Gastric Outlet Obstruction (GOO) — Surgical Perspective

from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm
from reportlab.lib import colors
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    HRFlowable, KeepTogether
)
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_JUSTIFY

OUTPUT = "/home/daytona/workspace/goo-pdf/Gastric_Outlet_Obstruction.pdf"

doc = SimpleDocTemplate(
    OUTPUT,
    pagesize=A4,
    rightMargin=2*cm, leftMargin=2*cm,
    topMargin=2.5*cm, bottomMargin=2.5*cm,
    title="Gastric Outlet Obstruction – Surgical Overview",
    author="Orris Medical"
)

styles = getSampleStyleSheet()

# Custom styles
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h3_style = ParagraphStyle(
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body_style = ParagraphStyle(
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bullet_style = ParagraphStyle(
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callout_style = ParagraphStyle(
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def h1(text):
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def h2(text):
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def h3(text):
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def p(text):
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def bp(text):
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def callout(text):
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def warn(text):
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def src(text):
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def hr():
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# Table helper
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    return t

# ── Content ──────────────────────────────────────────────────────────────────
story = []

# Title block
story.append(Spacer(1, 0.3*cm))
story.append(Paragraph("Gastric Outlet Obstruction", title_style))
story.append(Paragraph("A Comprehensive Surgical Reference", subtitle_style))
story.append(hr())
story.append(p("<i>Compiled from: Current Surgical Therapy 14e · Yamada's Textbook of Gastroenterology 7e · "
               "Sleisenger &amp; Fordtran's GI and Liver Disease · Harrison's Principles 22e · "
               "Clinical GI Endoscopy 3e</i>"))
story.append(Spacer(1, 0.4*cm))

# ── 1. Definition ─────────────────────────────────────────────────────────────
story.append(h1("1. Definition & Overview"))
story.append(p(
    "Gastric outlet obstruction (GOO) is a clinical syndrome resulting from any mechanical impediment to "
    "gastric emptying at the level of the pylorus, antrum, or proximal duodenum. It is not a diagnosis "
    "in itself but a manifestation of an underlying disease process."
))

# ── 2. Etiology ───────────────────────────────────────────────────────────────
story.append(h1("2. Etiology & Differential Diagnosis"))
story.append(p(
    "Historically, peptic ulcer disease (PUD) accounted for approximately 90% of GOO cases. Today, PUD "
    "accounts for only ~5% in high-income countries, while malignancy now constitutes 50–80% of cases. "
    "In low- and medium-income countries, PUD-related GOO remains the dominant indication for surgical "
    "intervention (50–60% of complicated ulcer surgery)."
))

etiology_data = [
    ["Cause", "Relative Frequency / Notes"],
    ["Peptic ulcer disease (DU / pyloric channel ulcers)", "~5% in high-HDI; still dominant in low-HDI countries"],
    ["Malignancy (gastric, pancreatic, duodenal, periampullary)", "50–80%; most common cause in Western practice"],
    ["Zollinger-Ellison syndrome", "GOO in ~10% of ZES patients"],
    ["Crohn disease", "Granulomatous narrowing of pylorus/duodenum"],
    ["Pancreatic pseudocyst / pancreatitis", "Extrinsic compression"],
    ["Tuberculosis", "Especially in endemic regions; may need full-thickness biopsy"],
    ["Caustic ingestion", "Fibrotic pyloric/duodenal stricture"],
    ["Duodenal webs / congenital strictures", "Congenital or post-inflammatory"],
    ["Bezoars", "Functional obstruction"],
    ["Gastric volvulus / paraesophageal hernia", "Relapsing obstruction; intermittent and spontaneously resolving"],
]
story.append(make_table(etiology_data, col_widths=[9*cm, 8*cm]))
story.append(Spacer(1, 0.3*cm))

# ── 3. Pathophysiology ────────────────────────────────────────────────────────
story.append(h1("3. Pathophysiology"))
story.append(h2("In PUD-related GOO:"))
story.append(bp("<b>Acute / reversible component:</b> Edema and pyloric spasm around an active pyloric channel or duodenal ulcer"))
story.append(bp("<b>Chronic / irreversible component:</b> Fibrosis, scarring, and gastric atony from repeated cycles of ulceration and healing"))
story.append(h2("Metabolic Consequence of High-Grade Obstruction"))
story.append(callout(
    "<b>Hypokalemic Hypochloremic Metabolic Alkalosis</b><br/>"
    "Mechanism: Repeated vomiting of gastric acid → loss of H⁺ and Cl⁻ → compensatory renal HCO₃⁻ "
    "retention and K⁺ wasting. Obstruction is proximal to the ampulla of Vater, so vomitus is "
    "<b>nonbilious</b>. This metabolic derangement MUST be corrected before any surgical intervention."
))

