Overview
Definition:
Internal hernia after Roux-en-Y Gastric Bypass (RYGB) refers to the protrusion of abdominal contents through a surgically created defect in the mesentery or peritoneum, typically occurring at the Petersen's defect (mesoenterocolic hernia), the superior mesenteric defect (meso-gastric hernia), or the jejuno-jejunal mesentery
These hernias can lead to internal strangulation and bowel obstruction, presenting as a significant surgical emergency post-bariatric surgery.
Epidemiology:
The incidence of internal hernias after RYGB varies widely in literature, ranging from 0.2% to 5.6%
The risk increases with time post-bypass, with a significant proportion occurring more than 1 year after surgery
Risk factors include a narrow Petersen's defect, rapid weight loss, and advanced age
Early diagnosis and prompt surgical intervention are crucial for favorable outcomes.
Clinical Significance:
Internal hernias post-RYGB are a major cause of late abdominal pain and bowel obstruction in this patient population
Failure to diagnose and treat can result in bowel ischemia, necrosis, perforation, and sepsis, leading to high morbidity and mortality
Understanding the subtle clinical presentations and diagnostic modalities is paramount for bariatric surgeons and general surgeons managing these complex cases.
Clinical Presentation
Symptoms:
Epigastric or diffuse abdominal pain, often colicky
Nausea and vomiting, which may be bilious
Abdominal distension and obstipation
Intermittent symptoms of partial obstruction
In strangulated hernias: severe, constant pain, signs of peritonitis, and hemodynamic instability
Sometimes, vague symptoms like bloating or early satiety can precede frank obstruction.
Signs:
Tenderness on abdominal palpation, which may be diffuse or localized
Guarding and rebound tenderness in cases of strangulation or peritonitis
Distended abdomen
Absent or hypoactive bowel sounds
Palpable abdominal mass in rare instances
Vital sign abnormalities may include tachycardia and hypotension in strangulated or septic patients.
Diagnostic Criteria:
There are no strict diagnostic criteria but a high index of suspicion in any RYGB patient presenting with recurrent or acute abdominal pain and signs of obstruction is paramount
Imaging findings, particularly CT scan, showing clustered bowel loops in specific anatomical locations and signs of obstruction or ischemia, are critical for diagnosis.
Diagnostic Approach
History Taking:
Detailed history of RYGB procedure, including date, surgeon, and any specific anatomical considerations mentioned
Onset, duration, character, and radiation of abdominal pain
Associated symptoms like nausea, vomiting, and bowel habits
Previous episodes of abdominal pain or partial obstruction
Medications, especially NSAIDs or opioids, which can affect bowel motility
Red flags include sudden onset of severe pain, fever, and hemodynamic compromise.
Physical Examination:
A thorough abdominal examination focusing on inspection for distension or surgical scars, auscultation for bowel sounds (presence, frequency, quality), percussion for tympany or dullness, and palpation for tenderness, rigidity, guarding, and masses
Evaluate for signs of dehydration and hypovolemia
Rectal examination may reveal empty vaults in complete obstruction.
Investigations:
Complete Blood Count (CBC) may show leukocytosis in strangulation or ischemia
Electrolytes and renal function tests to assess hydration status
Serum lactate for signs of ischemia
Plain abdominal X-rays may show dilated loops of small bowel and air-fluid levels, but are often non-specific
Computed Tomography (CT) scan with oral and IV contrast is the investigation of choice
it can reveal closed-loop obstructions, clustered bowel loops (small bowel feces sign), mesenteric edema, venous thrombosis, or free air
MRI can be an alternative in select cases
Diagnostic laparoscopy is often definitive.
Differential Diagnosis:
Other causes of abdominal pain post-RYGB include marginal ulcer disease, internal abscess, adhesions, incisional hernia, cholecystitis, pancreatitis, and urinary tract infection
Differentiating internal hernia from these conditions is crucial, with imaging playing a key role
The characteristic clustered bowel loops in specific locations often point towards internal hernia.
Management
Initial Management:
Immediate resuscitation with intravenous fluids, pain control with analgesics, and nasogastric decompression to relieve distension and vomiting
Broad-spectrum antibiotics should be initiated if strangulation or perforation is suspected
Strict NPO (nil per os) status is maintained.
Surgical Management:
Surgical reduction of internal hernia is the definitive treatment
This is typically performed laparoscopically, allowing for less invasive surgery and faster recovery
The primary goal is to reduce the herniated bowel, relieve any strangulation, and close the mesenteric defects
If bowel necrosis is present, resection and anastomosis are necessary
Primary closure of Petersen's defect and other relevant mesenteric defects is performed to prevent recurrence
In cases of severe adhesions or extensive necrosis, conversion to open laparotomy may be required.
Supportive Care:
Postoperative care involves continued IV fluids, pain management, monitoring for bowel function return, and gradual reintroduction of oral intake
Strict monitoring for signs of anastomotic leak, infection, or recurrent obstruction is essential
Nutritional support may be required, especially if bowel resection was performed.
Complications
Early Complications:
Bowel ischemia and necrosis
Bowel perforation
Sepsis
Anastomotic leak if bowel resection was performed
Wound infection
Deep vein thrombosis
Pulmonary embolism.
Late Complications:
Recurrent internal hernia if defects are not adequately closed
Adhesions leading to further bowel obstruction
Malabsorption and nutritional deficiencies
Incisional hernia if open laparotomy was performed.
Prevention Strategies:
Meticulous closure of all mesenteric defects during the primary RYGB procedure is the most effective preventive strategy
This includes narrow closure of Petersen's defect and the defects around the jejuno-jejunal anastomosis
Routine intraoperative inspection for potential hernia sites and prophylactic closure should be considered
Patient education on recognizing symptoms of potential complications is also important.
Prognosis
Factors Affecting Prognosis:
Timeliness of diagnosis and intervention
Degree of bowel ischemia or necrosis at presentation
Patient's overall health status and comorbidities
Presence of complications like sepsis or perforation
Adequacy of defect closure during repair.
Outcomes:
With prompt diagnosis and laparoscopic reduction, outcomes are generally excellent, with low morbidity and mortality
Patients typically experience significant relief from symptoms
However, if delayed, outcomes can be severe, with increased rates of bowel resection, prolonged hospitalization, and increased risk of mortality
Recurrence rates can be reduced with careful surgical technique.
Follow Up:
Regular follow-up is recommended, particularly in the initial postoperative period, to monitor for any signs of complications
Patients should be advised to seek immediate medical attention for any recurrent or severe abdominal pain, vomiting, or changes in bowel habits
Long-term follow-up may focus on nutritional status and early recognition of any new abdominal symptoms.
Key Points
Exam Focus:
High index of suspicion for internal hernia in RYGB patients with acute/recurrent abdominal pain
Petersen's defect is the most common site
CT scan with contrast is the investigation of choice
Laparoscopic reduction and closure of defects is the standard treatment
Bowel ischemia/necrosis are critical complications.
Clinical Pearls:
Always consider internal hernia in the differential for any post-RYGB patient with new-onset or recurrent abdominal pain, especially if colicky or associated with nausea/vomiting
The "small bowel feces sign" on CT scan is highly suggestive of internal hernia
Prophylactic closure of mesenteric defects during primary RYGB is crucial for prevention.
Common Mistakes:
Delaying surgical intervention due to low suspicion or misdiagnosis
Inadequate closure of mesenteric defects during the primary surgery or revision
Over-reliance on plain X-rays and underutilization of CT scan
Failure to recognize signs of bowel ischemia or strangulation early.