The retroperitoneal space

Pus or blood in the retroperitoneal space tends to track to the corresponding iliac fossa. If a retroperitoneal abscess devel­ops, it should be evacuated by the nearest route through the abdominal wall, avoiding opening the peritoneum. Should the retroperitoneal collection be found at laparotomy, it must be drained by a counter-incision in the flank. Pus frequently develops from a renal or spinal source and is sometimes tuberculous (‘cold abscess’): tracking can develop alongside the psoas muscle and appear in the groin, where it must be distinguished from other swellings (e.g. hernia, Chapter 62). Retroperitoneal haematoma may be caused by fractured spine, a leaking abdominal aneurysm, acute pancreatitis or a ruptured kidney.

Retroperitoneal cyst

A cyst developing in the retroperitoneal space often attains very large dimensions, and has at first to be distinguished from a hydronephrosis. Even after the latter condition has been eliminated by scanning or orography, a retroperitoneal cyst can seldom be diagnosed with certainty from a retroperitoneal tumour until displayed at operation. The cyst may be unilocular or multilocular. Many of these cysts are believed to be derived from a remnant of the Wolffian duct, in which case they are filled with clear fluid. Others are teratomatous and are filled with sebaceous material.

Excision of these and other retroperitoneal swellings is best performed through a transperitoneal incision.

Idiopathic retroperitoneal fibrosis

This is one of a group of fibromatoses (others being Dupuytren’s contracture and Peyronies disease). Most cases are idiopathic, hut many causes are known (Table 56.9). Familial cases are known, involving mediastinal fibrosis, sclerosing cholangitis, Riedel’s thyroiditis and orbital pseudotumour. An autoimmune link has not been demonstrated. Extensive collagen deposition surrounds the ureters, mostly at the level of the pelvic brim or below. Most patients present with ureteric obstruc­tion, often with renal failure (Chapter 64): cases due to malignancy are treated appropriately according to the cause, but the prognosis is often poor.

Primary retroperitoneal neoplasms arising from connective tissues

Retroperitoneal lipoma, in the first instance, is usually mistaken for a hydronephrosis, a diagnosis which is ruled out by ultrasonography, CT scan or orography. Women are more often affected. These swellings sometimes reach an immense size. A retroperitoneal lipoma sometimes undergoes myxomatous degeneration, a complication which does not occur in a lipoma in any other part of the body. Moreover, a retroperitoneal lipoma is often malignant (liposarcoma) (Fig. 56.16) and may increase rapidly in size.

Retroperitoneal sarcoma presents signs similar to a retroperitoneal lipoma. The patient may seek advice on account of a swelling or because of indefinite abdominal pain. On other occasions the tumour, by pres­sure on the colon, causes symptoms of subacute intestinal obstruction. On examination a smooth fixed mass, which is not tender, is palpated. The most probable original diagnosis is that of a neoplasm of the kidney .This is ruled out by scanning or orography. The ureter, however, is liable to become displaced by the tumour. Exploratory laparotomy should be performed and when possible the tumour is removed. Often it is found widely disseminated in the retroperitoneal space, rendering complete removal impossible, in which case a portion is excised for microscopy. Even when excised at a comparatively early stage, recurrence always takes place, and these rumours must he looked upon as being necessarily fatal. Radiotherapy sometimes keeps recurrences in abeyance for a time.

Removal of a retroperitoneal cyst or neoplasm. After the anterior abdominal wall has been opened and the diagnosis of a retroperitoneal tumour has been confirmed, the incision is extended as necessary. The small intestine is packed away in the upper abdomen or exteriorised and the caecum and the sigmoid colon are relegated to their respective fossae. The posterior peritoneum is then incised throughout its length over the area to be exposed, the incision being parallel to the left border of the aorta. The peritoneum is dissected from the tumour which is removed as completely as possible.