# ── 4. Clinical Features ──────────────────────────────────────────────────────
story.append(h1("4. Clinical Features"))
features = [
    "Nausea and <b>nonbilious vomiting</b> — often of undigested food from hours or days prior",
    "Epigastric distension and fullness",
    "Early satiety",
    "Weight loss and malnutrition",
    "<b>Succussion splash</b> on abdominal auscultation (retained gastric contents)",
    "Dehydration in high-grade or prolonged obstruction",
    "Clinical features of the underlying etiology (e.g., jaundice with pancreatic cancer)",
]
for f in features:
    story.append(bp(f))

# ── 5. Investigations ─────────────────────────────────────────────────────────
story.append(h1("5. Investigations"))
story.append(callout(
    "<b>Initial Stabilization First:</b> Decompress stomach with large-bore NGT (reduces aspiration risk), "
    "correct fluid and electrolyte imbalances (particularly hypokalemic hypochloremic alkalosis), "
    "initiate IV PPIs. These steps are usually necessary <i>before</i> endoscopy or contrast studies."
))
story.append(h2("Investigations"))
invest_data = [
    ["Investigation", "Role & Notes"],
    ["EGD with biopsy", "Mandatory. Identifies intrinsic lesion, excludes malignancy, allows therapeutic intervention. Decompress/fast stomach first. Endoscopic biopsies ± EUS for deep/suspicious lesions."],
    ["CT abdomen (with contrast)", "Usually first imaging step. Identifies extrinsic compression, dilated stomach, nature of obstruction, metastatic disease."],
    ["Upper GI fluoroscopy (barium)", "Characterizes stricture geometry and length; complements endoscopy."],
    ["Endoscopic ultrasound (EUS)", "If malignancy suspected or EUS-guided therapy planned; superior for local staging."],
    ["Saline load test", "Historical: 750 mL saline via NGT; aspiration >400 mL at 30 min = mechanical obstruction. Residual <200 mL = resolution. Less used now."],
    ["Labs", "Electrolytes, CBC, LFTs, amylase. Serum gastrin if ZES suspected. ABG if alkalosis suspected."],
]
story.append(make_table(invest_data, col_widths=[5*cm, 12*cm]))
story.append(Spacer(1, 0.3*cm))

# ── 6. Management Overview ────────────────────────────────────────────────────
story.append(h1("6. General Management Principles"))
gm = [
    "Decompress stomach (large-bore NGT)",
    "Correct electrolyte and fluid abnormalities — particularly hypokalemic hypochloremic alkalosis",
    "Nutritional support — IV nutrition if necessary; nasojejunal feeds once feasible",
    "IV proton pump inhibitors — reduce gastric secretions",
    "Identify the underlying etiology — guides definitive management",
    "Multidisciplinary team involvement (surgery, gastroenterology, oncology if malignant)",
]
for g in gm:
    story.append(bp(g))

# ── 7. Benign GOO (PUD) ───────────────────────────────────────────────────────
story.append(h1("7. Benign GOO — PUD-Related Management"))
story.append(h2("Non-operative / Endoscopic"))
story.append(bp("<b>H. pylori eradication</b> + NSAID cessation → most patients respond to acid suppression initially"))
story.append(bp("Full-dose oral PPIs long-term after obstruction resolves; may discontinue if H. pylori eradicated and antral deformity resolves"))
story.append(bp("<b>Endoscopic balloon dilation</b> may delay surgery for 1–2 years in ~50% of patients; most requiring hospitalization or repeated dilation will ultimately need surgery"))
story.append(Spacer(1, 0.2*cm))

story.append(h2("Surgical Options"))
story.append(h3("Option 1: Vagotomy + Antrectomy (V/A) — Gold Standard"))
story.append(p(
    "V/A is the gold standard surgical procedure for obstructing duodenal ulcer. It provides the lowest "
    "ulcer recurrence rate and confirms the benign diagnosis by resecting the obstruction."
))
va_data = [
    ["Aspect", "Details"],
    ["Advantages", "Lowest recurrence rate; confirms benign diagnosis by resecting obstruction; removes risk of missed cancer"],
    ["Disadvantages", "Operative mortality ~2%; higher technical complexity; difficult duodenal stump if ulcer penetrates posteriorly"],
    ["Reconstruction", "Antecolic isoperistaltic Billroth II gastrojejunostomy (afferent loop on greater curvature, efferent on lesser). Avoid Roux-en-Y with large gastric remnant → risk of marginal ulcer and delayed gastric emptying"],
    ["Key steps", "Truncal vagotomy first → antrectomy → B-II reconstruction"],
    ["Staple technique", "Chronically obstructed stomach is unusually thick-walled — use appropriately large staple cartridges to prevent dehiscence"],
    ["Obstruction", "Must be resected and included in specimen"],
    ["Prepyloric lesion", "Ensure distal staple line is truly distal to the pylorus — prevents retained antrum syndrome"],
    ["Difficult duodenum", "If obstruction is in the 2nd part of duodenum, consider HPB consultation; cancer must be excluded if obstruction site is left in situ"],
]
story.append(make_table(va_data, col_widths=[5*cm, 12*cm]))
story.append(Spacer(1, 0.3*cm))

