Hernias

Congenital (failure of normal closure)

• Patent processus vaginalis: the peritoneal diverticulum that accompanies testicular descent fails to obliterate, leaving a preformed sac at the deep inguinal ring — the mechanism of every indirect inguinal hernia and of pediatric hydrocele. Explains why prematurity and low birth weight are strong risk factors and why infant inguinal hernias are essentially always indirect.
• Persistent umbilical ring: incomplete fibrous closure after cord separation; most common in infants, with a well-described higher incidence in Black infants and in trisomy 21 and congenital hypothyroidism.

Acquired fascial degeneration

• Transversalis fascia attenuation: age-related loss of tensile strength within Hesselbach triangle produces the direct inguinal hernia — a bulge through a weakened floor rather than a patent tract.
• Altered collagen metabolism: a shifted type III:type I collagen ratio and matrix metalloproteinase excess weaken fascia; hence hernia clustering in Ehlers-Danlos and Marfan syndromes, in smokers, and the recognized association between inguinal hernia and abdominal aortic aneurysm.
• Incisional/wound failure: fascial closure disrupted by surgical site infection, technical failure, or impaired healing; incisional hernia is the commonest ventral hernia in adults.

• Defect formation: Loss of structural integrity in the fascia, peritoneum, or muscular layers due to trauma, surgery, congenital weakness, or degenerative changes. Collagen abnormalities (seen in connective tissue disorders) increase hernia risk by reducing tissue tensile strength.

• Increased intra-abdominal pressure: Chronic elevation of abdominal pressure from obesity, chronic cough, constipation, heavy lifting, or straining facilitates herniation through existing or developing wall defects. Laplace's law dictates that wall tension increases with increasing radius and pressure.

• Incarceration mechanism: As the hernia enlarges, the hernia sac narrows at the neck (fascial defect), creating a constricting ring. Viscera become trapped within the sac, unable to reduce back through the defect. This compromise of vascular supply leads to local edema, which further restricts blood flow.

• Strangulation cascade: Progressive ischemia from impaired blood flow develops when venous drainage is compromised before arterial supply. Tissue hypoxia leads to necrosis, bacterial translocation, and sepsis. Irreversible tissue damage can occur within 6-8 hours of complete vascular compromise.

• Inflammation and fibrosis: Repeated herniation causes inflammatory changes in the hernia sac and surrounding tissues, with chronic inflammation promoting fibrosis and adhesion formation that may complicate surgical repair.

• Asymptomatic bulge: Many hernias present as a painless, visible or palpable bulge that increases with standing, straining, or coughing and reduces when lying down. This represents simple herniation without complications. Patient may report a sensation of fullness or mild discomfort, particularly after prolonged activity.

• Mild to moderate pain and discomfort: Localized pain at the hernia site, often described as a dull ache or pressure sensation. Pain typically worsens with exertion, standing for prolonged periods, or heavy lifting. This suggests tension on the fascial defect or mild inflammatory changes.

• Incarceration presentation: Acute onset of severe, constant pain at the hernia site accompanied by tenderness, swelling, and erythema. The hernia becomes firm, tense, and irreducible (cannot be manually pushed back). Nausea and mild abdominal distension may occur. Symptoms may have been preceded by a period of intermittent reducibility.

• Strangulation (surgical emergency): In addition to signs of incarceration, patients develop signs of bowel obstruction (vomiting, absolute constipation, abdominal distension) and systemic toxicity (fever, tachycardia, hypotension, altered mental status). Skin overlying the hernia may become discolored (erythematous, purple, or black), indicating tissue necrosis. Shock may develop rapidly.

• Bowel obstruction symptoms: Depending on content, patients may experience nausea, vomiting, abdominal pain, and constipation. Small bowel hernias commonly present with obstruction. Large bowel hernias may cause constipation with less pronounced vomiting.

