Given its rarity, there are no established guidelines for the treatment of peritoneal mesothelioma. The modern approach to malignant peritoneal mesothelioma includes cytoreductive surgery, hyperthermic intraperitoneal chemotherapy (HIPEC), intraperitoneal chemotherapy, and intravenous chemotherapy. These are often used in conjunction and in a complementary fashion, and this multifaceted approach has significantly improved outcomes when compared to intravenous chemotherapy alone. For instance, the reported median survival time for patients with stage IV mesothelioma as reported by the American Cancer Society is 12 months; however, with adequate cytoreduction, intraperitoneal, and intravenous chemotherapy combined, some authors report 10-year survival rates projected at nearly 75%.

Multiple factors have been shown to be significant in predicting the outcome and overall survival. Age greater than 60 at surgery, more overall disease burden (defined as a PCI greater than 15), complete cytoreduction (no visible disease), and epitheliod subtype pathology have all been shown to be predictors of both mortality and disease progression. These known predictors notwithstanding, many patients with advanced peritoneal mesothelioma are still surgical candidates, and even patients with the highest possible score on the peritoneal carcinomatosis index (39) can be completely reduced to a PCI of 0 with adequate surgery.

Treatment is variable, both due to its rarity and to its frequently slow-growing nature. Treatment ranges from watchful waiting to debulking and hyperthermic intraperitoneal chemotherapy (HIPEC, also called intraperitoneal hyperthermic chemotherapy, IPHC) with cytoreductive surgery.

The production of pancreatic enzymes is suppressed by restricting the patient's oral intake of food patient in conjunction with the use of long-acting somatostatin analogues. The patient's nutrition is maintained by total parenteral nutrition.

This treatment is continued for 2–3 weeks, and the patient is observed for improvement. If no improvement is seen, the patient may receive endoscopic or surgical treatment. If surgical treatment is followed, an ERCP is needed to identify the site of the leak.

Fistulectomy is done in which the involved part of the pancreas is also removed.

Asbestos is a known cause of peritoneal mesothelioma in humans.

A 1975 study of three small villages in central Cappadocia, Turkey—Tuzköy, Karain and Sarıhıdır—found that peritoneal mesothelioma was causing 50% of all deaths. Initially, this was attributed to erionite, a zeolite mineral with similar properties to asbestos, but detailed epidemiological investigation demonstrated that the substance causes the disease mostly in families with a genetic predisposition to mineral fiber carcinogenesis. The studies are being extended to other parts of the region.

Treatment of Meigs' syndrome consists of thoracentesis and paracentesis to drain off the excess fluid (exudate), and unilateral salpingo-oophorectomy or wedge resection to correct the underlying cause.

Chemotherapy (typically the agent Mitomycin C) may be infused directly into the abdominal cavity after cytoreductive surgery to kill remaining microscopic cancerous tumors and free floating cells. The heated chemotherapy (HIPEC) is perfused throughout the abdominal cavity for an hour or two as the last step in the surgery, or ports are installed to allow circulation and/or drainage of the chemicals for one to five days after surgery, known as early postoperative intraperitoneal chemotherapy (EPIC). EPIC may be given in multiple cycles for several months after surgery.

Systemic chemotherapy may be administered as additional or adjuvant treatment. Due to the increased availability of new chemotherapies developed for colon and colorectal cancer patients, some patients have experienced stability in tumor growth with systemic chemotherapy. Systemic chemotherapy is reserved for patients with advanced disease, recurrent disease, or disease that has spread to the lymph nodes or distant sites.

This disease may recur following surgery and chemotherapy. Periodic post operative CT scans and tumor marker laboratory tests are used to monitor the disease for any tumor regrowth.

Since the mechanism behind chylothorax is not well understood, treatment options are limited. Drainage of the fluid out of the pleural space is essential to obviate damage to organs, especially the inhibition of lung function by the counter pressure of the chyle. Another treatment option is pleuroperitoneal shunting (creating a communication channel between pleural space and peritoneal cavity). By this surgical technique loss of essential triglycerides that escape the thoracic duct can be prevented. Omitting fat (in particular FFA) from the diet is essential. Either surgical or chemical pleurodesis are options: the leaking of lymphatic fluids is stopped by irritating the lungs and chest wall, resulting in a sterile inflammation. This causes the lung and the chest wall to be fused together which prevents the leaking of lymphatic fluids into the pleural space. The medication octreotide has been shown to be beneficial and in some cases will stop the chylothorax after a few weeks.

In animals, the most effective form of treatment until recently has been surgical ligation of the thoracic duct combined with partial pericardectomy. There is at least one case report (in a cat) of clinical response to treatment with rutin.

