Postoperative Ileus vs Intestinal Obstruction 43 Moshe Schein Sai Sajja The postoperative fart is the best music to the surgeon s ears... Five days ago you removed this patient s perforated appendix (> Chap. 28); you gave him antibiotics for 2 3 days (> Chap. 42), and by today you expected him to eat (> Chap. 41) and go home. Instead, your patient lies in bed with a long face and a distended abdomen, vomiting bile from time to time.and the family is asking you what you are asking yourself what is the problem? Definitions and Mechanisms The term ileus as used in this book, and in daily practice, signifies a paralytic ileus the opposite of mechanical ileus, which is a synonym for intestinal obstruction. In essence, the latter consists of a mechanical stoppage to the normal transit along the intestine whereas the former denotes hindered transit because the intestines are lazy. In previous chapters you noted that ileus of the small bowel, colon or both, can be secondary to a variety of intra-abdominal (e.g. acute appendicitis), retroperitoneal (e.g. hematoma) or extra-abdominal (e.g. hypokalemia) causes, which adversely affect normal intestinal motility. Following abdominal operations, however, ileus is a normal phenomenon its magnitude directly proportional to the magnitude of the operation. In general, the more you do within the abdomen, the more you manipulate, the more prolonged will be the postoperative ileus. Ileus Unlike mechanical intestinal obstruction, which involves a segment of the (small) bowel, postoperative ileus concerns the whole length of the gut, from the stomach to the rectum. As mentioned in > Chap. 41, physiological postoperative ileus resolves gradually. The small bowel resumes activity almost immediately, followed, a day or so later, by the stomach, and then the colon, being the laziest, is the last to start moving.
370 Moshe Schein Sai Sajja The magnitude of the postoperative ileus correlates to some extent with that of the operation performed and the specific underlying condition. Major dissections, prolonged intestinal displacement and exposure, denuded and inflamed peritoneum, residual intra- or retro-peritoneal pus or clots, are associated with a prolonged ileus. Thus, for example, after simple appendectomy for non-perforated appendicitis, ileus should be almost non-existent, whereas after a laparotomy for a ruptured abdominal aortic aneurysm (> Chap. 37) expect the ileus to be prolonged. Common postoperative factors, which can aggravate ileus, are the administration of opiates and electrolyte imbalance. While the physiological postoperative ileus is diffuse, ileus due to complications may be local.a classical example of a local ileus is a postoperative abscess (> Chap. 44) that may paralyze an adjacent segment of bowel. For example, a localized leak from an ileo-transverse anastomosis after right hemicolectomy may paralyze the adjacent duodenum, mimicking a picture of gastric outlet obstruction. Early Postoperative Mechanical Intestinal Obstruction You became familiar with small bowel obstruction (SBO) in > Chap. 21. Early postoperative SBO (EPSBO) is defined as one developing immediately after the operation or within 4 weeks. Two primary mechanisms are responsible: adhesions and internal hernia. Early post-laparotomy adhesions are immature, inflammatory, poor in collagen thus soft and vascular. Such characteristics indicate that early adhesions may resolve spontaneously and that surgical lysis may be difficult, traumatic to involved viscera and bloody. Postoperative adhesions may be diffuse, involving the whole length of the small bowel in multiple sites, as is occasionally seen following extensive lysis of adhesions for SBO (> Chap. 21). Localized obstructing adhesions may also develop at the operative site with the bowel adherent, for instance, to exposed Marlex mesh or raw peritoneal surface. The operation also may create new potential spaces into which the bowel can herniate to be obstructed forming internal hernias. Typical examples are the partially closed pelvic peritoneum after abdomino-perineal resection, or the space behind an emerging colostomy. The narrower the opening into the space, the more likely the bowel is to be trapped. Diagnosis Failure of your patient to eat, fart or evacuate his bowel within 5 days after a laparotomy signifies a persistent ileus. The abdomen is usually distended and silent to auscultation. Plain abdominal X-ray typically discloses significant gaseous
43 Postoperative Ileus vs Intestinal Obstruction 371 distension of both the small bowel and the colon (> Chaps. 4 and 5). The diagnosis of EPSBO in the recently operated abdomen is much subtler. Textbooks teach you that on abdominal auscultation ileus is silent and SBO noisy this may be theoretically true but almost impossible to assess in the recently operated upon belly. If your patient has already passed flatus or defecated and then ceases to manifest these comforting features, SBO is the most likely diagnosis. The truth is that in most instances the patient will improve spontaneously without you ever knowing whether it was an EPSBO or just an ileus. The natural tendency of the operating surgeon is to attribute the failure to progress to an ileus rather than SBO and to procrastinate. Procrastination is not a good idea, however. A distended and non-eating patient is prone to the iatrogenic hazards of nasogastric tubes, intravenous lines, parenteral nutrition, and bed rest (> Chap. 40). Be active and proceed with diagnostic