Post-Whipple (POD 13): Pain Abdomen + Bilious Vomiting - Differential Diagnosis and Approach

Likely Causes (Differential Diagnosis)

1. Delayed Gastric Emptying (DGE) - Most Common

• Mechanism: Loss of the pylorus/duodenal pacemaker, division of vagal fibres, disruption of motilin-stimulated MMC activity, and the influence of intra-abdominal complications (especially pancreatic fistula)
• Presentation: Nausea, bilious vomiting, epigastric fullness, high NGT output - starting around POD 7-10 and persisting into the second and third week
• Key ISGPS Grades:
  • Grade A: NGT needed POD 4-7 or reinserted after POD 3
  • Grade B: NGT needed POD 8-14
  • Grade C: NGT needed beyond POD 14
• This patient at POD 13 fits Grade B/C DGE

2. Pancreatic Fistula / Postoperative Pancreatic Fistula (POPF)

• Second most common complication (~14%), and a major driver of secondary DGE
• Leak at the pancreaticojejunostomy leads to peri-anastomotic inflammation and fluid collections, which paralyze gastric motility
• Defined by drain amylase >3x upper normal on or after POD 3 with clinically relevant output (>50 mL/day by day 7)
• If high-output (>200 mL/day) or symptomatic: make patient NPO + TPN; drain management is the first line; most seal conservatively
• If undrained, can progress to intra-abdominal abscess, sepsis, and haemorrhage

3. Afferent Loop Obstruction / Syndrome

• The afferent limb is the jejunal loop proximal to the hepatico-/pancreaticojejunostomy carrying bile and pancreatic juice
• Mechanism: Mechanical obstruction (adhesions, internal hernia, kink, stricture at anastomosis) causes accumulation of bile + pancreatic secretions under pressure
• Classic presentation: Episodic cramping epigastric pain with forceful, projectile bilious vomiting that gives sudden and dramatic relief - the hallmark of afferent loop syndrome
• In the acute post-op period (POD 13), this can be life-threatening as sustained high pressure causes:
  • Bowel ischemia
  • Duodenal stump blowout
  • Biliary peritonitis
• Diagnosis: CT abdomen showing dilated afferent loop, failure to visualise afferent limb on endoscopy, HIDA scan with failure of radionuclide passage
• Management: Prompt surgical correction - conversion to Roux-en-Y, enteroenterostomy, or endoscopic stenting in selected cases

4. Efferent Loop Obstruction

• Less common than afferent loop obstruction but occurs within the first postoperative month
• Caused by adhesions, retroanastomotic internal hernia, stricture, or jejunogastric intussusception
• Presentation: Colicky left upper quadrant/epigastric pain, bilious vomiting, abdominal distension
• Diagnosis: CT with oral contrast showing failure of contrast to enter the efferent limb
• Management: Almost always requires operative intervention - reduction of internal hernia, resection with re-anastomosis

5. Intra-abdominal Collection / Abscess

• Can develop secondary to pancreatic fistula, bile leak, or anastomotic dehiscence
• Presents with fever, abdominal pain, localised tenderness, rising inflammatory markers
• Bilious vomiting occurs from associated ileus/DGE
• Management: CT-guided percutaneous drainage; antibiotics; bowel rest

6. Hepaticojejunostomy (Bile Duct) Anastomotic Leak / Stricture

• Biliary leak after PD: median occurrence day 6-7 post-op; bile leak or early stricture can cause cholangitis and bilious vomiting
• More likely to manifest as fever + jaundice + RUQ pain
• Diagnosis: Elevated bilirubin in drain fluid (>3x serum bilirubin); MRCP/PTC; CT scan
• Management: Drain placement + antibiotics; ERCP/PTC if accessible

7. Postoperative Ileus / Small Bowel Obstruction

• General adhesive ileus or mechanical SBO from early adhesions
• Presents with distension, absence of bowel sounds, vomiting
• Plain AXR + CT for diagnosis

8. Less Common but Must-Not-Miss Causes

Diagnostic Approach

Step 1 - Clinical Assessment

• History: Time since last oral intake, character of vomiting (quantity, colour, relationship to meals, relief after vomiting), fever, drain output character and volume, associated diarrhoea/constipation, relief of pain after vomiting (suggests afferent loop)
• Examination: Vitals (fever, tachycardia, hypotension suggest sepsis/fistula), abdominal tenderness localisation, distension, drain site assessment, NGT output assessment

Step 2 - Initial Investigations

• Blood: CBC (WBC, Hb), CRP, serum procalcitonin, LFTs (bilirubin, ALP), serum amylase/lipase, creatinine, electrolytes, coagulation
• Drain fluid (if drain in situ): Amylase (POPF?), bilirubin (bile leak?), triglycerides (chyle leak?), culture/sensitivity
• Blood cultures if febrile

Step 3 - Imaging (Key Investigation)

• CT Abdomen with IV contrast (with oral contrast if efferent loop obstruction suspected):
  • Look for: dilated afferent or efferent loop, pancreatic or biliary anastomotic leak, intra-abdominal collection, pneumoperitoneum, mesenteric oedema/ischaemia, portal vein thrombosis
  • This is the single most useful investigation in this setting
• Plain AXR: Quick screen for air under diaphragm, ileus, or SBO pattern
• Upper GI series (water-soluble contrast) or HIDA scan if CT inconclusive for loop obstruction
• Upper GI Endoscopy: Assessment of gastrojejunostomy anastomosis, exclusion of anastomotic leak, evaluation of DGE

