A direct inguinal hernia is less common (~25–30% of inguinal hernias) and usually occurs in men over 40 years of age.

Men have an 8 times higher incidence of inguinal hernia than women.

Many people are managed through day surgery centers, and are able to return to work within a week or two, while intense activities are prohibited for a longer period. People who have their hernias repaired with mesh often recover within a month, though pain can last longer. Surgical complications include pain that lasts more than three months, surgical site infections, nerve and blood vessel injuries, injury to nearby organs, and hernia recurrence. Pain that lasts more than three months occurs in about 10% of people following hernia repair.

About 27% of males and 3% of females develop a groin hernia at some time in their life. In 2013 about 25 million people had a hernia. Inguinal, femoral and abdominal hernias resulted in 32,500 deaths globally in 2013 and 50,500 in 1990.

Femoral hernias are more common in multiparous females which results from elevated intra-abdominal pressure that dilates the femoral vein and which in turn stretches femoral ring. Such a constant pressure causes preperitoneal fat to insinuate in the femoral ring consequence of which is development of femoral peritoneal sac.

An inguinal hernia is a protrusion of abdominal-cavity contents through the inguinal canal. Symptoms are present in about 66% of affected people. This may include pain or discomfort especially with coughing, exercise, or bowel movements. Often it gets worse throughout the day and improves when lying down. A bulging area may occur that becomes larger when bearing down. Inguinal hernias occur more often on the right than left side. The main concern is strangulation, where the blood supply to part of the intestine is blocked. This usually produces severe pain and tenderness of the area.

Risk factors for the development of a hernia include: smoking, chronic obstructive pulmonary disease, obesity, pregnancy, peritoneal dialysis, collagen vascular disease, and previous open appendectomy, among others. Hernias are partly genetic and occur more often in certain families. It is unclear if inguinal hernias are associated with heavy lifting. Hernias can often be diagnosed based on signs and symptoms. Occasionally medical imaging is used to confirm the diagnosis or rule out other possible causes.

Groin hernias that do not cause symptoms in males do not need to be repaired. Repair, however, is generally recommended in females due to the higher rate of femoral hernias which have more complications. If strangulation occurs immediate surgery is required. Repair may be done by open surgery or by laparoscopic surgery. Open surgery has the benefit of possibly being done under local anesthesia rather than general anesthesia. Laparoscopic surgery generally has less pain following the procedure.

In 2015 inguinal, femoral and abdominal hernias affected about 18.5 million people. About 27% of males and 3% of females develop a groin hernia at some time in their life. Groin hernias occur most often before the age of one and after the age of fifty. Globally, inguinal, femoral and abdominal hernias resulted in 60,000 deaths in 2015 and 55,000 in 1990.

An acquired umbilical hernia directly results from increased intra-abdominal pressure caused by obesity, heavy lifting, a long history of coughing, or multiple pregnancies.

Navels with the umbilical tip protruding past the umbilical skin ("outies") are often mistaken for umbilical hernias, which are a completely different shape. Treatment for cosmetic purposes is not necessary, unless there are Incarceration refers to the inability to reduce the hernia back into the abdominal cavity. Prolonged incarceration can lead to tissue ischemia (strangulation) and shock when untreated.

Umbilical hernias are rare. With a study involving Africans, 92% of children had protrusions, 49% of adults, and 90% of pregnant women. However, a much smaller amount actually suffered from hernias: only 23% of children, 8% of adults, and 15% of pregnant women.

When the orifice is small (< 1 or 2 cm), 90% close within 3 years (some sources state 85% of all umbilical hernias, regardless of size), and if these hernias are asymptomatic, reducible, and don't enlarge, no surgery is needed (and in other cases it must be considered).

In dogs, perineal hernia usually is found on the right side. Most cases are in older intact (not neutered) male dogs (93 percent in one study). Breeds that may be at risk include Welsh Corgis, Boxers, Australian Kelpies, Boston Terriers, Collies, Dachshunds, Old English Sheepdogs, and Pekingese. Perineal hernias are rare in female dogs and uncommon in cats.

Dogs with benign prostatic hyperplasia have been found to have increased relaxin levels and suspected subsequent weakening of the pelvic diaphragm. In cats, perineal hernias are seen most commonly following perineal urethrostomy surgery or secondary to megacolon. Medical treatment consists of treatment of the underlying disease, enemas, and stool softeners. Because only about 20 percent of cases treated medically are free of symptoms, surgery is often necessary. Recurrence is common with or without surgery.

Several surgeries have been described for perineal hernias in dogs. The current standard involves transposition of the internal obturator muscle. This technique has a lower recurrence and complication rate than traditional hernia repair. A new technique uses porcine small intestinal submucosa as a biomaterial to help repair the defect. This is can also be done in combination with internal obturator muscle transposition, especially when that muscle is weak.

Femoral hernias, like most other hernias, usually need operative intervention. This should ideally be done as an elective (non-emergency) procedure. However, because of the high incidence of complications, femoral hernias often need emergency surgery.

