Internal Abdominal Hernias

An internal abdominal hernia is defined as the protrusion of a viscus through a normal or abnormal aperture within the confines of the peritoneal cavity. The hernial orifice may be a preexisting anatomic structure, such as the foramen of Winslow, or a pathologic defect of congenital or acquired origin.

The literature on the subject has been composed principally of case reports, often based on observations made at surgery or autopsy. The role of preoperative radiologic diagnosis of internal hernias has generally not been appreciated. Indeed, in the differential diagnosis of radiographic findings of intestinal obstruction or unusual-appearing grouping of bowel loops,1-5 "some type of internal hernia" is often loosely entertained without a precise appreciation of types and distinctive findings. However, with an awareness of the underlying anatomic features and of the dynamics of intestinal entrapment, the correct diagnosis of an internal hernia can be made in most instances.

The nomenclature of a specific hernia is determined by the location of the hernial ring and not by the eventual position of the sac or the involved intestinal loops. Internal hernias within the lesser sac, for example, may occur from various directions, namely, through the foramen of Winslow or through defects in the transverse mesocolon or lesser omentum. Based on their anatomic location of origin, internal hernias may be conveniently classified into the following groups:

1. Paraduodenal

2. Foramen of Winslow

3. Pericecal

4. Intersigmoid

5. Transmesenteric and transmesocolic

6. Retroanastomotic

The majority of internal hernias result from congenital anomalies of intestinal rotation and peritoneal at-tachment.6-9 Acquired defects of the mesentery or peritoneum secondary to abdominal surgery or trauma may also serve as the hernial ring.10-13 The retroperitoneal group of internal hernias is more frequently encountered in adults, whereas the transmesenteric types are more commonly present in the pediatric age group.6,8,14 The autopsy incidence of internal hernia has been reported to be between 0.2 and 0.9%.6,15 Many are small and easily reducible, so that they may remain relatively asymptomatic during life.16,17 In other cases, the patients present with a history of intermittent attacks of vague epigastric discomfort, colicky periumbilical pain, nausea, vomiting—especially after intake of a large meal— and recurrent intestinal obstruction. The discomfort may be altered or relieved by change in position. Internal hernias account for 0.5-3% of all cases of intestinal obstruction,6,18 with a very high rate of mortality, exceeding 50% in most series.6,12,19 Delayed diagnosis leads to extensive and often irreparable intestinal damage. Adhesions between the intestinal loops or between the bowel and hernial sac develop, further resulting in obstruction or circulatory compromise.20

Figure 16-1 summarizes the relative incidence of internal hernias at the various susceptible sites. In general, the small bowel examination provides the most useful diagnostic hallmarks, which include (a) abnormal location and disturbed arrangement of the small intestine; (b) sacculation and crowding ofseveral small bowel loops owing to encapsulation within the hernial sac (serial radiographs and fluoroscopy with palpation and change in the patient's position may disclose that the loops cannot be separated but rather move in toto); and (c) segmental

Transmesenteric Internal Hernia

Fig. 16-1. Location and relative incidence of internal hernias according to the collective review by Hansmann and Morton : (A) paraduodenal hernias, 53%; (B) pericecal hernias, 13%; (C) foramen of Winslow hernias, 8%; (D) transmesenteric hernias, 8%; (E) hernias into pelvic structures, 7%;(F) transmesosigmoid hernias, 6%. (Reproduced from Ghahremani and Meyers.16)

Fig. 16-1. Location and relative incidence of internal hernias according to the collective review by Hansmann and Morton : (A) paraduodenal hernias, 53%; (B) pericecal hernias, 13%; (C) foramen of Winslow hernias, 8%; (D) transmesenteric hernias, 8%; (E) hernias into pelvic structures, 7%;(F) transmesosigmoid hernias, 6%. (Reproduced from Ghahremani and Meyers.16)

dilatation and prolonged stasis within the herniated loops.

Without a specific radiologic diagnosis, a small internal hernia may not be evident at laparotomy for a variety of reasons: the hernia may reduce spontaneously or following inadvertent traction on small bowel loops at the time of surgery; the usual exploratory laparotomy is often inadequate for evaluation of all significant peritoneal fossae and possible mesenteric defects that represent the potential sites of herniation; and the potential space of a peritoneal fossa is generally not evident from the rela-

17 20 22

tively small size of its orifice. ' '

Baby Sleeping

Baby Sleeping

Everything You Need To Know About Baby Sleeping. Your baby is going to be sleeping a lot. During the first few months, your baby will sleep for most of theday. You may not get any real interaction, or reactions other than sleep and crying.

Get My Free Ebook


Post a comment