschisis Omphalocele
ETIOLOGY Extrusion of abdominal contents through Failure of lateral walls to migrate at umbilical
abdominal folds (typically right of umbilicus) ring persistent midline herniation of
abdominal contents into umbilical cord
COVERAGE Not covered by peritoneum or amnion A ; Surrounded by peritoneum B (light gray shiny
“the guts come out of the gap (schism) in the sac); “abdominal contents are sealed in the
letter G” letter O”
ASSOCIATIONS Not associated with chromosome abnormalities; Associated with congenital anomalies (eg,
favorable prognosis trisomies 13 and 18, Beckwith-Wiedemann
syndrome) and other structural abnormalities
(eg, cardiac, GU, neural tube)
A B
Congenital umbilical Failure of umbilical ring to close after physiologic herniation of the midgut. Small defects usually
hernia close spontaneously.
, GASTROINTESTINAL `G̀ASTROINTESTINAL—EMBRYOLOGY SEC TION III 359
Tracheoesophageal Esophageal atresia (EA) with distal tracheoesophageal fistula (TEF) is the most common (85%)
anomalies and often presents as polyhydramnios in utero (due to inability of fetus to swallow amniotic fluid).
Neonates drool, choke, and vomit with first feeding. TEFs allow air to enter stomach (visible on
CXR). Cyanosis is 2° to laryngospasm (to avoid reflux-related aspiration). Clinical test: failure to
pass nasogastric tube into stomach.
In H-type, the fistula resembles the letter H. In pure EA, CXR shows gasless abdomen.
Trachea Esophagus Tracheoesophageal
fistula
Esophageal
atresia
Normal anatomy Pure EA Pure TEF EA with distal TEF
(atresia or stenosis) (H-type) (most common)
Gastric
bubble
Normal Gasless stomach Prominent gastric bubble
Intestinal atresia Presents with bilious vomiting and abdominal distension within first 1–2 days of life.
A
Duodenal atresia—failure to recanalize. Abdominal x-ray A shows “double bubble” (dilated
stomach, proximal duodenum). Associated with Down syndrome.
Jejunal and ileal atresia—disruption of mesenteric vessels (typically SMA) ischemic necrosis of
fetal intestine segmental resorption: bowel becomes discontinuous. X-ray shows dilated loops of
small bowel with air-fluid levels.
Hypertrophic pyloric Most common cause of gastric outlet obstruction in infants (1:600). Palpable olive-shaped mass in
stenosis epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ∼ 2–6 weeks old.
A
More common in firstborn males; associated with exposure to macrolides.
Results in hypokalemic hypochloremic metabolic alkalosis (2° to vomiting of gastric acid and
stomach
pyloric wall subsequent volume contraction).
Ultrasound shows thickened and lengthened pylorus A .
ic
lor el
Treatment: surgical incision of pyloric muscles (pyloromyotomy).
py ann
c h