• Important clinical pearls: A painless, easily reducible hernia does not require urgent intervention but should be managed electively to prevent future complications. Conversely, inability to reduce a hernia that was previously reducible is a red flag for incarceration. Tachycardia and fever in a patient with hernia suggest strangulation until proven otherwise. Up to 10-30% of hernias will eventually become incarcerated, making elective repair appropriate for most symptomatic hernias in surgical candidates.

• Physical examination: The gold standard diagnostic method. Inspect the abdomen or relevant region with the patient standing, supine, and performing Valsalva maneuver or coughing to demonstrate the bulge. Palpate to assess size, consistency, reducibility, and presence of tenderness. A distinct "defect" in the fascia can often be felt. Characterize the contents if possible (soft, compressible, or firm). Always examine the contralateral side for occult hernias, as bilateral hernias occur in up to 30% of patients.

• Imaging studies (for diagnostic confirmation or complicated hernias):
• Ultrasound: First-line imaging if physical exam is inconclusive. High sensitivity and specificity; shows the defect, contents, and signs of compromise. No radiation; can be performed at bedside.
• CT scan: Gold standard for imaging, particularly useful in obese patients or when suspecting complex/occult hernias. Excellent for evaluating contents and assessing for incarceration or strangulation. Essential in acute presentations to rule out strangulation and plan repair.
• MRI: Less commonly used; reserved for specific indications (e.g., detailed preoperative planning in complex ventral hernias). Superior soft tissue contrast but impractical acutely.

• Laboratory findings: In uncomplicated hernias, labs are typically normal. In strangulated hernias, expect leukocytosis, elevated lactate (indicates tissue ischemia), and elevated creatinine (from fluid shift). These findings should prompt immediate surgical intervention.

• Important diagnostic considerations: Occult hernias can be missed on routine exam, especially in obese patients or those with extensive scarring; maintain high suspicion in patients with unexplained obstruction symptoms. Femoral hernias are easily missed because they often present with groin pain without obvious bulge. Internal hernias (through ligaments, mesenteric defects, or post-surgical openings) cannot be diagnosed clinically and require imaging. Always document hernia type, location, size, contents, and reducibility for surgical planning.

• Conservative (watchful waiting): Appropriate for asymptomatic or minimally symptomatic hernias in patients without contraindications to surgery. Involves observation for symptom development. Studies show 10-30% risk of future incarceration; therefore, patient counseling regarding symptoms of incarceration is essential. No medications prevent hernia progression. This approach is reasonable for elderly or high-risk surgical patients.

• Elective surgical repair (definitive treatment):
• Indications: Symptomatic hernias causing pain or functional limitation, risk of incarceration (femoral, small hiatal, sliding hernias), incarcerated hernias (urgent elective repair after reduction if possible), and hernias in younger patients with long life expectancy.
• Timing: Elective repairs are performed on a scheduled basis. Emergent repair is indicated for strangulated hernias or failed reduction attempts.
• Repair techniques:
• Primary closure: Approximation of fascial edges without mesh; appropriate for small, primary hernias with good tissue quality. Higher recurrence rates (10-30%) but avoids mesh-related complications.
• Mesh repair (tension-free): Standard for most hernias; significantly reduces recurrence rates to 5-15%. Mesh can be placed in onlay (over fascia), underlay/retrorectus (under muscle), or intraperitoneal (IPOM with barrier) positions. Choice depends on location, contamination risk, and patient factors.
• Laparoscopic/minimally invasive repair: Lower postoperative pain, faster recovery, smaller incisions. Contraindicated in emergency strangulation or contaminated fields. Requires specialized equipment and expertise.
• Robotic-assisted repair: Increasingly common; combines benefits of minimally invasive approach with superior visualization and ergonomics for complex repairs.
• Specific hernia types:
• Inguinal hernias: Lichtenstein tension-free mesh repair is standard; laparoscopic TEP or TAPP for bilateral or recurrent

