Overview
Definition:
Post-bariatric internal hernia refers to the entrapment of small bowel within a defect in the mesentery or peritoneal spaces, commonly occurring after bariatric surgical procedures like Roux-en-Y gastric bypass (RYGB)
Mesenteric defect closure aims to prevent or repair these hernias by obliterating potential spaces where herniation can occur.
Epidemiology:
Internal hernias are a significant cause of morbidity and mortality after RYGB, with reported incidence rates varying from 1% to 5%, and potentially higher in some series
Symptoms can occur years after the primary surgery
Risk factors include longer length of the Roux limb, wider mesenteric defects, and rapid weight loss.
Clinical Significance:
Internal hernias can lead to bowel obstruction, ischemia, infarction, and perforation, necessitating urgent surgical intervention
Early recognition and appropriate management of mesenteric defects during primary bariatric surgery, and prompt diagnosis of post-operative hernias, are crucial to improve patient outcomes and reduce mortality.
Clinical Presentation
Symptoms:
Intermittent or colicky abdominal pain
Nausea and vomiting
Abdominal distension
Change in bowel habits, typically constipation or obstipation
In advanced cases, signs of peritonitis or shock
Symptoms may be vague and chronic, or acute and severe.
Signs:
Abdominal tenderness, often localized or diffuse depending on ischemia
Guarding and rebound tenderness in cases of peritonitis
Distended abdomen
Absent or hyperactive bowel sounds
Palpable abdominal mass in some instances
Vital sign derangements such as tachycardia and hypotension in severe cases.
Diagnostic Criteria:
No specific universally established diagnostic criteria exist for post-bariatric internal hernias
Diagnosis is primarily based on a high index of suspicion in patients with a history of bariatric surgery presenting with compatible symptoms, supported by imaging findings suggestive of internal herniation and bowel obstruction.
Diagnostic Approach
History Taking:
Detailed history of prior bariatric surgery, including type of procedure, date, and any intraoperative findings
Characterization of abdominal pain (onset, duration, severity, radiation, relieving/aggravating factors)
Associated gastrointestinal symptoms: nausea, vomiting, bowel habit changes
Previous episodes of abdominal pain or obstruction
Review of medications and diet.
Physical Examination:
Thorough abdominal examination: inspection for distension or scars
auscultation for bowel sounds
palpation for tenderness, rigidity, guarding, masses
percussion for tympany
Assess for signs of dehydration and hemodynamic instability
Rectal examination may reveal obstipation.
Investigations:
Laboratory investigations: Complete blood count (leukocytosis may indicate ischemia or perforation)
Electrolytes, renal function tests, liver function tests to assess for dehydration and organ dysfunction
Lactate levels may be elevated in bowel ischemia
Imaging: Computed tomography (CT) scan of the abdomen and pelvis with intravenous contrast is the investigation of choice
It can identify dilated loops of small bowel, a transition point, mesenteric edema or congestion, and direct visualization of the mesenteric defect or herniated contents
Ultrasound may be useful in identifying free fluid but is less sensitive for specific hernia diagnosis
Plain abdominal X-rays may show dilated loops of bowel and air-fluid levels, but are less specific.
Differential Diagnosis:
Other causes of bowel obstruction (e.g., adhesions from prior surgery, strictures)
Gastroenteritis
Appendicitis
Diverticulitis
Pancreatitis
Biliary colic
Peptic ulcer disease
Incarcerated ventral or incisional hernia at a different site.
Management
Initial Management:
Immediate resuscitation with intravenous fluids
Nasogastric tube decompression to relieve distension and vomiting
Analgesia
Broad-spectrum intravenous antibiotics if signs of peritonitis or sepsis are present
Urgent surgical consultation.
Medical Management:
Primarily supportive and aimed at stabilization prior to surgery
Strict NPO status
Correction of electrolyte imbalances
Pain management
No specific pharmacological treatment for the hernia itself, beyond supportive measures.
Surgical Management:
Urgent surgical exploration is indicated for suspected internal hernia with signs of obstruction or ischemia
The approach can be laparoscopic or open, depending on patient stability, surgeon preference, and extent of findings
During surgery, the internal hernia is identified, the herniated bowel is reduced, and the offending mesenteric defect is closed
Techniques for closure include direct suturing of mesenteric edges with non-absorbable sutures or tacking sutures to obliterate the defect
Specific defects include Petersen's space (between the afferent limb and the transverse mesocolon), and defects at the jejuno-jejunal or gastro-jejunal anastomoses.
Supportive Care:
Postoperative care includes continued fluid management, pain control, monitoring of vital signs and urine output, and gradual advancement of diet
Nutritional support may be required for patients with prolonged ileus or malabsorption
Close monitoring for signs of anastomotic leak or recurrent hernia is essential.
Complications
Early Complications:
Bowel ischemia or infarction requiring resection
Anastomotic leak
Intra-abdominal abscess
Bleeding
Injury to adjacent organs
Prolonged ileus
Recurrent hernia if defect is not adequately closed.
Late Complications:
Chronic abdominal pain
Adhesions and subsequent bowel obstruction
Recurrent internal hernia
Malabsorption syndromes
Stricture formation at sites of ischemia or previous repair.
Prevention Strategies:
Meticulous closure of all mesenteric defects encountered during bariatric surgery, particularly after RYGB
Use of non-absorbable sutures
Consideration of tacking sutures to obliterate potential spaces
Careful operative technique to minimize tension on mesenteric closures
Patient education regarding warning signs of internal hernia post-operatively.
Prognosis
Factors Affecting Prognosis:
Timeliness of diagnosis and intervention is the most critical factor
Degree of bowel ischemia at presentation
Presence of perforation or peritonitis
Patient comorbidities
Technical success of hernia reduction and defect closure.
Outcomes:
With prompt diagnosis and timely surgical intervention before significant ischemia or perforation, outcomes are generally good, with resolution of symptoms and low recurrence rates if defects are adequately closed
Delayed presentation with bowel infarction or peritonitis significantly increases morbidity and mortality.
Follow Up:
Regular clinical follow-up is recommended, especially in the first year post-operatively, to monitor for any recurrence of symptoms
Patients should be educated to report any new or worsening abdominal pain, nausea, or vomiting promptly
Long-term surveillance may be warranted in select high-risk individuals.
Key Points
Exam Focus:
Recognize internal hernias as a major complication of RYGB
Understand the common locations of mesenteric defects (Petersen's, jejuno-jejunal, gastro-jejunal)
CT scan is the investigation of choice
Urgent surgical intervention is paramount
Meticulous mesenteric defect closure during primary surgery is key for prevention.
Clinical Pearls:
Always have a high index of suspicion for internal hernia in any patient with prior bariatric surgery presenting with abdominal pain and vomiting
Consider the time elapsed since surgery – symptoms can present years later
Do not underestimate the severity of vague abdominal pain in these patients
Recalcitrant or intermittent abdominal pain post-bariatric surgery should prompt investigation for occult internal hernia.
Common Mistakes:
Delaying surgical exploration in suspected cases
Inadequate closure of mesenteric defects during primary bariatric surgery
Misinterpreting CT findings, especially subtle signs of mesenteric ischemia
Treating presumed non-specific abdominal pain without ruling out critical pathology like internal hernia.