story.append(h3("Option 2: Vagotomy + Gastrojejunostomy (V/GJ) — Good Alternative"))
story.append(p(
    "V/GJ is a good alternative, particularly where laparoscopic surgery is planned or where the operative "
    "risk of V/A is judged to be too high."
))
vgj_data = [
    ["Aspect", "Details"],
    ["Advantages", "Lower operative mortality; readily performed laparoscopically; reversible if dumping becomes intolerable"],
    ["Disadvantages", "Obstructing cancer may be missed (no resection of obstructing lesion); risk of marginal ulcer"],
    ["Technique", "Bilateral truncal or posterior truncal + anterior HSV vagotomy; loop gastrojejunostomy to dependent greater curvature (antecolic, isoperistaltic); 6–8 cm cleared of gastroepipolic branches for anastomosis site"],
    ["Follow-up", "Close clinical follow-up for 2 years mandatory; if not doing well clinically, re-explore and convert to distal gastrectomy including obstruction site"],
]
story.append(make_table(vgj_data, col_widths=[5*cm, 12*cm]))
story.append(Spacer(1, 0.3*cm))

story.append(h2("Comparison: V/A vs. V/GJ"))
comp_data = [
    ["", "Vagotomy + Antrectomy (V/A)", "Vagotomy + Gastrojejunostomy (V/GJ)"],
    ["Recurrence rate", "Lower", "Higher (marginal ulcer risk)"],
    ["Operative mortality", "~2%", "Lower"],
    ["Confirms benign diagnosis", "Yes (specimen sent)", "No (obstruction not resected)"],
    ["Laparoscopic", "Possible but complex", "Readily performed"],
    ["Reversible", "No", "Yes"],
    ["Cancer missed risk", "No", "Yes"],
    ["Standard", "Gold standard", "Acceptable alternative"],
]
story.append(make_table(comp_data, col_widths=[5.5*cm, 6*cm, 6*cm]))
story.append(Spacer(1, 0.3*cm))

# ── 8. Difficult Duodenal Stump ───────────────────────────────────────────────
story.append(h1("8. Management of the Difficult Duodenal Stump"))
story.append(p(
    "If the ulcer has destroyed the posterior duodenal wall, standard stapled closure may not be possible. "
    "This is one of the most feared complications in ulcer surgery — duodenal stump leak carries very high "
    "operative mortality."
))
stump = [
    "Sew anterior edge of the open duodenum to the proximal/distal 'lip' of the ulcer on the pancreas with interrupted sutures; ensure complete hemostasis in the ulcer bed",
    "Test closure by placing NG tip at the ligament of Treitz (through GJ) and distending duodenum with air; add sutures as needed until air-tight",
    "Cover closure with well-vascularized omentum held with 2–3 strategic sutures",
    "Place multiple closed-suction drains in the right upper quadrant",
    "<b>Duodenal decompression options:</b> (1) Retrograde tube via proximal jejunum [preferred]; (2) Lateral duodenostomy; (3) NG tube threaded through GJ into afferent limb and secured to nose",
    "<b>Avoid:</b> Placing a large tube directly into the end of the duodenal stump — invariably leaks around it and should only be used if no other option exists",
    "If secure closure seems impossible, avoid distal gastrectomy altogether and perform V/GJ instead",
]
for s in stump:
    story.append(bp(s))

# ── 9. Malignant GOO ─────────────────────────────────────────────────────────
story.append(h1("9. Malignant GOO — Management"))
story.append(p(
    "Malignant GOO is caused by pancreatic, periampullary, gastric, or duodenal cancer. Most patients "
    "have advanced, unresectable disease at presentation. Management is palliative and should be "
    "individualized based on expected survival, resectability, and performance status."
))

story.append(h2("A. Endoscopic SEMS (Self-Expandable Metal Stent)"))
sems = [
    "~90% of patients can tolerate a soft or regular diet after successful SEMS placement",
    "Uncovered SEMS preferred for tumor in-growth control; occlusion from in-growth can be managed with placement of a covered SEMS within the existing stent",
    "<b>Critical:</b> Biliary stenting must be performed <i>before</i> duodenal stenting — biliary access is technically very difficult after a duodenal SEMS is in place",
    "Outpatient or brief admission procedure; appropriate for patients with limited prognosis",
    "Re-intervention for stent malfunction is feasible in most cases",
]
for s in sems:
    story.append(bp(s))
story.append(Spacer(1, 0.2*cm))

story.append(h2("B. Surgical Gastrojejunostomy (GJ)"))
sgj = [
    "Retrocolic or antecolic loop/Roux-en-Y gastrojejunostomy",
    "Open or laparoscopic; laparoscopic approach allows more rapid initiation of systemic anticancer therapy",
    "<b>Important:</b> Presence of a duodenal stent makes subsequent pancreaticoduodenectomy (Whipple procedure) technically significantly more difficult — avoid duodenal stenting in potentially resectable patients",
    "More durable than SEMS for patients with longer expected survival",
    "Prophylactic GJ at the time of open biliary bypass (for found-unresectable disease at laparotomy) is advisable even in asymptomatic patients",
]
for s in sgj:
    story.append(bp(s))
story.append(Spacer(1, 0.2*cm))

story.append(h2("C. EUS-Guided Gastroenterostomy (EUS-GE)"))
story.append(p(
    "An emerging technique where EUS guides creation of a gastroenteric anastomosis using a lumen-apposing "
    "metal stent (LAMS). Highly effective for both benign and malignant GOO. Recent meta-analyses (2024–2026) "
    "show comparable or superior outcomes to SEMS with lower reintervention rates, and comparable outcomes "
    "to surgical GJ with potentially less morbidity. Further standardization is still required."
))
story.append(Spacer(1, 0.2*cm))

story.append(h2("Decision Framework for Malignant GOO (Pancreatic / Periampullary Cancer)"))
dec_data = [
    ["Clinical Scenario", "Preferred Approach"],
    ["Operable tumor, neoadjuvant therapy planned", "Laparoscopic/robotic gastrojejunostomy"],
    ["Advanced disease, limited expected survival", "Duodenal SEMS (outpatient, minimally invasive)"],
    ["Combined duodenal + distal bile duct obstruction, operable disease", "PTC for biliary decompression + laparoscopic GJ (avoid duodenal stent pre-operatively)"],
    ["Combined obstruction, advanced/palliative disease", "Duodenal SEMS ± biliary SEMS ± venting gastrostomy"],
    ["Found unresectable at laparotomy (open abdomen)", "Proceed with open biliary bypass ± prophylactic GJ"],
    ["Repeated SEMS occlusion, reasonable performance status", "Operative biliary/gastric bypass if technically feasible; PTC if best supportive care planned"],
]
story.append(make_table(dec_data, col_widths=[8*cm, 9*cm]))
story.append(Spacer(1, 0.3*cm))

story.append(warn(
    "It is usually a mistake to persist with repeated endoscopic attempts at clearing a SEMS once "
    "repetitive occlusions have begun to occur — consider operative bypass at that point."
))

# ── 10. Postoperative Management ─────────────────────────────────────────────
story.append(h1("10. Postoperative Management"))
post = [
    "High-dose IV PPIs in the early postoperative period — may decrease rebleeding risk",
    "Long-term PPI therapy if: chronic aspirin/NSAIDs required, anticoagulation needed, or H. pylori not eradicated",
    "<b>Smoking cessation</b> — imperative; ulcer recurrence is almost inevitable after definitive surgery if patient continues to smoke",
    "If NSAIDs are medically necessary post-op: consider selective COX-2 inhibitor + long-term PPI",
    "Monitor for early rebleeding: upper endoscopy + CT angiography / standard arteriography",
    "Patients treated with V/GJ for obstructing DU: mandatory close 2-year clinical follow-up to ensure no missed cancer",
    "No evidence that transfusion triggers need to be increased after ulcer surgery",
]
for po in post:
    story.append(bp(po))

# ── 11. Complications ─────────────────────────────────────────────────────────
story.append(h1("11. Complications"))
comp2_data = [
    ["Complication", "Comment & Management"],
    ["Duodenal stump leak", "Most feared; risk increased with difficult stump. Manage with drainage, duodenal decompression, IV nutrition, reoperation if generalized peritonitis develops."],
    ["Retained antrum syndrome", "Hypergastrinemia + marginal ulceration after B-II if antrum not completely resected. Ensure distal staple line is past pylorus."],
    ["Marginal ulcer", "More common after V/GJ than V/A. Treat with PPIs; may require reoperation."],
    ["Delayed gastric emptying", "Especially with Roux-en-Y reconstruction + large gastric remnant; prokinetics, NGT decompression."],
    ["Dumping syndrome", "Early (osmotic, 15–30 min post-meal) and late (reactive hypoglycemia, 2–3 hrs post-meal) forms after vagotomy + drainage procedures. Dietary modification first-line."],
    ["Afferent loop syndrome", "After Billroth II reconstruction — bilious vomiting, pain; may need surgical revision."],
    ["Alkaline reflux gastritis", "After B-II; bile reflux into gastric remnant; may require conversion to Roux-en-Y."],
    ["Anastomotic leak", "General surgical complication; managed with drainage and reoperation if necessary."],
]
story.append(make_table(comp2_data, col_widths=[5.5*cm, 11.5*cm]))
story.append(Spacer(1, 0.3*cm))

# ── 12. Recent Evidence ───────────────────────────────────────────────────────
story.append(h1("12. Recent Evidence (2024–2026)"))
story.append(p("Three high-quality systematic reviews/meta-analyses have recently updated the evidence base for GOO management:"))

ev_data = [
    ["PMID", "Authors / Journal", "Findings"],
    ["39465748", "Jain et al., Medicine, Oct 2024", "EUS-GE vs. duodenal stenting for malignant GOO: EUS-GE shows comparable or superior outcomes with lower reintervention rates than SEMS placement."],
    ["39761155", "Canakis et al., J Clin Gastroenterol, Feb 2026", "EUS-GE for benign GOO: Meta-analysis confirms efficacy; further standardization needed before routine adoption."],
    ["41558906", "Maida et al., Dig Liver Dis, Mar 2026", "EUS-GJ vs. surgical GJ for malignant GOO: EUS-GE is a competitive alternative to surgical gastrojejunostomy with comparable efficacy and potentially less morbidity."],
]
story.append(make_table(ev_data, col_widths=[2.5*cm, 5.5*cm, 9*cm]))
story.append(Spacer(1, 0.2*cm))
story.append(warn(
    "These recent meta-analyses suggest EUS-GE is gaining ground as an alternative to both open/laparoscopic "
    "surgery and luminal stenting in carefully selected patients — a shift from what older textbook editions "
    "describe. Surgical trainees should be aware of this rapidly evolving landscape."
))

# ── 13. Key Surgical Takeaways ────────────────────────────────────────────────
story.append(h1("13. Key Surgical Takeaways"))
takeaways = [
    "<b>V/A = gold standard</b> for benign obstructing duodenal ulcer; V/GJ is a good laparoscopic alternative with slightly higher recurrence risk",
    "<b>Always biopsy and exclude malignancy</b> before committing to a benign ulcer repair — the differential must include pancreatic, duodenal, and pyloric channel cancer",
    "<b>Duodenal stump management</b> is a critical technical challenge in Billroth II — have a bailout plan before starting the case",
    "<b>Malignant GOO management</b> hinges on expected survival and resectability: short survival → SEMS; longer survival/operable → laparoscopic GJ",
    "<b>Biliary obstruction must be addressed first</b> (PTC or biliary stent) before duodenal stenting in combined obstruction",
    "<b>Electrolyte correction</b> (hypokalemic hypochloremic alkalosis) before any operative intervention is mandatory",
    "<b>EUS-GE is emerging</b> as a third option alongside SEMS and surgery — know when to involve advanced endoscopists",
    "Patients with <b>ZES</b> require dedicated work-up (fasting serum gastrin, secretin stimulation test, localization imaging) — GOO occurs in ~10%",
    "In low/middle-income countries, <b>PUD remains the dominant cause</b> of GOO; H. pylori eradication and acid suppression are foundations of long-term management",
]
for t in takeaways:
    story.append(bp(t))

# Footer note
story.append(Spacer(1, 0.5*cm))
story.append(hr())
story.append(src(
    "Current Surgical Therapy 14e (Cameron & Cameron) · "
    "Yamada's Textbook of Gastroenterology 7e · "
    "Sleisenger & Fordtran's GI and Liver Disease · "
    "Harrison's Principles of Internal Medicine 22e · "
    "Clinical GI Endoscopy 3e"
))
story.append(p("<font size='8' color='#aaaaaa'>Generated by Orris Medical Assistant | May 2026 | For educational purposes only.</font>"))

# Build
doc.build(story)
print(f"PDF created: {OUTPUT}")