Acute appendicitis is a usual cause of acute abdomen, and the clinical pictures vary from patient to patient. Patients with suspicious appendicitis are preliminarily evaluated by the Alvarado score to assess the risk of appendicitis [3]. The score is composed of history, results of physical examination and laboratory data [3]. The patient with a higher Alvarado score possesses a higher likelihood of appendicitis. Further imaging studies are indicated in patients with Alvarado score greater than 4, and have at least intermediate probability of acute appendicitis [4, 5].
In this presented case, he had no specific symptoms and signs except for leukocytosis at first, with the Alvarado score 3. The CT scan also disclosed negative results. However, more symptoms developed after he was discharged from the ER. At the time of his revisiting ER, the Alvarado score reached 4, and repeated CT scan revealed appendicitis with ileus. Though some reports suggested that leukocytosis as well as elevated C-reactive protein achieve satisfactory sensitivity in setting up the diagnosis, neither of the two test results can confirm or rule out acute appendicitis [6]. Back to our patient, there was no supportive evidence to start the treatment for acute appendicitis at the first visit. However, it might be reasonable to keep the patient observed in the ER. If his condition deteriorated or the calculated Alvarado score increased gradually, repeated CT scan was reasonable to achieve a definite diagnosis.
The classification of acute appendicitis is important as the treatment strategies may differ [4]. Traditionally, surgeons divide acute appendicitis into two groups: simple or complicated. For the former, which is defined as an inflamed appendix without signs of gangrene, perforation, intra-peritoneal purulent fluid, contained phlegmon or intra-peritoneal abscess, appendectomy remains a golden standard of the treatment [4]. Despite the fact that some opposing clinicians propose the potential benefits of non-operative initial management for simple appendicitis, there is still no satisfactory quality evidence to support sole antibiotics treatment for appendicitis [7, 8]. As to the treatment of complicated appendicitis, firm conclusions fail to be drawn [4]. Some studies claim that operation is associated with more complications, and that non-operative treatment is a better option [9, 10], while others advocate aggressive operation, assuming that non-operation treatment leads to higher recurrent rate [11].
Acute appendicitis complicated with small bowel obstruction is uncommon, which could be classified into four types: mechanical obstruction, paralytic ileus, ischemia and strangulation [2]. The adhesion from the peri-appendicular inflammation is the culprit of mechanical obstruction. Paralytic ileus is the result of perforated appendicitis, which leads to generalized or localized peritonitis. The thromboembolic event happening in the ileal artery and its branches following the appendicitis leads to the ischemic type [12]. Moreover, the inflamed appendix wrapped around a long loop of small bowel creates a closed loop obstruction which is strangulated [13]. Early surgical intervention is important in patients of appendicitis with bowel obstruction. Whichever features of intestinal obstruction predominate, midline vertical incision was suggested, for the reason that the exact pathological type is nearly impossible to be determined beforehand. McBurney's incision may be enough if the obstruction is paralytic or mechanical. However, it would be dangerous to incise at the McBurney's point when strangulation or mesenteric ischemia presents, as these pathological changes are likely to be overlooked through a small and lateral approach [2]. There were no convincing studies comparing the outcome of open surgery and laparoscopic approach, but a case report proposed that laparoscopic surgery should be performed if the etiology of bowel obstruction other than appendicitis was suspected [14].
Postoperative ileus (POI) is a frequent complication after abdominal surgery; however, the definition and the diagnosis of the disease underlie wide variation. Some reports define it as no passage of flatus or stool and tolerance of an oral diet on the postoperative day 3 (POD3). They also name the patient with “prolonged” POI if two or more of the following five conditions presented since POD4: nausea or vomiting; inability to tolerate an oral diet for more than 24 h; absence of flatus for more than 24 h; abdominal distension, and radiologic confirmation [15]. However, different experts characterize it by different duration and clinical parameters [16, 17]. Furthermore, there is no consensus on the necessary diagnostic tools. Some experts preferred plain films, while others order CT scan or water-soluble contrast studies such as Urografin study, or even the combination of various tests [18, 19].