Incisional hernias are usually caused by a weakness of the surgical wounds, which may be caused by hematoma, seroma, or infection, all of which result in decreased wound healing. They may also be caused by increased intra-abdominal pressure due to a chronic cough (as in COPD), constipation, urinary obstruction (as in BPH), pregnancy, or ascites. They can also result from poor surgical technique.

Internal hernias occur when there is protrusion of an internal organ into a retroperitoneal fossa or a foramen (congenital or acquired) in the abdominal cavity. If a loop of bowel passes through the mesenteric defect, that loop is at risk for incarceration, strangulation, or for becoming the lead point of a small bowel obstruction. Internal hernias can also trap adipose tissue (fat) and nerves. Unlike more common forms of hernias, the trapped tissue protrudes inward, rather than outward.

Mesenteric defects commonly occur in trauma, such as gunshot wounds to the abdomen. In trauma victims, the defect is usually closed, sometimes with resection of the associated bowel, which may have lost its blood supply. Also mesenteric defects are intentionally created in the Roux-en-Y gastric bypass procedure, being classically known as a Petersen's hernia. The mesenteric defect in such cases, called "Petersen's defect", is located between the transverse colon and the mesentery of the alimentary limb (the segment of the jejunum from the jejunojejunostomy until the connection with the proximal segment of the stomach) at the level of the jejunojejunostomy.

Internal hernias are difficult to identify in women, and misdiagnosis with endometriosis or idiopathic chronic pelvic pain is very common. One cause of misdiagnosis that when the woman lies down flat on an examination table, all of the medical signs of the hernia disappear. The hernia can typically only be detected when symptoms are present, so diagnosis requires positioning the woman's body in a way that provokes symptoms.

Both internal hernias and umbilical hernias are more common in women than men.

In humans, a major cause of perineal hernia is perineal surgery without adequate reconstruction. In some cases, particularly surgeries to remove the coccyx and distal sacrum, adequate reconstruction is very difficult to achieve. The posterior perineum is a preferred point of access for surgery in the pelvic cavity, particularly in the presacral space. Surgeries here include repair of rectal prolapse and anterior meningocele, radical perineal prostatectomy, removal of tumors including sacrococcygeal teratoma, and coccygectomy. Perineal hernia is a common complication of coccygectomy in adults, but not in infants and children (see coccygectomy).

The standard surgical technique for repair of perineal hernia uses a prosthetic mesh, but this technique has a high rate of failure due to insufficient anchoring. Promising new techniques to reduce the rate of failure include an orthopedic anchoring system, a gluteus maximus muscle flap, an acellular human dermis graft, and an acellular pig collagen graft.

Clinically, incisional hernias present as a bulge or protrusion at or near the area of a surgical incision. Virtually any prior abdominal operation can develop an incisional hernia at the scar area (provided adequate healing does not occur due to infection), including large abdominal procedures such as intestinal or vascular surgery, and small incisions, such as (appendix removal or abdominal exploratory surgery). While incisional hernias can occur at any incision, they tend to occur more commonly along a straight line from the xiphoid process of the sternum straight down to the pubis, and are more complex in these regions. Hernias in these areas have a high rate of recurrence if repaired via a simple suture technique under tension. For this reason, it is especially advised that these be repaired via a tension free repair method using a synthetic mesh.

Bochdalek hernias make up about 0.17% to 6% of all diaphragmatic hernia cases and about one in every 2200 to 12,500 births every year. Babies who are born with a Bochdalek hernia are more than likely to have another birth defect caused by the hernia. About twenty percent of those children born with a Bochdalek hernia, also have a congenital heart defect. In addition, infants born with this condition may also have other abnormalities. "Between five and sixteen [percent of infants] have a chromosomal abnormality." In most cases, left-sided hernias or Bochdalek hernias have a ratio of 3:2 of males to females. In other words, Bochdalek hernias are more common in men.

These hernias should be repaired because of the high risk of strangulation; fortunately, surgery is straightforward, with only larger defects requiring a mesh prosthesis. Varied Spigelian hernia mesh repair techniques have been described, although evidence suggests laparoscopy results in less morbidity and shorter hospitalization compared with open procedures. Mesh-free laparoscopic suture repair is feasible and safe. This novel uncomplicated approach to small Spigelian hernias combines the benefits of laparoscopic localization, reduction, and closure without the morbidity and cost associated with foreign material.

An obturator hernia is a rare type of hernia of the pelvic floor in which pelvic or abdominal contents protrudes through the obturator foramen. Because of differences in anatomy, it is much more common in women, especially multiparous and older women who have recently lost a lot of weight. The diagnosis is often made intraoperatively after presenting with bowel obstruction.

The Howship–Romberg sign is suggestive of an obturator hernia, exacerbated by thigh extension, medial rotation and abduction. It is characterized by lancilating pain in the medial thigh/obturator distribution, extending to the knee; caused by hernia compression of the obturator nerve.