Pneumoperitoneum is (abnormal presence of air or other gas) in the peritoneal cavity, a potential space within the abdominal cavity. The most common cause is a perforated abdominal viscus, generally a perforated peptic ulcer, although any part of the bowel may perforate from a benign ulcer, tumor or abdominal trauma. A perforated appendix seldom causes a pneumoperitoneum.

In the mid-twentieth century, an "artificial" pneumoperitoneum was sometimes intentionally administered as a treatment for a hiatal hernia. This was achieved by insufflating the abdomen with carbon dioxide. The practice is currently used by surgical teams in order to perform laparoscopic surgery.

Pneumoperitoneum can be described as peritoneal emphysema, just as pneumomediastinum can be called mediastinal emphysema, but "pneumoperitoneum" is the usual name.

A pancreatic fistula is an abnormal communication between the pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic ducts. An "external" pancreatic fistula is one that communicates with the skin, and is also known as a pancreaticocutaneous fistula, whereas an internal pancreatic fistula communicates with other internal organs or spaces. Pancreatic fistulas can be caused by pancreatic disease, trauma, or surgery.

In medicine, Meigs' syndrome, also Meigs syndrome or Demons-Meigs syndrome, is the triad of ascites, pleural effusion, and benign ovarian tumor (ovarian fibroma, fibrothecoma, Brenner tumour, and occasionally granulosa cell tumour). Meigs' syndrome resolves after the resection of the tumor. Because the transdiaphragmatic lymphatic channels are larger in diameter on the right, the pleural effusion is classically on the right side. The causes of the ascites and pleural effusion are poorly understood. Atypical Meigs' syndrome, characterized by a benign pelvic mass with right-sided pleural effusion but without ascites, can also occur. As in Meigs syndrome, pleural effusion resolves after removal of the pelvic mass.

Depending on the severity of the patient's state, the management of peritonitis may include:

- General supportive measures such as vigorous intravenous rehydration and correction of electrolyte disturbances.

- Antibiotics are usually administered intravenously, but they may also be infused directly into the peritoneum. The empiric choice of broad-spectrum antibiotics often consist of multiple drugs, and should be targeted against the most likely agents, depending on the cause of peritonitis (see above); once one or more agents are actually isolated, therapy will of course be target on them.

- Gram positive and gram negative organisms must be covered. Out of the cephalosporins, cefoxitin and cefotetan can be used to cover gram positive bacteria, gram negative bacteria, and anaerobic bacteria. Beta-lactams with beta lactamase inhibitors can also be used, examples include ampicillin/sulbactam, piperacillin/tazobactam, and ticarcillin/clavulanate. Carbapenems are also an option when treating primary peritonitis as all of the carbapenems cover gram positives, gram negatives, and anaerobes except for ertapenem. The only fluoroquinolone that can be used is moxifloxacin because this is the only fluoroquinolone that covers anaerobes. Finally, tigecycline is a tetracycline that can be used due to its coverage of gram positives and gram negatives. Empiric therapy will often require multiple drugs from different classes.

- Surgery (laparotomy) is needed to perform a full exploration and lavage of the peritoneum, as well as to correct any gross anatomical damage that may have caused peritonitis. The exception is spontaneous bacterial peritonitis, which does not always benefit from surgery and may be treated with antibiotics in the first instance.

In medicine, the Sister Mary Joseph nodule or more commonly node, also called Sister Mary Joseph sign, refers to a palpable nodule bulging into the umbilicus as a result of metastasis of a malignant cancer in the pelvis or abdomen.

Gastrointestinal malignancies account for about half of underlying sources (most commonly gastric cancer, colonic cancer or pancreatic cancer, mostly of the tail and body of the pancreas), and men are even more likely to have an underlying cancer of the gastrointestinal tract. Gynecological cancers account for about 1 in 4 cases (primarily ovarian cancer and also uterine cancer). Nodules will also, rarely, originate from appendix cancer spillage Pseudomyxoma peritonei. Unknown primary tumors and rarely, urinary or respiratory tract malignancies cause umbilical metastases. How exactly the metastases reach the umbilicus remains largely unknown. Proposed mechanisms for the spread of cancer cells to the umbilicus include direct transperitoneal spread, via the lymphatics which run alongside the obliterated umbilical vein, hematogenous spread, or via remnant structures such as the falciform ligament, median umbilical ligament, or a remnant of the vitelline duct. Sister Mary Joseph nodule is associated with multiple peritoneal metastases and a poor prognosis.

If properly treated, typical cases of surgically correctable peritonitis (e.g., perforated peptic ulcer, appendicitis, and diverticulitis) have a mortality rate of about <10% in otherwise healthy patients. The mortality rate rises to about 40% in the elderly, or in those with significant underlying illness, as well as cases that present late (after 48 hours).