Complications of the hernia itself

• Incarceration: viscera trapped at the fibrous neck; the hernia becomes firm, tender, and irreducible. Signals the need for urgent surgical evaluation because it precedes strangulation.
• Strangulation (surgical emergency): venous outflow occludes before arterial inflow, so edema worsens the constriction until arterial supply fails. Look for skin discoloration over the sac, peritonitis, fever, tachycardia, leukocytosis, and elevated lactate. Requires resuscitation, broad-spectrum antibiotics, and emergent exploration with bowel resection if nonviable — an approach consistent with the World Society of Emergency Surgery emergency hernia guidance.
• Small bowel obstruction: the hernia acts as a closed-loop point of transition; a groin hernia is a classic extrinsic cause and must be sought on exam in any obstruction.
• Richter hernia (emergency): only the antimesenteric bowel wall herniates, so the lumen stays patent — the patient strangulates and perforates without obstructive symptoms. Most feared in femoral hernias.
• Reduction en masse (emergency): forceful taxis pushes the sac and its constricting ring into the abdomen; the bowel remains strangulated while the bulge disappears, giving false reassurance.

Complications of repair

• Recurrence: from tension, missed defects, infection, or persistent risk factors; tension-free mesh repair is standard largely to reduce this.
• Chronic postherniorrhaphy inguinal pain: entrapment or injury of the ilioinguinal, iliohypogastric, or genital branch of the genitofemoral nerve; the leading long-term morbidity after open inguinal repair per HerniaSurge.
• Ischemic orchitis and testicular atrophy: pampiniform plexus thrombosis after cord dissection; presents as a swollen, tender testis days postoperatively.
• Laparoscopic-specific injuries: external iliac vessels in the triangle of doom; lateral femoral cutaneous and genitofemoral nerves in the triangle of pain; also bladder and vas deferens injury.
• Mesh infection, seroma, erosion, or enterocutaneous fistula; and after large ventral repair, abdominal compartment syndrome from loss of domain — an emergency.
• Postoperative urinary retention, common after groin repair, particularly in older men.

• Inferior epigastric vessels are the landmark: indirect hernias arise lateral to them through the deep ring (patent processus vaginalis, may reach the scrotum); direct hernias bulge medial to them through Hesselbach triangle (rectus sheath medially, inferior epigastric vessels laterally, inguinal ligament inferiorly). Indirect is the most common hernia in both sexes — the classic distractor is assuming women get femoral hernias most often.
• Femoral hernia = below the inguinal ligament, lateral to the pubic tubercle, medial to the femoral vein. Highest risk of incarceration and strangulation of any groin hernia; per HerniaSurge, femoral hernias warrant repair even when asymptomatic — watchful waiting is not an option.
• Do not force reduction of a hernia that is tender, discolored, or associated with peritonitis. The single best next step is fluid resuscitation, broad-spectrum antibiotics, and emergent operative exploration; taxis risks reduction en masse and returning dead bowel to the abdomen.
• Richter hernia strangulates without obstruction — a patient with a tender femoral bulge, fever, and leukocytosis but ongoing flatus still needs the operating room.
• Pediatrics splits two ways: umbilical hernias usually close spontaneously and are observed to roughly school age unless incarcerated or very large; inguinal hernias in infants never resolve, carry a high incarceration risk, and are repaired promptly after diagnosis.
• Watchful waiting is defensible only for minimally symptomatic inguinal hernias in men (HerniaSurge), and most such patients eventually cross over to surgery.
• Eponyms examiners love: Littre (Meckel diverticulum in the sac), Amyand (appendix in an inguinal sac), Spigelian (semilunar line, lateral to rectus, often occult and prone to incarceration), obturator with the Howship-Romberg sign (medial thigh pain on internal rotation) in a thin elderly woman.
• A new groin hernia in an older adult is not automatically benign: exclude the pressure driver — ascites, chronic cough, or obstructing colonic malignancy.