steps in parallel to therapy. Management A management algorithm is presented in > Fig. 43.1. Pass an NG tube if not already in situ to decompress the stomach, prevent aerophagia, relieve nausea and vomiting, and measure gastric residue. Carefully search for and correct, if present, potential causes of prolonged ileus: Opiates are the most common promoters of ileus; pain should be controlled but not excessively and for too long. Measure and correct electrolyte imbalances. Consider and exclude the possibility that an intra-abdominal complication is the cause of the ileus or EPSBO. A hematoma, an abscess, an anastomotic leak, postoperative pancreatitis, postoperative acalculus cholecystitis all can produce ileus or mimic EPSBO. Significant hypoalbuminemia leads to generalized edema,involving the bowel too. Edematous and swollen bowel does not move well; this is called hypoalbuminemic enteropathy and should be considered. Some claim that manual abdominal massage, positional changes and/or chewing gum hasten the resolution of ileus. We carry chewing gum in our pockets and distribute it generously to our postoperative patients. Even if it does not alleviate ileus it will surely promote salivary flow and oral hygiene in the fasting patient and improve his or her mood. Practically speaking if on the fifth post-laparotomy day your patient still has features of ileus/epsbo we recommend a plain abdominal X-ray to assess the gas pattern (> Chaps. 4 and 5). If the latter suggests an ileus or EPSBO a Gastrografin challenge as described in > Chap. 21 may be useful in relieving both conditions.
372 Moshe Schein Sai Sajja Fig. 43.1. Management algorithm When the clinical picture suggests one of the above mentioned intra-abdominal causes of persistent ileus, an abdominal CT is indicated to pinpoint the problem and, at times, to guide treatment. Failure of the Gastrografin to arrive at the colon denotes an EPSBO.In the early postoperative phase this is not an indication for a laparotomy. Intestinal strangulation almost never occurs in this situation and spontaneous resolution is common. Resolution of SBO, however, rarely occurs beyond postoperative days 10 12. In the absence of intra- or extra-abdominal causes for ileus, and when the ileus does not respond to the Gastrografin challenge, the diagnosis is EPSBO. Do not rush to re-operate; treat conservatively while providing nutritional support (> Chap. 41). Lack of resolution beyond 10 14 days is an indication for re-laparotomy, which in itself may be difficult and hazardous because of the typical early dense and vascular adhesions cementing the bowel at many points.
43 Postoperative Ileus vs Intestinal Obstruction 373 Specific Considerations The various primary operations may result in different and specific types of postoperative obstruction as summarized in > Table 43.1. Table 43.1. Early postoperative small bowel obstruction (EPSBO): special consideration Primary Question Consideration operation Laparotomy Was the obstructing If not consider an for SBO point dealt with? earlier re-operation Abdominal- Is the small bowel If yes consider an perineal prolapsing into a earlier re-operation resection pelvic space (CT)? Colostomy, Is the small bowel If yes consider an ileostomy caught behind the earlier operation stoma (contrast/ct)? Appendectomy Is there a pelvic abscess If yes consider or stump phlegmon? percutaneous drainage and/or antibiotics Laparoscopy Is the bowel caught in If yes operate a trocar site (CT)? immediately Radiation How severe and extensive If no consider proenteritis was the process? longed non operative Is it resectable? management Carcinomatosis How severe and extensive If no continue was the process? prolonged palliative/ Is it resectable? symptomatic approach Frozen abdomen Was the abdomen If yes consider pro- frozen during index longed non-operative operation? management Intestinal anastomosis Anastomotic obstruction: a bowel anastomosis at any level may cause early postoperative upper gastrointestinal, small bowel or colonic obstruction. A self-limiting mini anastomotic leak, associated with local phlegmon, is often responsible but under diagnosed. Diagnosis is reached with a contrast study or CT. Most such early postoperative anastomotic obstructions are soft and edematous resolving spontaneously within a week or two
374 Moshe Schein Sai Sajja EPSBO Following Laparoscopy Cholecystectomy, trans-peritoneal hernia repair and appendectomy are the three most common procedures associated with postlaparoscopic EPSBO. The mechanism of obstruction is adhesive in half of the patients and small bowel incarceration at the port site in the other half. All port site herniations involve the usage of 10 or 12 mm trocars and the umbilical port is the commonest site. In the majority of port site herniations adequate fascial closure was achieved at the initial operation. However, adequate closure of the fascial defect does not preclude the possibility of trocar site incarceration of bowel: a strangulated Richter s hernia may develop, with the bowel caught in the preperitoneal space behind a well-repaired fascial defect. Another cause for EPSBO following laparoscopic surgery are spilled gallstones during cholecystectomy, which can lead to the development of an inflammatory mass to which the bowel adheres. Therefore remember that when EPSBO follows laparoscopy the first question on your mind should be whether the bowel is caught partially, or fully, in one of the trocar sites. Because physical findings