Urografin study is widely reported to play both diagnostic and therapeutic parts in adhesive small bowel obstruction [20]. The study acts as similar roles in patients with POI. By Urografin study, surgeons are able to differentiate paralytic ileus with mechanical intestinal obstruction, and to distinguish those who need emergent surgery [21]. Moreover, the high osmolarity of the water-soluble contrast medium is theoretically believed to reduce bowel wall edema, which further increase the luminal diameter and subsequently relieve the symptoms of POI [22]. Nevertheless, the study only shows benefits in patients with lower gastrointestinal symptoms [22]. Besides, in terms of the timing of the study, it was suggested to be done once surgeons assess the patients and suspect prolonged POI clinically since POD4 by some convincing clinical trials [22, 23].
Venara et.al. divide the pathophysiology of POI into three phases. The first one is neurological phase, which is involved by the activation of sympathetic tone, and the subsequently activated CycloOxygenase-2 (COX 2). The second phase is described as inflammatory phase. The phase was predominated by the inflammatory process, which may be disseminated from a localized inflammatory site, such as appendix, to surrounding peritoneal cavity. The increase of bowel wall permeability in this phase may induce bacterial translocation. Last but not least, the third phase, called vagal phase, is the recovery phase, which is caused by the elevation of vagal tone, the effects of acetylcholine and
serotonin, and its anti-inflammatory effects [24]. Once the inflammation resolves, the swelling of the bowel walls will relieve, and the bowel motility will recover gradually.
In this case, the localized peritonitis not merely caused paralytic ileus preoperatively, but also acts as risk factor for POI [25], which can be attributed to the second phase of pathophysiology. Besides, the more complicated the appendicitis is, the larger extent of the peritoneum tends to be damaged during the surgery, and the damaged peritoneum will further enhance the inflammation [25]. While we were managing our patient, the probability of the POI should be kept in mind, and took actions earlier once the symptoms presented.
Most of the treatments and preventions of POI are well-established. Non-medical management, such as fluid optimization and chewing gum [26], as well as medications, such as prokinetics and nonsteroidal anti-inflammatory drugs (NSAIDs) are the examples [18]. However, there has been no consensus about the timing of insertion and removal of the NG tube. Lots of the experts insert NG tubes when the patients have abdominal distension or tenderness and vomiting over 500 ml, and some remove the NG tube when the patients feel hungry subjectively [18].
The trend of postoperative care followed the concept of “Enhanced Recovery After Surgery (ERAS)” nowadays, advocating to remove the inserted tubes, including NG tubes, as well as commence oral feeding as soon as possible, and to reserve the use of opioids for pain control [27]. The concept was initially adopted in elective surgeries; however, it was also confirmed to decrease the complications and fasten the recovery of bowel motility after emergent abdominal surgeries in recent studies [28]. Early removal of NG tubes after the elective surgeries tends to decrease the risk of complications, accelerate the return to oral feeding, and significantly reduce patients’ discomfort [29]. Furthermore, in patients who underwent surgeries for small bowel obstruction, early removal of NG tubes was also proven to lower the risk of POI, and cause no severe complications [30].
In this case, the NG tube was removed on POD1 because of the minimal drainage amount. However, the patient suffered from abdominal distention and vomiting since POD2, and confirmed POI diagnosis by abdominal radiography and Urografin study on POD7. The conditions improved after the reinsertion of the NG tube. After the experience of managing such a case, we suggested that the NG tube should be left in situ after the surgery until decompression amount decreased to less than 200 mL per day or the presence of flatus or stool passage [32], and the NG tube should be reinserted immediately once the patient vomits. Intravenous Morphine should be limited, or better replaced by NSAIDs. Furthermore, Urografin study should be held until NG tube was inserted and recorded a fair amount. Thus, the passage of contrast medium can both achieve the therapeutic effect and the adequate diagnostic value. The suggested algorithm of insertion or removal of NG tubes is shown in Fig. 5 [31, 32].