Pathways of Extrapelvic Spread of Disease

Diseases arising from the pelvic contents may first manifest themselves by signs and symptoms remote from their source of origin. Gastrointestinal tract perforations, in particular, may dissect along anatomic planes of the pelvis to first present in the buttock, hip, thigh, and even the lower leg and the retroperitoneal space of the abdomen. Pain, mass, or crepitation at these sites may be very misleading since the origin of the underlying inflammatory condition or the neoplastic, traumatic, or foreign body perforation of the bowel within the pelvis often remains clinically occult. Radiologic evaluation may be crucial in redirecting the diagnostic and therapeutic approach as well as in documenting the extent of disease.

The most common extraabdominal extension of gastrointestinal tract perforations, beyond the development of ischiorectal abscesses, is to the buttocks, hips, and lower extremities. Spread of necrotizing fasciitis to the male genitalia (Fournier gangrene) is rare.1 Of the cases in the literature reported as subcutaneous emphysema of the leg arising from intestinal perforations,2-5 diver-ticulitis and appendicitis account for most of those resulting from infection. Carcinoma of the colon with perforation, uterine carcinoma, foreign body, and trauma to the rectum have been other causes.

Most cases of extraperitoneal spread reported have created serious diagnostic problems with admitting diagnoses of thrombophlebitis, sciatica, gas gangrene, inguinal abscess, Spigelian hernia, and even fractured hip, until surgery or autopsy uncovered a definitive diagnosis. The clinical presentation is often pain in the hip or buttock.2,6-10 With the development of crepitation, particularly in the thigh, incision may then display severe necrotizing fasciitis. It is often not until blunt dissection is then carried out along the femoral canal, be neath the inguinal ligament, that an extraperitoneal abscess is revealed as evidence of a more severe process extending from the pelvis.

The pathogenesis of subacute cellulitis and emphysema of gastrointestinal origin depends on four basic factors11: (a) perforation ofthe bowel, (b) an adequate pressure gradient between the lumen of the bowel and ultimately the subcutaneous space, (c) the anatomic site of perforation, and (d) infection.

The major mechanism of gas formation is not the gas-forming organisms in feces, but the pressure gradient between the lumen of the gut and surrounding tissue. Large pressure gradients are associated with vigorous peristaltic contractions.12 Gas pressures in the intestinal lumen may rise to more than 60 cm H20 during peristalsis, while soft-tissue tension is usually about 5 cm H2Q The intraabdominal pressure may be greatly increased by the contraction of the diaphragmatic and abdominal muscles. This increased pressure is transmitted to the contents of the intestinal tract and promotes their evacuation, especially at sites of perforation when the sphincters are intact.12,13 This mechanism, enhanced by bacterial gas formation, accounts for the rapidity of its accumulation.

The anatomic site of perforation largely determines the pathway of spread of the sinus tract to the subcutaneous position. The usual route of extravasation from the bowel is directly through a pathologic defect in the parietal peritoneum or fascia contiguous with this defect into the intermuscular planes and subcutaneous spaces. Solid parenchymatous organs and serous membranes have a relatively great resistance to the diffusion of gases, whereas loose areolar and fascial structures readily allow the passage of gas.

Cases of perforated diverticulitis or carcinoma of the sigmoid or descending colon usually present in the left leg or buttock, and appendicitis or perforation of the cecum in the right leg and buttock. Because of variations in position and length of the appendix and in redundancy of the sigmoid, perforations from these sites may extend to the side opposite to that ordinarily expected. Traumatic or neoplastic perforation of the rectum may present in either or both buttocks and legs. Spread from the pelvis may occur also into the abdominal wall and upward as an extraperitoneal abscess.3,14-16 The most common offending organism is Escherichia coli. Occasionally, cultures isolate Clostridium welchii, Aerobacter aerogenes, and Proteus.6'89'14'16

Surgical findings have not often localized the particular pathway of spread in the presence of a pelvic abscess with frequent necrotizing dissection toward the inguinal region, perineum, thigh and hip joint, buttock, and paravertebral gutter.8,14

I have established the correlation between the anatomic pathways and the radiologic documentation of the extrapelvic spread of disease.2 The insertions of the iliopsoas, piriformis, and obturator internus muscles, within their fascial investments, and the ensheathed penetrations of the superior gluteal arteries provide avenues of dissection to the buttocks, hips, and thighs.

Perinephric Extramedullary Hematopoiesis

Fig. 17—1. Midcoronal anatomic section through the pelvis at the level of the urinary bladder (B), prostate gland (PG), and loops of sigmoid colon (SiC).

The course and relationships of the psoas major (1), iliacus (2), obturator internus (3), levator ani (4), and gluteal muscles (5) are shown. These are invested by fascia. The superior gluteal vessels (arrows) pass out of the pelvis at the level of the greater sciatic foramina.

(Courtesy of Manuel Viamonte, Jr., M.D., Mt. Sinai Hospital, Miami Beach, FL. Reproduced from Meyers and Goodman.2)

Fig. 17—1. Midcoronal anatomic section through the pelvis at the level of the urinary bladder (B), prostate gland (PG), and loops of sigmoid colon (SiC).

The course and relationships of the psoas major (1), iliacus (2), obturator internus (3), levator ani (4), and gluteal muscles (5) are shown. These are invested by fascia. The superior gluteal vessels (arrows) pass out of the pelvis at the level of the greater sciatic foramina.

(Courtesy of Manuel Viamonte, Jr., M.D., Mt. Sinai Hospital, Miami Beach, FL. Reproduced from Meyers and Goodman.2)

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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