suggestive of this condition, such as a mass or exceptional tenderness at the trocar site, are rarely present, CT examination of the abdomen is recommended to provide an early diagnosis. CT detects the trocar site responsible for the EPSBO, allowing immediate operation to relieve the obstruction. Surgery can be carried out through the (extended) actual trocar site itself obviating the need for a formal laparotomy. Unlike EPSBO following open procedures postlaparoscopy obstruction usually won t resolve without a re-operation. You have to understand that postlaparoscopy EPSBO is a specific entity, which calls for immediate action. The Hostile Abdomen (see also > Chap. 21) Any mixed series of patients with EPSBO includes a subgroup of patients in whom the index operation has disclosed a hostile peritoneal cavity suggesting that any further surgery to relive the obstructive process would be hazardous and futile. To such group belong patients with extensive radiation enteritis in whom persisting obstruction can be defined as intestinal failure and who are best managed with long-term parenteral nutrition. Indiscriminate re-operation in such patients often leads to massive bowel resection, multiple fistulas and death, and should be avoided. Patients with evidence of peritoneal carcinomatosis at the index operation also belong to this group. In general, only one-third of patients with malignant bowel obstruction from peritoneal carcinomatosis will have prolonged postoperative palliation. Thus, EPSBO in such patients represents an ominous sign; abdominal re-operation should be avoided and future palliative treatment planned, based on
43 Postoperative Ileus vs Intestinal Obstruction 375 the individual patient s functional status and the burden of cancer. Finally, every surgeon has some personal experience with a little reported entity, the frozen abdomen, in which intractable SBO is caused by dense, vascular and inseparable adhesions fixing the bowel at many points. The astute surgeon knows when to abort early from a futile dissection before multiple enterotomies necessitating massive bowel resection are created. He also knows not to re-operate on such patients even if persisting EPSBO develops after what appeared to be a successful adhesiolysis. Prolonged parenteral nutrition over a period of months, with complete gastrointestinal rest, may allow the adhesions to mature with resolution of the SBO, or at least allowing a safer re-operation. Anastomotic Obstruction A bowel anastomosis at any level may cause early postoperative upper gastrointestinal, small bowel or colonic obstruction. Faulty technique (> Chap. 13) is usually the cause. A self-limiting mini anastomotic leak is often responsible but under-diagnosed (> Chap. 45). Diagnosis is reached with a contrast study (water soluble please!) or CT. Most such early postoperative anastomotic obstructions are soft and edematous, resolving spontaneously within a week or two. Do not rush to re-operate; gentle passage of an endoscope if accessible may confirm the diagnosis and dilate the lumen. Delayed Gastric Emptying Often the stomach fails to empty following a partial gastrectomy or a gastrojejunostomy for any indication. This is more common when a vagotomy has been performed or when a Roux-en-Y loop has been constructed. With Gastrografin study the contrast persistently sits in the stomach. The differential diagnosis is between a gastric ileus (gastroparesis) and mechanical obstruction at the gastrojejunostomy or below it. A complete discussion of the various post-gastrectomy syndromes is beyond the scope of this volume but remember this fundamental principle postoperative gastric paresis is self limiting it will always resolve spontaneously but may take as long as 6 weeks to do so. Exclude mechanical stomal obstruction with an endoscope or contrast study and then treat conservatively with nasogastric suction and nutritional support Try to pass a feeding tube distal to the stomach (> Chap. 41). Parenteral erythromycin has been shown to enhance gastric motility and is always worth a trial in this situation. Resist the devil within you tempting you to re-operate for gastric paresis for it will eventually resolve, while re-operation may only make things worse.
376 Moshe Schein Sai Sajja Prevention It is imperative to emphasize that you can, and ought to, prevent prolonged postoperative ileus or SBO by sound operative technique and attention to detail. Gentle dissection and handling of tissues, careful hemostasis to avoid hematoma formation, not using the cautery like a blowtorch, leaving as little foreign material as possible (e.g. large silk knots, spilled gallstones during laparoscopic cholecystectomy), not denuding the peritoneum unnecessarily, not creating orifices for internal hernias, carefully closing large port sites, and not catching loops of bowel during abdominal closure, are self explanatory essentials. We are not yet too impressed with the evidence supporting recently developed expensive commercial products that allegedly prevent adhesions. Summary: exclude and treat causes of persistent ileus, treat EPSBO conservatively as long as indicated, think about specific causes of SBO (e.g., herniation at a laparoscopic trocar site) and re-operate when necessary. In most instances ileus/epsbo will resolve spontaneously (> Fig. 43.2). Better to leave a piece of peritoneum on the bowel than a piece of bowel on the peritoneum. Fig. 43.2. Doctor, is it mechanical obstruction or ileus? Sh let me hear.