Management Algorithm

Bilious vomiting + pain at POD 13 post-Whipple
                    ↓
    Make NPO + IV access + fluid resuscitation
    Insert/reassess NGT → bilious aspirate volume
    Send bloods + drain fluid studies
                    ↓
         CT abdomen with contrast (URGENT)
                    ↓
    ┌───────────────┬──────────────┬──────────────────┐
    │               │              │                  │
Dilated         Collection/     No mechanical     Free fluid /
afferent loop   abscess         obstruction       pneumoperitoneum
    │               │              │                  │
    ↓               ↓              ↓                  ↓
Afferent loop   CT-guided       DGE - Grade B/C    Urgent surgical
obstruction:    drainage +       conservative       exploration
Urgent surgical  antibiotics     management
consult; likely
operative Rx

Conservative Management of DGE (if no mechanical cause found)

1. NGT insertion - Decompress stomach; measure output
2. NPO - Bowel rest
3. Nutritional support - Nasojejunal tube feeding (distal to the Roux limb) OR TPN if enteral route unavailable
4. Prokinetics:
   • Erythromycin 250 mg IV/oral TDS (motilin agonist) - first-line post-Whipple DGE; evidence from multiple RCTs
   • Metoclopramide 10 mg TDS as adjunct
5. Treat the underlying driver: If DGE is secondary to POPF, controlling the fistula is key (drain management, octreotide)
6. Octreotide 100-200 mcg SC TDS: reduces pancreatic secretion; helpful if concurrent POPF
7. DGE is self-limiting in >95% of cases; resolves within 4-6 weeks with conservative management

Summary Table

• Sabiston Textbook of Surgery, pp. 1789-1790
• Maingot's Abdominal Operations, pp. 3571
• Fischer's Mastery of Surgery, p. 3052
• Schwartz's Principles of Surgery

Delayed Gastric Emptying (DGE) vs. Dumping Syndrome

Core Distinction in One Line

DGE = stomach empties too slowly (or not at all). Dumping = stomach empties too fast.

Pathophysiology

Delayed Gastric Emptying

• Loss of the pyloric "pacemaker" (interstitial cells of Cajal) and duodenal motor coordination after Whipple/gastrectomy
• Vagal denervation disrupts receptive relaxation and antral motility
• Dysregulation of enteric neuropeptides (motilin, cholecystokinin)
• Stomach devascularisation and local inflammation (especially from concurrent POPF)
• Result: food and fluid stagnate in the stomach, which becomes dilated and atonic

Dumping Syndrome

• Loss of pyloric regulation (pylorus resected or bypassed) causes uncontrolled, rapid emptying of calorie-dense liquids into the small bowel
• A vagotomy dramatically worsens it - abolishes receptive relaxation of the proximal stomach, raising intragastric pressure and accelerating emptying
• Loss of duodenal mucosal feedback (acid/fat/sugar/osmolality sensors that normally slow emptying) when duodenum is bypassed
• Result: hyperosmolar chyme floods the small bowel before it can be processed

Types of Dumping

Side-by-Side Clinical Comparison

ISGPS Grading of DGE (2007 Consensus - Wente et al.)

Grade A is "clinically relevant" but self-limiting. Grade B/C significantly prolongs hospital stay and impacts adjuvant therapy timing.

Diagnosis

DGE

• Clinical: High NGT output, failed oral intake, distension without vasomotor features
• CT abdomen: Dilated stomach, no mechanical obstruction; rule out POPF/abscess as driver
• Gastrografin swallow: Confirms gastric distension + slow passage of contrast into jejunum
• Upper GI endoscopy: Exclude anastomotic stricture, ulcer, or compression
• No quantitative/biochemical diagnostic criteria - purely clinical + exclusion

Dumping Syndrome

• Primarily clinical: Symptom timing is the key diagnostic feature
• Modified oral glucose tolerance test (75 g glucose):
  • Early dumping positive: Haematocrit rise ≥3% OR heart rate rise ≥10 bpm at 30 min
  • Late dumping positive: Blood glucose <50 mg/dL at 1-3 hours
• Radionuclide gastric emptying test: Must specify liquid phase marker (most routine tests use solid-phase markers which test for DGE, not dumping)
• Gastric emptying scan has low sensitivity/specificity for dumping diagnosis and is not routinely needed

Treatment

DGE

Dumping Syndrome

Quick Memory Aid

DGE                          DUMPING
──────────────────────────   ──────────────────────────
Stomach won't empty          Stomach empties too fast
No vasomotor symptoms        Sweating, palpitations, syncope
Constant symptoms            Precisely timed post-meal
High NGT output              Low NGT output
Treat: NGT + prokinetics     Treat: diet + octreotide
Resolves spontaneously       May need long-term management
Diagnosis of exclusion       Clinical timing + glucose test

• Current Surgical Therapy 14e, pp. 647-648 (ISGPS DGE consensus table)
• Fischer's Mastery of Surgery, 8th ed., pp. 3041-3043
• Sabiston Textbook of Surgery, pp. 1787-1790
• Goldman-Cecil Medicine, p. 1467