Membranous layer of superficial abdominal fascia is continuous with corresponding layer of penis, scrotum, and perineum.

Extravasated urine from a ruptured penile urethra may accumulate deep to Scarpa’s fascia.

When incising the anterior abdominal wall lateral to the rectus abdominis, the blade penetrates successively the skin, the superficial fascia, the deep fascia, the external and internal oblique and transversus abdominis muscle layers, the transversalis fascia, the extraperitoneal connective tissue, and the parietal peritoneum.

Anterolateral abdominal incisions penetrate the skin, superficial and deep fasciae, muscle layers, transversalis fascia, extraperitoneal connective tissue, and parietal peritoneum.

When suturing lower abdominal wall incisions, surgeons may include the membranous layer of superficial fascia for added strength.

The inguinal canal is an oblique passage through the abdominal wall connecting the deep and superficial inguinal rings.

Persistent processus vaginalis predisposes to indirect inguinal hernia and hydrocele development.

The canal of Nuck may contain a herniated ovary and a uterine tube.

The inguinal ligament is the rolled-under inferior border of the external oblique aponeurosis between the ASIS and the pubic tubercle.

The inguinal canal transmits the spermatic cord in males and the round ligament of the uterus in females.

A hernia is protrusion of an organ from the space it usually occupies.

A hernia is the protrusion of a structure from the space it normally occupies through a weakness in the surrounding walls. Abdominal hernias occur most frequently in the inguinal region (groin) and usually involve a loop of small intestine, which may have its lumen obstructed (bowel obstruction) and/or its blood supply compromised (strangulation). Both are surgical emergencies. In females, an ovary or uterine tube may be the herniating structure.

Indirect inguinal hernias are the most common type of hernia in both sexes but are much more frequent in males.

Indirect inguinal hernias are by far the most frequent abdominal hernias in both sexes but are 6-7 times more common in males. The herniating structure exits the abdominal cavity at the deep inguinal ring lateral to the inferior epigastric vessels, traverses the inguinal canal, and exits the superficial inguinal ring to descend into the scrotum or labium majus. It follows the path of descent of the embryonic testis and is due to persistence of a saclike evagination of the peritoneal cavity, the processus vaginalis, that normally is obliterated shortly after birth.

Indirect inguinal hernias exit the abdominal cavity lateral to the inferior epigastric vessels, and direct inguinal hernias medial to them.

Inguinal hernia bulges are superior to the pubic tubercle, but femoral hernia bulges are inferior and lateral to the pubic tubercle.

Direct inguinal hernias are less common than indirect inguinal hernias. The herniating structure exits the abdominal cavity through the inguinal triangle, which is medial to the inferior epigastric vessels, and pushes through the superficial inguinal ring but seldom descends into the scrotum or labium majus. These hernias are more common in older males and are usually due to a weak or narrow conjoint tendon.

Features of the internal surface of the anterior abdominal wall are important in laparoscopic repair of abdominal hernias. Five peritoneal folds are raised over blood vessels or the fibrous remnants of fetal structures. The median umbilical fold is parietal peritoneum raised over the median umbilical ligament, a remnant of the fetal urachus. The paired medial umbilical folds overlie the obliterated distal portions of the umbilical arteries. The lateral umbilical folds are raised over the inferior epigastric arteries and veins. Depressions, or peritoneal fossae, bounded by these folds on each side of the midline are potential sites of hernias. The supravesical fossa lies between the median and medial umbilical folds. The medial inguinal fossa between medial and lateral umbilical folds corresponds to the inguinal triangle, where a direct inguinal hernia exits the abdominal cavity. The lateral inguinal fossa is the location of the deep inguinal ring, where an indirect inguinal hernia leaves the abdominal cavity.

On laparoscopic view, the medial inguinal fossa is the site of a direct inguinal hernia, while the lateral inguinal fossa is the site of an indirect inguinal hernia.

The gubernaculum is a fibrous cord that guides the descent of the fetal testis or ovary.

Cryptorchidism is the failure of one or both testes to descend into the scrotum. The undescended testis may lie anywhere along the path of the usual descent but usually is in the inguinal canal. Cryptorchidism results in increased risk of testicular cancer and decreased fertility. The normally descended testicle is also at risk.

Cryptorchidism is an undescended testis with the risk of testicular cancer and decreased fertility.

Torsion of the spermatic cord produces acute pain and swelling and can result in testicular necrosis and atrophy if not reduced promptly. The condition usually occurs just above the superior pole of the testis. Repair requires a high scrotal incision to untwist the cord, and the testis is sutured to the scrotal septum to prevent recurrence. Torsion frequently follows vigorous exercise in 10- to 20-year-olds and may be associated with congenital anomalies (e.g., a mobile, horizontally oriented testis [bell-clapper deformity] or cryptorchidism). In children, acute scrotal pain and swelling are assumed to be testicular torsion until proven otherwise.

Untreated testicular torsion results in testicular necrosis and atrophy.

The genital branch of the genitofemoral nerve innervates the cremaster muscle and is the efferent limb of the cremasteric reflex (L1), which is tested in males by stroking the upper medial thigh. Absence of the cremasteric reflex in children with acute scrotal pain and swelling supports a diagnosis of torsion.

Acute scrotal pain and swelling in children are assumed to be torsion of the testis until proven otherwise.

The right gonadal vein drains to the inferior vena cava, and the left gonadal vein drains to the left renal vein.

Varicocele is engorgement of the pampiniform plexus that produces a scrotal mass palpable as a “bag of worms.” Formation is usually on the left side due to incompetent venous valves and is benign, but varicocele on either side may indicate a retroperitoneal malignancy or fibrosis obstructing the testicular vein. A rapidly developing left-sided varicocele may be due to a renal tumor (renal cell carcinoma) that has spread along the renal vein.

Testicular cancer is the most common malignancy in young adult males. It spreads to the aortic (lumbar) nodes through the lymphatics accompanying the testicular artery. Blood supply and lymphatic drainage reflect the developmental origin of the testis from the posterior abdominal wall.

Testicular cancer metastasizes to aortic nodes, but scrotal cancer metastasizes to superficial inguinal nodes.

Transillumination of a scrotal mass detects hydrocele.

The tunica vaginalis testis or other remnants of the processus vaginalis may accumulate serous fluid (hydrocele) or blood (hematocele). With transillumination, a hydrocele produces a reddish glow, whereas light usually will not penetrate other scrotal masses such as a hematocele, solid tumor, or herniated bowel.

A spermatocele is a sperm-filled cyst that occurs near the head of the epididymis. It is usually asymptomatic and discovered on routine physical examination. Epididymitis is inflammation of the epididymis causing acute scrotal pain and swelling. It is common in young males with sexually transmitted infections or older males with urinary tract infections secondary to benign prostatic hyperplasia or other genitourinary problems.

Epididymitis is a common cause of acute scrotal pain and swelling in young, sexually active males.

Umbilical vessels can be catheterized in newborns to administer fluids or collect samples.

In postductal coarctation of the aorta, anastomoses between the superior and inferior epigastric arteries provide collateral circulation between the subclavian and external iliac arteries.

Superior-inferior epigastric artery anastomoses provide collateral circulation in postductal coarctation of the aorta.

Thoracoepigastric and superior-inferior epigastric veins provide caval-caval anastomoses to bypass vena caval obstruction.

Somatic pain from the parietal peritoneum is sharp and localized; visceral pain from the visceral peritoneum is diffuse and aching or cramping.

Mesenteries carry vessels and nerves between the body wall and the organs.

Intraperitoneal organs invaginate the peritoneal sac, while retroperitoneal organs remain posterior to the sac.

Common clinical disorders of the peritoneum are peritonitis and ascites. Peritonitis is inflammation of the peritoneum due to entrance into the peritoneal cavity of sterile materials such as bile (aseptic peritonitis) or bacterial contamination (septic peritonitis). Septic peritonitis commonly is due to a perforated viscus, such as the appendix or a peptic ulcer, and also typically develops over time in aseptic peritonitis. Septic peritonitis without bowel perforation (spontaneous bacterial peritonitis) may occur when ascites is present in cirrhosis of the liver or the nephrotic syndrome (massive protein loss in the urine with decreased serum albumin).

Peritonitis results from the introduction of sterile material or bacteria into the peritoneal cavity.

Ascites is excess fluid in the peritoneal cavity. It most commonly results from cirrhosis of the liver but may follow peritoneal malignancy, right-sided heart failure, or peritoneal tuberculosis. A needle is inserted into the peritoneal cavity to collect a sample for analysis or to drain fluid to relieve respiratory distress or abdominal pain (paracentesis).

The peritoneal cavity is subdivided into greater and lesser peritoneal sacs connected by the omental foramen.

Ascites is excess fluid in the peritoneal cavity due most often to cirrhosis.

A liver abscess in the subphrenic recess may erode through the diaphragm into the thorax. Cancer can spread quickly to adjacent organs.

The hepatorenal recess is the lowest point of the peritoneal cavity in a supine patient and may be infected from subphrenic recess or omental bursa.

Paracolic gutters are pathways for the spread of infection and cancer cells.

Fluid draining from the subphrenic recess or omental bursa collects in the hepatorenal recess in supine patients. In upright patients, the paracolic gutters provide a path for infection and cancer cells to spread into the lower abdomen or pelvis. Patients with peritonitis due to bacterial infections are treated with antibiotics and may be positioned sitting up to facilitate drainage into the pelvis, where absorption of toxins is slower.

In acute pancreatitis fluid may accumulate within or around the pancreas as a pancreatic pseudocyst, and most often enters the omental bursa (Figure 3-11). Pseudocysts may become infected and may compress or erode adjacent structures. The majority of cases of acute pancreatitis are due to alcohol abuse or a gallstone obstructing the distal bile duct. Patients show constant severe epigastric pain radiating to the back with fever, nausea, and vomiting. Seventy percent of acute pancreatitis patients have elevated serum amylase (hyperamylasemia) for about 3 days. In necrotizing pancreatitis blood may dissect along fascial planes to produce ecchymoses in the flank (Grey-Turner sign) or periumbilical region (Cullen sign).

Pancreatic pseudocyst is a fluid collection in pancreatitis, most frequently in the omental bursa.

Flank or periumbilical ecchymoses may signal necrotizing pancreatitis.

The omental foramen is bounded by the first part of the duodenum, hepatoduodenal ligament, caudate lobe, and inferior vena cava.

Inflammation caused by acute pancreatitis or a perforated posterior gastric ulcer may obstruct the omental foramen. Accumulated fluid in the lesser peritoneal sac (e.g., pancreatic pseudocyst) is evident on a CT scan. Rarely, a loop of small intestine may become entrapped in the omental foramen as an internal hernia and is in danger of bowel obstruction and strangulation. Since none of the boundaries of the foramen can be incised, the swollen intestine may have to be decompressed to allow extraction.

Differential diagnosis of small bowel obstruction includes an internal hernia in the absence of surgery or trauma history.

Longitudinal mucosal tears through the gastroesophageal junction, or gastric cardia (Mallory-Weiss tears) may cause severe upper gastrointestinal bleeding and vomiting of blood (hematemesis). They usually result from severe retching or vomiting in those with alcoholism or bulimia. A rupture of the distal esophagus in similar patients is Boerhaave syndrome. Severe epigastric pain and dyspnea are present, and the condition is fatal without treatment.

A Mallory-Weiss tear is a mucosal tear of the gastroesophageal junction from retching.

The most common causes of upper-GI bleeding are peptic ulcers, esophageal varices, and Mallory-Weiss tears.

In a sliding hiatal hernia, the gastroesophageal junction herniates through the esophageal hiatus of the diaphragm with part of the stomach (Figure 3-14), predisposing to gastroesophageal reflux. Heartburn from hiatal hernia can mimic the substernal pain of myocardial infarction but differs in that the pain is usually lessened when the patient sits upright or takes antacids. In the less common paraesophageal hiatal hernia the gastroesophageal junction remains in place, but the adjacent fundus herniates into the thorax. A paraesophageal hernia usually does not cause reflux.