The protrusion is put back within the abdomen in the correct position. Stitches are used to strengthen the weakness where the hernia has broken through.

The operation is usually performed under a general anaesthetic.

In most cases this is done as a day case without the need for an overnight stay.

A Richter's hernia occurs when the antimesenteric wall of the intestine protrudes through a defect in the abdominal wall. This is discrete from other types of abdominal hernias in that only one intestinal wall protrudes through the defect, such that the lumen of the intestine is incompletely contained in the defect, while the rest remains in the peritoneal cavity. If such a herniation becomes necrotic and is subsequently reduced during hernia repair, perforation and peritonitis may result. A Richter's hernia can result in strangulation and necrosis in the absence of intestinal obstruction. It is a relatively rare but dangerous type of hernia.

Richter's hernia have also been noted in laparoscopic port-sites, usually when the fascia is not closed for ports larger than 10mm. A high index of suspicion is required in the post operative period as this sinister problem can closely mimic more benign complications like port-site haematomas.

Treatment is resection and anastomosis.

Mortality increases with delay in surgical intervention.

Amyand's hernia is a rare form of an inguinal hernia (less than 1% of inguinal hernias) which occurs when the appendix is included in the hernial sac and becomes incarcerated. The condition is an eponymous disease named after a French surgeon, Claudius Amyand (1660-1740), who performed the first successful appendectomy in 1735.

Amyand's hernia is commonly misdiagnosed as an ordinary incarcerated hernia. Symptoms mimicking appendicitis may occur. Treatment consists of a combination of appendectomy and hernia repair.

A Spigelian hernia (or lateral ventral hernia) is a hernia through the Spigelian fascia, which is the aponeurotic layer between the rectus abdominis muscle medially, and the semilunar line laterally. These are generally interparietal hernias, meaning that they do not lie below the subcutaneous fat but penetrate between the muscles of the abdominal wall; therefore, there is often no notable swelling.

Spigelian hernias are usually small and therefore risk of strangulation is high. Most occur on the right side. (4th–7th decade of life.) Compared to other types of hernias they are rare.

Petit's hernia is a hernia that protrudes through the lumbar triangle. This triangle lies in the posterolateral abdominal wall and is bounded anteriorly by the free margin of external oblique muscle, posteriorly by the latissimus dorsi and inferiorly by the iliac crest. The neck (the spot where the hernia protrudes into the opening) is large, and therefore this hernia has a lower risk of strangulating than some other hernias.

Petit's hernia occurs more often in males than in females and more often on the left side than on the right.

Congenital diaphragmatic hernia has a mortality rate of 40–62%, with outcomes being more favorable in the absence of other congenital abnormalities. Individual rates vary greatly dependent upon multiple factors: size of hernia, organs involved, additional birth defects, and/or genetic problems, amount of lung growth, age and size at birth, type of treatments, timing of treatments, complications (such as infections) and lack of lung function.

Bochdalek hernia can be a life-threatening condition. Approximately 85.3% of newborns born with a Bochdalek hernia are immediately high risk. Infants born with a Bochdalek hernia have a "high mortality rate due to respiratory insufficiency". Between 25–60% of infants with a Bochdalek hernia die. The lungs, diaphragm, and digestive system are all forming at the same time, so when a Bochdalek hernia permits the abdominal organs to invade the chest cavity rather than remain under the diaphragm in the correct position, it puts the infant in critical condition. These "foreign bodies" in the chest cavity compress the lungs, impairing their proper development and causing pulmonary hypoplasia. Since the lungs of infants suffering from a Bochdalek hernia have fewer alveoli than normal lungs, Bochdalek hernias are life-threatening conditions due to respiratory distress. Also, if the invasion of the intestine or stomach punctures the lung, then the lungs cannot fill completely with air. The baby will not be healthy or stable with this condition because he or she cannot take in enough air and oxygen to keep the body operating properly. Like the lungs, the intestines may also have trouble developing correctly. If the intestines are trapped within the lungs, then the lungs and intestines may not be receiving the amount of blood they need to stay healthy and function properly.

Incidence of hiatal hernias increases with age; approximately 60% of individuals aged 50 or older have a hiatal hernia. Of these, 9% are symptomatic, depending on the competence of the lower esophageal sphincter (LES). 95% of these are "sliding" hiatus hernias, in which the LES protrudes above the diaphragm along with the stomach, and only 5% are the "rolling" type (paraesophageal), in which the LES remains stationary, but the stomach protrudes above the diaphragm.

Hiatus hernia are most common in North America and Western Europe and rare in rural African communities. Some have proposed that insufficient dietary fiber and the use of a high sitting position for defecation may increase the risk.

Symptomatic epigastric hernias are repaired with surgery. Even if they are asymptomatic, they can be surgically corrected for cosmetic reasons. In general, cosmetic surgery on infants is delayed until the infant is older and better able to tolerate anaesthesia.