Without being treated, generalised peritonitis almost always causes death. The stage magician Harry Houdini died this way, having contracted streptococcus peritonitis after his appendix ruptured and was removed too late to prevent spread of the infection.

Surgical decompression can be achieved by opening the abdominal wall and abdominal fascia anterior in order to physically create more space for the abdominal viscera. Once opened, the fascia can be bridged for support and to prevent loss of domain by a variety of medical devices (Bogota bag, artificial bur, and vacuum devices using negative pressure wound therapy ).

A peritoneal inclusion cyst is a cyst-like structure that appears in the pelvis due to non neoplastic reactive mesothelial proliferation, often as a consequence of prior episodes of pelvic inflammation, as can occur in pelvic inflammatory disease. It has the potential to mimic ovarian cysts, hydrosalpinx or even malignancy, due to its nonspecific anechoic appearance.

Patients with ascites underwent routine paracentesis, the incidence of active SBP ranged from 10% to 27% at the time of hospital admission.

Omental infarction, or omental torsion, is an acute vascular disorder which compromises tissue of the greater omentum—the largest peritoneal fold in the abdomen.

Treatment is directed at the underlying condition and usually surgical.

The condition is rare but serious, and appears in all mammals. It results from leakage of lymph fluid from the thoracic duct (or one of its tributaries). This can result from direct laceration (e.g., from surgery) or from nontraumatic causes. The most common nontraumatic cause is malignancy, especially lymphoma. Less common is left-heart failure, infections, and developmental abnormalities such as Down syndrome and Noonan syndrome.

Complications are often diagnosed post-operatively, which can be differentiated through duplex ultrasound scanning and are bit observed until 24 to 48 hours for early complications such as drainage, infection, formation of haematocele, rupture, etc., but also for 1 to 6 weeks during follow-up on out-patient basis.

Surgical intervention is nearly always required in form of exploratory laparotomy and closure of perforation with peritoneal wash. Occasionally they may be managed laparoscopically.

Conservative treatment including intravenous fluids, antibiotics, nasogastric aspiration and bowel rest is indicated only if the person is nontoxic and clinically stable.

A hydrocele is an accumulation of serous fluid in a body cavity. A hydrocele testis is the accumulation of fluids around a testicle. It is often caused by fluid secreted from a remnant piece of peritoneum wrapped around the testicle, called the tunica vaginalis. Provided there is no hernia present, hydrocoeles below the age of 1 year usually resolve spontaneously. Primary hydrocoeles may develop in adulthood, particularly in the elderly and in hot countries, by slow accumulation of serous fluid, presumably caused by impaired reabsorption, which appears to be the explanation for most primary hydroceles, although the reason remains obscure. A hydrocele can also be the result of a plugged inguinal lymphatic system caused by repeated, chronic infection of "Wuchereria bancrofti" or "Brugia malayi", two mosquito-borne parasites of Africa and Southeast Asia, respectively. As such, the condition would be a part of more diffuse sequelae commonly referred to as elephantiasis, which also affects the lymphatic system in other parts of the body.

In severe liver injuries (class ≥III), or those with hemodynamic instability, surgical correction is generally necessary. In these severe injuries a hepatopancreatobiliary surgeon may be utilized rather than a trauma surgeon given their expertise with the organ and generally yields better outcomes. Surgical techniques such as perihepatic packing or the use of the Pringle manoeuvre can be used to control hemorrhage. Temporary control of the hemorrhage can be accomplished through direct manual pressure to the wound site. In these severe cases it is important to prevent the progression of the trauma triad of death, which often requires the utilization of damage control surgery. The common cause of death while operating is exsanguination caused by profuse loss of blood volume. Rarely, surgery entails the use of liver resection, which removes the source of the bleeding and necrotic tissue. The drastic nature of this procedure means it can only be used in hemodynamically stable patients. Another rare procedure would be liver transplantation which is typically impractical due to the logistics of finding a proper organ donor in a timely fashion.

Kousnetzoff aluminium needle is used to suture liver tear. Co-opting sutures are placed perpendicular to already placed parallel mattress sutures on either side of lacerations. Other methods are tractotomy and mesh hepatorrhaphy.

Ascites is generally treated while an underlying cause is sought, in order to prevent complications, relieve symptoms, and prevent further progression. In patients with mild ascites, therapy is usually as an outpatient. The goal is weight loss of no more than 1.0 kg/day for patients with both ascites and peripheral edema and no more than 0.5 kg/day for patients with ascites alone. In those with severe ascites causing a tense abdomen, hospitalization is generally necessary for paracentesis.

Treatments in high SAAG ("transudate") are: